摘要 :
Recent advances in gas chromatography-mass spectrometry (GC-MS) (ionization sources at atmospheric pressure, fast GC, GCxGC, high resolution mass spectrometry, etc.) have significantly improved the capabilities of this technique, ...
展开
Recent advances in gas chromatography-mass spectrometry (GC-MS) (ionization sources at atmospheric pressure, fast GC, GCxGC, high resolution mass spectrometry, etc.) have significantly improved the capabilities of this technique, traditionally used to determine pesticides. Although liquid chromatography mass spectrometry (LC-MS/MS) is nowadays preferred, pyrethroids and organochlorine pesticides are more sensitive by GC-MS and a significant number of other pesticides work well by both techniques. Here, we critically review the development, instrumentation, approaches and applications of GC-MS, focusing on the analysis of pesticide residues published between 2000 and 2019 along with outstanding pioneer contributions, with special emphasis on those published after 2010. This review attempts to fill a void of information on the state-of-art of GC-MS for pesticide residue determination, describing the pros and cons of the different approaches, and the main applications. (C) 2019 Elsevier B.V. All rights reserved.
收起
摘要 :
Although gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) has been applied to the determination of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in various food samples, there is insufficient evidence to ...
展开
Although gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) has been applied to the determination of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in various food samples, there is insufficient evidence to evaluate its equivalence with gas chromatography-high resolution mass spectrometry (HRMS). In the present study, two GC-MS/MS instruments with different ion sources (advanced electron ionization [EI] and atmospheric pressure chemical ionization [APCI]) were evaluated for detecting trace levels of PCDD/Fs in various foods. GC-EI-MS/MS and GC-APCI-MS/MS showed good linear relationships for 17 PCDD/Fs (0.01-200 ng/mL, R~2 > 0.999), and the relative standard deviations of the relative response factors were 3-18%. The limit of quantitation range of the PCDD/Fs was 0.005-0.101 ng/mL with GC-APCI-MS/MS and 0.006-0.201 ng/mL with GC-EI-MS/MS. The capabilities of the GC-MS/MS methods were evaluated for determination of PCDD/Fs in reference materials and real food samples. Statistical analyses showed that the toxic equivalents (TEQs) were comparable to those obtained with GC-HRMS, and the methods had good sensitivity, repeatability, and reproducibility. No difference was found between the results from the GC-MS/MS techniques and GC-HRMS when the PCDD/Fs concentrations were greater than 10-2 pg/g. The results suggest that when the total TEQ is greater than 0.57 pg TEQ/g (lipid weight) or 0.052 pg TEQ/g (wet weight), GC-MS/MS techniques could be used as a complementary approach to GC-HRMS. Both GC-EI-MS/MS and GC-APCI-MS/MS have similar sensitivity, selectivity, and stability to HRMS and could be used as confirmation methods for the analysis of trace PCDD/Fs in animal foods.
收起
摘要 :
The distribution of pyrethroid insecticides in the environment was assessed by separately measuring concentrations in the dissolved and suspended sediment phases of surface water samples. Filtered water was extracted by HLB solid-...
展开
The distribution of pyrethroid insecticides in the environment was assessed by separately measuring concentrations in the dissolved and suspended sediment phases of surface water samples. Filtered water was extracted by HLB solid-phase extraction cartridges, while the sediment on the filter was sonicated and cleaned up using carbon and aluminum cartridges. Detection limits for the 13 pyrethroids analyzed by gas chromatography-tandem mass spectrometry were 0.5 to 1 ng L~(-1) for water and 2 to 6 ng g~(-1) for the suspended sediments. Seven pyrethroids were detected in six water samples collected from either urban or agricultural creeks, with bifenthrin detected the most frequently and at the highest concentrations. In spiked water samples and field samples, the majority of the pyrethroids were associated with the suspended sediments.
收起
摘要 :
Due to the high consumption level, cereals represent one of the major sources of human exposure to PAHs. Taking into account the low maximum permitted level (ML) established in the European Union (EU) for the sum of four priority ...
展开
Due to the high consumption level, cereals represent one of the major sources of human exposure to PAHs. Taking into account the low maximum permitted level (ML) established in the European Union (EU) for the sum of four priority PAHs (PAH4) in processed cereal-based foods, sensitive and selective analysis for very low concentrations of these carcinogenic compounds was developed and compared by applying two different analytical techniques. Elaborated methods demonstrated appropriate performance in PAHs analysis even at low contamination levels. Limits of detection (LOD) for the PAH4 varied between 0.002 mu g kg (1) and 0.006 mu g kg (1), recoveries were in the range of 92-103% for GC-MS/MS and 108-117% for GC-HRMS. Elaborated methods were applied for the analysis of 35 Latvian cereals and bread samples. The concentrations of PAH4 were in a range of 0.22-1.62 mu g kg (1) with 14% of samples exceeding the current EU maximum permitted levels. (C) 2016 Elsevier Ltd. All rights reserved.
收起
摘要 :
Synthetic musks and organophosphorus pesticides represent a potential risk to the human health since exposure can lead to distinct types of carcinogenesis and endocrine disorders. These are lipophilic compounds as such, prone to d...
展开
Synthetic musks and organophosphorus pesticides represent a potential risk to the human health since exposure can lead to distinct types of carcinogenesis and endocrine disorders. These are lipophilic compounds as such, prone to deposit and persist in fat tissues, mainly in adipose tissue. Very few studies have reported on the occurrence and accumulation profile of these contaminants in human adipose tissue.
收起
摘要 :
New database building and MS subtraction algorithms have been developed for automated, sequential two-dimensional gas chromatography/mass spectrometry (GC-GC/MS). This paper reports the first use of a database building tool, with ...
展开
New database building and MS subtraction algorithms have been developed for automated, sequential two-dimensional gas chromatography/mass spectrometry (GC-GC/MS). This paper reports the first use of a database building tool, with full mass spectrum subtraction, that does not rely on high resolution MS data. The software was used to automatically inspect GC-GC/MS data of high elevation tea from Yunnan, China, to build a database of 350 target compounds. The database was then used with spectral deconvolution to identify 285 compounds by GC/MS of the same tea. Targeted analysis of low elevation tea by GC/MS resulted in the detection of 275 compounds. Non-targeted analysis, using MS subtraction, yielded an additional eight metabolites, unique to low elevation tea. (C) 2017 Elsevier B.V. All rights reserved.
收起
摘要 :
To analysze the dynamic degradation and final residues of acephate and its metabolite methamidophos, field-experiments with pakchoi (Brassica campestris L.) in open field and greenhouse were carried out in Beijing, China in 2004 a...
展开
To analysze the dynamic degradation and final residues of acephate and its metabolite methamidophos, field-experiments with pakchoi (Brassica campestris L.) in open field and greenhouse were carried out in Beijing, China in 2004 and 2005. The degradation dynamics and final residues were determined by gas chro-matography (GC) equipped with a pulsed flame photometric detector and GC coupled to mass spectrometry (MS)/MS after acephate was applied on open field and green house pakchoi (B. campestris L.). The dynamic degradation results showed that the half-lives of acephate and methamidophos in open field pakchoi were 1.36 days with dynamic degradation equation C_t = 133.01e~(-0.5107t), and 2.86 days with C_t = 6.5753e~(-0.2422t), respectively. While the half-lives of acephate and methamidophos in the green-
house were 1.07 days with C_t = 59.134e~(-0.4353t) and 0.79 days with C_t = 0.2703e~(-0.2595t), respectively. The final residue analysis demonstrated that >50% of total methamidophos were resulted from the degradation of acephate 7 and 18 days after it was applied on the greenhouse pakchoi, respectively. While in the open-field pakchoi, >90% of total methamidophos was found to be the metabolite of acephate.
收起
摘要 :
A multiresidue method for the analysis of pesticides in fresh produce has been developed using salt-out acetonitrile extraction, solid-phase dispersive cleanup with octadecyl-bonded silica (C_(18)), and graphitized carbon black/pr...
展开
A multiresidue method for the analysis of pesticides in fresh produce has been developed using salt-out acetonitrile extraction, solid-phase dispersive cleanup with octadecyl-bonded silica (C_(18)), and graphitized carbon black/primary-secondary amine (GCB/PSA) sorbents and toluene, followed by capillary gas chromatography-mass spectrometry in selected ion monitoring mode (GC-MS/SIM) or -tandem mass spectrometry (GC-MS/MS). Quantitation was determined from calibration curves using matrix-matched standards ranging from 3.3 to 6667 ng/mL with r~2 > 0.99, and geometric mean limits of quantitation were typically 8.4 and 3.4 fig/kg for GC-MS/SIM and GC-MS/MS, respectively. Identification was determined by using target and qualifier ions and qualifier-to-target ratios for GC-MS/SIM and two ion transitions for GC-MS/MS. Fortification studies (10, 25, 100, and 500 μg/kg) were performed on 167 organohalogen, organophosphorus, and pyrethroid pesticides in 10 different commodities (apple, broccoli, carrot, onion, orange, pea, peach, potato, spinach, and tomato). The mean percent recoveries were 90 ± 14, 87 ± 14, 89 ± 14, and 92 ± 14% for GC-MS/SIM and 95 ± 22, 93 ± 14, 93 ± 13, and 97 ± 13% for GC-MS/MS at 10, 25, 100, and 500 μg/kg, respectively. GC-MS/MS was shown to be more effective than GC-MS/SIM due to its specificity and sensitivity in detecting pesticides in fresh produce samples. The method, based on concepts from the multiresidue procedure used by the Canadian Food Inspection Agency and QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe), was shown to be efficient in screening, identifying, and quantitating pesticides in fresh produce samples.
收起
摘要 :
Drug screening is an important issue in clinical and forensic toxicology. Gas chromatography coupled to mass spectrometry (GC-MS) remains the gold standard technique for the screening of unknown compounds in urine samples. However...
展开
Drug screening is an important issue in clinical and forensic toxicology. Gas chromatography coupled to mass spectrometry (GC-MS) remains the gold standard technique for the screening of unknown compounds in urine samples. However, this technique requires substantial sample preparation, which is time consuming. Moreover, some common drugs such as cannabis cannot be easily detected in urine using general procedures. In this work, a sample preparation protocol for treating 200 μL of urine in less than 30 min is described. The enzymatic hydrolysis of glucuro-conjugates was performed in 5 min thanks to the use of microwaves. The use of a deconvolution software allowed reducing the GC-MS run to 10 min, without impairing the quality of the compound identifications. Comparing the results from 139 authentic urine samples to those obtained using the current routine analysis indicated this method performed well. Moreover, additional 5-min GC-MS/MS programs are described, enabling a very sensitive target screening of 54 drugs, including THC-COOH or buprenorphine, without further sample preparation. These methods appeared as an interesting alternative to immuno-assays based screening. The analytical strategy presented in this article proved to be a promising approach for systematic toxicological analysis (STA) of drugs in urine.
收起
摘要 :
In order to study the drying process and the degradation processes of alkyd resins, different types of alkyds for art works were investigated by pyrolysis-gas chromatography and mass spectrometry (Py-GC/MS) with double-shot techni...
展开
In order to study the drying process and the degradation processes of alkyd resins, different types of alkyds for art works were investigated by pyrolysis-gas chromatography and mass spectrometry (Py-GC/MS) with double-shot technique, thermally assisted hydrolysis and methylation (THM-GC/MS) as well as GC/MS after derivatized with the reagent of m-trifluoromethylphenyl trimethylammonium (Meth-Prep Ⅱ) methods. By using Py-GC/MS with double-shot technique, the oxidization products of alkyds including 2-octenal, 2-decenal, 2,4-decadienal, nonanal and 2-undecenal could be detected during drying, while the main component of alkyd - phthalic anhydride was found in higher amount in aged samples than unaged ones, indicating the formation of free phthalic anhydride during aging. The characterization of the main components of alkyds such as dibasic acid, polyol and drying oil can be achieved by using the techniques (THM-GC/MS) and GC/MS with the derivatization reagent Meth-Prep II. The decrease of unsaturated fatty acids and increase of phthalic anhydride were observed in the aged alkyd samples by those two techniques. The complementation of different analytical techniques provided several and different results, which are useful for a better understanding of the drying and degradation properties of alkyd resins.
收起
原文获取