Agilent GC and GC-MS Scientists Answer Your Most FAQ

Ask the Agilent experts Part Two GC and GCMS scientists answer your most frequently asked questions. In today’s event, we’ll hear answers to common questions relating to such juicy topics as gas leaks, gas filters, carrier gases for mass spectrometry, and conditioning your column. So, if you’re a GC or GCMS user, this event will offer insight and advice to these topics and more. Our two Agilent GC experts for this webinar are Vanessa Abercrombie and Angie Smith Henry. Vanessa is a GC applications chemist at Agilent in Folsom, California. She has a broad background in GC and GCMS, including experience as an instrumental chemist, I bought technology in Virginia, working under contract to the FBI Laboratory Division. Prior to that, Vanessa worked for ETS labs in Santa Lena, California, as an analytical chemist, where she researched and developed quantitative separations by GCMS and UHPLC for beer, wine and spirits. She holds a Master of forensic science from the George Washington University and a Bachelor of Arts in chemistry from Sonoma State University. Algae is an applications chemist for GC and MS supplies at Agilent in Wilmington, Delaware. Previously, she was an applications chemist for the MSD solutions and applications group with a focus on developing analyzers and applications for energy, chemical and environmental markets. And she holds a PhD in physical chemistry from Lehigh University, and a BS in chemistry from Juniata College. Don’t forget, if you have a question for Vanessa and Angie, you could submit them by clicking the Ask a Question button below. typing in your question, and clicking or care. Will forward all your questions to Vanessa and Angie, who will be happy to follow up with you after today’s webinar. However, first, I’m going to hand you over to our moderator for today’s event, Diane Turner. Diane is director and Senior Consultant of anthias. Consulting in Cambridgeshire, UK, a Warwick University graduate, Diane completed her master’s in analytical chemistry and started her career in environmental chemistry led to gaining significant experience as an applications chemist. Diane’s area of research through her PhD studies at the Aachen University was disease diagnosis. She has developed methods for and given support and training for companies in most industries around the world for more than 20 years. Diane halls, voluntary roles with the Royal Society of Chemistry and other scientific organizations. And so over to you, Diane. Many thanks, David. And welcome to the second edition of Ask the Experts. The first question we have in this session is what happens if there’s a leak in my gas lines? And can I ask Andy to answer that question, please? Absolutely. And that is a great question. So I think we’ve discussed a bit before about leaks causing an increase in column bleed. But this won’t be the only chromatographic symptom that you’re going to see. With respect to oxygen in your column, your peak sheets going to start to suffer. And to demonstrate this, we’re going to look at a common analyte used in some texts, test mixes to ethyl hexanoic acid and how its symmetry is affected with the increase in both temperature and oxygen. So in this experiment, a wax column was held at a final temperature for 12 hours with a controlled amount of oxygen in the carrier gas so we could get a really detailed understanding of how the amount of gas and temperature affects that peak shape. So you can see that the peak shape for the two ethyl hexanoic acid at 250 degrees for 12 hours looks pretty great. But as we increase the final temperature and add 10 parts per million of oxygen to the tear gas or symmetry starts to degrade and we see more peak tailing. And that’s happening because your face is getting irreparably damaged. That causes a peak tailing, and at which point, you may need to clip off a part of the front end column, or worst case scenario, replace that entire column. And both of which are going to cause increased downtime and loss of your productivity. So a great way to keep leaks out of your GC is using those self tightening nuts because you don’t have to remember to re tighten the nut after thermal cycles. They have that spring driven piston design that adjust to the natural expansion and contraction that happens during your multiple GC of insect goals. And you don’t need tools to use them, it’s just hand tightened. And of course, we have one for your GC inlet and detectors and the mass spec transfer line, as well. And both use the same polyamid graphite Farrells. So you can have one Farrell to roll your whole GC makes life very, very nice and easy. And they’re one of the easiest ways to prevent oxygen from getting into the GC flowpath. So there’s a few other problems that can be caused with a leak, you can get elevated background, I think we’ve talked about this before we get reduced peak response and of course, our aforementioned peak tailing a specific for GCMs. You may shorten your filament and electron multiple layer lifetimes and that is causing increased sores, and mass spec mint maintenance. But, you know, how do we lead check every part of our GCMs both inside and out, you can use a leak detector, and especially our new Agilent cross lab, cartridge system leak detector. And it works really well at spotting leaks even down to three microliters per minute for gases like helium or hydrogen. Going to take just a little more time to talk about this new leak detector. It’s designed on that same handheld unit as the ATM flow meter. So it’s one bass can be used for both cartridges, whether it’s the leak detector or flow meter, no, I don’t think we tend to use the same thing at the same time. So one base to do both the work. This leak detector can also detect nitrogen leaks. So that’s nice. It’s not quite as sensitive as it is to hydrogen and helium because we’re referencing to the thermal conductivity of ambient air. But you can still find your nitrogen or oxygen leaks. And the table just shown on the bottom right here gives you a couple examples of the minimum detectable leak rates for a handful of gases. And these aren’t just your GCS, remember, you got an ICP our guns, not the cheapest gas in the world. So that would be a good one to use a leak detector on. But let’s talk about where we should use the leak detector in the lab and around our instruments. Let’s start at the gas source. Doesn’t matter if it’s a cylinder or a tower connection. Because your whole building has helium or hydrogen plumbed to it, you need to check those connection points they can and absolutely will leak. And remember your regulator, if you have an old regulator, it’s going to age over time it wears, it can cause leaks. Next, following the gas line, we go to our filter connections and our gas clean filter system. Be sure to let me check this wage like fittings and the ring both the top and the bottom of the ring of that system to make sure it is fully leak tight. And of course, if you have more than one gas filter, do them all. If we flip around, or GCMs in this case, and look at the back, we need to check every single one of those fittings behind the GC, except for the ones that are instrument air going to your fid. We can’t really like detect on those ones. And I know everyone asks, Do I really have to check every single T every single connection? Absolutely. There’s a lot of parts that you could have leaks come up from. And let’s reduce your problems with your EPCs and call them and also do not use snoop. Snoop can be really bad for those electronic pressure control modules and your flow path if it gets into the gas line. So please don’t use Snoop use a leak detector right now. So he said we could check on the outside we can also check on the inside of the GC. We need to make sure to check the septum not in turn top. Those septum nuts were out over time and leak. I’ve had it happen to myself so I know it’s true. And sometimes our turn types just aren’t tight enough. So check it with the leak detector. Once we look in the oven, check your inlet and detector connections even if you self tightening nuts just the first time you put them in. Check it and make sure you’ve got good connection. Moving along to the column. If you use capillary flow technology or CFT, check those connections. No matter if it’s a purge, or on purge device, we don’t want any leaks coming in and destroying our columns and our analyses. And then last but not least, is our mass spec transfer line. Again, even if we’re using self tightening that it’s just always a good habit to double check that leak fitting, or that fitting for leaks. The only problem is leak detector isn’t going to help us too much on the mass spec. So specifically focusing on that part of the detector, we need to check our vent valve, the transfer line, which we talked about, and then also the analyzer side door. So one way to leak check your mass spec is with a bitterest free electronics duster, because you can do some live manual tune profiling of the ions to find your leaks. And we like to do that because it’s a really quick way to sniff them out. Now, if you aren’t sure what mass is to look for, you can enter the cast number into the NIS library or search for this vector online to help ID, your mastercharge ratios. And so we just wanted to show you a quick way of how to do this in manual tune. In my case, the electronics Duster has mastercharge ratios of 69 and 83. So we’re going to navigate to the manual tune from the instrument drop down menu when we’re in our normal mass center acquisition, and then you click Edit tune parameters. And then on the top right, there’s a profile tab, click on Profile, and we’ll do some live tuning. Enter your mass to charge ratio values, set your window I like point five because it gives me a nice tight window. And then you spray three short bursts of electronic duster at each spot. Wait about 15 to 30 seconds between each because it will light up really fast. If you have a leak. You’ll do it at the vent about your transfer line your side door. And then make sure you check the entire length from the side door because leaks don’t just happen at one spot. Had it happen in the back. It’s a really pain in the neck when you miss that one. So it’s one way to do it. The other way is if you don’t have electronics duster, or ran out, you can instead run an air water check. Great and easy way to do it. You can navigate to tune in vacuum control. And then there’s a tune menu, you’ll find air and water check. Click that. And you can run it or tune evaluation if you don’t have the electronic stressors. But remember, you don’t have to to check for leaks. But let’s make sure we are leak free so we don’t destroy our consumables. Wonderful Many thanks, Andy out Vanessa, do you have anything to add to that face? I would say if you suspect that you have a leak. First and foremost, don’t panic. And don’t take your oven up to a high temperature, because that’s when you could start damaging some phase. So first, start with the usual suspects. So a lot of times if you think about what might have just been done, did you just replace a septum or replace the liner start there. And also kind of work your way from the easiest things to fix and then go down through the GC. One thing I like to do with the electronic duster, if I’m going to be doing that magnet manual tune, I actually will, I’ll work backwards. So I’ll spray the analyzer door first, then I would spray the transfer line and then kind of move through because what will happen is if you say spray the inlet first with your adjuster, and then you try and go back to really quickly Wait 30 seconds and then say spray or transfer line well, and then maybe you see a peak right away? Well, it might not necessarily mean that it was either the the transfer line because your gases have to move through your column. There is that hold of time that every column has that that’s the amount of time that compounds stay in, move their way through the column without interacting with the column phase. And that’s what’s happening if you were say, to spray the inlet first. And so you’ve got to give it maybe if I sprayed the inlet first, I usually give it about two to three minutes depending on the column. Obviously, if you’re going to be using a 60 meter column, maybe give it three to four minutes to see what’s going on. And then to try and just but that’s also why when I’m using dust off, or electronic duster thing, I go from the door first because if you’ve had that door open to say clean your source or whatnot, that O ring can sometimes get a little bit bendy and so you want to before you close it up. You want to make sure that that’s all nice and tight. And that’s where as Andy said, sometimes you could have a leak coming from the back of the analyzer door. So that’s, it’s, you know, just kind of work your way through. And I know Andy was talking about the new leak detector. Actually, before we even had that, I was using the flow meter, that kind of that part that goes with it to try and identify some leaks a long time ago. So I’d had this one weird situation with headspace system, or all of a sudden our flows are just really off, we couldn’t figure out where it was going. And because all of our leaks were tight on the GC itself. But as we were checking our split line, and our split that line checking those flows, we realized that there was something happening from that connection from the headspace. And so actually, that helped me diagnose, there was one small connection of just two copper pipes that are two of the of my lines, gas lines, I’ve had a connector that wasn’t tight enough. So if I had had the the leak detector, at that point, it would have been a lot easier. But at least even using that flow meter was another great tool that I could at least help to diagnose where that leak was. And also, if you’re looking at your air and water check, and you see a higher level of nitrogen versus oxygen, that is usually telling me that my leak is probably coming from inside the GC, whereas if your leak is on the outside, you’ll have more oxygen in it. So kind of just look at those values to kind of figure out where that leak might be. And just yeah, don’t panic. It’ll be okay. Just don’t take it up to temperature, and you’ll be fine. Fantastic advice many things, Vanessa, of course, yeah, the key thing for me is that if you don’t go and use a leak detector for leaks coming out of the system, and like spray gas, for leaks going into the system, and you just go right and just going to tighten everything, then what you could do is go and fix one leak and create leaks elsewhere. Because, of course, over tightening fittings will also create leaks. And when you have a fitting as overtightened new, the only thing you can do is go and replace that Farrell or replace that fitting to go and really fix it. So don’t jump in. Don’t try and tighten everything up. Really identify the source of the leak before you do anything further, which I think you both agree on. Yeah, and slowly tighten things, especially self tightening column nuts, don’t take any tools to it. I’ve seen people start transfer lines this way. So just go just a little bit. Even if it’s a standard. Nut like just go very small, very baby steps. You can always go more, it’s a lot harder to go back and replace transfer line. Absolutely, yeah, I’ve seen the bottom of inlets as well bent at bottom. And better than the ends of trans people have really like got their shoulder behind it. tightening it, especially with gratifies Farrell. Farrell is just like really getting into it and stuff. And it’s just like no, no, not gonna cost you change about some money to replace is not good. squeaking is bad. I always do the one finger test. If I can move it with one finger, it’s least if you can’t move it with one finger, then essentially, then it’s probably going to be tight enough. So yeah, yeah, one thing just There we go. Brilliant. Thank you very much. Yeah, it’s just fascinating either. Yeah, in some ways, leaks are horrible, but I love diagnosing them and tracking them down and determining where they are. And it’s just like, and again, yeah, one of the things of course, is if your cylinder is outside, and that first cold snap when in the ultimate becomes winter. And of course over the summer or your fittings have expanded and then suddenly, they’re now contracting and suddenly, your your cylinder disc depletes of all the gas because it’s something that first. So again, that’s a little bit of advice, as well as if you’ve got anything outside or anything where temperature changes massively, then that’s also really key to go look at. But brilliant. Thank you very much. Okay, so I’m gonna move on to our second question, which is why do I need gas filters? And can I ask Vanessa to address that first, please? Of course, and Angie, if you could move one more. So guess call filters you need them. I don’t care how clean you think your gas lines are. You want to have those gas filters connected to your system. So there’s two parts with the gas filter that we got to talk about. There’s the oxygen and the moisture. So these are two different things that will affect your column and your GC differently. So let’s look at just with oxygen itself. So with this one we were using a four nines helium to test this out so not our normal five nines and with this, you see with the the black line that is with no filter and then we have Looking at that same, same four nines with a filter. So this is what we see is actually a five times drop in the background once we’ve added this gas filter. So this is really important for protecting our system from oxygen. And if you can move one more place. And so water is also the other big issue. So we want to make sure you know, depending on whatever your environment is, in the summertime, it might be more humid where you are, or you might have had some crazy rainstorms, and who knows what’s going on and the humidity in your building. So with that, we want to make sure that we have that moisture trapped on our gasoline filter to protect our system. With this, you can see that that gasoline filter lowered that water signal by a factor of 10. And with this, it will actually you know, help to explore apps who think expand our lifetime, much longer for our column in our chromatography. So these are just the first parts that we want to look at with just the gasoline filter. And now if you can move to the next slide, there’s something I always want to remind people of is that there is also in addition to a gasoline filter, we call this the big universal trap. So the big universal trap is a great thing to have installed as well into your system to help also protect the lifetime, not only of your gas filter, but also your GC. And it’s important to also mount it vertically for it to actually function properly. So this it works together. And also one thing I like to do with this big universal trap is I write the date that I install it on there, because a lot of times this might be behind a wall or underneath the desk. So you want to make sure that you know the last time you replaced it. Because if for some reason you start seeing your guests and filter, maybe get spent more recently or more frequently, that’s when it could be you need to remember to change your big universal track out as well. So both are very important. And now we can move to the next slide, please. So here’s another example. So using low purity gas, that can contain oxygen and other contaminants. And if you don’t already know how bad oxygen is for your column, you have an experiment that can show just how bad the chromatogram on top shows ultra high purity helium gas and from injection one to injection 20 shown in blue. So with here we have no change in retention time or sensitivity. Now in the bottom chromatogram we adopt our helium carrier gas with approximately 5% Oxygen. And you can see the difference between injection one and injection 20 in blue, you can see the dramatic decrease in response and retention time shift from that first peak. And if we look at the elevated baseline in the background at that higher temperatures, that’s the oxygen inflicting permanent irreversible damage on your column, which then results in a lot of other chromatographic issues. So it ultimately means that there’s going to be more money spent on filaments, liners columns, and pretty much means that you’re going to be doing way more maintenance, like cleaning your source more frequently. So the first cure for this potential problem is using ultra high purity carry your gas. So it’s essential for GCMs that you want to use five, nine, so 99.9995% or greater. So the second tip would be also using these are our carrier gas filters. So adjuvants, gas, clean GCMs filters can be used with any mass spec, as well as any GC doesn’t have to be with a mass spec. And one awesome thing about these gas filters is that they’re clear so you can see when the indicator starts to go bad. And it also makes it easier for those to monitor those indicators more closely, incorrect leaks when you start to see them happen, and start to replace what you need to write up right away. So we do recommend changing these annually to avoid any kind of potential damage. But also it could be more frequently depending on what you see. When the look at the indicator on the gasoline filter starts to change, you can also tell if your leak might be upstream or downstream. So if the color changes from the top down, that could indicate a problem with your gas supply. So maybe your cylinder has a connection that might have a leak. Or for some reason, instead of getting the ultra pure gas that you thought was going to be delivered. It could have been you know, maybe four nines instead. And then if the indicator changes from bottom to the top that could actually indicate more of a leak going on in your GCMs. So this could help you to figure out how to correct the problem and then keep your system running properly. And if you could move on to the Next. So there is also another one that I like to talk about. And this is kind of the difference between using gas cylinders and gas generators. So first, both of these, you do still want to use your gasoline filters, we do recommend them. So let’s talk about a little bit of the pros and cons. So with gas cylinders, you are in charge of the pressure delivery that you need, you adjust your regulator as need be, you can have them in a wide variety of different gases. So you can have helium, nitrogen, if you’re doing CI, you have your methane. So and then also size, depending on your gas cabinet, or whatever gas setup you have, you can change that. And pretty much the only maintenance, once you have your gas lines nice and tight, you would just need to replace them when it’s empty. But the downside is you might have to be reliant on the gas company for their availability or potential for delivery, which can change depending on what’s going on. I know I’ve talked to some people where the gas company has the available gases, but they might not have the people who can deliver them at a certain time. So that is really, you know, up to you. Now with gas generators, you’re not reliant on a gas company, but they do need routine maintenance. I know with I have a hydrogen, I have an air compressor, zero air and nitrogen generator in my lab. And they do all require a little bit different maintenance. And right now I’m going to be probably replacing a membrane on my air compressor. So it’s like you have to pay attention to what’s going on. Same thing for hydrogen generators, you have to make sure that those are routinely maintained, because I have heard of not in my lab, but in other labs, you could have potentially water get through a membrane. So this is also why if you are using a Hydrogen Generator, I also recommend using a moisture trap in line after that. Now will that save you have all this on the membrane goes? No, but it is a potential a little protection, and it should be very good. I have not had any issues with my nitrogen system. So I will just say that. But I do also make sure that I routinely I maintain them, I see what’s going on. If I try and preempt I trying to see what might be happening with delivery. There is also a max delivery capacity of various generators. So depending on how many systems you have, you may need to have more than one helium or sorry, one more than one Hydrogen Generator or more than one nitrogen generator, depending on what you’re working on. I know for myself I was trying to get I maxed out my nitrogen output because I had way more I forgot that I didn’t always have all of these F IDs on and all my ECG is on at the same time. And then I was wondering why it was the thing is shutting down on me. And that’s because I exceeded that limit. And I needed to factor in what I’m working on. So that you do have to think about that delivery capacity of what you’re doing. There can be an initial cost as you’re having to buy the generator, and also making sure that you have the right amount of power circuits around because we don’t want to overload circuits, you always want to make sure that everything’s nice and balanced. And the one downside is there is no helium gas generators. So you do still need if you’re going to be using helium as your carrier gas, you do still need to purchase cylinders. But you know what, they’re both great options. It really just depends what works best for your lab. And like we said before, they both need that gasoline filter, because let’s just protect ourselves. It’s like a nice little security blanket like it’s gonna be right there, see what’s going on. And you can see if there’s any extra moisture oxygen in the line. And if there’s any maintenance you need to do, you can take care of that. Wonderful. Thanks, Vanessa. And I totally agree. You know, in some situations you like, Oh, I really need cylinders, and sometimes actually no gas generated is by far the best option. So again, I totally agree. Andy, do you have anything to add to that, please? I think Vanessa did a great review on gas filters and just built on our kind of elite discussion that keep our systems really great and clean. I know, in my experience, we have a lot of whole building generations so we don’t have to worry about it in some cases at the bottom. But even though we’re using towers in our labs and just pulling off the main source, there was a point where they’re using the flexible metal. It was like stainless steel braided connections for some of the big connections from outside to inside. And they actually went through in didn’t leak checking on it because our guests filters were going faster than we expected these normally They last a pretty good long time and at least a year and we’re looking at them and say how in like six months or that one went in like a month, what is going on, they went back and leech checked, and actually were able to decrease how much helium we ordered, because they clean up all those braided lines. So that is one nice part of the gas filter is if there’s a spot coming in with leaks, or, you know, as Vanessa said, a bad batch of gas, and whether that’s, you know, nitrogen or hydrogen or helium, those will catch it and help you diagnose it, find it, fix it, and then, you know, kind of save you any headaches of why don’t I have the sensitivity I used? Absolutely. And how about the hydrocarbons as well, I mean, how important is it to have, you know, remove those hydrocarbons as well. Especially if you have like instrument air, and I know, we’ve got like a big compressor, and someone did a unofficial anecdotal study on their FIDM, where they didn’t have filters on it. And they can watch the background like, kind of oscillate with when the, the the pump was like turning on because the hydrocarbons would pump up or just like, Yeah, put a filter on now one place. Absolutely. And of course, you know, and the thing with cylinders, of course, is making sure that you don’t ever completely empty your cylinder. Because of course, you know, when you’ve got pressure in there, I mean, a cylinder, even with high purity, it never has zero impurities in there. Of course, you know whether when you’ve got pressure in there, it keeps all the impurities pushed the walls of that cylinder. And of course, when you empty the cylinder, they all come out and start coming into the system. So I always say kind of like about when that when I’m a scuba diver. And once when I run out of air, and honestly, the last bit of air that you’re breathing, it tastes like putting your mouth right next to an old car exhaust, it’s pretty GCMs it’s, you would never ever completely empty your cylinder ever again, I think. But of course, again, protective measures of having a gasoline filter is really important. So hopefully, you’re not going to have leaks, hopefully you’re not gonna have problems, like I just mentioned, they’re there for protection and very useful for that. Right. And don’t try some of these experiments yourself. We will do them for you trust us. We will just write this for you and tell you what happened. Absolutely. I was just looking at some of your chromatograms just now going I’m glad that’s not my column. Brilliant. Thank you so much. Okay, so I’m going to move on to question three then. So should you use helium or hydrogen as a carrier gas when you’re doing your analysis using GCMs? So I think Angie is going to answer that, please. Absolutely. And this is our favorite answer. It’s It depends. So I think Vanessa, and I joke we should just call a webinar series, it depends. And because that seems to be always our answer. The first off, why would you even want to use hydrogen. Because if you look at your van Deeter curves, you can see that hydrogen can has more optimal velocity at a higher velocity. So you can potentially have a faster analysis. There’s also the potential for lower temperature separations, moving to your more efficient columns. So I think 30 meter, point two 5.25. As we shortcut, the statement of it is really popular in most helium cases moving to hydrogen, you pretty well should move to a 20 meter, point one eight, because of the difference in your gas pressures, you could have a negative psi technically, for hydrogen with that 30 meter column. And so that’s just so you can move to that more efficient column and kind of slide through and do that faster analysis. Hydrogen can be available on demand with a Hydrogen Generator. So you know, kind of frees you up from that helium supply pressure that seems to come and go every few years. And a lot of cases if you have other detectors other than a mass spec in your lab, you’re already using it for fid and some of your other detectors so you may already have around it, maybe not. I think I want to do hydrogen for a carrier gas. And just a reminder that you know, hydrogen is safe. It’s not scary. We’re not dealing with the Hindenburg anymore. We have you know, shut offs on the system to make sure that systems protected and keeps everyone safe. So you there really shouldn’t be too much fear and especially Since smoking I don’t think is allowed in labs anymore, for extra better on that one. But it’s always good to have a healthy respect for any gases you’re working with. So just hydrogen safe, you can use it just don’t be, you know, careless with it, of course. You know, but it also it’s extremely diffused, so it’s gonna kind of go out really quickly. So we have to think about a few things as we talk about a transition from helium to hydrogen, especially as a carrier gas. So your gas line is going to be changed. Really, we suggest using stainless steel lines when you’re working with hydrogen, because if you have that old copper line that’s been on there for 1015 50 years, it’s going to get all types of pitted and fun, things are going to come out of your copper with hydrogen. So please, switch to stainless steel, use a gasoline filter, You especially want to add a large moisture trap. If you’re doing a Hydrogen Generator, like it was necessary just to protect yourself, give yourself some caution. And we really want to scrub out any of our impurities. So big universal trap followed by our gasoline filter helps you identify when your different parts need to be replaced. To do so what else we need to do. Of course, we already talked about a faster analysis, you really need to decrease your flow for your mass spec source. Because we need to get optimum ionization. You know, when you’re using helium as a carrier gas, our optimum flow rate is around one, one and a half mils per minute, best is going to point eight to 1.2, especially for the high efficiency source. So you need to kind of drop that down a little bit, when using hydrogen, you can still hold close to that point eight, one, don’t go too much lower. And definitely don’t go too fast. Because you can dilute the ions in your source and decrease your sensitivity. We also know that hydrogen has the risk of decency, decreasing your sensitivity already, just with the nature of hydrogen, and the mass spec source. don’t always see eye to eye depending on your compounds. But we’ll talk a little bit about that on the next slide. See what else we talked about. And we also need to make sure those vacuum pumps aren’t having to work really, really hard. You also need to consider that your mass discharge ratios and your eye on ratios may look a little different. Again, this is coming into the factor of think about what is in your mass spec. You know that is a big metal source, using stainless steel, stainless steel and hydrogen love to create catalytic reactions. And I’ll see some other inert sources may as well do you really need to be careful when searching its programs against NIST. Because those were collected with helium as your carrier, yes, you need to watch those iron ratios, and probably do a one to one comparison of what it looked like with helium versus hydrogen, you have no change. That’s okay, you know, you’re good. If you have major changes, you might need to think about what you’re doing. And of course, when you’re changing carrier gases, you absolutely need to change your tune file. helium and hydrogen are very different animals, you need a new tune file. Some things to avoid, avoid your chlorinated solvents dichloromethane, your sulfur solvents, carbon disulfide chemical reactions occurring with hydrogen in the inlet, you put some water, you put some hydrogen, you put the hot inlet together, and you’ll make some lovely hydrochloric acid. So let’s please avoid that, as best we can. And you kind of talked a little bit about with your metal in the stores hydrogen is not inert. Helium is lovely because it’s inert. The hydrogen can have those potential interactions happen, especially at elevated temperatures. So it’s going to keep a slightly cooler inlet, potentially a slightly cooler, mass spec source and quad as well. So hydrogen GCMs might work for you, but it may not be perfect for everyone. And we want to just give you an example why it doesn’t necessarily work for everyone. So here in the top less left, the figure is the mismas spectrum for nitrobenzene. And that’s in helium carrier gas or molecular ions when 23 mastercharge ratio and 93 mass to charge ratio is just a small component of the mass spectrum. What happens when we introduce hydrogen carrier gas instead with GCMs is we see a flip in the abundance of 93 and one 23 And that’s indicating that nitrobenzene has been converted to AnnaLynne. Basically hydrogenated our nitrobenzene in the source. And we know it’s happening in the source, because it’s alluding at the time of nitrobenzene, not AnnaLynne, which was earlier. And then this was confirmed in those extracted ion chromatograms, that are to the right 93 is a lot bigger than it’s supposed to be. So we don’t want to see hydrogenation in the source with hydrogen carrier gas, because we want to detect and report what is actually in the sample. And that can get really confusing. If you have hydrogenation. Hopefully, I haven’t scared everyone off of using hydrogen it just needs means you need to take some time and think about what’s best for your system. You know, our recommendations are using a nine millimeter extraction lens, if you have an inert plus, or an extractor system, that’ll give you the best response based on all the experiments on myself and some other colleagues have done, lower that column flow rate compared to the helium flow rate, probably gonna have to do some retention time and method development. But that’s the fun part of our job, right? It’s always best to switch that more efficient column. Using if you use that standard 30 meter. Your pressure, as I said, at the control module will be about one psi, it’s a little bit too low, or a lot a bit too low, you generally want your pressure on your control module to be at least 10 ballparks, you know, eight, fine 20 Fine one not fine. So it’s also like, is it better to switch that smaller column diameter and as best you can to get the similar theoretical plates if possible? No, it’s not always possible. But we we do our best. Always, always, always, always, always, always use gas filters. And especially with a Hydrogen Generator, make sure it’s producing hydrogen at least to 80 to 100% efficiency, we need really good efficient hydrogen production to keep up our carrier gas flow rates. And then you may want to allow your system some longer time to bake out, especially on initial setup. If you’ve always run helium systems may need to kind of settle in and clean out a little bit longer, because hydrogen is going in there and scrubbing around any type of dirt it might find. To avoid, there are some things we avoid, if you can, chlorinated solvents and hot inlets. As I said, you might create some hydrochloric acid and that doesn’t agree with columns, I believe that might at your column. So let’s not do that. It’s also better to avoid our heavily chlorinated compounds, because they can be chlorinate. So another form of hydrogenation, your PCBs. You know, some a lot of your pesticides are heavily chlorinated. They’re not going to be happy compounds around hydrogen, especially in the source, and then avoid your nitro compounds like nitrobenzene, again, likely to hydrogenate and replace those hydrogens rather quickly. So the question is, oh, what do we have left? What can we do? Honestly, the easiest ones to transfer to hydrogen carrier gas, or hydrocarbon analyses, or polycyclic, aromatic hydrocarbons. They they’re just happy as as can be around hydrogen. So those are options, you could most easily switch to hydrogen on your GCMs and then evaluate others from there. I’ll get off my hydrogen soapbox for a little while. Oh, brilliant, many thanks, Andy. Yes, lots to think about there, isn’t it? And I mean, it is so worth it, I think in the end, because you know, but you do have to put the effort in, you can’t just spend your costs and go Lalalalala, by that method will just run out in the hydrogen now and expect it all to work, you do have to do a little bit of work, etc. There. So, Vanessa, do you have anything to add? Please? I will say it because Angie covered a lot. The one thing that you can totally do is if you’re wondering how much time you might be able to save use it by switching to hydrogen, you can use our method translator to just verify so put your current parameters into, say the left side column, saying that you’re using helium, and then put in that you’re going to change the gas on the right column to hydrogen, you can check for if you’re going to change column dimensions. So seeing how much time you’ll be, you’ll be able to say by going from the 30 meter standard to a 20 meter high efficiency column. You can also say you know, best efficiency, and it will give you already these inputs of here’s the values that you’re going to get and you can actually then just apply that to the new method. So once like we said it’s not for everything, and there will be some differences but if you’re watching To do that, that’s a way where you can see what that benefits going to get you. Because that’s a really great way just for speeding things up. If you are using for those hydrocarbons, or those pH is where, say if you, you need that extra time, if you’re doing a lot of high throughput analysis, that’s one thing where you can show your managers or whatnot, hey, here is our cost benefit analysis, we can run X number more samples in a day, with quality controls, maintaining ISO regulations, whatnot. And here’s maybe where we can start, say, if you want it to show that the benefit or why you want to get the Hydrogen Generator, here’s where it can benefit you. So excellent. I mean, it was actually one of my Agilent GCMs systems. So first of all, it’s all it’s all installed with stainless steel tubing, but we actually have hydrogen and helium is a carrier gas. And what I have then is I have the hydrogen comes in, the helium comes in a big filter for each and it goes to a gas selection valve. And I can then switch between helium or hydrogen. And of course, then go into my configuration and tell it it’s using hydrogen or helium, but it’s great for those applications you’re not sure about. So you can develop your methods using the right columns and everything but with helium, and then you can switch over purchase system through and then tweak your parameters and the hydrogen. And then you’ve got direct comparison on the same GCMs system for both helium and hydrogen. And that is just brilliant for data. Because it’s not even like say, Oh, it’s a different system. Therefore, it will give me the slightly different results, you can do an exact comparison, which is brilliant. And you know, it just takes like five minutes to switch between the two. So I don’t know if you’ve got any customers doing that. But I definitely recommend it for those all those ones, where you say you’re using the same instrument, but for different applications, and some are good for hydrogen and some are good, not so good. You have to use helium, but you want to reduce your helium consumption. So that is an option that I’ve had running for quite a few years, actually, on one of our systems, it works quite well. So brilliant. Thank you very much. Okay, so I’m going to move on to Question four, which is how long should I condition my column? And I think Vanessa is going to be answering yes, then please. Yeah, yeah. So this is, like we said, you know, it all depends on what type of column that you’re going to be doing, using. So the time it takes and the temperature that you’re going to condition is going to vary depending on the phase of column that you’re using, as well as the maximum temperature you’re planning on operating at. So what I like to do is take my column up to that maximum temperature that I need to operate out without going above the maximum temperature stated on the box with the gas flow on and hold it there for about an hour. So again, this is going to vary depending on the type of column that you’re using and the maximum temperature. So I would say that a column is deemed condition when that baseline is flat, and no longer decreases, which is really easy to see if you’re looking at it on an fid. So this is a conditioning profile have a DD five H T column that I conditioned at 380 degrees for just over two hours. So this DB five H T column is on special high temperature temperature few silica. So I will just say it can be taken up to 400 degrees Celsius, but regular fused silica should not be taken above 350, because that’s the temperature limits of traditional polyamid FISA columns. So what you see is an initial jump in this baseline, and as the column is first taken up to temperature, and this is completely normal, but when it then it starts to decrease and levels at around 100 minutes at 380. This is when I would say that this column is conditioned and ready to run. If you don’t need to operate at that maximum temperature, then you don’t need to go up to that Max Max temperature. If you’re running an analysis, say that only needs to go up to 330 degrees and you’re using a DD five MSCI there’s no need to go in to try and go up to 350 degrees to condition that column. Likewise, I’ve done some other analysis where on 64 typeface columns where I might only be going to 120 degrees, I don’t need to condition that max temperature, it’s only for where you need to operate up. So something I also like to say is like it might not be two hours, it could be less, sometime your column might be ready to run and conditioned in one hour, or it might be need a little bit longer. You don’t necessarily need to condition your column overnight. I know a lot of I’ve been in other places where their last thing of the day, if they would they would change a column before they left and then they would hit condition and then just set that max temperature and leave for the night and come back in the morning. You don’t need to do that. I would actually suggest if you are using you know standard phases like normally with a routine analysis. I put together a method that I call say six to four condition or WACs condition where I know how long it’s going to take where I have a ramp up, and it’s just a straight in no injection, kind of I just hit run. And then it will bring my temperature back down once it’s done. So you don’t need to have it run overnight that if you have any leaks, that could actually then be a damage to that phase. So it doesn’t need to go that long. So I have to make sure that we mentioned that you really want to make sure you condition that column when it’s detected or connected to your detector, don’t condition your column with that end of the column just hanging out in the oven, because so oxygen is going to start to get into that column. And it’s going to as you’re up to temperature, that heat and that oxygen we’ve talked about is going to start degrading and eating up that column phase. So you really need to make you would have to then go back, if you did that clip about a meter or two from the end of your column hope that you had like got everything, then reinstall it into your detector, install it into your detector, and then get your detector ready to run. And that is just way too much work like we have way more things to do. Your then also wasting about two meters of columns and columns can be expensive. So why why waste that meter, you aren’t going to be damaging your detector your fit or your mass spec by conditioning with that column connected to your detector it’s going to run through it’s going to be fine. Trust me, I don’t like even if you’re going up at higher temperatures. Like this is a DB five HT phase. And we like I said we went up to 380 degrees. And that’s putting a lot of stress on a column. And you can see that that baseline did decrease and it actually went back down once I decreased temperature to the state like my my starting point, so you’re not going to damage it. And it’s just going to create way much more work for you if you don’t connect it to your detector. Now one thing I also like to talk about it when we’re talking about conditioning columns and maximum temperatures is every column is going to have a different kind of bleed profile that you’re looking at. So before I used to get started, like say when I’m running a blank, I like to maybe put one kind of bleed profile for that blank injection. So if down the road, I’m wondering, did my column bleed rays, or is this normal, I can then compare it to my starting point where I know everything’s okay. Because like we said, first of all column bleed is normal, that’s a normal process. And every column is going to be a little bit different depending on what phase you’re operating at, with or the the phase ratio, the thickness, thicker the phase, the higher the column lead, you’re going to see. And also, if it is a thicker phase, you may need to condition a little bit longer. If you’re using a thinner phase column, that’s going to be have less lead, it’s just because the amount of column phase that’s on there is going to start eventually interacting with your detector. And you will see that in your background, which is why also if you’re working with mass spec, we suggest you use MS columns because that has a lower natural column bleed, because we’ve worked on that because we want it to be more lower bleed to decrease our responses and interference for using with sensitive detectors. We got if you call them bleed as normal, whatever that baseline is, that’s where I like to say, Keep a keep a chromatogram of what it looked like when it started. And then that way, if you’re down the road thinking, This doesn’t look right, well, then you can go back and then compare it to an overlay. And yeah, just, it’s gonna be it’ll be good. You just don’t, you don’t have to go eight hours. It doesn’t have to be at the max temperature always and respect the temperature limits set on the column box. Don’t exceed it. Brilliant. Thanks, Vanessa. So of course, when you talk about maximum temperature, there’s two different maximum temperatures, which are on a box, which one are you talking about here, please. So you have two temperatures, there’s the program temperature, which is or the isothermal temperature and the program temperature. So that isothermal temperature is going to be that long term, the lower temperature on the box. So say if it says to 50 to 60, that 250 degrees, that lower temperature is your isothermal temperature and that’s where that column can hang out for a long time. And that program is at higher temperature. I like to look at it in terms of lifting weights or whatnot. That lesser temperature isothermal temperature is what that lighter said a weight that you can do a lot of reps on and you’re not going to hurt yourself. You’re still going to maybe challenge yourself a little bit and whatnot. But that program temperature is your heavier weight where you’re going to do less reps, where if you tried to do that same amount before your as your lights on the way you’re gonna hurt yourself. But regardless, think about for that over a long period of time, even if you’re holding a light set away, you’re still overtime, even just if you pulled your hands out. And like you even without weights, you’re you can’t hold your arms out for a very long time, it’s gonna hurt your muscles. So same thing with our column face. So that’s where you’re looking at those two. So when we talk about that, I would probably try and air more towards the ice thermal temperature, because that would be the max temperature I would try to get or if you do have to operate at that program max temperature, it’s going to be for shorter periods of time, maybe 10 minute segments, just kind of pay attention, it should you can condition at that program temperature, if you are going to operate at it if you need to just kind of watch what goes on. And that might be a real good case of when you want to have that brake bleed profile in your chromatograms to just verify back to it just to make sure you’re you’re good to go. Earlier, many thanks, Vanessa. Andy, did you have anything you want to add to that, please? My small point would be before you condition it, make sure it’s leak free. Because conditioning with leaks is not conditioning, it’s just breaking your column. or destroying your column, maybe a better statement, say you’re having if you’ve got leaks, you’ve got oxygen going in, it’s just going along and chewing on all that stationary phase. So it’s my only little caveat is leak free. And especially if it’s a mass spec, let it settle in, it’s allowed to like just let it chill and come down and leave, check it and then just like show the oxygen waters nice and low. And you know, you pass your air water check that it’s okay, yep, you know what my oxygen is under 2%. Alright, now we are ready to condition. That’s my little caveat on it. Absolutely, especially if you install a column and it hasn’t even been properly sealed. So you’re gonna have water in there, you’re gonna have oxygen in there. So don’t just put it in and ramp it straight up that conditioning temperature because you need to purge those out. But first, and especially if you’ve got a more polar column, like you know, you’ve got a wax column, you’re going to have a lot of interactions with oxygen and moisture in there. So it’s going to take a while, you know, time to just purge those out before you start going up to really high temperatures. Because otherwise, you’re gonna get oxidation in your stationary phase and start damaging it straightaway. So I always do like a gentle, gradual up to that final temperature for my for conditioning. Absolutely. Brilliant. Thank you very much. Lots of really good tips there. So thank you. So I have got one final question here. So which has come in. So what is the most basic maintenance that a user can do to maintain the longevity of a GC? I would say because this is very wide ranging. And the biggest thing you can do is pay attention. Pay attention to your what’s happening with your GC, pay attention to your quality controls, pay attention to what you’re injecting, and also with your mass spec tune, pay attention to what’s going on kind of just be present in your analysis and how things are acting over time. Because if you’re not paying attention, if you just keep running, running, running, you could miss a lot of warning signs over time. So just if all the sudden you see your quality control, your response start to decrease. Everything may pass if you’re using internal standard, all of a sudden you see your internal standard response and everything drop. That’s an indication. If you you know, pay attention to your syringe flow or your syringe in mobility before you start an injector sequence. If you’re injecting some dirty things, I I’ve done it myself where I haven’t checked that and then all of a sudden my first or second injection and then z’s, and I have to replace it. You know, just pay attention. That’s the biggest thing. Right, thanks, Andy. Do you have any tips, please? Yeah, I was gonna be like, oh, sure you change your lighter but Vanessa’s point is a lot better is actually last week. I was working on my I was remoting into my system from home. And looking at it like oh man, this syringe must be z because I’m seeing like nothing in my mass spec. Or like my total and chromatic I’m like, oh, man, it’s broken. Stop the sequence. They’ll deal with it later. And I look at it and I’m like, Wait, my mass spec pressure is way higher than it supposed to be, you know my mass spec pressure and I try to keep an eye on it because I am paranoid about numbers is usually like nine times 10 to the negative six and that’s just where that one usually sits out. I’m like this two times 10 to the negative it will their event. There’s something wrong let’s event and and I was chatting with a colleague and she Like, yeah, there’s something wrong. And I’m like, Okay, let me run a diagnostic test on the inlet quick. So nice part of the ad series on GCS is we can do a web UI and do some diagnostics, I click no inlet pressure and leak restriction test. Okay, it passes the pressure. And then the leak says it’s 92 mils per minute. And I’m like, there’s a huge problem there. So I, you know, everything got kind of turned down, and I went in the next morning, I checked the inlet and like, turned out, you know, and that’s fine, like in the oven, and there’s a column break, like, half a meter, maybe a meter from the inlet, and I’m like, Ah, but if I wouldn’t have paid attention to that pressure, I could have been like, Oh, I’ll be with that. Tomorrow, whatever. But luckily, I knew my system well enough to say, there’s a huge problem. Let me cool it off, let me vent it, and I prevented, you know, burning out anything on my mass spec, but just stopping waiting and saying, Vince, you know, you know, obviously, I’d replaced calm is broken, but you know, better to find it, then then find it out 24 hours later, and then you gotta wait the cool and, you know, 15 other things. So, I think Vanessa is probably the best advice for keeping longevity is pay attention. You know, the first time you set up your system, you’re not going to know is that normal? Is that normal, write it down, and try and just be like, alright, this is what it starts at, hey, I let it sit for 24 hours, this is this is what the new normal, okay, and then just track from there. And it is annoying that every systems a little bit different. Well, that mess back likes to sit it nine times 10 to the negative six, my triple quad likes to sit it, you know, two times 10 to the negative fifths. So I need, I need to make sure that, you know, my brain keeps those separate. So we have a little bit of a pain in the neck, but pay attention. Knowledge he sees are individuals, and this is why I give them names. That’s true. That sounds like the same thing. They’ve all got their own little characters, and it’s getting to know them, the better you know them, the better you can see when they’re not well, like having pets really isn’t that you know, you get to know their little quirks. And then, you know, when they’re not doing their normal quirks are doing something different, you kind of like right in there, or what’s happening here, maybe off to the vets or something like that. But I mean, for me, I would say one of the tips is have looking out for dirt. If you can see where dirt is you can really understand what’s going on the system, but also where else you need to go and do maintenance. So you know, what do you go and change your life and don’t just throw it away, take it out and examine it, you know, if you’ve got some glass wall in there, the dirt sits on top of the glass, well, you know, it’s gone no further, the dirt underneath that glass wall, it’s probably gone down further, maybe a head of the column needs to trim and stuff because it hasn’t all been trapped. If you feel dirt on the outside of your liner, you know, you’re going to need to take out the column and give your inside of your inlet a really good claim. So you know, I love Well, I don’t know I don’t like that. But I love looking for and using it to track where other potential problems are. So you know, don’t just throw things away look. And again, when you take your septum out, look underneath is that coring under there. There’s coring underneath it is the set under your septum. It’s most likely it’s little bits have gone inside your liners. Now you need to go and take your liner out, because otherwise you’ll be analyzing those bits as well. So yeah, track that judge. Absolutely. So brilliant. Thank you very much for answering these great questions. Yeah, we’ve had some really, really interesting ones. So thanks to everyone. Well, thank you, Diane, and Vanessa, and Angie for that excellent discussion. We’ve covered a lot of ground over the past hour, and hopefully helped with some of the issues you face in your GC and GC ms analysis. We do know that there are plenty more questions still to address. And we look forward to doing that in the next part of this series. Don’t forget if you have a GCL GCMs question, you can still submit it using the Ask a Question button below. We’ll try to accommodate some of these in our follow up future sessions. Thanks also to our scientific partners in this event being Agilent for all their technical input and support. a recorded version of today’s discussion will be available soon. You’ll all receive a link to this as soon as it’s ready. And so with that, I’d like to thank you all for logging in and listening today. Thank you and goodbye.