Electron Impact Mode Research Articles

Dust dynamics: distribution patterns of semi-volatile organic chemicals across particle sizes in varied indoor microenvironments.

An extensive analysis of the distribution patterns of three distinct classes of semi-volatile organic chemicals (SVOCs)-phthalates (PAEs), organophosphate flame retardants (OPFRs), and polycyclic aromatic hydrocarbons (PAHs)-across four distinct size fractions of dust (25, 50, 100, and 200μm) was conducted. The dust samples were sourced from AC filter, covered car parking lots, households, hotels, mosques, and car floors. To generate the four fractions, ten dust samples from each microenvironment were pooled and sieved utilizing sieving apparatus with the appropriate mesh size. Selected SVOCs were quantified utilizing gas chromatography-mass spectrometry in electron impact (EI) mode. Results unveiled diverse contamination levels among dust fractions, showcasing car parking lot dust with the lowest chemical contamination, while car floor dust displayed the highest levels of PAHs and OPFRs, peaking at 28.3µg/g and 43.2µg/g, respectively. In contrast, mosque and household floor dust exhibited the highest concentrations of phthalates, with values of 985µg/g and 846µg/g, respectively. Across the analyzed microenvironments, we observed a trend where concentrations of SVOCs tended to rise as dust particles decreased in size, forming a visually striking pattern. This phenomenon was particularly pronounced in dust samples collected from car floors and parking lots. Among SVOCs, PAEs emerged as the predominant contributors with > 90% followed by OPFRs and PAHs. The high levels of OPFRs in car floor dust align logically with the fact that numerous interior components of cars are treated with OPFRs, within a compact indoor microenvironment, to comply to fire safety regulations. Furthermore, petroleum products are a major source of PAHs in the environment and all the sampled cars in the study had combustion engines. Consequently, car dust is more likely to be polluted with PAHs stemming from petroleum combustion. Although previous investigations have noted an increase in heavy metals and brominated flame retardants with decreasing dust particles, this is the first study analyzing these SVOCs in different fractions of dust from various microenvironments. However, aside from two specific microenvironments, the observed pattern of escalating SVOC concentrations with smaller dust particle sizes was not corroborated among the examined microenvironments. This divergence in concentration trends suggests the potential involvement of supplementary variables in influencing SVOC distributions within dust particles.

Assessment of pheniramine in alternative biological matrices by liquid chromatography tandem mass spectrometry.

Pheniramine is an over-the-counter antihistamine drug. Its accessibility and low cost made it more popular among drug abusers in Pakistan. In this study, pheniramine was quantified in both conventional and alternative specimens of twenty chronic drug abusers, aged 16-50years, who were positive for pheniramine in comprehensive toxicological screening for drugs by gas chromatography with mass spectral detection in positive electron impact mode. Pheniramine was extracted from biological specimens using solid phase extraction and liquid chromatography tandem mass spectrometry was employed for quantification. Chromatographic separation was carried out on a Poroshell120EC-18 (2.1mm × 50mm × 2.7µm) column using water-acetonitrile in formic acid (0.1%) mobile phase in gradient elution mode with 500μL/min flow rate. Positive electrospray ionization mode and multi-reaction monitoring with ion transitionsm/z241.3 → 195.8 and 167.1 for pheniramine andm/zm/z247.6 → 173.1 for pheniramine-d6 were employed. The quantification method showed good linear ranges of 2-1000ng/mL in blood, urine, and oral fluid; 2-1000ng/mg in hair and 5-1000ng/mg in nail with ≥ 0.985% coefficient of linearity. The retention time of pheniramine was 3.0 ± 0.1min. The detection and lower quantification limits were 1ng/mL and 2ng/mL for blood, urine, oral fluid and hair whereas 2.5ng/mg and 5ng/mg for nail, respectively. Mean extraction recovery and ionization suppression ranged 86.3-95.1% and -4.6 to -14.4% in the studied matrices. Intra-day and inter-day precision were 4.1-9.3% and 2.8-11.2%, respectively. Pheniramine levels in specimens of drug abusers were 23-480ng/mL in blood, 72-735ng/mL in urine, 25-379ng/mL in oral fluid, 10-170ng/mg in hair and 8-86ng/mg in nail specimens. Alternative specimens are of utmost significance in clinical and medico-legal cases. In this study, authors compared matrix-matched calibration curves to blood calibration curve and obtained results within ± 10%; thereby justifying the use of blood calibration curve for urine, oral fluid, hair, and nail specimens.

Determination of persistent organochlorine pollutants in human serum by combining liquid-liquid extraction and solid-phase extraction with gas chromatography-tandem mass spectrometry

Persistent organochlorine pollutants (POCPs) are a group of “forever chemicals” that are ubiquitous in the environment and pose adverse health effects to humans. However, the lack of sensitive and widely applicable analytical method for internal POCPs exposure assessment puts limits on the researches of health risk evaluations. Therefore, we developed a method for the measurement of 43 POCPs in human serum using gas chromatography-tandem mass spectrometry (GC-MS/MS). Serum samples were treated with methanol and acid to precipitate protein and remove lipids, respectively. 13C-labeled analogue was spiked and liquid-liquid extraction (LLE) was performed to extract target analytes by hexane and methyl tert-butyl ether. The extract was purified by solid-phase extraction (SPE) and eluted with dichloromethane. The eluate was concentrated under nitrogen stream and reconstituted with toluene. Samples were analyzed by GC-MS/MS operated in electron impact (EI) and multiple reaction monitoring (MRM) mode. Calibration curves of all target analytes showed favorable linearity within the concentration range of 0.008 to 10 μg/L for different POCPs, with regression coefficients above 0.991. The method detection limits and limits of quantification ranged from 0.005 to 0.10 μg/L and 0.017 to 0.34 μg/L, respectively. The recoveries and precision of all analytes at 3 different spike levels were in the range of 65.3 % to 121.8 % and 1.8 % to 13.9 %, respectively. The matrix effects (ME) ranged from 74.9 % to 125.6 %. The results of measuring quality control samples from the National Institute of Standards and Technology (NIST) were with relative deviations of less than 30 %. With an optimized sample preparation procedure, the proposed method has successfully achieved in improving extraction efficiency and reducing ME. It was applied in the simultaneous determination of POCPs in a small volume of human serum in China National Human Biomonitoring.

Assessment of atmospheric pollution by oxygenated and nitrated derivatives of polycyclic aromatic hydrocarbons in two regions of the Czech Republic

In this study, a method for monitoring 16 representatives of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) and six oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) in airborne particulate matter (PM) was developed and validated. Soxhlet extraction, followed by solid phase extraction (SPE) on silica, was used to isolate the target compounds. Instrumental analysis was performed by gas chromatography coupled with (tandem) mass spectrometry (GC-MS(/MS)) operated in electron impact (EI) and negative ion chemical ionization (NICI) modes. GC-EI-MS/MS was selected for further experiments due to its higher selectivity of measurement and ability to measure derivatives simultaneously with 20 commonly analyzed PAHs (EU + US EPA priority list). This is the first study documenting the simultaneous analysis of OPAHs, NPAHs, and parent PAHs in a single run. This analysis strategy was successfully validated at two concentration levels of artificial contamination, i.e., 0.8 and 4 ng per filter, with recoveries in the 70–104% range and less than 23% repeatability. The newly developed method was used for the analysis of 45 air samples from two cities in the Czech Republic, namely Ceske Budejovice and Most (a place with heavy industry), and two sampling seasons (February vs. May 2017). Five representatives were found in all samples from the oxy-PAH group, with 9,10-anthraquinone (9,10-ANTQ) being the most abundant (0.010–2.49 ng m−3 air). Three major nitro-PAHs, namely 9-nitroanthracene (9-nANT), 2-nitrofluoranthene (2-nFA), and 1-nitropyrene (1-nPYR), were found in 89%, 96%, and 33% of the samples, respectively, found in concentration ranges of <0.60–902, <0.60–276, and <0.60–117 pg m−3 air. Slightly higher levels of oxy- and nitro-PAHs were found in Ceske Budejovice compared to Most, but the difference was not statistically significant (p-value >0.05). A statistically significant difference was observed between February and May, where the concentrations in February were up to 20 and 50 times higher for individual oxy- and nitro-PAHs, respectively, in both regions. The diagnostic ratio 2-nFA/1-nPYR >5 showed that indirect emissions were the primary nitro-PAH source in Most of nitro-PAHs in Most and in both sampling campaigns. In Ceske Budejovice, the opposite trend was observed in winter, i.e. 2-nFA/1-nPYR <5, indicating direct emissions as the main source. In summary, direct emissions of OPAHs and NPAHs originate from fossil (transportation-related) and solid fuel (heating-related) combustion. In contrast, indirect emissions are related to atmospheric reactions of PAHs with OH radicals (spring, winter) and NO3 radicals (winter). The total TEQB[a]P was higher in winter than spring, with higher inhalation cancer risk.

Simple multi-residue analysis of persistent organic pollutants and molecular tracers in atmospheric samples

We present a simple, selective and sensitive analytical method to quantitatively determine a wide range of halogenated persistent organic pollutants and molecular tracers in atmospheric samples. Identification and quantification was carried out by high-resolution gas chromatography, hyphenated with low-resolution mass spectrometry operating in electron impact (EI) and electron capture negative ionization (ECNI) mode. Optimization on a number of instrumental parameters was conducted to obtain ultra-trace detection limits, in the range of few fg/m3 for organohalogen compounds. Repeatability and reproducibility of the method was thoroughly evaluated. The analysis was validated with standard reference materials and successfully applied to actual atmospheric samples. The proposed multi-residue method provides a precise, affordable and practical procedure of sample analysis for environmental research laboratories with conventional instrumentation on a routine basis.•A simple combination of alumina, florisil and silica gel adsorbents was applied to sufficiently isolate polychlorinated biphenyls, organochlorine pesticides, polycyclic aromatic hydrocarbons, long chain n-alkanes, hopanes and steranes.•Full elution was achieved in two successive fractions, using small volumes of n-hexane and n-hexane/dichloromethane to recover all target substances.•To maximize analytical response, optimization was applied for three operating parameters in ECNI mode: i) ion source temperature; ii) emission current; and iii) electron energy.

Multiresidue Pesticide Analysis in Tea Using GC–MS/MS to Determine 12 Pesticide Residues (GB 2763-2021)

Pesticides are widely used on tea plants, and pesticide residues are of significant concern to consumers. The National Food Safety Standard Maximum Residue Limits for Pesticides in Food (GB 2763-2021) was recently amended. However, detection methods for pesticides newly added to the list of residues in beverages have not yet been established. For that reason, this study developed a solid-phase extraction (SPE) and gas chromatography-tandem mass spectrometry (GC-MS/MS) method for determining the residues of 12 pesticides, including four newly added, in black and green tea. Sample preparation processes (sample extraction, SPE clean-up, elution solvent, and elution volume) were optimized to monitor these residues reliably. Multiple reaction monitoring (MRM) was used for GC-MS/MS electron impact (EI) mode determination. Finally, satisfactory recoveries (70.7-113.0% for green tea and 72.0-99.1% for black tea) were achieved at three concentrations (10 μg/kg, 20 μg/kg, and 100 μg/kg). The LOQs were 0.04-8.69 μg/kg, and the LODs were 0.01-3.14 μg/kg. This study provides a reliable and sensitive workflow for determining 12 pesticide residues in tea, filling a gap in the newly revised National Standards.

Multiresidue pesticide analysis in green chilli using GC–MS/MS using modified QuEChERS method with highly efficient Fe3O4@CFR@GO nanocomposite

• Fe 3 O 4 @CFR@GO was tested for the elimination of pigments in pesticide analysis. • Fe 3 O 4 @CFR@GO showed an excellent clean-up efficiency. • Satisfactory purification and recovery effects were achieved in chilli matrices. The presence of pesticide residues in food and vegetables is a growing concern for consumers. In order to monitor these residues reliably, a selective and sensitive, multi-residue system has been developed and validated in green chilli by gas chromatography-tandem mass spectrometry (GC–MS/MS). Fe 3 O 4 @CFR@GO (Fe 3 O 4 @Catechol Formaldehyde Resin@Graphene Oxide) magnetic nanocomposite is used as reversed dispersive solid phase extraction (r-DSPE) materials. Fe 3 O 4 @CFR@GO magnetic nanocomposite is synthesized, characterised by XRD, FTIR and SEM. Comparative investigations have shown that Fe 3 O 4 @CFR@GO magnetic nanocomposite not only has high pigment removal efficiency, but also has more clean-up than typical graphitized carbon black (GCB). The processing of two multiple reaction monitoring (MRM) transformations for each analyte is done by GC–MS/MS in electron impact (EI) mode. Precision and accuracy were tested by recovery studies. The technique proved to be reliable and sensitive in green chilli samples for the routine testing of 35 pesticides.

Multiresidue pesticide analysis in tomato using GC-MS/MS using modified QuEChERS method with titanium-coated graphite with CNT-ABS nanocomposite as dispersive solid-phase extraction materials

Abstract The presence of pesticide residues in food and vegetables is a growing concern for consumers. To monitor these residues reliably, a selective and sensitive multiresidue system has been developed and validated in tomato by gas chromatography–tandem mass spectrometry (GC-MS/MS). Titanium-coated graphite with carbon nanotube (CNT) in acrylonitrile–butadiene–styrene (ABS) used as reversed-dispersive solid-phase (extraction materials with modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method. Titanium-coated graphite with CNT-ABS is synthesized, characterized by X-ray diffraction and scanning electron microscopy. The clean-up performance of titanium-coated graphite with CNT-ABS was demonstrated to be better to primary secondary amine and graphitized carbon black cartridges. The processing of two multiple reaction monitoring transformations for each analyte is done using GC-MS/MS in electron impact mode. Satisfactory purification and recovery effects (74%–100%) of 35 pesticides were achieved in tomato matrices when using 5 mg of titanium-coated graphite ABS-CNT nanocomposite. It was observed that quinolphos and deltamethrin are present above the maximum residue limit. The technique proved to be reliable and sensitive in tomato samples for the routine testing of 35 pesticides.

Simultaneous determination of six haloacetonitriles in finished water for drinking by purge and trap-gas chromatography-triple quadrupole mass spectrometry

目前卤乙腈作为我国非受监管的消毒副产物广泛存在于饮用出厂水中,可产生多种毒性,缺乏相关标准检测依据。研究建立了吹扫捕集-气相色谱-三重四极杆质谱同时测定饮用出厂水中氯乙腈、二氯乙腈、三氯乙腈、溴乙腈、溴氯乙腈、二溴乙腈的分析方法。吹扫捕集技术应用于卤乙腈的测定,实现了样品经采集后全程自动测定,有害试剂零消耗。同时吹扫捕集法相比固相微萃取法,样品制备的速度更快,成本更低。实验考察了样品6 h内目标组分的稳定性;比较了7#(2,6-二苯基对苯醚)、10#(2,6-二苯基对苯醚/硅胶/碳分子筛)、11#(疏水活性炭)、12#(疏水活性炭)捕集阱对目标组分响应的影响;考察了4种型号色谱柱(VF-5、Rxi-624、DB-VRX、HP-INNOWAX)对色谱峰形的影响。实验条件经优化,确定了吹扫捕集采用10#捕集阱,将25 mL水样于35 ℃吹扫11 min,于190 ℃解析1 min。气相色谱分流进样,分流比1:10,使用Rxi-624Sil MS色谱柱(60 m×0.25 mm×1.40 μm)程序升温分离,线速度30 cm/s,在MRM模式下检测,外标法定量。结果表明,6种卤乙腈的基质效应为0.85~1.09,在各自范围内线性良好,r>0.9991,方法检出限为0.8~120.0 ng/L,定量限为1.5~300.0 ng/L, 3水平平均加标回收率为84.2%~106%,相对标准偏差(RSD)为1.81%~10.7%。对38份出厂水样品进行测定,卤乙腈总检出率为92.1%,含量为0.0101~1.28 μg/L。该方法高效、灵敏、环保,为针对卤乙腈类新兴消毒副产物开展监测及健康风险评估提供了优质的技术选择。

Determination of atmospheric organochlorine pesticides using isotope dilution high-resolution gas chromatography/high-resolution mass spectrometry

建立了测定大气中25种有机氯农药(OCPs)的同位素稀释-高分辨气相色谱/高分辨质谱法(ID-HRGC/HRMS)。样品用正己烷/二氯甲烷(1:1, v/v)进行加速溶剂萃取(ASE)。通过柱洗脱实验、单柱和组合柱净化实验,最终确定样品的净化方案为弗罗里硅土固相萃取柱和石墨化炭黑固相萃取柱组合净化。样品萃取液净化后进行HRGC/HRMS分析。采用平均相对响应因子(RRF)法对样品中目标物进行定量,6点校准溶液RRF的相对标准偏差(RSD)均≤20%。线性范围为0.4~800 μg/L,相关系数R2均>0.992。对空白样品依次进行100 pg、400 pg和15 ng水平下的加标试验,各添加水平下OCPs测定值的RSD为0.64%~16%,加标回收率为67.2%~135%。穿透试验表明,滤膜+聚氨酯泡沫/聚氨酯泡沫作为吸附介质的大体积主动大气采样器(AAS)在采集环境空气时,五氯苯极易发生穿透,有效采样模式待进一步研究。在上述采样模式下,六氯苯的有效采样体积较小,标准状态(101.325 kPa, 273 K)采样体积应≤30 m3,其他OCPs应≤1200 m3。以上述体积计算,25种目标化合物的检出限为0.002~0.7 pg/m3。对北京环境空气样品分析测定,结果显示除反式-环氧七氯、异狄氏剂、顺式-九氯和4,4'-滴滴滴在部分样品中未检出外,其他OCPs均为100%检出;六氯苯浓度在514~563 pg/m3之间,其他OCPs的浓度在0.01~18.9 pg/m3之间;替代标回收率为33.9%~155%。由于现有相关监测标准的仪器灵敏度较低、方法检出限较高,已无法满足目前空气中痕量OCPs的测定需求,因此亟待修订新的高灵敏度监测方法标准。该方法适用于目前大气中OCPs的超痕量水平分析,为新标准的制订奠定基础,也为国家履行相关国际公约提供有力技术指导。

Advances in the development of detection techniques for organophosphate ester flame retardants in food

Organophosphate ester (OPE)-based flame retardants and plasticizers are widely utilized in various industrial products, and are being increasingly used as substitutes for gradually phased brominated flame retardants (BFRs). According to the different types of substituents used, OPEs are mainly divided into alkyls, halogenated compounds, and aromatics, which have widely varying physicochemical properties. OPEs can induce neurotoxicity, carcinogenicity, and damage in endocrine and reproductive systems in humans. Examples of halogenated OPE are tris(2-chloroisopropyl) phosphate (TCIPP) and tris(1,3-dichloropropyl) phosphate (TDCIPP), which are suspected to be carcinogenic. OPEs have emerged as pollutants in environmental and food matrices as a result of volatilization and abrasion processes. Due to its low content in the food matrix and serious background interference, there is a lack of reliable and sensitive analytical methods. Recently, there has been a focus on the detection of OPE flame retardants in food. In this paper, we have reviewed the current status and development trends of OPE detection methods in various foodstuffs. First, the physicochemical properties of more than 30 common OPEs were summarized. Even when using the same extraction solvent, there are obvious differences in extraction efficiency according to different compound properties. To simultaneously analyze multi-component OPE flame retardants in food, it is very important to choose the appropriate extraction solvent to meet the required extraction efficiency of compounds with a wide range of polarities. In addition, although OPE flame retardants are not easily hydrolyzed under neutral conditions, they will degrade to a certain extent under strong acidic and alkaline conditions. It is worth mentioning that avoiding the removal of lipids and other interferences in food matrices under strong acidic and alkaline conditions. Different pretreatment methods, such as accelerated solvent extraction, matrix solid-phase dispersion extraction, microwave-assisted extraction, ultrasonic-assisted extraction, QuEChERS, solid-phase extraction, gel permeation chromatography, and dispersive solid-phase extraction are also compared. Combining the advantages of ultrasonic assisted extraction (UAE) and QuEChERS pretreatment technology can reduce the waste of extraction solvent and internal standard solution. For lipid-rich matrices like biological samples, it is necessary to remove lipid interference by SPE columns or GPC purification. Furthermore, the characteristics of separation and detection techniques, such as GC, GC-MS/MS, and LC-MS/MS, are discussed. Comparing detection limits and recovery data with those reported in the literature, GC-MS/MS can provide improved selectivity, precision, and limits of detection in complex food matrices, but LC-MS often suffers from ion suppression, matrix interferences, and incomplete separation of some OPEs. Since electron impact (EI) has higher ionization efficiency, it produces many fragment ions, thus creating a more complete spectral library, which is conducive to structural identification. When using GC-MS/MS to determine OPE flame retardants, the EI mode was usually used. However, positive chemical ionization (PCI) and electron capture negative ionization (ECNI) modes were also used sometimes. In the section on quality control, the main sources of standards and internal standards, possible sources of blank contamination, and the research status of measures to reduce matrix effects have been reviewed. To avoid blank contamination, all the laboratory equipment should be carefully cleaned, heated at high temperatures, and rinsed with polar or non-polar organic solvents in order to remove all interfering organic residues. Isotopically labeled internal standard and isotopic dilution mass spectrum quantification methods are used to reduce matrix effects. Owing to the limited availability of commercial standards and the relatively high cost, alternative approaches, such as matrix-matched calibration or standard addition methods, are required. The screening and identification of unknown metabolites of OPEs and related analytical methods based on high resolution mass spectrometry could also be studied for precursor OPEs in foodstuffs in the future.

GC/MS analysis on anorectics adulterated in traditional chinese medicines

A gas chromatography/mass spectrometry analytic method was developed for simultaneously identifying and quantitating anorectics synthetic drugs illegally adulterated in traditional Chinese medicines (TCM). A model sample of TCM (Farng-Feng-Tong-Shewg-Saan) was spiked with 11 kinds of synthetic drugs: amphetamine, methamphetamine, methylphenidate, clobenzorex, phentermine, fenfluramine, phenylpropanolamine, caffeine, mazindol, diazepam, diethylpropion. The sample was extracted with methanol. The GC/MS conditions were as follows: initial temperature 70°C, holding 2 mins., ramping rate was 10°C/min by linear, final temperature 280°C, holding 5 mins. The samples were scanned by HP5973 GC/MSD with a quadrupole mass filter in an electron impact mode (70eV), and a total ion current (TIC) chromatogram was obtained with multiple peaks. Comparison was made of the mass chromatograms and retention time of each peak with a created library. The matching quality of each synthetic drug spiked in TCM was not less than 85%. The retention time of each ingredient was consisted with the data created in the library. In quantitative analysis, this method with selected ion monitoring (SIM) analysis was performed. Dextromethophan HBr (50 μg/) was used as internal standard. Excellent calibration curves of each analytic compounds had ploted, and correlation coefficients were between 0.9967 and 0.9999, The RSD of interday and intraday studies was between 3.48∼5.52% and 3.07∼6.66%. The results showed that the established method is quite suitable for determination of anorectics adulterated in TCM samples. By this method, the following was found: 0.44 mg/tab of mazindol in high-fibrous food tablets; 24.35 mg/cap of clobenzorex, 1.06 mg/cap of caffeine, and 0.54 mg/cap of diazepam in herbal capsules; 28.42 mg/cap of phentermine in slimming capsules; 27.33 mg/pack of phentermine and 11,75 mg/sachet of caffeine in TCM dispensing packs.

Studies on multiresidue determination of pesticides in fruits and vegetables by gas chromatography/mass spectrometry

A multiresidue method using gas chromatography/mass spectrometry (GC/MS) was evaluated for the determination of several pesticides in fruits and vegetables. The pesticides were extracted using a slightly modified Luke multiresidue procedure, separated by capillary column gas chromatography and detected by mass chromatography with quadrupole mass spectrometer in the electron impact mode. Recovery studies of chlorpyrifos, diazinon, endosulfan, fenarimol, fenvalerate, folpet, iprodione, malathion, methamidophos, phosmet and procymidone were performed at the 0.5 ppm spike level in cherry tomatoes, chin-chian pe-tsai, Chinese cabbages, kidney beans and oranges. Recoveries were between 64.6 and 124.6%, with the exception of methamidophos which produced interference due to the constituents of the samples. Coefficients of variation ranged between 0.3 and 17.6%, with an average of 5.3%. The estimated limits of detection of the pesticides (except methamidophos) in the crops were at the 0.1 ppm level. Because the mass spectrometer is capable of achieving higher levels of molecular specificity as compared to the traditional GC detectors and can be programmed to search for several hundred target ions simultaneously, GC/MS may be a promising method for the use of regulatory agencies with which to monitor pesticide residues in daily food products.

Detection and determination of phenformin in Chinese medicinal capsules by GC-MS and HPLC

Phenformin was prohibited by the ROC Department of Health in 1978. In this investigation, a GC-MS was used for the detection of phenformin in herbal preparation produced in Mainland China followed by determination by HPLC. For GC-MS, a HP-5MS capillary column was used. The initial column temperature was at 100°C for 2 min, ramping 10°C/min to 280°C, then holding at 280°C for 15 min. Ionization source temperature was at 230°C, and 70 eV electron impact mode was employed. HPLC was performed on a Cosmosil 5C18 AR (5 cm × 4.6 mm), and a μBondpak phenyl (30 cm × 3.9 mm) column using 0.01M potassium dihydrogenphosphate (pH 6.55) - acetonitrile (60:40, v/v) as eluent, with flow rate at 1.0 mL/min and detection wavelength set at 235 nm. Metformin was used as the internal standard. The interday and intraday precisions were less than 1.6%. The limit of detection and the limit of quantitation were 0.065 μg/mL and 0.20 μg/mL, respectively. The spike recovery was 102.7%. The average content of phenformin in the preparation was 3.45 mg per capsule.

Identification and Synthesis of Putative Pheromone Components of the Threatened Salt Marsh Bagworm Moth, Whittleia retiella (Lepidoptera: Psychidae)

Whittleia retiella (Newman, 1847) is a threatened salt marsh species of the bagworm moth family Psychidae. For its preservation it is necessary to develop efficient tools to survey its distribution and habitat requirements in order to use appropriate conservation methods. Such tools may be pheromone-based monitoring systems, which have documented efficacy in establishing the occurrence of cryptic insect species in nature. By using gas chromatography combined with electroantennographic detection (GC-EAD), we found two compounds in female W. retiella headspace samples and whole-body extracts that elicited electrophysiological activity in male antennae. Gas chromatograpy coupled with mass spectrometry (GC-MS) operating in electron impact (EI) mode and comparison of the analytical data with those of synthetic reference compounds showed the chemical structures of these putative pheromone components to be (1S)-1-methylpropyl (5Z)-dec-5-enoate and 1-methylethyl (5Z)-dec-5-enoate. Field assays using baits loaded with synthetic compounds revealed that conspecific males were attracted to (1S)-1-methylpropyl (5Z)-dec-5-enoate alone or in combination with 1-methylethyl (5Z)-dec-5-enoate, whereas 1-methylethyl (5Z)-dec-5-enoate neither attracted nor repelled males in the field assays when tested alone. This study shows the potential of using (1S)-1-methylpropyl (5Z)-dec-5-enoate for monitoring W. retiella to gather more detailed information about the geographic distribution and habitat needs of this rare moth.

Determination of carbazole and halogenated carbazoles in human serum samples using GC-MS/MS

Carbazole and halogenated carbazoles have been widely detected throughout the environment in soil, river deposits, and lake sediments. Human exposure to these compounds may occur through inhalation, drinking water, dietary intake and/or skin contact, and exposure levels in the body may be evaluated by measuring them in serum or blood. This paper reports the method development and validation for the analysis of carbazole and 11 halogenated carbazoles in human blood and/or serum samples. A small sample size of 100 μL of blood or serum was employed for the analysis. The samples were prepared through salting-out liquid-liquid extraction (LLE) by using hexane/ethyl acetate (4:1, v/v) as the extraction solvent and aqueous MgSO4 (37.5 wt%) as the salting-out regent, respectively. Sample analysis was performed using gas-chromatography (GC) coupled with a tandem mass spectrometer (MS/MS) in an electron impact (EI) mode. The developed method demonstrated low detection limits in the range of 0.02–0.27 ng/mL, intra-day accuracy ranging from 81.2% to 125%, and inter-day accuracy from 91.0% to 117%. The intra- and inter-day precisions, calculated by relative standard deviations (RSDs), were in the ranges of 1.0–16.0% and 1.8–16.4%, respectively. The developed method was applied to the analysis of 50 human serum samples collected from pregnant women in Southern California in 2012. Low concentrations of carbazole were measured in 18 samples, while halogenated carbazoles were not detected in any of the samples.

Phytochemical Composition and Biological Activities of Wild Scolymus maculatus L.

Background: The wild population of spotted golden thistle, Scolymus maculatus, which belongs to the Compositae family, is believed to be one of the multi-curative wild plants mentioned in Flora Palaestina. This study aims to disclose the phytochemical composition, antioxidant potential, and antimicrobial activity of wild S. maculatus collected from the farms of Kabul, a village in northwest Galilee, for the first time. Methods: The phytochemical components of crude S. maculatus extracts from methanol, ethyl acetate, and n-hexane solvents were separated and identified using gas chromatography-mass spectrometry (GC-MS) in the electron impact (EI) mode. The free radical scavenging of the plant extracts was measured by DPPH assay. The microdilution test was used to determine the minimum inhibitory concentrations (MICs) of different S. maculatus extracts and to evaluate their antimicrobial activities. Results: Thirty-two phytochemicals were found in S. maculatus extracts including stigmasterol, γ-sitosterol, lupeol, lupeol acetate, and β-amyrin. Phytochemicals, such as 2-linoleoylglycerol, γ-sitosterol, β-amyrin, lupeol, (3α)-12-oleanen-3-yl acetate, and lupenyl acetate, were found to dominate the methanol extract. Most of these compounds were also observed in ethyl acetate and n-hexane extracts, but at different levels, in addition to some other minor compounds. The various extracts were investigated for their antioxidant and antimicrobial activity. The ethanolic and the methanolic extracts were shown to exhibit the highest free radical scavenging by DPPH assay with a half-maximally effective concentration (EC50) of 0.37 and 0.65 mg/mL respectively, while the other three extracts (aqueous, ethyl acetate and n-hexane) were less active and their EC50 (effective concentration at which DPPH radical was scavenged by 50%) were above 1.0 mg/mL. Moreover, MICs were determined to be effective against Staphylococcus aureus, Salmonella typhimurium, and Candida albicans microorganisms. Ethyl acetate and the ethanolic extracts are active against the three types of microorganisms at a minimum inhibitory concentration (MIC) of 0.5 mg/mL, while aqueous and the n-hexane extracts are inactive against Salmonella typhimurium. Conclusions: The results show that S. maculatus extracts are a rich source of compounds that can play an important role in human health, and in a broader context, in the treatment of various diseases, such antimicrobial and antioxidant-related ailments.

Influence of cosmetic hair treatments on cannabinoids in hair: Bleaching, perming and permanent coloring

Various cosmetic hair manipulations are known to interfere with drug of abuse concentrations in hair. It is important to evaluate the effects of cosmetic hair treatments as they can influence quantitative hair results. Only one study showed a significant decrease of THC after bleaching and coloring.The aim of the study was to investigate the effect of bleaching, perming and dyeing treatment on d-9-tetrahydrocannabinol (THC), but also Cannabidiol (CBD), Cannabinol (CBN) and 11-nor-D9-tetrahydrocannabinol-9-carboxylic acid (THC−COOH) in hair.Thirty THC-positive hair samples were selected in this study. A single hair lock was divided in 2 separate locks and the proximal 3 cm segment was analyzed. One lock served as control while the other lock was bleached, permed or dyed respectively. Hair was analyzed using a routine method including cleaning, treatment of hair with NaOH and 2 different SPE extractions for THC, CBN, CBD and THC−COOH respectively. Analysis was performed with routine methods using GC/MS-MS in electron impact (EI) mode for THC, CBN and CBD or negative chemical ionization (NCI) mode for THC−COOH after PTV-injection.Bleaching and perming reduced all cannabinoids concentration in hair; THC was more affected than THC−COOH, CBN and CBD. Bleaching caused strong chemical degradation on cannabinoids, while perming exerted more a leaching out effect. Permanent colorings in single applications had only little effects on cannabinoids.Finally this study highlights the importance of considering bleaching and perming for the correct interpretation of hair results.

Chemical composition of isoprene SOA under acidic and non-acidic conditions: effect of relative humidity.

The effect of acidity and relative humidity on bulk isoprene aerosol parameters has been investigated in several studies; however, few measurements have been conducted on individual aerosol compounds. The focus of this study has been the examination of the effect of acidity and relative humidity on secondary organic aerosol (SOA) chemical composition from isoprene photooxidation in the presence of nitrogen oxide (NOx). A detailed characterization of SOA at the molecular level was also investigated. Experiments were conducted in a 14.5 m3 smog chamber operated in flow mode. Based on a detailed analysis of mass spectra obtained from gas chromatography–mass spectrometry of silylated derivatives in electron impact and chemical ionization modes, ultra-high performance liquid chromatography/electrospray ionization/time-of-flight high-resolution mass spectrometry, and collision-induced dissociation in the negative ionization modes, we characterized not only typical isoprene products but also new oxygenated compounds. A series of nitroxy-organosulfates (NOSs) were tentatively identified on the basis of high-resolution mass spectra. Under acidic conditions, the major identified compounds include 2-methyltetrols (2MT), 2-methylglyceric acid (2mGA), and 2MT-OS. Other products identified include epoxydiols, mono- and dicarboxylic acids, other organic sulfates, and nitroxy- and nitrosoxy-OS. The contribution of SOA products from isoprene oxidation to PM2.5 was investigated by analyzing ambient aerosol collected at rural sites in Poland. Methyltetrols, 2mGA, and several organosulfates and nitroxy-OS were detected in both the field and laboratory samples. The influence of relative humidity on SOA formation was modest in non-acidic-seed experiments and stronger under acidic seed aerosol. Total secondary organic carbon decreased with increasing relative humidity under both acidic and non-acidic conditions. While the yields of some of the specific organic compounds decreased with increasing relative humidity, others varied in an indeterminate manner from changes in the relative humidity.

Application of GC–MS technique for the determination of homocysteine thiolactone in human urine

It is well established that homocysteine thiolactone (HTL) is associated with some health disorders, including cardiovascular diseases. HTL is a by-product of sulfur metabolic cycle. So far, its presence has been confirmed in human plasma and urine. It has been also shown that a vast majority of HTL is removed from human body through kidney. Thus, the aim of the current investigations has been the identification, separation and quantification of HTL in urine samples. For the first time a cheap, reliable and robust GC–MS method was developed for the determination of HTL in human urine in the form of its volatile isobutyl chloroformate derivative. Separation of the analyte and internal standard (homoserine lactone (HSL)) was achieved in 15 min followed by mass spectrometry detection (MS). Isocratic elution was accomplished with helium at a flow rate of 1 mL min−1 and a gradient of the column temperature was concomitant with the analysis. The mass spectrometer was set to the electron impact mode at 70 eV. The ion source, quadrupole and MS interface temperatures were set to 230 °C, 150 °C and 250 °C, respectively. Elaborated analytical procedure allows quantification of analyte in a linear range of 0.01–0.20 nmol mL−1 urine. The LOQ and LOD values were 0.01 and 0.005 nmol mL−1, respectively. The method accuracy ranged from 98.0% to 103.2%, while precision varied from 6.4% to 9.5% and from 10.7% to 16.9% for intra- and inter-day measurements, respectively. Finally, the method has been successfully implemented in the analysis of 12 urine samples donated by apparently healthy volunteers. Concentration of HTL ranged from <LOQ to 163 pmol mL−1 urine (0.51 to 13.1 μmol mol−1 Crn).