SPE General Procedures

series: [Analysis of Pesticides in Food and Environmental Samples, edited by Jose L. Tadeo]

Summary [1] #

samples or extracts are percolated through the cartridge and the compounds are sorbed on the solid phase materials, which have been previously conditioned and activated (Zhang et al., 2012). Then the interferences are removed by prewashing by organic solvents while the analytes are retained on the sorbents. More frequently, the interferences are retained in the cartridge and the analytes pass through and are collected for analysis.

Procedures [2] #

A typical SPE sequence includes the activation of the sorbent bed (wetting), removal of the excess of activation solvent (conditioning), application of the sample, removal of interferences (cleanup) and water, elution of the sorbed analytes, and reconstitution of the extract [3]. Exact conditions are usually specified by the manufacturer, and may vary significantly in types of solvents used for conditioning and elution. A general procedure for using SPE cartridges is as follows [4]:

  • Wash the cartridge with a small amount of relatively nonpolar solvent (e.g., ethyl acetate, acetone), followed by a relatively polar solvent (e.g., methanol), and finally water.
  • Without letting the cartridge become dry, pass the water sample (e.g., 1 L) through the column under vacuum at a relatively fast rate (e.g., 15 mL=min).
  • If the water sample contains an appreciable amount of suspended solids, filter the sample to remove suspended solids before loading.
  • After the sample is loaded, wash the cartridge with a small amount of water and dry the cartridge by passing air for a short time.
  • Elute the SPE cartridge with the same solvents used at the preparation step, except in a reversed order.
  • The eluate is dried with a small amount of anhydrous sodium sulfate and further evaporated to dryness under a gentle stream of nitrogen.
  • The residue is recovered in a small amount of solvent appropriate for GC or LC analysis.

Reference #

[1]p142, Applications in High Resolution Mass Spectrometrey Food Safety and Pesticide Residue Analysis, edited by Roberto Romero-González, ©2017 ELSEVIER.

[2] p237, Analysis of Pesticides in Food and Environmental Samples

[3] Soriano, J.M., Jimenez, B., Font, G., Molto, J.C., Analysis of carbamate pesticides and their metabolites in water by solid phase extraction and liquid chromatography: A review. Critical Reviews in Analytical Chemistry 2001, 31(1), 19–52.

[4] Baez, M.E., Lastra, O., Rodriguez, M., Solid phase extraction of halogenated pesticides from ground and surface waters and their determination by capillary gas chromatography. HRC-Journal of High Resolution Chromatography 1996, 19(10), 559–563.