Comparison of liquid-liquid and solid-phase extraction techniques for drugs in urine and effects on the lifetime and performance of fused-silica capillary columns

Contamination of a gas chromatographic system with involatile sample residues will cause degradation of the chromatograms. Deposition of sample residues from urine extracted by a liquid-liquid and a solid-phase cartridge extraction method for drugs of abuse is compared. Standards containing five different drug compounds were injected into a gas chromatograph equipped with a fused-silica capillary column following injections of urine extracts prepared by the two different extraction methods. The samples extracted by the liquid-liquid method contaminated the chromatographic system to a greater extent and much faster than those extracted by the solid-phase extraction method.