Determination of gamma-hydroxybutyrate in water and human urine by solid phase microextraction-gas chromatography/quadrupole ion trap spectrometry

A simple method of detection was developed for gamma-hydroxybutyrate (GHB). The method involves the derivatization of GHB using a hexyl-chloroformate procedure in aqueous media (such as water or urine), extraction of the derivatization product directly from the sample using solid-phase microextraction, and subsequent separation and detection with gas chromatography quadrupole ion trap mass spectrometry. The deuterated form of GHB (GHB-D6) is used as an internal standard for quantitation. The method was linear for GHB-spiked pure water samples from 2 to 150 microg/mL GHB with a detection limit of 0.2 microg/mL. Spiked urine samples showed linearity from 5 to 500 microg/mL GHB with a detection limit of 2 microg/mL. The SPME-GC/MS method is applied to actual case samples, and the results are compared to those values obtained using a conventional GC/MS method. Sensitivity and linearity are comparable to those seen using traditional methods of separation, yet the SPME method is superior due to the simplicity, speed of analysis, reduction in solvent waste, and ability to differentiate between GHB and gamma-butyrolactone (GBL).     

Improved method for the detection of TATP after explosion

TATP in post explosion exhibits was reported earlier to be best recovered from vapor phase. A typical procedure includes its adsorption on Amberlite XAD-7, elution with acetonitrile and analysis by GC/MS. In this work, improved recovery of TATP from the vapor phase was achieved by SPME using PDMS/DVB fiber and immediate sampling to GC/MS. The recovery of TATP by SPME was compared with headspace and with adsorption on Amberlite XAD-7 by spiking onto filter paper put in a 100 mL beaker. The limit of detection of TATP was 6.4 ng in these conditions, few orders magnitude more than in the other tested methods. Recovery of TATP in the presence of various solvents was also studied. Acetone, water, and mixtures of water:alcohols (1:1) were found to reduce the recovery of TATP. Using SPME, TATP has been identified in dozens of post-explosion cases.     

Headspace solid phase microextraction for the gas chromatographic analysis of methyl-parathion in post-mortem human samples. Application in a suicide case by intravenous injection

A simple and rapid procedure for the determination of methyl-parathion (m-p) in post-mortem biological samples was developed using headspace solid phase microextraction (SPME) and gas chromatography (GC) with nitrogen-phosphorous detection (NPD). Methyl-parathion was extracted on 85 microm polyacrylate SPME fiber. Salt addition, extraction temperature, and extraction time were optimized to enhance the sensitivity of the method. The linearity (y = 0.0473x - 0.0113, R2 = 0.9992) and the dynamic range (0.1-40 microg/ml) were found very satisfactory. The recoveries of methyl-parathion were found to be 46% in spiked human whole blood, 53% in spiked homogenized liver tissue, and 54% in spiked homogenized kidney tissue compared with samples prepared in water. The coefficients of variations for 2, 4, and 20 microg/ml of methyl-parathion in blood ranged from 0.9 to 5.1%, whereas the detection limit of the method was satisfactory (1 ng/ml in aqueous samples, 50 ng/ml in whole blood). The developed procedure was applied to post-mortem biological samples from a 21-year-old woman fatally poisoned (suicide) by intravenous injection of methyl-parathion. The intact insecticide was found in the post-mortem blood at a concentration of 24 microg/ml. No methyl-parathion was detected in the liver, kidneys, and gastric contents.     

Solid phase micro extraction coupled with on-column GC/ECD for the post-blast analysis of organic explosives

Gas chromatographic analysis with electron capture detection is very sensitive to post-blast residues and useful for the determination of organic explosive molecules. But many compounds extracted from the matrices may interfere with the explosives. Using SPME, most interfering compounds are eliminated so the identification is easier. Another advantage of the technique is a low limit of detection. In this study, four different SPME fibers were tested to analyze the most common encountered organic explosives including nitro aromatics, nitramines and nitro-esters. Different parameters were tested (desorption time, agitation, ...) and a special device has been created to optimize the agitation. Direct desorption effect of the SPME fiber on the column compared to normal split-splitless injection is shown. In this way, the degradation of the most sensitive molecules is decreased. An application to a real case is also described in this paper.     

Postmortem determination of the biological distribution of sufentanil and midazolam after an acute intoxication

A case is presented of a death caused by self-injection of sufentanil and midazolam. Biological fluids and tissues were analyzed for midazolam by high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS) and for sufentanil by GC/MS. Midazolam was extracted from basified fluids or tissues homogenated with n-butyl chloride and analyzed by HPLC by using a phosphate buffer: acetonitrile (60:40) mobile phase on a mu-Bondapak C18 column at 240 nm. Sufentanil was extracted from basified fluids and tissue homogenates with hexane:ethanol (19:1). GC/MS methodology for both compounds consisted of chromatographic separation on a 15-m by 0.25-mm inside diameter (ID) DB-5 (1.0-micron-thick film) bonded phase fused silica capillary column with helium carrier (29 cm/s) splitless injection at 260 degrees C; column 200 degrees C (0.8 min) 10 degrees C/min to 270 degrees C; and electron ionization and multiple ion detection for midazolam (m/z 310), methaqualone (IS, m/z 235), sufentanil (m/z 289), and fentanyl (IS, m/z 245). Sufentanil concentrations were: blood 1.1 ng/mL, urine 1.3 ng/mL, vitreous humor 1.2 ng/mL, liver 1.75 ng/g, and kidney 5.5 ng/g. Midazolam concentrations were: blood 50 ng/mL, urine 300 ng/mL, liver 930 ng/g, and kidney 290 ng/g. Cause of death was attributed to an acute sufentanil/midazolam intoxication and manner of death a suicide.     

Analysis of buprenorphine in urine specimens.

The simultaneous determination of buprenorphine (Temgesic) and its major metabolite, N-desalkylbuprenorphine, in urine samples has been studied. By using reversed-phase high-performance liquid chromatography (HPLC) with electrochemical detection, therapeutic concentrations of unconjugated buprenorphine down to 0.2 ng/mL, and 0.15 ng/mL for the metabolite, can be detected in urine samples. This method has been applied to a variety of urine samples from drug users. The possible analytical interference from several other regulated drugs has been studied. The results were also compared with those obtained from a commercial radioimmunoassay (RIA) test. This test is only capable of detecting buprenorphine concentrations higher than 1 ng/mL.     

Evaluation of a Headspace Solid‐Phase Microextraction Method for the Analysis of Ignitable Liquids in Fire Debris

The chemical analysis of fire debris represents a crucial part in fire investigations to determine the cause of a fire. A headspace solid‐phase microextraction (HS‐SPME) procedure for the detection of ignitable liquids in fire debris using a fiber coated with a mixture of three different sorbent materials (Divinylbenzene/Carboxen/Polydimethylsiloxane, DVB/CAR/PDMS) is described. Gasoline and diesel fuel were spiked upon a preburnt matrix (wood charcoal), extracted and concentrated with HS‐SPME and then analyzed with gas chromatography/mass spectrometry (GC/MS). The experimental conditions—extraction temperature, incubation and exposure time—were optimized. To assess the applicability of the method, fire debris samples were prepared in the smoke density chamber (SDC) and a controlled‐atmosphere cone calorimeter. The developed methods were successfully applied to burnt particleboard and carpet samples. The results demonstrate that the procedure that has been developed here is suitable for detecting these ignitable liquids in highly burnt debris.     

Forensic intoxication with clobazam: HPLC/DAD/MSD analysis

Clobazam (Castillium, Urbanil), a benzodiazepine often used as an anxiolytic and in the treatment of epilepsy, is considered a relatively safe drug. The authors present a fatal case with a 49-year-old female, found dead at home. She had been undergoing psychiatric treatment and was a chronic alcoholic. The autopsy findings were unremarkable, except for multivisceral congestion, steatosis and a small piece of a plastic blister pack in the stomach. Bronchopneumonia, bronchitis and bronchiolitis were also diagnosed. Anhigh-performance liquid chromatography (HPLC)/diode array detector (DAD)/mass spectrometry detection (MSD) with electrospray method was developed in order to detect, confirm and quantify clobazam in the post-mortem samples. In the chromatographic separation, a reversed-phase column C18 (2.1 x 150 mm, 3.5 microm) was used with a mobile phase of methanol and water, at a 0.25 ml/min flow rate. Carbonate buffer (pH 10.5) and 20 microl of prazepam (100 microg/ml) as internal standard were added to the samples. A simple and reliable liquid-liquid extraction method for the determination of clobazam in post-mortem samples was described. Calibration curves for clobazam were performed in blood, achieving linearity between 0.01 and 10 microg/ml and a detection limit of 1.0 ng/ml. The clobazam concentration found in post-mortem blood was 3.9 microg/ml, higher than the reported therapeutic concentration (0.1-0.4 microg/ml). The simultaneous acquisition by photodiode array detection and mass spectrometry detection results allowed benzodiazepines to be identified with sufficient certainty. An examination of all the available information suggested that death resulted from respiratory depression due to clobazam toxicity.     

血液、尿液中氯胺酮及其代谢物去甲氯胺酮的HPLC分析

目的 建立血液、尿液中氯胺酮及其代谢物去甲氯胺酮的高效液相色谱(HPLC)分析方法.方法 以非那西丁为内标,检材加入10%的氢氧化钠溶液调节pH值为14,用甲苯提取,离心后取有机层,水浴下吹干,乙腈定容后进HPLC仪分析.结果 检测血液中氯胺酮和去甲氯胺酮的线性范围均是0.05～10μg/mL(r2＞0.999 3),检测尿液中氯胺酮和去甲氯胺酮的线性范围均是0.01～50 μg/mL(r2＞0.999 5).氯胺酮和去甲氯胺酮在血液和尿液中的检测限分别是0.006 μg/mL和0.003 μg/mL.血液和尿液中氯胺酮和去甲氯胺酮的回收率不低于82.4%.检测血液和尿液中氯胺酮和去甲氯胺酮的日内精密度和日间精密度均小于10.0%.将所建的方法应用于给大鼠氯胺酮后的血液和尿液中的氯胺酮和去甲氯胺酮的测定,得到了氯胺酮和去甲氯胺酮在大鼠的药时曲线和尿排药速率曲线. 结论本方法简便、快捷,适用于血液、尿液中氯胺酮及其代谢物去甲氯胺酮的分析.     

Detection of trace drugs of abuse in baby formula using solid‐phase microextraction direct analysis in real‐time mass spectrometry (SPME‐DART‐MS)

The intentional or unintentional adulteration of baby formula with drugs of abuse is one of the many increasingly complex samples forensic chemists may have to analyze. This sample type presents a challenge because of a complex matrix that can mask the detection of trace drug residues. To enable screening of baby formula for trace levels of drugs, the use of solid‐phase microextraction (SPME) coupled with direct analysis in real‐time mass spectrometry (DART‐MS) was investigated. A suite of five drugs was used as adulterants and spiked into baby formula. Samples were then extracted using SPME fibers which were analyzed by DART‐MS. Development of a proof‐of‐concept method was completed by investigating the effects of the DART gas stream temperature and the linear speed of the sample holder. Optimal values of 350°C and 0.2 mm/s were found. Once the method was established, representative responses and sensitivities for the five drugs were measured and found to be in the range of single ng/mL to hundreds ng/mL. Additional studies found that the presence of the baby formula matrix increased analyte signal (relative to methanolic solutions) by greater than 200%. Comparison of the SPME‐DART‐MS method to a traditional DART‐MS method for trace drug detection found at least a factor of 13 improvement in signal for the drugs investigated. This work demonstrates that SPME‐DART‐MS is a viable technique for the screening of complex matrices, such as baby formula, for trace drug residues and that development of a comprehensive method is warranted.     

Evaluation of principal components analysis with high-performance liquid chromatography and photodiode array detection for the forensic differentiation of ballpoint pen inks.

Inks from seven black and eight blue ballpoint pens were separated by a high-performance liquid chromatography (HPLC) method utilizing a photodiode array detection (PDA). A classifier flowchart was designed for the chromatographic data based on the presence or absence of certain peaks at different wavelengths to qualitatively discriminate between the inks. The same data were quantitatively classified by principal components analysis (PCA) to estimate the separation between a pair of classes of ink samples. It was found that the black ballpoint pen inks were discriminated satisfactorily utilizing two-dimensional data of the peak areas and retention times at the optimum wavelengths. The blue pens were discriminated by analyzing the chromatographic data at four different wavelengths simultaneously with a cross-validated PCA. The results of this study indicated that HPLC-PDA coupled with chemometrics could make a powerful discriminating tool for the forensic chemist, especially when analyzing extensive and/or complex data.     

Comparative analysis of gamma-hydroxybutyrate and gamma-hydroxyvalerate using GC/MS and HPLC

This paper describes two analytical techniques used to separate and quantify gamma-hydroxybutyrate (GHB) and gamma-hydroxyvalerate (GHV). The first technique was a N,O-bis(trimethylsilyl)triflouro-acetimide-trimethylchlorosilane derivatization, followed by gas chromatography/mass spectrometry analysis using an HP-5 capillary column at a rate of 1.0 mL/min with a run time of 9.25 min. This technique was found to be sensitive (LOD 1 pg on column) and gave a low average error (5%) in a beverage study. When supplemented by a surrogate spike, the method yielded 97% analyte recovery from beverages. The second technique was high-performance liquid chromatography/UV (HPLC/UV) using a C-18 column with a (20:80% v/v) methanol:dibasic phosphoric buffer (10 mM, pH 3) at a rate of 1.00 mL/min with a run time of 7.5 min. UV detection occurred at 254 nm. This method was found to be less sensitive (LOD 0.05 microg on column) for direct analysis of aqueous samples. To remove interferences seen in the beverage study, a liquid-liquid extraction before HPLC analysis was tested. However, a decreased sensitivity (LOD 100 microg on column) and irreproducible peak profiles resulted.     

Rapid and simple method for direct determination of several amphetamines in seized tablets by GC--FID

A simple and rapid method for direct simultaneous determination of amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA) and N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB) in seized tablets was developed using gas chromatography with flame ionization detection. Separation of all six underivatized amphetamines, including diphenylamine as internal standard, was performed in about 6 min, using SPB-50 capillary column. Amphetamine and methamphetamine eluted with negligible tailing while the other amphetamines had highly symmetrical peaks. Sensitivity per component on-column was in the nanogram range, and reproducibility from 2.6 to 6.6% at low concentration (2.4 microg/mL) and from 1.2 to 2.6% at high (70 microg/mL) concentration. The method has a wide linear range, from Limit of detection (LOD) to almost 200 microg/mL, thus allowing analysis of different samples across a wide range of possible concentrations of amphetamines. This simple, fast and precise method using gas chromatography--flame ionization detector (GC--FID), in conjunction with other methods (TLC, IR, HPLC), can be used for identification of amphetamines and direct determination in seized tablets, especially in laboratories with heavy workload.     

A solid-phase microextraction method for the detection of ignitable liquids in fire debris

A solid-phase microextraction (SPME) procedure involving direct contact between the SPME fibers and the solid matrix and subsequent gas chromatography/mass spectrometric analysis for the detection of accelerants in fire debris is described. The extraction performances of six fibers (100 mum polydimethylsiloxane, 65 mum polydimethylsiloxane-divinylbenzene, 85 mum polyacrylate, 85 mum carboxen-polydimethylsiloxane, 70 mum Carbowax-divinylbenzene, and 50/30 mum divinylbenzene-Carboxen-polydimethylsiloxane) were investigated by directly immersing the fibers into gasoline, kerosene, and diesel fuel. For simulated fire debris, in the direct contact extraction method, the SPME fiber was kept in contact with the fire debris matrix during extraction by penetrating plastic bags wrapping the sample. This method gave comparable results to the headspace SPME method in the extraction of gasoline and kerosene, and gave an improved recovery of low-volatile components in the extraction of diesel fuel from fire debris. The results demonstrate that this procedure is suitable as a simple and rapid screening method for detecting ignitable liquids in fire debris packed in plastic bags.     

Cannabinoids determination in oral fluid by SPME–GC/MS and UHPLC–MS/MS and its application on suspected drivers

The confirmation of Δ9-tetrahydrocannabinol (THC) in oral fluid (OF) is an important issue for assessing Driving Under the Influence of Drugs (DUID). The aim of this research was to develop a highly sensitive method with minimal sample pre-treatment suitable for the analysis of small OF volumes (100 μL) for the confirmation of cannabinoids in DUID cases. Two methods were compared for the confirmation of THC in residual OF samples, obtained from a preliminary on-site screening with commercial devices. An ultra high performance LC–MS (UHPLC–MS/MS) method and an SPME–GC/MS method were hence developed. 100 μL of the residual mixture OF/preservative buffer or neat OF was simply added to 10 μL of THC-D3 (1 μg/mL) and submitted to the two different analyses: A — direct injection of 10 μL in UHPLC–MS/MS in positive electrospray ionisation (ESI) mode and B — sampling for 30 min with SPME (100 μm polydimethylsiloxane or PDMS fibre) and direct injection by desorption of the fibre in the GC injection port.The lowest limit of detection (LLOD) of THC was 2 ng/mL in UHPLC–MS/MS and 0.5 ng/mL in SPME–GC/MS. In addition, cannabidiol (CBD) and cannabinol (CBN) could be detected in GC/MS equipment at 2 ng/mL, whilst in UHPLC–MS/MS the LLOD was 20 ng/mL.Both methods were applied to 70 samples coming from roadside tests. By SPME–GC/MS analysis, THC was confirmed in 42 samples, whilst CBD was detected in 21 of them, along with CBN in 14 samples. THC concentrations ranged from traces below the lowest limit of quantification or LLOQ (2 ng/mL) up to 690 ng/mL.     

尿中氯胺酮及其代谢物盘鉴和GC/MS/SIM测定

目的 研究尿中氯胺酮(KET)及其代谢物去甲基氯胺酮(NKET)的盘鉴(Disk SPE)。方法 用含有化学键合C18和强酸型强阳离子交换(SCX)基团的萃取柱SPEC.C18 AR/MP3萃取,加入萃取柱前的尿样用0.1mol/L磷酸盐缓冲溶液(pH 6)稀释,洗脱溶剂为含2％(v/v)氨水的乙酸乙酯;以2,4,6-三硝基甲苯(TNT)为色谱内标,GC/MS/SIM检测。结果 在加标量为0.5μg/mL、2μg/mL和6μg/mL的控制尿样中,KET和NKET的平均回收率分别为91.5％和79.9％,6次测定的RSD均为8.7％;线性范围0.02-8μg/mL,线性相关系数分别为0.9819和0.9964;检出限(S/N=3)分别为6ng/mL和4ng/mL;总离子色谱图背景低,杂质少。同一根萃取柱重复使用8次以上未见性能下降;嫌疑尿样中检出KET和/或NKET,和常规的液液萃取结果相符。结论 该方法适用于尿中KET和NKET的同时测定。     

A preliminary study of the analysis of explosives using packed-column supercritical fluid chromatography with atmospheric pressure chemical ionisation mass spectrometric detection

A packed-column supercritical fluid chromatographic (SFC) separation of explosive compounds hyphenated to atmospheric pressure chemical ionisation (APCI) mass spectrometric (MS) detection has been developed. Nitroaromatics, nitramines and nitrate esters can be resolved and identified, with theoretical limits of detection of approximately 100 ng on column. This represents a development over previously described gas chromatography–thermal energy analysis (GC–TEA), gas chromatography– electron capture detection (GC–ECD) and SFC methods for the analysis of explosives due to the molecular identification afforded by the mass spectrometry. Explosives in the combinations expected in commercially available mixtures can be separated and identified. A successful application to a laboratory trial simulating casework is described.     

Qualitative and quantitative analysis of cephradine in biological materials by high performance liquid chromatography

A reversed phase high performance liquid chromatographic method was developed for the determination of cephradine, one of the commonly used antibiotics, in biological materials. Mimic samples for stomach contents, miso soup, were applied to high performance liquid chromatography (HPLC) after centrifugation and purification by Sep-Pak C18 cartridge treatment. Serum samples deproteinized or urine samples diluted were directly injected into the HPLC. The recoveries of cephradine from these materials were 95-97% and the detection limit was 0.01 microgram/injection. This method was applied to the analysis of cephradine in stomach contents obtained by autopsy. After purification by the cartridge treatment, cephradine in the sample was identified and determined by HPLC and further confirmed by thin-layer chromatography (TLC) and mass spectrometry (MS).     

New developments in SPME Part 2: Analysis of ammonium nitrate-based explosives

Solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) is a simple, reliable technique for the recovery and analysis of many organic explosives. However, this technique is impractical for the analysis of ammonium nitrate-type explosives due to the extreme polarity, low molecular weight, and high volatility of the amine moiety. This article describes an initial investigation of a derivatization process utilizing alkylchloroformates that converts ammonium nitrate and methylammonium nitrate into a form suitable for recovery by SPME and analysis by GC-MS.