Analysis of Cocaine and Its Metabolites from Biological Specimens Using Solid-Phase Extraction and Positive Ion Chemical Ionization Mass Spectrometry

Abstract

An accurate and reliable gas chromatographic-mass spectrometric method was developed to analyze tissue, whole blood, plasma, and urine samples for cocaine (COC) and its major metabolites. COC, benzoylecgonine (BZE), and ecgonine methyl ester (EME) were isolated from the biological matrix using solid-phase extraction, and the tert-butyldimethylsilyl derivatives of BZE, EME, and their deuterium-labeled internal standards were formed. Separation of the compounds was performed by capillary chromatography, and analysis was performed by positive ion chemical ionization mass spectrometry using methane and ammonia as the reagent gases. The tert-butyldimethylsilyl derivatives of BZE and EME were stable and produced mass spectral ions with higher mass-to-charge ratios than trimethylsilyl derivatives. Recovery of COC and its metabolites exceeded 80% at all three concentrations tested. Linearity of the method was established from 2.5 to 2000 microg/L. Intra-assay precision had a coefficient of variation (CV) of less than 9% for all analytes when tested at 10, 25, 100, and 200 microg/L. Interassay precision also had a CV of less than 9% for COC, BZE, and EME at 25 and 100 microg/L. At 200 microg/L, %CVs for COC, BZE, and EME were 11.5, 12.0, and 12.7, respectively. In addition to the analysis of COC, BZE, and EME, the method was used to quantitate cocaethylene and to identify norcocaine.

Screening of cocaine and its metabolites in human urine samples by direct analysis in real-time source coupled to time-of-flight mass spectrometry after online preconcentration utilizing microextraction by packed sorbent

“…Using DART alone for analysis of drugs of abuse at levels detected by other GC/MS and LC/MS techniques [22][23][24][25][26][27][28][29][30][31][32][33] is not achievable. Now, to improve the sensitivity of DART, sample pretreatment is required to preconcentrate the analytes because the current configuration does not have the highest transmission of ions into the mass spectrometer.…”

“…However, in the past decade, the use of LC/MS has significantly increased for routine analysis because of its sensitivity and affordability. Although several GC/MS methods for cocaine and metabolites in urine and whole blood have previously been developed and are being used in the laboratory, these procedures are relatively timeconsuming, taking up to several hours [22][23][24][25][26]. Because of the demand for speed, sensitivity, and less timeconsuming methods, several LC, LC/MS, and LC/ MS/MS methods have been developed over the past decade [27][28][29][30][31][32][33].…”

Determination of cocaine and cocaethylene in urine by solid‐phase microextraction and gas chromatography–mass spectrometry

“…Solid-phase extraction (SPE) has been generally employed to extract cocaine together with its polar metabolites such as benzoylecgonine, once conventional liquid-liquid extractions have not provided good recoveries for this kind of metabolite Stout et al, 2002;Diamond et al, 1996;Paul et al, 1998;Crouch et al, 1995). SPE provides cleaner extracts and avoids sample loss through emulsion formation.…”

“…For chromatographic analysis of benzoylecgonine (the main urinary cocaine metabolite), solidphase extraction (SPE) is preferred, followed by a derivatization step Stout et al, 2002;Diamond et al, 1996;Paul et al, 1998;Crouch et al, 1995).…”

Analysis of opiates, cocaine and metabolites in urine by high-performance liquid chromatography with diode array detection (HPLC-DAD)

“…Identifying these substances entails using screening techniques such as immunoassays (Kintz et al, 1992;Kaul et al, 1999) and quantifying them by chromatographic techniques (Tatsuno et al, 1996;Hall et al, 1999;Dams et al, 2003). In most cases, the identification and quantitation of opiates, cocaine and their metabolites in urine requires their prior solid-phase extraction, followed by GC/MS Wang et al, 1994;Crouch et al, 1995;Cárdenas et al, 1996). However, HPLC has emerged as an effective alternative to gas chromatography for this purpose because it allows a large number of substances to be separated without derivatization (Ferrara et al, 1992;Sukbuntherng et al, 1995;Fernández et al, 1996;Jeanville et al, 2001); also, its specificity can be enhanced by using a diode array detector (Koves, 1995;Tracqui and Kintz, 1995;Dams et al, 2002).…”