GC-FID determination of cocaine and its metabolites in human bile and vitreous humor

Abstract

Gas chromatography was used in combination with flame ionization detection (GC-FID) to develop a method for determining cocaine and its two metabolites, benzoylecgonine (BEG) and ecgonine methyl ester (EME), in bile and vitreous humor. The method used a 12 m x 0.2 mm i.d. column of 0.33 microm film thickness packed with 5% phenylmethylsiloxane, and proadifen as a reference compound. Drug-free bile and vitreous humor samples were used to prepare solutions of the target compounds at concentrations over the range 0.1-4 microg ml(-1) that were subjected to solid-phase extraction through Bond Elut Certify columns and derivatized with 99:1 (v/v) N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA)/trimethylchlorosilane (TMCS). Calibration graphs were highly linear, with correlation coefficients above 0.99 in all instances. Also, the precision of the method was found to be quite acceptable, with coefficients of variation less than 5% for bile and less than 7% for vitreous humor. The average extraction yields ranged from 73.6% to 91.2% for bile and from 71.5% to 92.2% for vitreous humor. The proposed method was used to analyse 26 samples of bile and as many of vitreous humor from individuals fatally poisoned by cocaine, whether alone or in combination with other drugs. The mean drug levels found were 0.75 and 1.54 microg ml(-1) for cocaine in bile and vitreous humor, respectively, 6.35 and 0.94 microg ml(-1) for BEG, and 2.18 and 0.61 microg ml(-1) for EME.

Chromatographic determination of drugs of abuse in vitreous humor using solid‐phase extraction

“…These results are comparable to those published by Logan and Stafford () to determine cocaine and BZE in vitreous humor. Other studies conducted on the same sample type, employing solid‐phase extraction and gas chromatography (Mackey‐Bojack et al ., ; Fernández et al ., ), gave values of LOD and LLOQ for cocaine and BZE slightly higher or similar to those presented in this work. The proposed methods by Pragst et al .…”

“…Solid‐phase extraction is commonly used in analytical laboratories as a sample preparation and a cleanup or preconcentration technique in the processing of biological fluids using different sorbents (Fernández et al ., ; Li et al ., ; Wey and Thormann, ; Aturki et al ., ). In order to optimize the extraction conditions, some previous tests were carried out.…”

“…Also, its limited irrigation preserves vitreous humor from blood infection. These features make vitreous humor a very useful specimen for the detection of drugs of abuse, when blood or urine specimens are not available (Drummer, ; Fernández et al ., ). It is well known that drugs of abuse and their metabolites enter vitreous humor as a result of passive diffusion from blood, with significant concentrations of drugs that are not strongly bound to proteins being found (Ziminski et al ., ; Cox et al ., ).…”

Simple method for determination of cocaine and main metabolites in urine by CE coupled to MS

“…Nevertheless, several methods for the analysis of COC and a few metabolites in biological samples have been reported in the literature, such as high-performance thin layer chromatography [3], high performance liquid chromatography with ultraviolet [3,8], fluorescence [9,10] or MS detection [11] and gas chromatography with MS [5,[12][13][14] or flame ionization detection [15]. However, it must be emphasized that none of the above literature methods contemplated the analysis of COC and all five metabolites depicted in Fig.…”

Desenvolvimento de metodologia analítica para a investigação de metilenodioxi derivados em amostras de humor vítreo em vítimas fatais de acidentes de trânsito

“…Além dos metilenodioxi derivados, o humor vítreo permite a detecção de outras drogas tais como canabinóides, cocaína e seus metabolitos e opióides (BERMEJO et al, 1992;FERNÁNDEZ et al, 2006;FURNARI et al, 2002;LIN;LIN, 2005;MACKEY-BOJACK;KIOSS;APPLE, 2000).…”