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Objective@#To optimize the pretreatment method of N-nitrosamine compounds in ready-to-eat aquatic products. @*Methods@#Market-sold ready-to-eat aquatic products were collected, homogenized and distilled by steam. The samples were extracted for 10 minutes using dispersive liquid-liquid microextraction (DLLME) with ethanol, trichloromethane and sodium chloride (3.0 g). After centrifugation, the organic phase in the lower layer was collected and subjected to gas chromatography-tandem mass spectrometry (GC-MS/MS). The six common N-nitrosamine compounds were determined in ready-to-eat aquatic products using multiple reaction monitoring mode (MRM) and quantified by the internal standard method. @*Results@#The optimized method exhibited a good linear relationship at concentrations of 10.0 to 500 μg/L for determination of 6 N-nitrosamine compounds (correlation coefficient of greater than 0.999), with 0.05 to 0.60 μg/kg limit of detection, 0.15 to 1.60 μg/kg limit of quantitation, mean spiked recovery rates of 71.8% to 108.9%, and relative standard deviations of 1.4% to 8.6%. N-Nitrosodimethylamine showed the highest detection rate in 20 market-sold ready-to-eat aquatic products (90%), and the detection rates of N-Nitrosopyrrolidine, N-Nitrosodiethylamine and N-dibutylnitrosamine were 15%, 10% and 10%, respectively. @*Conclusion@#Steam distillation combined with DLLME may optimize the pretreatment method of N-nitrosamine compounds in ready-to-eat aquatic products and meet the measurement requirements.
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Background Dicamba is widely used in agricultural production in China, but it is extremely soluble in water and can be harmful to human health when it enters the body via water drinking. It is necessary to establish an accurate, sensitive, and rapid detection method to determine the residues of dicamba in domestic drinking water. Objective To establish two methods for the determination of dicamba residues in drinking water by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS) respectively. Methods The conditions of the proposed method using HPLC-MS/MS included CAPCELL PAK ST chromatographic column, ammonium formate water solution and methanol as the mobile phase, and isocratic elution. The system was operated under multiple reaction monitoring mode and electrospray negative ionization mode. Trimethylsilylated diazomethane was used as a derivatizing agent for GC-MS/MS, and an external standard curve was used to evaluate the system. The residues of dicamba in seven water samples of tap water or secondary water supply from six regions in Chengdu were detected by the established systems to evaluate their applicability and to understand the status quo of dicamba residues in drinking water. Results For the HPLC-MS/MS, the linear range of dicamba was 1.00-100 μg·L−1, the regression equation was \begin{document}$\hat Y $\end{document}=1250.9X+2681.5, the correlation coefficient was 0.9988, the relative standard deviations were 1.23%-26.3%, the limit of detection was 0.95 μg·L−1, and the spiked recoveries were 91.8%-111%. For the GC-MS/MS, the linear range of dicamba was 0.200-10.0 μg·L−1, the regression equation was \begin{document}$\hat Y $\end{document}=190597X+40911, the correlation coefficient was 0.9993, the relative standard deviations were 0.64%-3.90%, the limit of detection was 0.18 μg·L−1, and the spiked recoveries were 97.3%-105%. No dicamba residue was identified in the seven water samples of tap water or secondary water supply from six regions in Chengdu by the proposed methods. Conclusion The two detection methods established in this study are sensitive and rapid, meet the requirements from the detection of dicamba residues in drinking water, and provide an experimental basis for subsequent research on the detection of dicamba residues. In the future, it is necessary to continue to pay attention to the pollution of dicamba in drinking water in Chengdu.
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Objective@#To optimize the determination of pentachlorophenol in wooden chopping boards through pretreatment of miniaturized samples.@*Methods@# The pretreated wooden chopping board samples were subjected to ultrasound extraction (1 mL of 0.5 mol/L K2CO3 added in 5 mL extraction solution) in 8 mL acetone and 2 mL water, followed by derivatization with 0.3 mL acetic anhydride, extraction with n-hexane and separation with DB-5ms column (30 m×0.25 mm, 0.25 μm). Gas chromatography tandem mass spectrometry (GC-MS/MS) was performed in multiple reaction monitoring (MRM) mode with quantitative analysis using the internal standard method.@*Results@#The GC-MS/MS assay showed a good linear relationship within the range of 0.01 to 0.2 µg/mL (R2>0.999), with a 0.003 mg/kg limit of detection and 0.01 mg/kg limit of quantitation. The mean recovery rates were 84.2% to 96.7% at spiked concentrations of 0.003, 0.01 and 0.03 mg/kg, with relative standard deviation of 2.2% to 6.1%.@*Conclusions@#The established GC-MS/MS assay is easy to perform, environment-friendly, highly accurate and sensitivity, which is feasible for determination of pentachlorophenol in wooden chopping boards.
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Background N-nitrosamines, a group of by-products of drinking water disinfection, have strong cytotoxicity to mammals. N-nitrosamines in drinking water are at the ng·L−1 level, and its accurate qualitative and quantitative analysis is difficult, so it is necessary to develop a sensitive and accurate method to determine N-nitrosamines in drinking water. Objective To establish a solid phase extraction-gas chromatography tandem mass spectrometry (GC-MS/MS) method for simultaneous determination of 10 kinds of N-nitrosamines in drinking water. To apply the established method to determine the levels of 10 kinds of N-nitrosamines in drinking water in Nanjing, and to understand the pollution status. Methods Coconut charcoal solid phase extraction (SPE) cartridge and HLB Pro SPE cartridge were compared for the extraction efficiency of 10 N-nitrosamines in drinking water. A coconut charcoal SPE cartridge and a HLB Pro SPE cartridge were concatenated using a SPE connector, and then formed two combinations: coconut charcoal (top)-HLB Pro (bottom) and HLB Pro (top)-coconut charcoal (bottom), to extract the spiked samples, and combined with direct and independent elution ways to obtain the best extraction efficiency. From November to December 2021, 9 raw water, 10 finished water, and 7 tap water samples were collected from 9 municipal water supply units in Nanjing with 1 L brown glass sampling bottles. An 1.0 L drinking water sample was added with the isotope internal standard to prepare a test sample containing an isotope internal standard concentration of 25 ng·L−1. The automatic SPE instrument loaded all the 1.0 L drinking water samples to the tandem SPE cartridge of the HLB Pro (top)-coconut charcoal (bottom) at the rate of 15 mL·min−1. After extraction, the HLB Pro SPE cartridge and coconut charcoal SPE cartridge were transferred to the solid phase extraction vacuum device and eluted with 10 mL of dichloromethane respectively, then the dichloromethane eluents were combined, and concentrated to about 1.0 mL by nitrogen blowing after a small amount of the upper aqueous phase was removed. The concentrated solution was detected by GC-MS/MS and quantified by isotope internal standard method. Results The comparison of sample spike recovery experiments showed that coconut charcoal solid phase extraction (SPE) cartridge and HLB Pro SPE cartridge presented highcomplementarity for the extraction efficiency of 10 N-nitrosamines in drinking water. Using HLB Pro (top)-coconut charcoal (bottom), independent elution, and combined with eluents, the optimal extraction efficiency was obtained. Under these conditions, by GC MS/MS, the 10 N-nitrosamines showed a good linear relationship within the range of 2–50 ng·L−1, the correlation coefficients were all greater than 0.9996, the method detection limit was 0.149–0.211 ng·L−1, and the limit of quantification was 0.596–0.844 ng·L−1. At the spiked concentrations of 5.0, 15, and 30 ng·L−1, the average recoveries of the 10 kinds of N-nitrosamines were 88.0%–104.8%, and the relative standard deviations were 1.22%–4.87%. When applying the method to determine the concentrations of the 10 N-nitrosamines in Nanjing drinking water, the results showed that the 10 N-nitrosamines were positive in different degrees in raw water, finish water, and terminal water, the detection rates were 0%–100%, and the concentrations were ND–27.6 ng·L−1. Conclusion This tandem solid phase extraction-gas chromatography tandem mass spectrometry method can achieve simultaneous determination of a variety of N-nitrosamines in drinking water with high sensitivity and high throughput.
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Objective@# To develop a magnetic solid-phase extraction combined with gas chromatography-tandem mass spectrometry (GC-MS/MS) based on pyrrole-modified magnetic nanoparticles to determine 16 types of phthalic acid esters (PAEs) in commercial liquors.@*Methods @#Fe3O4 magnetic nuclei were prepared by hydrothermal synthesis, and the polypyrrole-modified magnetic nanomaterials were prepared with the chemical oxidation method. Magnetic solid-phase extraction of beer, grape wine, rice wine and Chinese spirits was performed at 10% alcohol by volume, extraction duration of 20 min and ethyl acetate elution of 10 min, followed by addition of 1 g NaCl for reduction of emulsification effect. The 16 types of PAEs were determined using GC-MS/MS with DB-5MS capillary column (30 m×250 μm, 0.25 μm) under the mode of electron impact ionization (EI) and dynamic multiple reaction monitoring (dMRM), with quantitative analysis using the external standard method. The standard curve, detection limit, spike recovery rate and precision of GC-MS/MS for determination of 16 types of PAEs were evaluated.@*Results@#Pyrrole was successfully embedded onto the surface of magnetic nanoparticles in the form of polymer, and the magnetic nanoparticles modified by polypyrrole were well characterized, showing unapparent matrix and emulsification effects. There was a good linear relationship for the 16 types of PAEs at 50 to 5 000 ng/mL (r=0.999 5-0.999 9), and the spike recovery rate of 16 types of PAEs ranged from 71.61% to 110.50% at 100, 500 and 1 000 μg/kg, with relative standard deviations of 3.78% to 7.41%, detection limits of 0.02 to 1.47 μg/kg. PAEs were detected in 20 out of 50 liquor samples, with 30.00%, 60.00%, 40.00% and 70.00% detection rates in beer, grape wine, rice wine and Chinese spirits, respectively. @*Conclusions@#This method is sensitive to determine 16 types of PAEs in liquor samples, with unapparent matrix and emulsification effects, and the polypyrrole-modified magnetic composite nanoparticles present high adsorption of PAEs in liquor samples, which is feasible for monitoring of PAEs in multiple types of liquor samples.
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Objective We aimed to assess the association between urinary bisphenol A(BPA)concentrations and gestational age in pregnant women. Methods A total of 248 pregnant women were recruited from a maternal and child care hospital in Shanghai. A questionnaire survey was completed to collect socio-demographic information and spot urine samples were collected during pregnancy. Gas chromatography-tandem mass spectrometry(GC-MS/MS)was used to measure BPA concentrations in urine samples. Linear relationship between urinary BPA level and gestational age was assessed by using generalized additive models. Multivariate regression model was used to evaluate associations of prenatal BPA exposure with gestational age. Results BPA was detected in all the urine samples. Median value and geometric mean of urinary BPA levels were 0.85 μg/L and 1.21 μg/L, respectively. Linear relationship between urinary BPA concentration and gestational weeks was confirmed(non-linear P > 0.05). Positive association between urinary BPA level and gestational age was indicated(regression coefficient, β = 0.19;95%CI:0.04-0.35;P = 0.016). However, it was only observed in girls, stratified by sex of newborns(β = 0.18;95%CI:0.03-0.34;P = 0.020). After stratification by trimester, no significant association was found in the second or the third trimesters. Conclusion Pregnant women are extensively exposed to BPA. Urinary BPA exposure during pregnancy may extend gestational age, especially in girls.
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Objective To establish a method for determination of escitalopram in biological samples by ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction combined with gas chromatography-tandem mass spectrometry （GC-MS/MS） and provide evidences for forensic determination of cases related to escitalopram. Methods The 1-hexyl-3-methylimidazolium hexafluorophosphate （[C6MIM][PF6]） was selected as an extract solvent to process biological samples. Ultrasound-assisted extraction was used on the samples. Then the samples were detected by GC-MS/MS. Results The linear range of escitalopram in blood and liver were 5.56-1 111.10 ng/mL and 0.025-5.00 mg/g, respectively. The correlation coefficient （r） were greater than 0.999, limit of detection （LOD） were 4.00 ng/mL and 2.00 μg/g, limit of quantitation （LOQ） were 14.00 ng/mL and 6.00 μg/g, respectively. The extraction recovery rates were all greater than 50%, the interday and intraday precision were less than 20%. Escitalopram was detected in blood and liver samples from the actual poisoning case by this method with a content of 1.26 μg/mL and 0.44 mg/g, respectively. Conclusion The ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction combined with GC-MS/MS is environment friendly, rapid, has good enriching effect and consumes less organic solvent and can be used for forensic determination of escitalopram related cases.
Subject(s)
Citalopram , Gas Chromatography-Mass Spectrometry , Limit of Detection , Liquid Phase Microextraction , Tandem Mass SpectrometryABSTRACT
To evaluate the pesticide residue risk of Jinyinhua Formula Granules( made from Lonicerae Japonicae Flos) used in the market preliminarily,20 samples of Jinyinhua Formula Granules from 5 manufactures were collected randomly through the national evaluative sampling test program. Totally 262 pesticides( involving 270 chemical monomers) with monitoring significance to traditional Chinese medicinal materials were detected. Samples were extracted by high speed homogenate with acetonitrile as solvent. And their residues were analyzed by GC-MS/MS and LC-MS/MS in MRM mode. No less than 2 groups of characteristic ion pairs were adopted for qualitative detection,and the calibration curve method was used for quantitative detection. The results showed that 20 pesticides were detected in 20 batches of Jinyinhua Formula Granules,with an average of about 9 pesticides detected in every batch,but no restricted pesticide was detected. The detected pesticides were all at the trace level,which was far lower than the limit of the general food standard. Therefore,the safety risk was low in Jinyinhua Formula Granules. In this study,a screening method for pesticide residues in Jinyinhua Formula Granules was established for the first time. The method was accurate and rapid,and the detection indicators were highly targeted. The results could provide theoretical reference for the prevention and control of pesticide safety risks in Jinyinhua Formula Granules and even traditional Chinese medicine formula granules.
Subject(s)
Chromatography, Gas , Chromatography, Liquid , Drug Contamination , Drugs, Chinese Herbal , Pesticide Residues , Quality Control , Tandem Mass SpectrometryABSTRACT
A method of metal organic nanotubes-based dispersive solid phase extraction-gas chromatography-tandem mass spectrometry was developed for sensitive analysis of polychlorinated biphenyls in environmental water samples.Related important factors influencing enrichment efficiency, such as ionic strength, extraction time and amount of adsorbent, were investigated.Response surface methodology was used to optimize these factors in detail.Under the optimal conditions such as 4.92% (w/V) NaCl, 4.5 min of extraction time, 62.5 mg of adsorbent, and n-hexane as desorption solvent, wide linearity (2-1000 ng/L or 5-1000 ng/L), and low limits of detection (0.26-0.82 ng/L) were achieved.The intra-day and inter-day relative standard deviations were 0.8%-5.5% (200 ng/L, n=6)and 2.7%-7.4% (200 ng/L, n=6), respectively.Finally, this method was successfully applied to the sensitive analysis of 6 kinds of PCBs in environmental water samples, with satisfactory recoveries of 78.9%-113.3%.
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OBJECTIVE: To establish a method for simultaneous determination of 187 kinds of pesticides in flowers and fruits of traditional Chinese medicine (TCM) by using gas and liquid chromatography tandem mass spectrometry, taking medlar and honeysuckle as examples. METHODS: The forbidden, restrictted and commonly used pesticides were picked out as detecting indexes according to the principals of risk management. The factors affecting the extraction, purification, and detection were optimized, and the final condition was established as follows: the samples were extracted with acetonitrile, and cleaned-up by carb solid phase extraction column. The separation of target compounds were performed by capillary or liquid column, and quantitative analysis was carrid out by GC-MS/MS or LC-MS/MS with MRM model. Internal standard was used to improve the accuracy of this method. RESULTS: Honeysuckle flower and Wolfberry were used to evaluate the accuracy of this method. The calibration curves were linear in the range of 1-100 ng · mL-1 with correction coefficients of greater than 0.99. The recoveries of more than 88% pesticides were ranged from 70% to 120% at three spiked levels (5, 20 and 100 μg · kg-1). CONCLUSION: The detecting indexes in this method cover most forbidden and restricted pesticides, which is meaningful for the safety supervision of TCM. With the advantage of rapidness and accuracy, this method can be used for routine determination of multi-pesticides in flowers and fruits of TCM.
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A novel, simple and highly sensitive method was developed for the rapid analysis of phenolic antioxidants at trace level in edible oils. It was based on dispersive liquid-liquid microextraction ( DLLME ) and gas chromatography-mass/mass spectrometry ( GC-MS/MS) . Related important factors that may influence enrichment efficiency, such as type and volume of extraction solvent, type and volume of dispersive solvent, and extraction time were investigated and optimized in detail. The optimum conditions were as follows:a quick injection of 500 μL mixed solution ( methanol:acetonitrile=1:1 , V/V ) into 1 . 0 g oil sample with 3 mL n-hexane for 10 s of extraction time. Under the optimal conditions, the linearity (10-2000 ng/g), limits of detection (1. 5-2. 4 ng/g) and relative standard deviations (4. 0%-8. 3%) was obtained. The proposed method was applied for the analysis of 4 edible oil samples. Some of phenolic antioxidants were detected in three of them, and the recoveries of spiked samples were in the range of 81. 9%-118%.
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OBJECTIVE: To develop a GC-MS/MS method for the determination of the residues of 16 polycyclic aromatic hydrocarbons (PAHs) in Chinese herbal medicines. METHODS: Using isotope as internal standard, the sample was extracted by ethyl acetate and purified by solid phase extraction on C18 cartridges. GC-MS/MS method was used for the assay, with analyte protectants added to counteract the matrix effect. The chromatographic column was DB-5ms(0.25 mm × 30 m, 0.25 μm) with temperature programming and MRM detection. RESULTS: The calibration curves for the 16 kinds of typical PAHs were linear in the range of 1 - 100 ng · mL-1. The average recovery rate was 88.53% - 119.03% in the range of 1 -25 μg · kg-1 with RSDs of 1.25% - 14.70% (n = 3). The LOQs were 0.2 - 1 μg · kg-1. CONCLUSION: This method is specific, sensitive, accurate and can be used for residue detection of 16 typical kinds of PAHs in Chinese herbal medicines.
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Objective:To establish a GC-MS method for the simultaneous determination of 16 phthalate ester plasticizers in oral liquid preparations, compare the purification effect of liquid preparations by liquid-liquid extraction and solid phase extraction and opti-mize the operating parameters to determine the optimal experimental conditions. Methods:The samples were operated by liquid-liquid extraction and solid phase extraction, respectively. Selective ion monitor ( SIM) was adopt, phthalate esters were identified by the rela-tive abundance of major characteristic ions and the content was determined by an external standard method. Results:When the samples were operated by liquid-liquid extraction, the interference was strong with many impurity peaks. Therefore, the solid phase extraction was adopted for the sample pretreatment. GC-MS was used to detect the residues of 16 phthalate ester plasticizers in oral liquid prepara-tions. The detection limit was 0. 02μg·g-1 ,while the calibration curve showed good linearity within the range of 0. 25-8. 0μg·ml-1 with the correlation coefficient between 0. 990 7 and 0. 999 8. The average recoveries were 76. 0%-95. 4%. The relative standard devi-ations were between 2. 3% and 9. 6%(n=6). Conclusion: Pretreated by solid phase extraction, the residues of 16 phthalate ester plasticizers in oral liquid preparations can be detected by GC-MS with the properties of simple, fast, precise and sensitive, and it is suitable for the determination of phthalate esters in oral liquid preparations.
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A rapid headspace gas chromatography tandem mass spectrometric ( HS-GC/MS ) method was established for the analysis of volatile fatty acids ( VFAs ) in the feces. Feces were suspended by 6%phosphoric acid aqueous solution (1:2 m/V) and sealed in the headspace bottle for HS-GC/MS analysis. The HS-GC/MS method was optimized as follows: agitator temperature ( temp. ):80 ℃, syringe temp.:80 ℃, sample incubation time: 30 min, injection: 1 mL without split-flow. The chromatographic separation was performed on a DB-FFAP capillary column (30m×0. 25 mm×0. 25 μm) with injection port temp.:250 ℃. The temperature program ( initial temp. at 50 ℃ within first 1 min, and raised to 200 ℃ by 10 ℃/min) was employed by fixing the flow of carrier gas (high purity helium) at 1. 0 mL/min. The electron energy at -70 eV for electron impact ( EI ) ionization, ion source temp.: 250 ℃, transfer line temp.:280 ℃, the voltage of electron multiplier at 0. 95 kV. The spectra were recorded in the range of m/z 33-200 for full scan. The established HS-GC/MS method could be applied to analyze VGAs in the feces from human and rat appropriately. There are nine VFAs identified in the feces from human, and eight VFAs detected in the feces from rat by retrieving the NIST library, comparing with the standards and analyzing the MS data. Furthermore, the relative percentage contents of acetic acid, propionic acid and butyric acid accounted for roughly 85% of all VFAs by area normalization. The method is simple and sensitive, and it can be used to rapidly detect VFAs in the feces from human and rat.
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A comprehensive analytical method based on solid phase extraction-isotope dilution-gas chromatography tandem mass spectrometry has been developed for the determination of musk xylene in cosmetics. Various cosmetic samples, including cream, lotion, powder, shampoo and lipstick, were extracted under ultrasonication. The extract was centrifuged, and the upper solution was concentrated by rotary evaporator. The reconstructed solution was then cleaned up by Sep-Pak Silica solid phase extraction cartridge. Qualitative and quantitative analysis was carried out under the MRM mode after the chromatographic separation on DB-5 MS(30 m×0.25 mm, 0.25 μm) capillary column. The limit of quantitation(LOQ) for musk xylene was 5 μg/kg. The mean recoveries at the three spiked levels of 5-50 μg/kg were 81.1%-86.9%, with the intra-day precision less than 10% and the inter-day precision less than 12%. The method is accurate, rapid, sensitive and adapt to the inspection of musk xylene in cosmetics.