Solid-phase extraction—Thermal desorption—Gas chromatography with mass selective detection for the determination of drugs in urine

Abstract

Key WordsGas chromatography -mass spectrometry Solid-phase extraction-thermal desorption Prog ra m m ed-te m pe rat u re va po rise r Lidocaine and diazepam in urine SummarySolid-phase extraction (SPE) was combined with thermal clesorption (TD) and gas chromatographic (GC) analysis to determine drugs in urine. The extraction was performed inside a fritted GC liner using about 5 mg TENAX that was inserted into the liner on top of the frit. After extraction, the hner was placed into the injector of the GC and the analytes were thermally clesorbed by using a programmed-temperature vaporiser. Several sorbent materials were investigated for the applicability of SPETD-GC analysis. TENAX proved to be the most suitable sorbent, since hardly any interferences were observed and acceptable absolute recoveries (73 and 74%) were obtained for liclocaine and cliazepam. A mass selective detector (MSD) in the selected ion monitoring mode allowed detection of hclocaine and cliazepam clown to 0.5 ng 9 mL 1 using 50 I~L urine. The use of only5 mg of extraction material allowed rapid extraction, while a 10 m GC column provided a fast chromatographic system. As a result, the total analysis time was less than 20 min, including 5 min for drying the TENAX and 5 min for thermal clesorption. Thus, SPETD-GC-MS appears to be a powerful tool for the rapid analysis of biological samples.

Occurrence of residual water within disk-based solid-phase extraction and its effect on GC-MS measurement of organic extracts of environmental samples

“…3). For all examined SPE disks, the water contents decrease for increasing drying time similar to the investigation of van Hout et al [21], but with different rates for the various disk types. This effect was also observed for SPE cartridges by Chee et al and by Molina et al, but they did not further investigate it [16,36].…”

“…Certainly, the disadvantages of longer drying times are the high expenditure of time [5,21] and the possible loss of volatile compounds. Volatile compounds could evaporate during the drying process and hence reduce recoveries.…”

“…Surprisingly, hardly any study deals specifically with this subject, and in the existing ones, only few aspects are covered [6,11,12,18]. Pico et al studied the use of several drying agents for the effective removal of water traces from the desorption solvent [20], Zorita et al checked the effects on polychlorinated biphenyl (PCB) recoveries by drying the SPE disk under vacuum with and without additional drying in a desiccator [9], and van Hout et al determined the remaining amount of water in the stationary phase of SPE disks at different drying times [21]. Finally, Senseman and co-workers investigated four desiccation methods for SPE disks after enrichment of pesticides in order to determine whether enhanced stability would result when residual water was removed from the disks before storage.…”

SPE – Microwave‐assisted extraction coupled system for the extraction of pesticides from water samples

“…In the literature, there are only a few published papers dealing with SPE combined with another technique for elution of analytes: solid-phase microextraction (SPME) -supercritical fluid elution (SFE) applied in HPLC [6,7] and SPME-thermal desorption applied in GC [8]. Combination SPE-MAE [5] investigated in this paper is not limited to GC or HPLC determinations.…”