Determination of residual pharmaceuticals in edible animal tissues by continuous solid-phase extraction and gas chromatography-mass spectrometry

A sensitive, reliable method using continuous solid-phase extraction and gas chromatography-mass spectrometry was developed for the simultaneous determination of twenty pharmaceuticals including antibacterials, anti-epileptics, antiseptics, β-blockers, lipid regulators, hormones and non-steroidal anti-inflammatories at trace levels in edible animal tissues. The procedure involves deproteination and delipidation of samples by precipitation/centrifugation/filtration, followed by sample enrichment and cleanup by continuous solid-phase extraction. The proposed method was validated with quite good analytical results including low limits of detections (0.4-2.7 ng kg⁻¹ for 2 g of sample) and good linearity (r² > 0.995) throughout the studied concentration ranges. In addition, the method is quite accurate (recoveries ranged from 92 to 101%) and precise (within-day and between-day RSD values were less than 7%), which allows the determination of residual pharmaceuticals in tissues from agricultural farm and fish hatchery animals (pig, veal, lamb and chicken muscle, kidney and liver; and salmon, sea bass and sole flesh). The analytes most frequently found in the studied samples were the hormones estrone and 17β-estradiol, and the antibacterials florfenicol and pyrimethamine.     

Simultaneous determination of 3-monochloropropane-1,2-diol and acrylamide in food by gas chromatography-triple quadrupole mass spectrometry with coupled column separation

Both 3-monochloropropane-1,2-diol (3-MCPD) and acrylamide are contaminants found in heat-processed foods and their related products. A quantitative method was developed for the simultaneous determination of both contaminants in food by gas chromatography-triple quadrupole mass spectrometry (GC–MS/MS). The analytes were purified and extracted by the matrix solid-phase dispersion extraction (MSPDE) technique with Extrelut NT. A coupled column (a 3 m Innowax combined with a 30 m DB-5 ms) was developed to separate both compounds efficiently without derivatization. Triple quadrupole mass spectrometry in multiple reaction monitoring mode (MRM) was applied to suppress matrix interference and obtain good sensitivity in the determination of both analytes. The limit of detection (LOD) in the sample matrix was 5 μg kg⁻¹ for 3-MCPD or acrylamide. The average recoveries for 3-MCPD and acrylamide in different food matrices were 90.5–107% and 81.9–95.7%, respectively, with the intraday relative standard deviations (RSDs) of 5.6–13.5% and 5.3–13.4%, respectively. The interday RSDs were 6.1–12.6% for 3-MCPD and were 5.0–12.8% for acrylamide. Both contaminants were found in samples of bread, fried chips, fried instant noodles, soy sauce, and instant noodle flavoring. Neither 3-MCPD nor acrylamide was detected in the samples of dairy products (solid or liquid samples) and non-fried instant noodles.     

Identification of volatile components in Angelica species using supercritical-CO2 fluid extraction and solid phase microextraction coupled to gas chromatography-mass spectrometry

As a part of our search for environmentally friendly solvents to extract the active components of medicinal plants, two sampling techniques, supercritical fluid extraction (SFE) using CO(2) and solid-phase microextraction (SPME) were compared for their efficacy in the analysis of volatiles rhizome components emitted from the medicinal herbs Angelica gigas NAKAI (Korean danggui), Angelica sinensis (Chinese danggui), and Angelica acutiloba (Japanese danggui). A total of 54 compounds released from all of these varieties of Angelica rhizomes were separated and identified by gas chromatography-mass spectrometry (GC-MS). The composition of supercritical extracts from these plants was very different from the solid-phase microextraction products. More compounds were detected by SPME-GC-MS (41) than by SFE-GC-MS (17). The results of these analyses suggest that SFE may be useful for detecting the main components, decursinol angelate and decursin in Korean danggui, and butylidene dihydro-phthalide in both Chinese and Japanese danggui, whereas the results for SPME did not. The SFE method required specialized instrumentation, required little time to prepare the sample, and had a small sample size and no organic solvent. In sum, these results suggest that SFE is useful for extracting the volatile main components of danggui cultivars. Its simplicity, low cost and speed may allow SPME to increase the recovery of volatile components in general without disturbing the main components of the plant.     

Analysis for chloroanisoles and chlorophenols in cork by stir bar sorptive extraction and gas chromatography–mass spectrometry

A complete methodology for the determination of chloroanisoles and chlorophenols in cork material is proposed. The determination is accomplished by means of a previous liquid–solid extraction followed by stir bar sorptive extraction (SBSE) coupled to gas chromatography–mass spectrometry (GC–MS). Two different liquid–solid extraction experiments were conducted and eight compounds considered (2,6-dichloroanisole, 2,4-dichloroanisole, 2,4,6-trichloroanisole, 2,4,6-trichlorophenol, 2,3,4,6-tetrachloroanisole, 2,3,4,6-tetrachlorophenol, pentachloroanisole and pentachlorophenol). From the results obtained we can conclude that high volume extraction extending extraction time up to 24 h is the best choice if we have to release compounds from the inner surfaces of cork stoppers. Recovery percentages ranged from 51% for pentachloroanisole to 81% for 2,4-dichloroanisole. This method allows the determination of an array of compounds involved in cork taint at very low levels from 1.2 ng g⁻¹ for 2,4,6-tricholoroanisole to 23.03 ng g⁻¹ for 2,3,4,6-tetrachlorophenol.     

Determination of cyclic and linear siloxanes in soil samples by ultrasonic-assisted extraction and gas chromatography-mass spectrometry

A rapid method, based on sonication-assisted extraction in small columns (SAESC) and subsequent quantification and identification by gas chromatography-mass spectrometry (GC-MS), was developed for the determination of cyclic and linear siloxanes in soil. In the experiments with spiked samples (10-50 ng g(-1)), the recovery of cyclic and linear siloxanes ranged from 87.7 to 108.0% and from 84.9 to 107.6%, respectively. The validated method was used to determine the levels of these compounds in various types of soil samples collected from different locations in Spain. The cyclic siloxanes, decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) were detected in all the soil samples analyzed at concentrations from 9.2 to 56.9 ng g(-1) for D5 and from 5.8 to 27.1 ng g(-1) for D6 in agricultural soils and from 22 to 184 ng g(-1) for D5 and from 28 to 483 ng g(-1) for D6 in industrial soils. The total linear siloxanes concentrations (L5-L14) (sum of the 10 congeners) ranged from 191 to 292 ng g(-1) in agricultural soils and from 1411 to 8532 ng g(-1) in industrial soils.     

Determination of 3-chloro-1,2-propanediol in biological samples by quick-easy-cheap-effective-rugged-and-safe extraction coupled with gas chromatography-mass spectrometry and its biodistribution in rats

3-Chloro-1,2-propanediol is a common food contaminant, but reports on its determination in biological tissues are lacking. In the present study, a method was developed to detect 3-chloro-1,2-propanediol contents in rat tissues by quick-easy-cheap-effective-rugged-and-safe extraction and gas chromatography-mass spectrometry analysis. Biological samples were extracted with ethyl acetate and purified with adsorbents. The optimized adsorbent for each sample was selected from 4–5 combinations of N-propylethylenediamine, octadecylsilane, graphitized carbon black, strong anion exchange, and florisil. Extracted 3-chloro-1,2-propanediol was derivatized with heptafluorobutyric anhydride and subjected to gas chromatography-mass spectrometry. This method had good linearity (correlation coefficients >0.99) in the range of 2–2000 ng/g for blood, kidney, liver, testis, and brain samples. The limits of detection were under 0.8 ng/g; the limits of quantification were 2 ng/g; the recovery rates were 85%–102%; and the matrix effects were 1.98%–7.67%. This method also had good precision. The dynamic changes in 3-chloro-1,2-propanediol in rats gavaged with 20 mg/kg b.w. for 24 h were detected using this method. The 3-chloro-1,2-propanediol content in each tissue sharply increased to a peak, rapidly decreased within 2 h, and stabilized at 12 h. 3-Chloro-1,2-propanediol persisted in the kidney, testis, and liver 24 h after gavage.     

Determination of tricyclic antidepressants in human plasma using pipette tip solid-phase extraction and gas chromatography-mass spectrometry

A method for the simultaneous extraction of four tricyclic antidepressants from human plasma samples using pipette tip SPE with MonoTip C(18) tips is presented. Human plasma (0.1 mL) containing four tricyclic antidepressants (amitriptyline, amoxapine, imipramine, and trimipramine) and an internal standard (IS), protriptyline, was mixed with 0.4 mL of distilled water and 100 microL 1 M NaOH solution. After centrifugation of the mixture, the supernatant was extracted to the C(18) phase of the tip by 20 repeated aspirating/dispensing cycles using a manual micropipettor. The analytes retained in the tip were eluted with methanol by five repeated aspirating/dispensing cycles. Without evaporation and reconstitution, the eluate was directly injected into a gas chromatograph injector and detected by a mass spectrometer with SIM in the positive-ion electron impact mode. Recovery of the four antidepressants and IS spiked into human plasma was 80.2-92.1%. The regression equations for the four antidepressants showed excellent linearity in the range of 0.2-40 ng/0.1 mL. LODs and LOQs for the four drugs were 0.05-0.2 ng/0.1 mL and 0.2-0.5 ng/0.1 mL, respectively. Intra- and interday CVs for the four drugs in plasma were no greater than 9.5%.     

Selective pressurized liquid extraction of estrogenic compounds in soil and analysis by gas chromatography-mass spectrometry

A selective pressurized liquid extraction (SPLE) method, followed by gas chromatography–mass spectrometry (GC–MS), for the simultaneous extraction and clean-up of estrone (E1), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), estriol (E3) and bisphenol A (BPA) from soil samples is described. The on-line clean-up of soil by SPLE was achieved using different organic matter retainers, including silica, alumina and Florisil, the most effective being silica. Thus, different amounts of silica, in conjunction with different extraction solvents (acetone, ethyl acetate, isohexane and dichloromethane), either alone or in combination, were used to extract the target chemicals from spiked soil samples. It was shown that 3 g silica resulted in satisfactory rates of recovery of target compounds and acetone:dichloromethane (1:3, v/v) was efficient in extracting and eluting estrogenic compounds for SPLE. Variables affecting the SPLE efficiency, including temperature and pressure were studied; the optimum parameters were 60 °C and 1500 psi, respectively. The limits of detection (LODs) of the proposed method were 0.02–0.37 ng g⁻¹ for the different estrogenic chemicals studied. The outputs using the proposed method were linear over the range from 0.1 to 120 ng g⁻¹ for E1, E2, EE2, 0.2–120 ng g⁻¹ for E3, and 0.5–120 ng g⁻¹ for BPA. The optimized method was further verified by performing spiking experiments in natural soil matrices; good rates of recovery and reproducibility were achieved for all selected compounds and the method was successfully applied to soil samples from Northeast Scotland, for the determination of the target compounds.     

Determination of cocaine and cocaethylene in urine by solid-phase microextraction and gas chromatography-mass spectrometry

In order to evaluate recent cocaine exposure or its coingestion with ethanol, a simple and sensitive solid-phase microextraction (SPME) procedure for determination of cocaine and cocaethylene in urine was developed and validated. A polydimethylsiloxane fibre (100 microm) was submersed in the urine sample for 20 min under magnetic stirring after alkalinization with solid buffer (NaHCO(3):K(2)CO(3), 2:1). Gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring mode (SIM). The limits of quantification were 5.0 ng/mL for both analytes. Good inter- and intra-assay precision was also observed (coefficient of variation <9%).     

Determination of volatile nitrosamines in meat products by microwave-assisted extraction and dispersive liquid-liquid microextraction coupled to gas chromatography-mass spectrometry

Microwave-assisted extraction (MAE) and dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) were evaluated for use in the extraction and preconcentration of volatile nitrosamines in meat products. Parameters affecting MAE, such as the extraction solvent used, and DLLME, including the nature and volume of the extracting and disperser solvents, extraction time, salt addition and centrifugation time, were optimized. In the MAE method, 0.25g of sample mass was extracted in 10mL NaOH (0.05M) in a closed-vessel system. For DLLME, 1.5mL of methanol (disperser solvent) containing 20μL of carbon tetrachloride (extraction solvent) was rapidly injected by syringe into 5mL of the sample extract solution (previously adjusted to pH 6), thereby forming a cloudy solution. Phase separation was performed by centrifugation, and a volume of 3μL of the sedimented phase was analyzed by GC-MS. The enrichment factors provided by DLLME varied from 220 to 342 for N-nitrosodiethylamine and N-nitrosopiperidine, respectively. The matrix effect was evaluated for different samples, and it was concluded that sample quantification can be carried out by aqueous calibration. Under the optimized conditions, detection limits ranged from 0.003 to 0.014ngmL(-1) for NPIP and NMEA, respectively (0.12-0.56ngg(-1) in the meat products).     

Application of in-vial membrane assisted solvent extraction to the determination of polycyclic aromatic hydrocarbons in seawater by gas chromatography-mass spectrometry

A device for membrane assisted solvent extraction from an aqueous sample to an organic solvent within a micro-vial compatible with a chromatography auto-sampler was used to extract trace amounts of seven polycyclic aromatic hydrocarbons from seawater. The device consisted in an assembly of a volumetric flask containing the sample and a micro-vial containing the organic solvent by means of a screw stopper in which the septum was replaced by a sized piece of a membrane. Extraction conditions (nature of the organic solvent, extraction time, presence of ethanol in the donor phase, ionic content of the donor phase, characteristics of the membrane and volumes of donor and acceptor phases) were studied in order to find the conditions for maximum extraction. Analytical performance characteristics have also been established. The extraction efficiency was between 12.5 and 23%, which implies an enrichment factor value above 40. The repeatability and reproducibility were in the range of 8.6–10.0% and 13–19%, respectively. Detection limits were in the range of 24–39 ng L⁻¹. Nine seawater samples have been studied. Most of the concentrations were under the limits of detection. Naphthalene and phenanthrene contents have been determined in a sample using the method of standard additions, and concentrations 100 and 91 ng L⁻¹, respectively.     

Simultaneous profiling analysis of alkylphenols and amines by gas chromatography and gas chromatography–mass spectrometry

Two-phase O-ethoxycarbonylation was performed to alkylphenols in acidic solution with ethyl chloroformate present in dichloromethane phase fortified with triethylamine with subsequent N-ethoxycarbonylation of amines after adjusting to alkaline pH. The resulting ethoxycarbonyl derivatives were subjected to pentafluoropropionylation, clean-up and concentration for analysis by gas chromatography and gas chromatography–mass spectrometry. The present method was linear (r ≥ 0.9959) in the range of 0.5–10.0 μg ml^−l with good precision (≤9.5%) and accuracy (−8.9 to 9.5%) for 20 phenols and 27 amines examined, allowing simultaneous screening for a total of one alkylphenol and four amines from wine and beer.     

Derivatization followed by gas chromatography-mass spectrometry for quantification of ethyl carbamate in alcoholic beverages

A sensitive and rapid analytical methodology based on derivatization followed by gas chromatography-mass spectrometry (GC-MS) was developed for the quantitative determination of the toxic contaminant ethyl carbamate (EC, urethane, C(2)H(5)OCONH(2)) in alcoholic samples. EC was extracted using liquid-liquid extraction technique, and then silylated with bis-(trimethylsilyl)trifluoroacetamide, analysed finally by GC-MS. The isopropyl carbamate was used as the internal standard for quantitative analysis of EC in alcoholic samples. In this work, the sample extraction and derivatization reaction conditions were investigated, and the optimal extraction conditions obtained were: pH 9 and solvent of ethyl acetate, and the derivatization conditions were: derivatization reaction temperature of 80°C and time duration of 30 min. With the optimal conditions, the method validations were also studied. In the validation studies, EC exhibited good linearity with a regression coefficient of 0.9999. The limit of detection and limit of quantification were 0.30 and 5.0 μg/kg, respectively. The precision was less than 8.4%. Finally, the proposed technique was successfully applied to the analysis of EC in 35 kinds of alcoholic samples. The experimental results have demonstrated that the proposed technique is a fast, reliable and low-cost method for determination of EC in alcoholic samples.     

Determination of carbetamide in groundwater by micro liquid-liquid extraction and gas chromatography-mass spectrometry

Summary A method is proposed for the determination of carbetamide in water below European Union guidelines (detection limit,DL, below 0.1 μgL⁻¹). Micro liquid-liquid extraction with dichloromethane affords carbetamide which is converted to aniline by hydrolysis. Identification and quantification of aniline was performed by GC-MS. The retention time was 4.24 min. Quantification was achieved by single-ion monitoring (SIM) atm/z 66 and 93. Clean-up is not necessary before SIM. Deuterated anthracene (²H₁₀-anthracene) was used as internal standard. The method was used to determine carbetamide in different types of water sample spiked at very low concentration levels (0.13–10.00 μgL⁻¹). TheDL was 0.04 μgL⁻¹. The effect of the presence of other carbamates was also studied.     

Simultaneous extraction and clean-up of polybrominated diphenyl ethers and polychlorinated biphenyls from sheep liver tissue by selective pressurized liquid extraction and analysis by gas chromatography-mass spectrometry

We describe a selective pressurized liquid extraction (SPLE) method, followed by gas chromatography–mass spectrometry (GC–MS), for the simultaneous extraction and clean-up of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in sheep liver tissue samples. The on-line clean-up of liver tissue by SPLE was tested using differing amount of acid-modified silica (sulphuric acid:silica gel, 1:2, w/w), the most effective amount being 20 g. Different extraction solvents (iso-hexane and dichloromethane), either alone or in various combinations, were used to extract these target compounds from spiked liver samples. Variables affecting the SPLE extraction efficiency, including temperature, pressure, number of extraction cycles and static extraction time were studied; the optimum parameters were 80 °C, 10.3 MPa, 2 cycles and 5 min, respectively. The SPLE based method was compared with more traditional Soxhlet, off-line PLE, ultrasonic and heating extraction methods. Overall the mean percentage recoveries for all target chemicals using SPLE were 86–103% (n = 3, SD < 9%), and compared favourably with the Soxhlet (63–109%, n = 3, SD < 8%), off-line PLE (82–104%, n = 3, SD < 18%), ultrasonic (86–99%, n = 3, SD < 11%) and heating (72–102%, n = 3, SD < 21%) extraction methods. The limits of detection of the proposed method were 5–96 pg g⁻¹ and 2–29 pg g⁻¹ for the different PBDE and PCB chemicals studied, respectively. The outputs of the proposed method were linear over the range from 0.02 to 30 ng g⁻¹, for all PCB and PBDE congeners except for PBDE 100 and 153 (0.05–30 ng g⁻¹) and PBDE 183 (0.1–30 ng g⁻¹). The method was successfully applied to sheep liver samples for the determination of the target PBDE and PCB compounds.     

Evaluation of solid-phase micro-extraction coupled to gas chromatography-mass spectrometry for the headspace analysis of volatile compounds in cocoa products

The aroma profile of cocoa products was investigated by headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC–MS). SPME fibers coated with 100 μm polydimethylsiloxane coating (PDMS), 65 μm polydimethylsiloxane/divinylbenzene coating (PDMS-DVB), 75 μm carboxen/polydimethylsiloxane coating (CAR-PDMS) and 50/30 μm divinylbenzene/carboxen on polydimethylsiloxane on a StableFlex fiber (DVB/CAR-PDMS) were evaluated. Several extraction times and temperature conditions were also tested to achieve optimum recovery. Suspensions of the samples in distilled water or in brine (25% NaCl in distilled water) were investigated to examine their effect on the composition of the headspace. The SPME fiber coated with 50/30 μm DVB/CAR-PDMS afforded the highest extraction efficiency, particularly when the samples were extracted at 60 °C for 15 min under dry conditions with toluene as an internal standard. Forty-five compounds were extracted and tentatively identified, most of which have previously been reported as odor-active compounds. The method developed allows sensitive and representative analysis of cocoa products with high reproducibility. Further research is ongoing to study chocolate making processes using this method for the quantitative analysis of volatile compounds contributing to the flavor/odor profile.     

微波辅助萃取-气相色谱质谱法检测生物体内的多溴联苯醚

建立了微波辅助萃取-气相色谱质谱法测定生物样品中的多溴联苯醚(PBDEs)的方法,优化了萃取剂的种类、萃取剂用量、萃取时间等微波萃取条件和GC-MS仪器分析条件。正己烷-丙酮混合溶剂提取后,经实验室自制的多层硅胶柱分离纯化,用气相色谱-质谱进行测定,该方法基质加标回收率在60%～77%之间,相对标准偏差在11%～18%之间,方法的检测限为0.03～0.20ng/g,适用于生物样品中PBDEs的测定。     

Multiresidue determination of thermolabile insecticides in cereal products by gas chromatography-mass spectrometry: evaluation with on-column injection and conventional hot splitless injection

This communication presents a study on the simultaneous determination of thermolabile N-methylcarbamate and organophosphorus insecticides in cereal products by gas chromatography-mass spectrometry. The thermal stability of the multiple insecticides was evaluated with conventional hot splitless injection and on-column injection. The results obtained by GC-MS with these two injection techniques were compared in terms of the recovery, the limit of detection, the limit of qualification, and the reproducibility. With on-column injection, the pesticide recoveries in cereal samples were better than 82%, with relative standard deviations lower than 5.4%. The limits of qualification for most insecticides were in the range of 0.009-0.08 mg/kg, i. e. lower than the maximum residue limits established for insecticides in cereal products by the European Union. The long-term stability using on-column injection for analysis of insecticides in real samples was evaluated and normal chromatographic performance could be obtained within 50 analyses. The results revealed that it was possible for application of on-column injection in the analysis of thermolabile multiple insecticides in food sample after comprehensive sample clean-up, despite the highly contaminated nature of the column system.     

芦蒿秸秆超临界CO2萃取物的气相色谱-质谱分析

芦蒿(Artemisia selengensis Trucz.)秸秆超临界CO2萃取物的挥发性成分,运用毛细管气相色谱-质谱联用法进行了分析,用气相色谱面积归一化法测定了各成分的质量分数.经毛细管色谱分离出33个峰,并鉴定出峰所对应的化合物.其主要化学成分为1-氯-3-(3-氯代丙氧基)丙烷、[1R-(1α,4aβ,10aα)]-1,2,3,4,4a9,10a-八氢-1,4a-二甲基-7-(1-甲基乙基)-1-菲羧酸、5,5-二甲基-1-乙基1,3-环戊二烯等.为进一步开发利用芦蒿资源提供了科学依据.     

Rapid and sensitive detection of fipronil and its metabolites in edible oils by solid‐phase extraction based on humic acid bonded silica combined with gas chromatography with electron capture detection

Solid‐phase extraction based on humic acid bonded silica followed by gas chromatography with electron capture detection was developed to determine fipronil and its metabolites in edible oil. To achieve the best extraction performance, we systematically investigated a series of solid‐phase extraction parameters. Under the optimized conditions, the method was validated according to linearity, recovery, and precision. Good linearities were obtained with R² more than 0.9996 for all analytes. The limits of detection were between 0.3 and 0.5 ng/g, and the recoveries ranged from 83.1 to 104.0% at three spiked concentrations with intra‐ and interday relative standard deviation values less than 8.7%. Finally, the proposed method was applied to determine fipronil and its metabolites in 11 edible oil samples taken from Wuhan markets. Fipronil was detectable in four samples with concentrations ranging from 3.0 to 5.2 ng/g. In China, the maximum residue limits of fipronil in some vegetables and maize are 20 and 100 ng/g (GB/T 2763‐2014), respectively. The residues of fipronil and its metabolites in commercial edible oils might exhibit some potential threat to human health as a result of high consumption of edible oil as part of daily intake.