Sensitive Gas Chromatography-tandem Mass Spectrometry Research Articles

GC-MS Method for Quantification and Pharmacokinetic Study of Four Volatile Compounds in Rat Plasma after Oral Administration of Commiphora myrrh (Nees) Engl. Resin and In Vitro Cytotoxic Evaluation

A rapid, simple, and sensitive gas chromatography–tandem mass spectrometry (GC–MS) method was established and validated for simultaneous determination of four volatile compounds, namely curzerene, methoxyfuranodiene, β-elemene, and α-pinene in rat plasma samples after oral administration of the resin extract of Commiphora myrrh using limonene as an internal standard (IS). Liquid-liquid extraction using hexane and ethyl acetate (1:1) mixture as an extracting agent was used for the samples extraction procedure. The GC–MS system was operated under selective ion monitoring (SIM) mode using Perkin Elmer Elite 5MS column (30 m × 0.25 mm × 0.25 µm film thickness). Specificity, linearity, precision, accuracy, extraction recovery, and stability were used to validate the developed method. The assay showed good linearity (r2 ≥ 0.998), and the lowest limits of quantification (LLOQ) were 3.97–21.38 ng/mL for the four analytes. This assay was successfully applied to pharmacokinetic studies of the four volatile compounds in rat plasma. The antiproliferative activity of these volatile compounds was evaluated against lung carcinoma (A549) and colon (LoVo) cell lines, were each compound caused variable inhibition on cells proliferation and methoxyfuranodiene exerted the strong antiproliferative activity against both cell line according to IC50 values.

Establishment and Validation of a GC-MS/MS Method for the Quantification of Penicillin G Residues in Poultry Eggs.

A simple and sensitive gas chromatography–tandem mass spectrometry (GC–MS/MS) method was established for the quantitative screening of penicillin G residues in chicken and duck eggs (whole egg, yolk and albumen). The analyte was separated on a TG-1MS capillary column (30.0 m × 0.25 mm i.d., 0.25 μm) with an external calibration method and electron impact (EI) ionization. Samples were pretreated using an accelerated solvent extraction (ASE) procedure followed by solid-phase extraction (SPE) on HLB cartridges (60 mg/3 mL). The derivative, which was safer and easier to store than penicillin G, was obtained by reacting trimethylsilyl diazomethane (TMSD) with penicillin G. The method was validated by the following parameters: linearity, accuracy, precision, limit of detection (LOD) and limit of quantification (LOQ). The matrix-matched calibration curves had good linearity (R2 ≥ 0.9994) within the concentration range of LOQ–200.0 µg/kg for penicillin G in the sample matrices. In the same concentration range, the accuracy, in terms of recovery, was 80.31–94.50%; the relative standard deviation (RSD), intra-day RSD and inter-day RSD ranged from 1.24 to 3.44%, 2.13 to 4.82% and 2.74 to 6.13%, respectively. The LODs and LOQs of penicillin G in the matrices were in the ranges of 1.70–3.20 and 6.10–8.50 μg/kg, respectively. The applicability of the GC–MS/MS method was demonstrated by the determination of poultry eggs obtained from local markets with no penicillin G residues.

Optimization of a rapid sample pretreatment for the quantification of COCAINE and its main metabolites in hair through a new and validated GC-MS/MS method

We developed and validated a new rapid and sensitive gas chromatography-tandem mass spectrometry method for the determination of cocaine and its metabolites benzoylecgonine, norcocaine, ecgonine methyl esther and cocaethylene in hair of consumers. Hair samples were firstly decontaminated with three subsequent dichloromethane washes, then incubated for one hour with M3® buffer to promote analytes solubilization and stabilization and finally solid phase extracted. All extracts were derivatized and injected into GC–MS/MS with electron impact ionization. Multiple Reaction Monitoring was used for the acquisition of characteristic analytes ion transitions reaching a high sensitivity 0.01 ng/mg COC and metabolites limit of quantification. The method was linear in the COC and metabolites calibration ranges (LLOQ-10 ng/mg and LLOQ-1 ng/mg, respectively). Intra-assay and inter-assay precision were always lower than 15 %, accuracy never exceeded ± 6.6 %. The main advantages of the presented method are the fast, simple and innovative pretreatment procedure together with the instrumental sensitivity that allowed to measure also less concentrated metabolites.

A Selective and Sensitive Gas Chromatography-Tandem Mass Spectrometry Method for Quantitation of Synthetic Musks in Human Serum.

Synthetic musk compounds are widely used as fragrances in many consumer products; however, information on human exposure and health effects is limited. Also, analytical methods for their quantification in biological matrices are limited. In this study, an integrated method was developed and validated for the analysis of selected synthetic musk compounds in human serum. The method is based on liquid-liquid extraction (LLE), sample clean-up by solid-phase extraction (SPE), and separation and detection by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). The method demonstrated good recoveries (86-105%) and high sensitivity, with low method detection limits (MDLs) ranging from 0.04 to 0.17 µg/L. The method was applied to the analysis of 10 synthetic musk compounds in 40 serum samples collected from Canadian women aged 20-44 years (20 individual samples collected in 2014 and 20 pooled samples collected in 2006). The most commonly detected compound was Galaxolide (HHCB), with median concentrations of 0.59 µg/L in samples collected in 2006, and 0.34 µg/L for samples collected in 2014. Musk ketone (MK) was not detected in any of the samples collected in 2006, but was detected in 60% of the samples collected in 2014 with a median concentration of 0.29 µg/L. Tonalide (AHTN) was detected in only one sample above its MDL (0.12 µg/L). This is the first study in Canada to report levels of synthetic musks in human. The data generated from this study has been used in risk screening assessment by Environment and Climate Change Canada and Health Canada.

The gut microbiota is a major regulator of androgen metabolism in intestinal contents.

Androgens exert important effects both in androgen-responsive tissues and in the intestinal tract. To determine the impact of the gut microbiota (GM) on intestinal androgen metabolism, we measured unconjugated (free) and glucuronidated androgen levels in intestinal contents from the small intestine, with a low bacterial density, and from cecum and colon, with a high bacterial density. Using a specific, sensitive gas chromatography-tandem mass spectrometry method, we detected high levels of glucuronidated testosterone (T) and dihydrotestosterone (DHT) in small intestinal content of mice of both sexes, whereas in the distal intestine we observed remarkably high levels of free DHT, exceeding serum levels by >20-fold. Similarly, in young adult men high levels of unconjugated DHT, >70-fold higher than in serum, were detected in feces. In contrast to mice with a normal GM composition, germ-free mice had high levels of glucuronidated T and DHT, but very low free DHT levels, in the distal intestine. These findings demonstrate that the GM is involved in intestinal metabolism and deglucuronidation of DHT and T, resulting in extremely high free levels of the most potent androgen, DHT, in the colonic content of young and healthy mice and men.

Determination of residue levels of the avicide 3-chloro-4-methylaniline hydrochloride in red-winged blackbirds (Agelaius phoeniceus) by gas chromatography-tandem mass spectrometry

The avicide 3‑chloro‑4‑methylanaline hydrochloride (chloro‑p‑toluidine hydrochloride, CPTH, DRC-1339) is used to control pest bird species that damage agricultural crops. A specific and sensitive gas chromatography-tandem mass spectrometry method was developed and validated for the determination of CPTH in avian breast muscle, GI tract, kidney, and liver. Tissue samples were extracted with a solution of acidified water and acetonitrile. The sample was made basic and cleaned up with a combination of liquid-liquid partitioning and solid phase extraction. Separation was achieved using a HP-5 ultra-inert GC column (15 M, 0.25 μm film) with detection on a triple quadrupole mass spectrometer in multiple reaction monitoring (MRM) mode. The monitored transition for CPTH was m/z 140.9 → 106.2 for quantitation and 139.9 → 105.2 and 139.9 → 77.2 for confirmation. The linear range was 5 to 5000 ng/mL. The precision for the determination of CPTH in all tissues averaged 7.2% and the accuracy averaged 6.7%. The recovery of CPTH fortified at 5 different levels averaged 101% in liver, 98.8% in GI tract, 92.9% in breast muscle, and 87.9% in kidney. The established method was successfully used to determine CPTH residue levels in red-winged blackbirds exposed to three different doses of CPTH.

Inorganic arsenic contents in infant rice powders and infant rice snacks marketed in Korea determined by a highly sensitive gas chromatography-tandem mass spectrometry following derivatization with British Anti-Lewisite.

Toxic inorganic arsenic (iAs) has been reported to be present in high quantity in rice and rice-based products. The inorganic arsenic contents in infant foods (n=59) of ready-to-cook infant rice powders and infant rice snacks marketed in Korea were determined by a highly sensitive gas chromatography-tandem mass spectrometry (GC-MS/MS). The mean iAs contents in the infant rice powder and infant rice snacks were 65.6 and 54.0μg/kg, respectively. The percentages of rice powders and rice snack containing iAs over the maximum level (100μg/kg) set by EU for the infant foods were found to be 21, and 6%, respectively. This result clearly suggested that regulation regarding the maximum limit of iAs levels for the baby rice products is urgently needed to be set in Korea. This represents the first report on the iAs levels in ready-to-cook infant rice powder products and infant snacks marketed in Korea.

Inorganic arsenic contents in ready-to-eat rice products and various Korean rice determined by a highly sensitive gas chromatography-tandem mass spectrometry

Rice and rice products have been reported to contain high contents of toxic inorganic arsenic (iAs). The inorganic arsenic contents in microwavable ready-to-eat rice products (n=30) and different types of Korean rice (n=102) were determined by a gas chromatography-tandem mass spectrometry (GC–MS/MS). The method showed low limit of detection (0.015pg), high intra- and inter-day repeatability (<7.3%, RSD), and recovery rates (90–117%). The mean iAs content in the ready-to-eat rice products was 59μgkg−1 (dry weight basis). The mean iAs contents in polished white, brown, black, and waxy rice were 65, 109, 91, and 66μgkg−1, respectively. The percentages of ready-to-eat rice products, white, brown, black, and waxy rice containing iAs over the maximum level (100μgkg−1) set by EU for the infant foods were 17, 4, 70, 36 and 0%, respectively.

Comprehensive determination of polycyclic aromatic hydrocarbons in Chinese herbal medicines by solid phase extraction and gas chromatography coupled to tandem mass spectrometry.

A simple and highly sensitive gas chromatography-tandem mass spectrometry (GC-MS/MS) method combined with solid-phase extraction cleanup was established for the comprehensive determination of 16 Environmental Protection Agency (EPA) polycyclic aromatic hydrocarbons (PAHs) in various kinds of Chinese herbal medicines (CHMs). A solid-phase extraction (SPE) purification strategy, including three parallel procedures, was developed depending on sample type, and satisfactory purification performances were achieved for all selected CHMs. The limits of detection ranged from 0.12 to 1.08μgkg(-1) for the analyzed PAHs. The average recoveries were in the range of 65.9% to 100.8%, except for naphthalene (43.8%-75.9%), and the relative standard deviations were ≤12.8%. The proposed method was successfully applied to the analysis of PAHs in 24 CHMs including five roots, three stems, four flowers, two fruits, four seeds, three leaves, and three barks. In the samples analyzed, all 16 PAHs are present. Their sum ranges from 21.1 to 2236.3μgkg(-1). The entire procedure was shown to be effective and conveniently fast, and may serve as an alternative screening protocol for the determination of PAHs in CHMs.

Investigation on pharmacokinetics, tissue distribution and excretion of 1-triacontanol in rats by gas chromatography-tandem mass spectrometry (GC-MS/MS)

1. 1-Triacontanol (TA) recently shows promising anti-tumor activity. The present study was aimed to develop a sensitive gas chromatography-tandem mass spectrometry method to explore the pharmacokinetic profiles, distribution and excretion of TA in Sprague-Dawley rats after oral administration of TA. Chromatography separation was performed on a HP-5MS column. 1-Octacosanal was used as the internal standard (IS). Quantification of TA and IS was carried out at m/z 495.6 → 97.0 and m/z 467.5 → 97.0, respectively, in positive electron ionization and multiple reaction monitoring mode. The pharmacokinetic parameters were calculated by non-compartmental analysis.2. The area under concentration-time curve AUC0–6 h and AUC0–∞ for TA at 60 mg/kg were 87.737±13.574 and 93.617±17.62, respectively. The mean residence time was 3.25 ± 0.17 h. In addition, the elimination half-lives (t1/2) were (2.37±1.23, 1.27±0.49, 2.07±0.93) h after single oral administration of 30, 60 and 120 mg/kg of TA. After oral administration, TA was extensively distributed in stomach and intestine. The majority of TA excreted via feces, and its accumulative excretion ratio during the period of 72 h was 26.68 ± 7.14%, but only 0.0023 ± 0.0015% and 0.0027 ± 0.0006% for urines and bile, respectively. The absolute bioavailability (F, %) of TA was about 2.0%.

Studies on the minor metabolite 6a‐hydroxy‐androstenedione for doping control purposes and its contribution to the steroid profile

Recent publications have shown that the concentrations of minor metabolites such as formestane and 6a-hydroxy-androstenedione (6aOHADION) are import parameters, capable of increasing the specificity and efficiency of steroid abuse screening. The importance of such minor metabolites has been recognized for some time, but setting up concentration thresholds is not that straightforward with a single quadrupole gas chromatograph mass spectrometer (GC-MS) because of the low concentrations; this is especially the case for 6aOH-ADION. The main aim of this study was to propose a concentration threshold above which the detected 6aOH-ADION is considered suspicious and isotope ratio mass spectrometry (IRMS) is recommended. Routine doping control samples (2128) from athletes that entered our lab and were not found suspicious for the intake of any doping substance were used to determine the baseline concentrations of 6a-OH-ADION. For this purpose, the more sensitive gas chromatography-tandem mass spectrometry (GC-MS/MS) was used, capable of quantifying these low concentrations with high reliability. A urinary concentration threshold of 5 ng/mL was set. Concentrations above this threshold are considered suspicious and are forwarded to IRMS for confirmation in routine practice. In addition, an IRMS method was developed, capable of determining the 13C value of 6aOH-ADION. If a urine sample has an elevated 6aOH-ADION concentration and normal 13C values for the traditional IRMS target compounds, we are still able to check the 13C value of 6aOH-ADION. Six excretion studies were executed to stress the applicability of the threshold by visualizing the concentration and δ13C value time profiles of 6aOH-ADION.

Sensitive GC-MS/MS Method to Measure Deuterium Labeled Deoxyadenosine in DNA from Limited Mouse Cell Populations

A rapid and sensitive gas chromatography-tandem mass spectrometry (GC-MS/MS) method was developed to quantitatively measure low levels of DNA base deoxyadenosine (dA) and its isotopologues (e.g., dA M+1) from limited mouse cell populations. Mice undergoing allogeneic hematopoietic transplantation (AHSCT) received deuterated water at biologically relevant time intervals post AHSCT, allowing labeling of DNA upon cell division, which was detected as the dA M+1 isotopologue. Targeted mouse cell populations were isolated from lymphoid organs and purified by multiparameter fluorescence activated cell sorting. Cell lysis, DNA extraction, and hydrolysis were accomplished using available commercial procedures. The novel analytical method utilized a hydrophilic-lipophilic balanced sample preparation, rapid online hot GC inlet gas phase sample derivatization, fast GC low thermal mass technology, and a recently marketed GC-MS/MS system. Calibration standards containing dA and fortified with relevant levels of dA M+1 (0.25-20%) and dA M+5 (internal standard) were used for sample quantitation. The method employed a quadratic fit for calibration of dA M+1 (0.25-20%) and dA, demonstrated excellent accuracy and precision, and had limits of detection of 100 fg on-column for the dA isotopologues. The method was validated and required only 20 000 cells to characterize population dynamics of cells involved in the biology of chronic graft-versus-host disease, the main cause of late morbidity and nonrelapse-mortality following AHSCT. The high sensitivity and specificity of the method makes it useful for investigating in vivo kinetics on limited and important cell populations (e.g., T regulatory cells) from disease conditions or in disease models that are immune-mediated, such as diabetes, human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), arthritis, inflammatory bowel disease, and multiple sclerosis.

Pollution level and human health risk assessment of some pesticides and polychlorinated biphenyls in Nantong of Southeast China

Food consumption is one of the key exposure routes of humans to contaminants. This article evaluated the residue levels of 51 pesticides and 16 polychlorinated biphenyls (PCBs) in selected fish and food items which were commonly consumed in the Nantong area of Jiangsu Province, Southeast China. The 51 pesticides and 16 PCBs were analyzed by highly sensitive gas chromatographytandem mass spectrometry (GC-MS/MS). The results showed that organochlorine pesticides such as dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and mirex and other pesticides including chlorpyrifos, pyrethroid pesticides, metolachlor, pyridaben and trifluralin were frequently detected in the samples, which was consistent with the accumulation level and characteristics of these toxic chemicals in human adipose tissue of people living in Nantong. Meanwhile, correlation of the residue level of toxic chemicals with their physical chemical properties and historic use pattern in Nantong area was observed. Combined with dietary survey results at the same sampling locations, human health risk assessment of ingestion through the dietary route was performed. The results suggested that the non-cancer risks of the chemicals investigated can be considered negligible in the Nantong area, however, the cancer risks from lifetime dietary exposure to DDTs and HCB have exceeded the acceptable levels.

Accumulation levels and characteristics of some pesticides in human adipose tissue samples from Southeast China

This paper presents a comprehensive study of pesticide levels and bio-accumulation characteristics in human adipose tissues among residents of Southeast China. A large number of adipose samples (n=633) were selected for 58 pesticides and were analyzed by high sensitive Gas Chromatography–Tandem Mass Spectrometry (GC–MS/MS). The results showed that POPs pesticides were frequently detected, including 2,4′-DDD, 2,4′-DDE, 2,4′-DDT, 4,4′-DDD, 4,4′-DDE, 4,4′-DDT, α-HCH, β-HCH, γ-HCH, δ-HCH, hexachlorobenzene (HCB), and mirex. Other detected pesticide species were dicofol, methamidophos and chlordimeform, which have rarely been reported. Comparing to different countries, the concentrations of total DDT and HCH in these three Chinese southeastern sites were in the middle range, whereas the HCB and mirex were in the lower end. A significant correlation was observed between region as well as age and POPs pesticide levels. Some pesticide residue levels were also found significantly correlated to occupation. However, there was no significant correlation between gender and pesticides. Meanwhile, it is interesting to find that mortality of malignant tumors tends to associate with the pesticides levels in human adipose tissue. More importantly, the measured data presented in this study provide realistic information which is useful for assessing human exposure to pesticides in the general population of Southeast China.

Levels of Polychlorinated Biphenyls in Human Adipose Tissue Samples from Southeast China

This paper presents a comprehensive study of polychlorinated biphenyl (PCB) levels and homologue profiles in human adipose tissues among residents of Southeast China. A large number of samples (n = 303) were selected for a number of PCB congeners (n = 62) which were analyzed by highly sensitive gas chromatography-tandem mass spectrometry (GC-MS/MS). The total mean PCB concentrations were 27.2 microg/kg fat (n = 159) in Anhui Province and 17.2 microg/kg fat (n = 144) in Jiangsu Province. A significant correlation was observed between age and PCB levels but not found between gender and PCB levels. The relationship between the environmental contaminant levels and the PCB concentration in adipose tissue was also investigated. It was found that the higher PCB concentrations in human adipose tissue were associated with the higher environmental PCB levels in the corresponding regions. The PCB homologue profiles of the human adipose tissue in China are different from those in the world, similarly to the different PCB homologue pattern between Chinese and global soils. The concept of the urban fractionation effect in the environment may be applicable to explain the PCB homologue profiles and PCB levels in the human adipose tissues collected from different provinces in China. The data presented in this study can provide useful information on human exposures to PCBs in the general population of Southeast China.

Monitoring of pyrethroid metabolites in human urine using solid-phase extraction followed by gas chromatography-tandem mass spectrometry

A method was developed for the determination of cis-, and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (Cl 2CA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid ( cis-Br 2CA cis-, trans), 2-(4-chlorophenyl)-3-methylbutyric acid (2-ClBA), and 3-phenoxybenzoic acid (3-PBA) in human urine. These compounds are major metabolites of commonly used synthetic pyrethroids permethrin, acrinathrin, cypermethrin, fenvelarate, deltamethrin, cyfluthrin and cyhalothrin. The method involves extraction of metabolites using solid-phase extraction, additional liquid–liquid extraction clean-up and derivatization followed by detection and quantification by sensitive gas chromatography-tandem mass spectrometry. 3-(2-methoxyphenoxy) benzoic acid was used as an internal standard. Recoveries of spiked compounds ranged between 92.3 and 113.3%, and 87.4 and 121.1% at fortification levels of 100 and 10 ng ml −1, respectively. The relative standard deviation was lower than 14.6% in all cases. The method was employed to detect and quantify pyrethroid metabolites in the urine of pest control operators and non-occupationally exposed subjects. The concentration of metabolites ranged from 269 pg ml −1 for one of the non-exposed subjects to 2.8 ng ml −1 for one of the exposed pest control operators.