Simultaneous quantification of morphine and cocaine in hair samples from drug addicts by GC-EI/MS

The development of analytical techniques that enable the use of hair as an alternative matrix for the analysis of drugs of abuse is useful for confirming the exposure in a larger time window (weeks to months, depending on the length of the hair shaft). In the present study a methodology aimed at the simultaneous quantification of cocaine and morphine in human hair was developed and validated. After decontamination, hair samples (20?mg) were incubated with a mixture of methanol/hydrochloric acid (2:1) at 65?°C overnight (~16?h) in order to extract the drugs of the matrix. Purification was performed by solid-phase extraction using mixed-mode extraction cartridges. After derivatization with N-methyl-N-(trimethylsilyl) trifluoroacetamide, blank, standards and samples were analyzed by gas chromatography/electron impact-mass spectrometry (GC-EI/MS). The method proved to be selective, as there were no interferences of endogenous compounds with the same retention time as cocaine, morphine and ethylmorphine (internal standard). The regression analysis for both analytes showed linearity in the range 0.25-10.00?ng/mg with correlation coefficients ranging from 0.9989 to 0.9991. The coefficients of variation oscillated between 0.83 and 14.60%. The limits of detection were 0.01 and 0.02?ng/mg, and the limits of quantification were 0.03 and 0.06?ng/mg for cocaine and morphine, respectively. The proposed GC-EI/MS method provided an accurate and simple assay with adequate precision and recovery for the quantification of cocaine and morphine in hair samples. The proof of applicability was performed in hair samples obtained from drug addicts enrolled in a Regional Detoxification Treatment Center. The importance of hair samples is highlighted, since positives results were obtained when urine immunoassay analyses were negative. Copyright ? 2012 John Wiley & Sons, Ltd.     

Development and validation of an LC‐MS/MS method for quantification of Δ9‐tetrahydrocannabinolic acid A (THCA‐A), THC,CBN and CBD in hair

For analysis of hair samples derived from a pilot study (‘in vivo’ contamination of hair by sidestream marijuana smoke), an LC‐MS/MS method was developed and validated for the simultaneous quantification of Δ9‐tetrahydrocannabinolic acid A (THCA‐A), Δ9‐tetrahydrocannabinol (THC), cannabinol (CBN) and cannabidiol (CBD). Hair samples were extracted in methanol for 4 h under occasional shaking at room temperature, after adding THC‐D₃, CBN‐D₃, CBD‐D₃ and THCA‐A‐D₃ as an in‐house synthesized internal standard. The analytes were separated by gradient elution on a Luna C18 column using 0.1% HCOOH and ACN + 0.1% HCOOH. Data acquisition was performed on a QTrap 4000 in electrospray ionization‐multi reaction monitoring mode. Validation was carried out according to the guidelines of the German Society of Toxicological and Forensic Chemistry (GTFCh). Limit of detection and lower limit of quantification were 2.5 pg/mg for THCA‐A and 20 pg/mg for THC, CBN and CBD. A linear calibration model was applicable for all analytes over a range of 2.5 pg/mg or 20 pg/mg to 1000 pg/mg, using a weighting factor 1/x. Selectivity was shown for 12 blank hair samples from different sources. Accuracy and precision data were within the required limits for all analytes (bias between ?0.2% and 6.4%, RSD between 3.7% and 11.5%). The dried hair extracts were stable over a time period of one to five days in the dark at room temperature. Processed sample stability (maximum decrease of analyte peak area below 25%) was considerably enhanced by adding 0.25% lecithin (w/v) in ACN + 0.1% HCOOH for reconstitution. Extraction efficiency for CBD was generally very low using methanol extraction. Hence, for effective extraction of CBD alkaline hydrolysis is recommended. Copyright © 2013 John Wiley & Sons, Ltd.     

Determination of five sulfonylurea herbicides in environmental waters and soil by ultra high performance liquid chromatography with tandem mass spectrometry after extraction using graphene

A fast and novel analytical method was developed for the determination of trace levels of sulfonylurea herbicides in water and soil samples. Graphene was used as a sorbent for extraction, and ultra high performance liquid chromatography with tandem mass spectrometry was used for quantification. Five sulfonylurea herbicides were preconcentrated from water samples using a graphene‐loaded packed cartridge, while extraction from soil samples was performed in a single step using graphene‐supported matrix solid‐phase dispersion. Under the optimized conditions, the calibration plots were linear in the range between 5 and 1000 ng/L for water samples, and between 1 and 200 ng/g for soil samples. All correlation coefficients (R) were >0.99. The limits of detection for water and soil samples were 0.28–0.53 ng/L and 0.08–0.26 ng/g, respectively. This method was successfully applied to the analysis of spiked samples of environmental water and soil, with recoveries ranging from 84.2–109.3 and 86.12–103.2%, respectively, all with relative standard deviations of <10%.     

Magnetic solid‐phase extraction or dispersive liquid–liquid microextraction for pyrethroid determination in environmental samples

The determination of 15 pyrethroids in soil and water samples was carried out by gas chromatography with mass spectrometry. Compounds were extracted from the soil samples (4 g) using solid–liquid extraction and then salting‐out assisted liquid–liquid extraction. The acetonitrile phase obtained (0.8 mL) was used as a dispersant solvent, to which 75 μL of chloroform was added as an extractant solvent, submitting the mixture to dispersive liquid–liquid microextraction. For the analysis of water samples (40 mL), magnetic solid‐phase extraction was performed using nanocomposites of magnetic nanoparticles and multiwalled carbon nanotubes as sorbent material (10 mg). The mixture was shaken for 45 min at room temperature before separation with a magnet and desorption with 3 mL of acetone using ultrasounds for 5 min. The solvent was evaporated and reconstituted with 100 μL acetonitrile before injection. Matrix‐matched calibration is recommended for quantification of soil samples, while water samples can be quantified by standards calibration. The limits of detection were in the range of 0.03–0.5 ng/g (soil) and 0.09–0.24 ng/mL (water), depending on the analyte. The analyzed environmental samples did not contain the studied pyrethroids, at least above the corresponding limits of detection.     

Identification and quantification of thymol metabolites in plasma,liver and duodenal wall of broiler chickens using UHPLC‐ESI‐QTOF‐MS

In the present study, we aimed to develop a method for thymol sulfate and thymol glucuronide determination in plasma, liver and duodenal wall of broiler chickens after feeding with a Thymus vulgaris essential oil at the different concentrations (0.01, 0.05 and 0.1% w /w). UHPLC coupled with accurate‐mass QTOF‐MS was used for identification and quantification of thymol metabolites. Novel Waters Oasis Prime HLB solid‐phase extraction cartridges were applied to sample clean‐up with extraction recoveries ranged from 85 to 92%. The presence of thymol glucuronide was confirmed by MS software according to molecular formula, score, mass error and double bond equivalent. In terms of validation, calibration curves of thymol sulfate were constructed in matrix samples with linearity from 3.91 to 250.0 ng/mL and correlation coefficients were within the range of 0.9979–0.9995. Limits of detection were 0.97, 0.29 and 0.63 ng/mL and limits of quantification were 3.23, 0.97 and 2.09 ng/mL for plasma, liver and duodenal wall, respectively. Intra‐day and inter‐day precision expressed as relative standard deviation were <4.35%. To highlight, thymol metabolites were directly detected for the first time in liver and duodenal wall and this method was shown to be successfully applicable for investigation of thymol metabolism in chickens after thyme essential oil ingestion.     

Rapid detection of ketamine and norketamine in rat hair using micropulverized extraction and ultra‐performance liquid chromatography–electrospray ionization mass spectrometry

A new method for the rapid and simultaneous detection of ketamine and its major metabolite, norketamine, in rat hair has been developed by combining micropulverized extraction and ultraperformance liquid chromatography–electrospray ionization mass spectrometry. By using reversed‐phase UPLC, ketamine and norketamine were well separated within 2 min. Using ketamine‐dosed rat hair, the conditions for micropulverized extraction were optimized, and the limits of detection and quantification of the developed method were found to be 1.7 and 5.7 pg/mg hair for ketamine, respectively. The precisions achieved with this method were slightly better than that obtained with conventional acidic methanol extraction method. Using this proposed method, analysis of the washed rat hair could be completed within 16–17 min. This method is expected to be applied for the analysis of the hair samples of not only rats but also ketamine abusers. Copyright © 2009 John Wiley & Sons, Ltd.     

Simultaneous determination of piperaquine and its N‐oxidated metabolite in rat plasma using LC‐MS/MS

A sensitive and efficient liquid chromatography tandem mass spectrometry method was developed and validated for the simultaneous determination of piperaquine (PQ) and its N ‐oxidated metabolite (PQ‐M) in plasma. A simple protein precipitation procedure was used for sample preparation. Adequate chromatographic retention was achieved on a C₁₈ column under gradient elution with acetonitrile and 2 mm aqueous ammonium acetate containing 0.15% formic acid and 0.05% trifluoroacetic acid. A triple‐quadrupole mass spectrometer equipped with an electrospray source was set up in the positive ion mode and multiple reaction monitoring mode. The method was linear in the range of 2.0–400.0 ng/mL for PQ and 1.0–50.0 ng/mL for PQ‐M with suitable accuracy, precision and extraction recovery. The lower limits of detection (LLOD) were established at 0.4 and 0.2 ng/mL for PQ and PQ‐M, respectively, using 40 μL of plasma sample. The matrix effect was negligible under the current conditions. No effect was found for co‐administrated artemisinin drugs or hemolysis on the quantification of PQ and PQ‐M. Stability testing showed that two analytes remained stable under all relevant analytical conditions. The validated method was successfully applied to a pharmacokinetic study performed in rats after a single oral administration of PQ (60 mg/kg).     

Electro‐assisted solid‐phase microextraction based on poly(3,4‐ethylenedioxythiophen) combined with GC for the quantification of tricyclic antidepressants

In this study, a platinum wire coated with poly(3,4‐ethylenedioxythiophen) was used as an electro‐assisted solid‐phase microextraction fiber for the quantification of tricyclic antidepressant drugs in biological samples by coupling to GC employing a flame ionization detector. In this study, an electric field increased the extraction rate and recovery. The fiber used as a solid phase was synthesized by the electropolymerization of 3,4‐ethylenedioxythiophen monomers onto a platinum wire. The ability of this fiber to extract imipramine, desipramine, and clomipramine by using the electro‐assisted solid‐phase microextraction technique was evaluated. The effect of various parameters that influence the extraction efficiency, which include solution temperature, extraction time, stirring rate, ionic strength, time and temperature of desorption, and thickness of the fiber, was optimized. Under optimized conditions, the linear ranges and regression coefficients of calibration curves were in the range of 0.5–250 and 0.990–0.998 ng/mL, respectively. Detection limits were in the range of 0.15–0.45 ng/mL. Finally, this method was applied to the determination of drugs in urine and wastewater samples and recoveries were 4.8–108.9%.     

Mixed-mode solid-phase extraction for sample cleanup in hair analysis for methadone and its main metabolite

A simple and rapid method for the determination of methadone and its main metabolite EDDP in hair has been developed and validated. The analytes were completely extracted from the matrix after a short alkaline incubation, and the extracts were further cleaned up by solid‐phase extraction using mixed‐mode cartridges. Linearity was obtained from 0.1 (lower limit of quantitation, LLOQ) to 30 ng/mg for both compounds, with correlation coefficients higher than 0.99. Intra‐ and interday precision and accuracy were in conformity with internationally accepted guidelines for bioanalytical method validation, and the cleanup procedure presented mean extraction efficiencies higher than 90% for both analytes. This high efficiency greatly contributed to the low limits of quantitation achieved, and therefore this method can be successfully applied in the determination of methadone and EDDP in hair samples in clinical and forensic scenarios where these compounds are involved. Copyright © 2010 John Wiley & Sons, Ltd.     

High performance liquid chromatography-high resolution mass spectrometry and micropulverized extraction for the quantification of amphetamines, cocaine, opioids, benzodiazepines, antidepressants and hallucinogens in 2.5 mg hair samples

A high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) method for simultaneous screening and quantification of 28 drugs was developed and validated for 2.5 mg hair samples. Target drugs and their metabolites included amphetamines, cocaine, opioids, benzodiazepines, antidepressants, and hallucinogens. After decontamination, hair samples were extracted with 200 μL of a mixture of water: acetonitrile:1 M trifluoroacetic acid (80:10:10, v/v) using a 5 min simultaneous pulverization/extraction step. The extracts were analysed by HPLC-HRMS in an Orbitrap at a nominal resolution of 60,000, with concomitant in source collisional experiments (in source CID). Gradient elution on an Atlantis T3 column resolved 28 target compounds and 5 internal standards. Total chromatographic run time was 26 min. Calibration was achieved by linear regression analysis utilizing six calibration points; R2 ranged from 0.9964 to 0.9999, the limits of quantification were 0.1 ng/mg for 8 compounds, 0.2 ng/mg for 16 compounds and 0.5 ng/mg for 4 compounds; mean relative errors from -21% to +23% were obtained; relative standard deviation, used to estimate repeatability and intermediate reproducibility at three concentrations, was always less than 20%. Process efficiency and recoveries for all analytes were better than 65 and 73%, respectively, at any concentration. The method was applied to hair samples from forensic investigations that contained a broad assortment of drugs of abuse and pharmaceuticals. The use of concomitant HRMS full scan and CID afforded the possibility of retrospective analysis for discovering untargeted drugs.     

Determination of (4‐(1,3‐dioxo‐1,3‐dihydro‐2H‐isoindol‐ 2‐yl)‐N′‐[(4‐ethoxyphenyl) methylidene] benzohydrazide,a novel anti‐inflammatory agent,in biological fluids by UPLC‐MS/MS: Assay development,validation and in vitro metabolic stability study

A thalidomide analog, (4‐(1,3‐dioxo‐1,3‐dihydro‐2H‐isoindol‐2‐yl)‐N ′‐[(4‐ethoxyphenyl) methylidene] benzohydrazide), has been identified as a promising broad‐spectrum anti‐inflammatory agent in previous study. In this study, a sensitive and selective UPLC‐MS/MS assay was developed and validated for its determination in rat plasma samples. The chromatographic separation was performed on an Aquity BEH C₁₈ column using mobile phase comprising of acetonitrile and 10 mm ammonium acetate in the ratio of 85: 15, at flow rate of 0.3 mL/min. The detection and quantification were performed in positive multiple reaction monitoring mode by parent to daughter ion transition of 414.06 ˃ 148.05 for analyte and 411.18 ˃ 191.07 for internal standard (risperidone), respectively using electrospray ionization source. The sample extraction process consisted of liquid–liquid extraction method using diethyl ether as the extracting solvent. The assay was validated by following FDA guidelines and all parameters were found to be within acceptable limits. The linearity was between 10.1 and 2500 ng/mL and the lower limit of quantification was 10.1 ng/mL. The reported results indicate that the assay could meet the requirement for analysis of this compound in amounts expected to the present in actual samples. Further, in vitro metabolic stability study was performed in rat liver microsomes by using the validated assay.     

Application of carbon nanotubes modified with a Keggin polyoxometalate as a new sorbent for the hollow‐fiber micro‐solid‐phase extraction of trace naproxen in hair samples with fluorescence spectrophotometry using factorial experimental design

A sensitive technique to determinate naproxen in hair samples was developed using hollow‐fiber micro‐solid‐phase combined with fluorescence spectrophotometry. The incorporation of multi‐walled carbon nanotubes modified with a Keggin polyoxometalate into a silica matrix prepared by the sol–gel method was reported. In this research, the Keggin carbon nanotubes /silica composite was used in the pores and lumen of a hollow fiber as the hollow‐fiber micro‐solid‐phase extraction device. The device was used for the microextraction of the analyte from hair and water samples under the optimized conditions. An orthogonal array experimental design with an OA24 (4⁶) matrix was employed to optimize the conditions. The effect of six factors influencing the extraction efficiency was investigated: pH, salt, volume of donor and desorption phase, extraction and desorption time. The effect of each factor was estimated using individual contributions as response functions in the screening process. Analysis of variance was employed for estimating the main significant factors and their contributions in the extraction. Calibration curve plot displayed linearity over a range of 0.2–10 ng/mL with detection limits of 0.072 and 0.08 ng/mL for hair and aqueous samples, respectively. The relative recoveries in the hair and aqueous matrices ranged from 103–95%. The relative standard deviation for fiber‐to‐fiber repeatability was 3.9%.     

Different miniaturized extraction methodologies followed by GC–MS/MS analysis for the determination of UV filters in beach sand

Four different miniaturized methodologies were developed and applied to the analysis of 11 UV filters in sand samples. These approaches were based on ultrasound and vortex extractions, on‐column lixiviation, and ultrasound extraction followed by solid‐phase microextraction. Gas chromatography with tandem mass spectrometry was used for quantitative analysis. The analytical performance provided by the four methods was evaluated in terms of linearity, accuracy, precision, and limits of quantification. Lixiviation was discarded since it provided the lowest recoveries and the highest limits of quantification. In contrast, ultrasound and vortex extractions, and ultrasound extraction followed by solid‐phase microextraction were suitable, with recoveries in general >85% and limits of quantification at the low ng/g level. Moreover, ultrasound extraction followed by solid‐phase microextraction allowed using external calibration with aqueous standards and it provided higher sensitivity, with limits of quantification in general one order of magnitude lower than those achieved with the other techniques. The methodologies were applied for the analysis of four marine sand samples, and the results were statistically compared performing an analysis of variance. Eight out of the eleven target UV filters were detected. Octocrylene was found at very high concentrations (up to 1000 ng/g) followed by ethylhexyl salicylate, 4‐methylbenzylidene camphor, homosalate, and 2‐ethylhexyl methoxycinnamate.     

Determination of polychlorinated biphenyls by liquid chromatography–atmospheric pressure photoionization–mass spectrometry

This study presents the atmospheric pressure photoionization (APPI) of high‐chlorinated (five or more chlorine atoms) polychlorinated biphenyls (PCBs) using toluene as dopant, after liquid chromatographic separation. Mass spectra of PCB 101, 118, 138, 153, 180, 199, 206 and 209 were recorded by using liquid chromatography‐APPI‐tandem mass spectrometry (LC‐APPI‐MS/MS) in negative ion full scan mode. Intense peaks appeared at m/z that correspond to [M ? Cl + O]^? ions, where M is the analyte molecule. Furthermore, a detailed strategy, which includes designs of experiments, for the development and optimization of LC‐APPI‐MS/MS methods is described. Following this strategy, a sensitive and accurate method with low instrumental limits of detection, ranging from 0.29 pg for PCB 209 to 8.3 pg for PCB 101 on column, was developed. For the separation of the analytes, a Waters XSELECT HSS T3 (100 mm × 2.1 mm, 2.5 µm) column was used with methanol/water as elution system. This method was applied for the determination of the above PCBs in water samples (surface water, tap water and treated wastewater). For the extraction of PCBs from water samples, a simple liquid–liquid extraction with dichloromethane was used. Method limits of quantification, ranged from 4.8 ng l^?1, for PCB 199, to 9.4 ng l^?1, for PCB 180, and the recoveries ranged from 73%, for PCB 101, to 96%, for PCB 199. The estimated analytical figures were appropriate for trace analysis of high‐chlorinated PCBs in real samples. Copyright © 2014 John Wiley & Sons, Ltd.     

Construction of a portable sample preparation device with a magnetic poly(methacrylic acid‐co‐ethylene dimethacrylate) monolith as the extraction medium and its application in the enrichment of UV filters in water samples

A portable sample preparation device with a magnetic polymer monolith as the extraction medium was constructed. The monolith was synthesized by polymerizing methacrylic acid and ethylene dimethacrylate around a cylindrical magnet. In this way, the monolith with a magnetic core could be readily attached to the extraction device by magnetism. The constructed device was evaluated for the enrichment of UV filters in water samples, followed by high‐performance liquid chromatographic analysis. The extraction efficiency for the targets was satisfactory with no matrix interference. Good linearities were obtained for the UV filters with the correlation coefficients >0.9986. The limits of detection and quantification for the UV filters were 0.3–0.8 and 1.0–2.4 ng/mL, respectively. The recoveries of the UV filters from the spiked water samples at the concentration of 100 ng/mL were 95.3–101.7%, with relative standard deviations <10%. Accordingly, the proposed portable device was demonstrated to be suitable for on‐site simultaneous sampling, purification, and preconcentration within a single step.     

Simultaneous determination of morphine‐6‐d‐glucuronide,morphine‐3‐d‐glucuronide and morphine in human plasma and urine by ultra‐performance liquid chromatography–tandem mass spectrometry: Application to M6G injection pharmacokinetic study

A robust ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method for the determination of morphine‐6‐d ‐glucuronide (M6G), morphine‐3‐d ‐glucuronide (M3G) and morphine (MOR) in human plasma and urine has been developed and validated. The analytes of interest were extracted from plasma by protein precipitation. The urine sample was prepared by dilution. Both plasma and urine samples were chromatographed on an Acquity UPLC HSS T₃ column using gradient elution. Detection was performed on a Xevo TQ‐S tandem mass spectrometer in multiple reaction monitoring mode using positive electrospray ionization. Matrix interferences were not observed at the retention time of the analytes and internal standard, naloxone‐D5. The lower limits of quantitation of plasma and urine were 2/0.5/0.5 and 20/4/2 ng/mL for M6G/M3G/MOR, respectively. Calibration curves were linear over the concentration ranges of 2–2000/0.5–500/0.5–500 and 20–20,000/4–4000/2–2000 ng/mL for M6G/M3G/MOR in plasma and urine samples, respectively. The precision was <7.14% and the accuracy was within 85–115%. Furthermore, stability of the analytes at various conditions, dilution integrity, extraction recovery and matrix effect were assessed. Finally, this quantitative method was successfully applied to the pharmacokinetic study of M6G injection in Chinese noncancer pain patients.     

Magnetic solid‐phase extraction of polycyclic aromatic hydrocarbons in water samples by Fe3O4@polypyrrole/carbon nanotubes

A magnetic solid‐phase extraction method coupled with gas chromatography was proposed for the determination of polycyclic aromatic hydrocarbons in the environmental water samples. The magnetic adsorbent was prepared by incorporating Fe₃O₄ nanoparticles, multi‐walled carbon nanotubes, and polypyrrole. The main factors affecting the extraction efficiency including the amount of the sorbents, desorption conditions, extraction time, salt concentration, and sample solution pH were investigated and optimized. Under the optimum conditions, good linearity was obtained within the range of 0.03?100 ng/mL for all analytes, with correlation coefficients ranging from 0.9942 to 0.9973. The method detection limits (S/N = 3) were in the range of 0.01–0.04 ng/mL and the limits of quantification (S/N = 10) were 0.03–0.1 ng/mL. Repeatability of the method was assessed through five consecutive extractions of independently prepared solutions at concentrations of 0.1, 10, and 100 ng/mL of the compounds. The observed repeatability ranged 3.4–10.9% depending of the compound considered. The proposed method was successfully applied in the analysis of PAHs in environmental samples (tap, well, river, and wastewater). The recoveries of the method ranged between 93.4 and 99.0%. The procedure proved to be efficient and environmentally friendly.     

New application of chitosan‐grafted polyaniline in dispersive solid‐phase extraction for the separation and determination of phthalate esters in milk using high‐performance liquid chromatography

Chitosan‐grafted polyaniline was synthesized and applied as a sorbent for the preconcentration of phthalate esters in dispersive solid‐phase extraction. By coupling dispersive solid‐phase extraction with high‐performance liquid chromatography and response surface methodology (central composite design), a reliable, sensitive, and cost‐effective method for simultaneous determination of phthalate esters including dimethyl phthalate, di‐n‐butyl phthalate, and di(2‐ethylhexyl)phthalate was developed. The morphology of sorbent had been studied by scanning electron microscopy and its chemical structure confirmed by Fourier transform infrared spectroscopy. Under optimum condition, good linearity was observed in the range of 5.0–5000.0 ng/mL. The limits of detection (S/N = 3) and limits of quantification (S/N = 10) were 0.1–0.3 and 0.3–1 ng/mL, respectively. The relative standard deviations were less than 8.8%. Finally, this procedure was employed for extraction of trace amounts of phthalic acid esters in milk samples, the relative recoveries ranged from 82 to 103%.     

Application of liquid–liquid microextraction for the effective separation and simultaneous determination of 11 pharmaceuticals in wastewater samples using high‐performance liquid chromatography with tandem mass spectrometry

A dispersive liquid–liquid microextraction method for the simultaneous determination of 11 pharmaceuticals has been developed. The method is based on a microextraction procedure applied to wastewater samples from different regions of Hungary followed by high‐performance liquid chromatography with mass spectrometry. The effect of the nature of the extractant, dispersive solvent, different additives, and extraction time were examined on the extraction efficiently of the dispersive liquid–liquid microextraction method. Under optimal conditions, the linearity for determining the pharmaceuticals was in the range of 1–500 ng/mL, with the correlation coefficients ranging from 0.9922 to 0.9995. The limits of detection and limits of quantification were in the range of 0.31–6.65 and 0.93–22.18 ng/mL, respectively.     

Hydrophilic interaction liquid chromatography–tandem mass spectrometry (HILIC-MS/MS) determination of cocaine and its metabolites benzoylecgonine, ecgonine methyl ester, and cocaethylene in hair samples

This study reports the development and validation of a method using hydrophilic interaction liquid chromatography–tandem mass spectrometry (HILIC-MS/MS) for the analysis of cocaine and its metabolites benzoylecgonine (BE), ecgonine methyl ester (EME), and cocaethylene (CE) in hair samples. Decontamination was performed as follows: Firstly, the aliquot of hair was briefly rinsed with 2 mL dichloromethane, then was washed three times with 10 mL 0.01 M phosphate buffer, pH 6, for 15 min, followed by 2 mL 2-propanol for less than 2 min, and, finally, a last rinse with 2 mL dichloromethane was again done. Cocaine compounds were extracted from 10 mg of hair by incubation with 2 mL 0.1 M HCl at 50 °C for 12 h and purified by solid phase extraction with Oasis MCX cartridges. Analysis was performed by LC-MS/MS using an Atlantis HILIC silica chromatographic column. The method was fully validated. Linearity was established over the concentration range 0.020–10.0 ng/mg for cocaine (COC), 0.010–10.0 ng/mg for BE and CE, and 0.005–2.0 ng/mg for EME, and the correlation coefficients were all >0.99. Extraction efficiency was >70% for all analytes. Limits of detection were 0.0005 ng/mg for CE and 0.001 ng/mg for the other analytes (COC, BE, and EME). Lower limits of quantification were the lowest points of the calibration curves with acceptable accuracy and precision (coefficient of variation ≤20%). Intra- and inter-day imprecision ranged between 1.5% and 9.5% and 0.7% and 12.6%, respectively. Intra- and inter-day inaccuracy ranged from 0.5% to 12.3% and from 0.7% to 7.1%, respectively. With regard to matrix effects, suppression was <27.5% in all cases. The method was applied to the analysis of several samples derived from forensic cases.