Simple Gas Chromatography-mass Spectrometry Research Articles

Development and Validation of a Single Step GC/MS Method for the Determination of 41 Drugs and Drugs of Abuse in Postmortem Blood

A toxicology laboratory often receives a high number of samples from cases (autopsies or clinical) that may require the quick delivery of trustworthy, accurate results. Thus, there is a great need for a fast and reliable method that is capable of identifying and determining a large number of drugs and drugs of abuse in biological matrices, and especially in blood. In the present study, we describe the development of a fast and simple gas chromatography–mass spectrometry (GC-MS) method for the determination of 41 drugs and drugs of abuse (DOA) in blood. Sample pre-treatment by alkaline liquid–liquid extraction (LLE) was studied through the utilization of different solvents and solvent-to-sample ratios (v/v), which aimed to achieve a greater extraction efficiency and detection sensitivity with a decreased need for large sample volumes. Butyl acetate with a sample-to-solvent ratio of 4:1 (1 mL blood: 0.25 mL butyl acetate) was the most efficient. The method was validated for all analytes, and the evaluation parameters were within the acceptance criteria. The coefficient of determination (R2) was between 0.9934 and 1, the limits of detection (LODs) ranged between 1 ng/mL and 113 ng/mL, and the limits of quantification (LOQs) were between 4 ng/mL and 375 ng/mL for all analytes. The determinations were accurate (accuracy% from 84% to 114%) and precise (RSD% from 0.66% to 14.8% for low concentrations). Deconvolution Reporting Software (DRS) for GC-MS was optimized and applied for data analysis to enhance the identification potential, thereby avoiding false identifications (false positives) and increased productivity. The NIST Automated Mass Spectral Deconvolution and Identification Software (AMDIS) and the analytical utility Retention Time Lock (RTL) Database Library assisted in data evaluation. The method was applied to 89 postmortem cases (history of mental disorders and use of psychiatric pharmaceuticals) in which diazepam (0.13 to 4.34 μg/mL), citalopram (0.04 to 0.24 μg/mL), alprazolam (0.01 to 0.12 μg/mL), olanzapine (0.009 to 0.083 μg/mL), mirtazapine (0.01 to 0.33 μg/mL), venlafaxine (0.006 to 0.92 μg/mL), haloperidol (0.007 to 0.13 μg/mL), and zolpidem (0.01 to 0.16 μg/mL) were successfully quantitated.

A review of extraction methods for the analysis of pharmaceuticals in environmental waters

Pharmaceuticals play a vital role in the prosperity of human and veterinarian health by diagnosing, treating, or preventing diseases. Produced in large quantities for various applications, pharmaceuticals primarily enter the environment through wastewater systems. Historically, the ability to detect pharmaceuticals in environmental waters has been limited. However, growing technological advancements are changing pharmaceutical detection capabilities and our understanding of their occurrence in environmental waters. The analysis of pharmaceuticals in the environment began with simple gas chromatography-mass spectrometry and evolved to using liquid chromatography-tandem mass spectrometry as the dominant method. Many of these methods require sample extraction, with solid phase extraction (SPE) being the most popular. Additionally, miniaturized and on-line extraction procedures have also attracted a lot of attention. Nevertheless, approaches involving large volume injections without the need for sample enrichment have made significant strides in recent years. The aim of this review is to provide an overview of extraction methods for environmental water samples containing trace levels of pharmaceuticals and how current applications will mold how they are analyzed in the future.

Aroma Profile Characterization of Mahi-Mahi and Tuna for Determining Spoilage Using Purge and Trap Gas Chromatography-Mass Spectrometry.

Alcohols, aldehydes, ketones, amines, and sulfur compounds are essential aroma compounds related to fish flavor and spoilage. Gas chromatography-mass spectrometry (GC-MS) is an instrument that is widely used to identify and quantify volatile and semi-volatile compounds in fish products. In this research, a simple and accurate GC-MS method was developed to determine the aroma profile of mahi-mahi and tuna for chemical indicators of spoilage. In the developed GC-MS method, trichloroacetic acid (TCA) solution was used to extract analytes from homogenized fish samples. The purge and trap system was used for sample introduction, and the GC-MS with an RTX-Volatile Amine column was able to separate compounds without a derivatization procedure. The created purge and trap gas chromatography-mass spectrometry (PT-GC-MS) method could identify and quantify twenty aroma compounds in mahi-mahi (Coryphaena hippurus) and 16 volatile compounds in yellowfin tuna (Thunnus albacares) associated with fish spoilage. The amines (dimethylamine, trimethylamine, isobutylamine, 3-methylbutylamine, and 2-methylbutanamine), alcohols (2-ethylhexanol, 1-penten-3-ol and isoamyl alcohol, ethanol), aldehydes (2-methylbutanal, 3-methylbutanal, benzaldehyde), ketones (acetone, 2,3-butanedione, 2-butanone, acetoin), and dimethyl disulfide strongly statistically correlated with poorer quality tuna and mahi-mahi and were considered as the key spoilage indicators. PRACTICAL APPLICATION: A simplified and rapid purge and trap gas chromatography-mass spectrometry (PT-GC-MS) method developed in this research was able to identify and quantify important spoilage compounds in mahi-mahi and yellowfin tuna. This method is an efficient analytical method for determining volatile profiles of fish samples for industry analytical labs or the government. The identified analytical quality markers can be used to monitor the spoilage level of tuna and mahi-mahi.

Simple and Fast Gas-chromatography Mass Spectrometry Assay to Assess Delta 9-Tetrahydrocannabinol and Cannabidiol in Dogs Treated with Medical Cannabis for Canine Epilepsy.

To date, an increasing number of pet owners, especially in the USA, are using cannabis-derived products containing generally delta 9-tetrahydrocannabinol (THC) and cannabidiol (CBD) to help their animals' health. Unfortunately, studies on the clinical use of cannabinoids in veterinary medicine are still limited, and the application of analytical methodologies for the determination of cannabinoids in animal (especially dog) biological matrices such as plasma, is still missing. A reliable, fast, accurate, simple gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the quantification of THC and CBD in plasma samples of eight dogs under therapeutic treatment for epilepsy and receiving oral administration of medical cannabis (Bediol). The method was linear for both the analytes under investigation with coefficients of determination (r2) of at least 0.99. Absolute analytical recovery (mean ± SD) ranged from 80.6 ± 6.2% for THC and 81.7 ± 4.3% for CBD. The matrix effect showed less than 10% analytical suppression due to endogenous substances for both the analytes. The intra-assay and inter-assay precision values ranged from 4.9% to 12.7%, and from 5.2% to 8.7% respectively. The intra-assay and inter-assay accuracy values ranged from 2.3% to 9.6% and from 3.4% to 13.0%, respectively. The validated method was successfully applied to real samples; moreover, to assess the potential of the method applicability and robustness in future veterinary clinical studies on cannabinoids therapy, we attempted to follow the kinetic of THC and CBD in the plasma of two dogs under therapy at different times after Bediol administration.

Risk Mitigation Methods for Removal of Pesticide Residues in Brinjal for Food Safety

The commercial production of highly cultivated and consumed brinjal is highly dependent on regular usage of insecticides to protect the crop from insect pests. The increased consumer awareness and legal issues on food safety, with special reference to insecticide residues in foods, led us to attempt for cheap and effective methods for removal of pesticide residues to address the issues of consumer and food safety, as the farmers are not following the Good Agricultural Practices i.e pre-harvest intervals. The most commonly used pesticides such as profenophos, chlorpyriphos, dimethoate, malathion, phosalone, quinalphos, triazophos and -cyhalothrin were sprayed at recommended doses at brinjal formation stage, samples were collected at 2 hours after treatment to quantify the deposits. The samples were subjected to various household treatments (tap water wash, lemon water wash, dipping in 2% salt water for 15 min, dipping in 2% tamarind water for 10 min, washing with 0.1% sodium bicarbonate solution, washing with 4% acetic acid solution, biowash, cooking), each in three replications, and analysed for residues using validated quick,easy cheap rugged and simple method (Quechers method and GC-ECD, (GAS Chromatography Electron capture detector) FPD(Flame photometric detector) and GC-MS(Gas Chromatography Mass spectrometry) so as to estimate the % removal and their effectiveness. Out of all treatments, dipping in 2% salt solution for 10 minutes is very effective in removing 45%, 43%, 52%, 50%, 54%, 48% and 76% of dimethoate, chlorpyriphos, quinalphos, profenophos, phosalone, -cyhalothrin and malathion, respectively, and cooking removed insecticides in the range 55-80%. Dipping fruits and vegetables in 2% salt solution for 15 minutes is the best household method for removal of pesticide residues, and also the method is effective in reducing the residues below MRL (Maximum Residue Limits).

Quantitative Analysis and Discrimination of Steamed and Non-Steamed Rhizomes of Curcuma wenyujin by GC–MS and HPLC

Simple gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) methods were developed for quantifying eight volatile compounds and 10 sesquiterpenoids, respectively. GC-MS analysis was performed on an HP-5MS capillary column (30 m×0.25 mm i.d.) coated with 0.25 μm film 5% phenyl-95% methylpolysiloxane and selected ion monitoring was used for quantification. Four volatile and previously unquantified monoterpenoids were determined. HPLC analysis was performed on a C18 column with water and acetonitrile as mobile phase. The proposed method, determined 10 non-polar and polar sesquiterpenoids simultaneously, which covered a wider polar range of analytes and had a more perfect resolution. Among them, five sesquiterpenoids were not determined before and some specific components, (4S,5S)-germacrone-4,5-epoxide, curcumenone and dehydrocurdione were completely separated for the first time. Both methods were validated for linearity, limit of detection and quantification, precision, accuracy, recovery and system suitability. The methods were simple, effective, reliable and successfully applied to global detection and analysis of volatile and non-volatile components of steamed and non-steamed rhizomes of Curcuma wenyujin (Wen-E-Zhu (WEZ) and Pian-Jiang-Huang (PJH)). Multivariate statistical analysis was employed to distinguish PJH and WEZ and seven chemical components, including (4S,5S)-germacrone-4,5-epoxide, curcumenone, β-elemene, curzerene, borneol, isoborneol and camphor, were screened as chemical markers. The present study provided a promising method for accurate discrimination of the herbal medicines with the same origin.

Development and validation of a fast and simple multi-analyte procedure for quantification of 40 drugs relevant to emergency toxicology using GC-MS and one-point calibration.

Diagnosis and prognosis of poisonings should be confirmed by comprehensive screening and reliable quantification of xenobiotics, for example by gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS). The turnaround time should be short enough to have an impact on clinical decisions. In emergency toxicology, quantification using full-scan acquisition is preferable because this allows screening and quantification of expected and unexpected drugs in one run. Therefore, a multi-analyte full-scan GC-MS approach was developed and validated with liquid-liquid extraction and one-point calibration for quantification of 40 drugs relevant to emergency toxicology. Validation showed that 36 drugs could be determined quickly, accurately, and reliably in the range of upper therapeutic to toxic concentrations. Daily one-point calibration with calibrators stored for up to four weeks reduced workload and turn-around time to less than 1 h. In summary, the multi-analyte approach with simple liquid-liquid extraction, GC-MS identification, and quantification over fast one-point calibration could successfully be applied to proficiency tests and real case samples.

Gas chromatography-mass spectrometry method for rapid identification and differentiation ofBurkholderia pseudomalleiandBurkholderia malleifrom each other,Burkholderia thailandensisand several members of theBurkholderia cepaciacomplex

To develop a simple gas chromatography-mass spectrometry (GC-MS) method for the detection and differentiation of Burkholderia pseudomallei and Burkholderia mallei from each other, Burkholderia thailandensis and several members of the Burkholderia cepacia complex. Biomarkers were generated by one-step thermochemolysis (TCM) and analysed using a GC-MS system. Fragments of poly-3-hydroxybutyrate-co-hydroxyvalerate [poly(3HBA-co-3HVA)] produced by TCM were useful biomarkers. Several cellular fatty acid methyl esters were important in differentiating the various Burkholderia species. A statistical discrimination algorithm was constructed using a combination of biomarkers. The identities of four B. pseudomallei strains, four B. mallei strains and one strain of each near neighbour were confirmed in a statistically designed test using the algorithm. The detection limit for this method was found to be approximately 4000 cells. The method is fast, accurate and easy to use. The algorithm is robust against different growth conditions (medium and temperature). This assay may prove beneficial in a clinical diagnostic setting, where the rapid identification of B. pseudomallei is essential to effective treatment. This method could also be easily employed after a biological attack to confirm the presence of either B. pseudomallei or B. mallei.

Simultaneous analysis of synthetic cannabinoids in the materials seized during drug trafficking using GC-MS

A rapid and simple gas chromatography-mass spectrometry (GC-MS) method was developed and validated to identify and quantify synthetic cannabinoids in the materials seized during drug trafficking. Accuracy and reproducibility of the method were improved by using deuterated JWH-018 and JWH-073 as internal standards. Validation results of the GC-MS method showed that it was suitable for simultaneous qualitative and quantitative analyses of synthetic cannabinoids, and we analyzed synthetic cannabinoids in seized materials using the validated GC-MS method. As a result of the analysis, ten species of synthetic cannabinoids were identified in dried leaves (n = 40), bulk powders (n = 6), and tablets (n = 14) seized in Korea during 2009-2012, as a single ingredient or as a mixture with other active co-ingredients. JWH-018 and JWH-073 were the most frequently identified compounds in the seized materials. Synthetic cannabinoids in the dried leaves showed broad concentration ranges, which may cause unexpected toxicity to abusers. The bulk powders were considered as raw materials used to prepare legal highs, and they contained single ingredient of JWH-073, JWH-019, or JWH-250 with the purity over 70 %. In contrast, JWH-018 and JWH-073 contents in the tablets were 7.1-13.8 and 3.0-10.2 mg/g, respectively. Relatively low contents in the tablets suggest that the synthetic cannabinoids may have been added to the tablets as supplements to other active co-ingredients.

Rapid and Simple GC–MS Method for Determination of Psychotropic Phenylalkylamine Derivatives in Nails Using Micro‐Pulverized Extraction*

A rapid and simple gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the simultaneous detection and quantification of five psychotropic phenylalkylamines (amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, and norketamine) in toenails. After external decontamination, nail clippings were mechanically pulverized with a bead mill and then incubated in methanol under ultrasonication at 50°C for 1 h. The resulting solutions were evaporated to dryness, derivatized, and analyzed by GC-MS. The intra- and inter-day precisions were within 10.7% and 13.9%, respectively. The intra- and inter-day accuracies were -4.2% to 5.0% and -2.4% to 8.4%, respectively. Limits of detection and quantification for each analyte were lower than 0.024 and 0.08 ng/mg, respectively. The recoveries were in the range of 80.6-87.5%. The results indicated that the proposed method is a simple, rapid, accurate, and precise for quantification of five phenylalkylamines in nails. The method was successfully applied to the simultaneous detection and quantification of phenylalkylamines in nail samples of possible drug abusers.

Multipesticide residue analysis in maize combining acetonitrile-based extraction with dispersive liquid–liquid microextraction followed by gas chromatography–mass spectrometry

A fast and simple gas chromatography–mass spectrometry (GC–MS) method for determination of forty-one pesticide residues in maize is introduced. The sample preparation involves liquid–liquid partitioning with acetonitrile in presence of anhydrous MgSO 4 and NaCl (QuEChERS) followed by dispersive liquid–liquid microextraction (DLLME) using carbon tetrachloride as extractive solvent and the extract obtained by QuEChERS as dispersive solvent. The main factors influencing DLLME efficiency including extractive solvent type and volume as well as the volume of dispersive solvent were evaluated in this study. The DLLME procedure effectively provides an enrichment of the extract and a cleanup of certain polar matrix components, which can maximize the sensitivity when a single quadrupole MS is used. For validation purposes, recoveries studies were carried out at two concentration levels, yielding recovery rates in the range 70–120% for 82% of the analytes. A good linearity and precision, with relative standard deviations generally below 20% were obtained for all forty-one pesticides. The limits of detection obtained were lower than 19 μg kg −1 for more than 63% of the analytes. In two of a total of ten samples of maize, residues of lindane, tefluthrin, pirimicarb, folpet and bifenthrin were found, although at levels below the maximum limit established for this kind of samples.

Simultaneous Determination of Estradiol Valerate and Medroxyprogesterone Acetate in a Tablet Formulation by Gas Chromatography-Mass Spectrometry

A new and simple gas chromatography-mass spectrometry (GC-MS) method has been developed for simultaneous determination of estradiol valerate (EV) and medroxyprogesterone acetate (MPA) in a tablet formulation. The validation of the proposed method was carried out for selectivity, linearity, accuracy, precision, recovery, limits of detection and quantification. The developed method can be used for routine quality control (QC) analysis of titled drugs in combination in tablet formulation.

Determination of Phenazopyridine in Human Plasma by GC--MS and its Pharmacokinetics

A sensitive, selective, and simple gas chromatography-mass spectrometry method is developed for quantitation of phenazopyridine (PAP) in human plasma using internal standard (diazepam). PAP and IS are extracted from plasma by liquid-liquid extraction and analyzed on a DB-5MS column with mass selective detector. Excellent linearity is found between 5-500 ng/mL (r = 0.9992, n = 7) for PAP in human plasma. The limit of detection is 0.3 ng/mL. Intra- and Inter-day precisions expressed as the relative standard deviation for the method are 1.37-6.69% and 1.24-6.01%, respectively. Extraction efficiency is more than 90%, and recoveries are in the range of 92.65-96.21%. This method is successfully applied for the pharmacokinetics and bioequivalence of 2 formulations of PAP in 18 healthy male volunteers who received a single 200 mg dose of each formulation.

Reproducibility of gas chromatography–mass spectrometry measurements of 2H labeling of water: Application for measuring body composition in mice

Deuterium-labeled water ( 2H 2O) has emerged as a novel isotope tracer. Following the administration of 2H 2O, it is possible to study the dynamics of carbohydrate, protein, lipid, and DNA and to determine body composition. Those studies require reliable measurements of the 2H labeling of water. Although simple gas chromatography–mass spectrometry (GC–MS) methods have been developed for measuring the 2H enrichment of biological fluids, investigators have not reported on the intra- and/or interdaily variability of the measurements. We have experimentally examined the reproducibility of one GC–MS method for measuring the 2H labeling of water. Briefly, hydrogen (deuterium) atoms in water were exchanged with those bound to acetone, and the 2H labeling of acetone was then determined under electron impact ionization. We found that the coefficient of variation is generally less than 0.5% when water is labeled between 0 and 2.8 mole percentage excess 2H. We demonstrated that this highly reproducible result allows one to use 2H 2O and the “acetone method” to measure physiological parameters such as body composition in mice.

Characterization of archaeological frankincense by gas chromatography–mass spectrometry

A simple gas chromatography–mass spectrometry (GC–MS) method has been developed for the characterization of frankincense in archaeological samples. After trimethylsilylation of the methanolic extract, 15 triterpenoids have been found among the chemical constituents of commercial olibanum (α-boswellic acid, 3- O-acetyl-α-boswellic acid, β-boswellic acid, 3- O-acetyl-β-boswellic acid, α-amyrin, β-amyrin, lupeol, 3- epi-α-amyrin, 3- epi-β-amyrin, 3- epi-lupeol, α-amyrenone, β-amyrenone, lupenone, 3α-hydroxy-lup-20(29)-en-24-oic acid and 3- O-acetyl-hydroxy-lup-20(29)-en-24-oic acid). These compounds have been unequivocally identified by retention time and mass spectral comparison with pure standards previously isolated, for the most part, in our laboratory. Within these triterpenes, acid ones, the corresponding O-acetates, and their products of degradation were found to be characteristic of frankincense ( Boswellia resin). The presence of these unusual triterpenic compounds in an archaeological resinous sample, recovered during excavations from Dahshour site (Egypt, XIIth Dynasty), enabled us to identify unambiguously frankincense resin among several other materials. Additional chromatographic peaks of this sample were assigned to broad chemical classes using retention time and mass spectra features.

Determination of alkylmethylphosphonic acids, the main metabolites of organophosphorus nerve agents, in biofluids by gas chromatography-mass spectrometry and liquid-liquid-solid-phase-transfer-catalyzed pentafluorobenzylation.

A simple gas chromatography-mass spectrometry (GC-MS) procedure has been developed for the main metabolites of organophosphorus nerve agents, alkylmethylphosphonic acids (AMPAs; alkyl = Et, i-Pr, and pinacolyl) in biofluids via extractive pentafluorobenzylation. The derivatization was carried out under liquid-liquid-solid-phase-transfer conditions using a polymer-bound tri-n-butylmethylphosphonium bromide as a catalyst. AMPAs in aqueous samples were semiquantitatively extracted into a small-volume organic layer as their pentafluorobenzyl derivatives at pH 4.5 (85 degrees C). Sample pretreatments for urine, serum, and saliva were each examined to minimize matrix interference. The detection limits of APMAs by electron-impact ionization GC-MS were around 50 ng/mL and 2.5-10 ng/mL in the full-scan and selected-ion monitoring modes, respectively. In order to detect trace-level AMPAs, negative-ion chemical ionization (NICI) was also employed to enhance sensitivity. The detection limits of AMPAs in biofluids were typically 60 pg/mL by GC-NICI-MS.

Simultaneous determination and enantiomeric resolution of mecoprop and dichlorprop in soil samples by high-performance liquid chromatography and gas chromatography–mass spectrometry

A rapid, precise and sensitive method was developed for the quantitative simultaneous determination of mecoprop and dichlorprop in soil samples by reversed-phase high-performance liquid chromatography (HPLC), thus making it very appropriate for degradation studies where many samples have to be analysed. This method was supplemented with a simple gas chromatography–mass spectrometry (GC–MS) ion trap method developed using a chiral permethylated-β-cyclodextrin stationary phase in order to determine the relative amounts of the R and S enantiomeric forms of these herbicides. Recovery rates for natural soils were around 80% at concentrations of 0.5 and 1.0 μg/g. Lower recoveries were achieved for the 10% peat-modified soil samples. The analytical sensitivity of the HPLC technique was 0.11 and 0.07 ng/μl, for 20 μl injections, for mecoprop and dichlorprop, respectively.

Quantitation of Propofol Metabolite, 2,6-Diisopropyl-1,4-quinol, by Gas Chromatography-Mass Spectrometry

Propofol is an intravenous anaesthetic widely used for induction and maintenance of anaesthesia and for sedation. A sensitive and simple gas chromatography-mass spectrometry (GC-MS) method for the determination of 2,6-diisopropyl-1,4-quinol, the major hydroxylated propofol metabolite, is presented. Thymol was used as internal standard. Thymol and 2,6-diisopropyl-1,4-quinol are extracted under basic conditions. The extraction efficiencies for quinol metabolite was > 90 %. Standard curves were linear over the ranges of 50 to 2500 ng ml−1. This assay represents an alternative to existing methods of 2,6-diisopropyl-1,4-quinol analysis, which use HPLC. The assay was applied to the analysis of propofol metabolism in vitro by rat liver microsomes.