凝胶渗透色谱净化-气质联用法测定土壤中三嗪类除草剂

建立了以超声波提取、凝胶渗透色谱净化(GPC)、HP-5 MS石英毛细管柱分离、E1离子源质谱法测定土壤中13种三嗪类除草剂的多残留检测方法.三嗪类除草剂的添加水平为0.010～0.100 mg/kg时,平均回收率为72.1%～118.3%,相对标准偏差为2.6%～19.8%(n=4);方法的检出限为0.30～2.50μg/kg.     

基于混合固定相色谱柱的SPE-HPLC法检测环境水体中三嗪类除草剂

利用混合固定相色谱柱(Optimix SCX/C8)分析了8种三嗪类化合物,在0.01 mol/L乙酸钠缓冲溶液(pH4.2)-CH3CN(75：25,V/V)等度洗脱的流动相条件下,实现了利用液相色谱方法分离同分异构体敌草净和西草净,并对比了相同色谱条件下8种目标物在C8色谱柱上的分离效果;比较了PEP和C18固相萃...     

Simultaneous determination of triazine herbicides in rice by high-performance liquid chromatography coupled with high resolution and high mass accuracy hybrid linear ion trap-orbitrap mass spectrometry

A method was developed for the simultaneous determination of 10 triazine herbicides (cyanazine, simazine, simetryn, metribuzin, atrazine, ametryn, terbuthylazine, prometryn, terbutryn, and dimethametryn) in rice samples by high resolution and high mass accuracy hybrid linear ion trap-Orbitrap mass spectrometer. After extraction with acetonitrile and evaporation, the herbicides were redissolved in n-hexane and purified on a Florisil solid-phase extraction column. All compounds were separated within 12 min, producing more than 11 data points for each herbicide and high mass accuracy quantified ions which the mass errors of absolute value were less than 1.9 ppm in pure solution and 2.1 ppm in the matrix-matched standards solution. The method was validated in terms of the limits of detection and the limits of quantification. The linearity was satisfactory, with a correlation coefficient of >0.9975. Precision and recovery studies were evaluated at three concentration levels for Japonica, Indica, and Glutinous rice matrix. The mean recoveries obtained for all analytes in spiked Xiushui 03, Liangyoupeijiu, and Taihunuo rice samples were 83.3–99.0%, 82.0–99.7%, and 84.2–99.4%, respectively, with relative standard deviation in range 1.7–10.6%, 1.2–10.7%, and 1.9–11.6% for spiked rice samples, respectively. The intra-day precision (n = 5) for the 10 herbicides in rice samples spiked at an intermediate level was between 2.8% and 7.9%, and the inter-day precision over 10 days (n = 10) was between 5.5% and 15.9%.     

Evaluation of double solid-phase extraction system for determining triazine herbicides in milk

Summary High-performance liquid chromatography with UV detection was used to determine eight triazine herbicides in milk. Solid-phase extraction was performed using a double trap; first, a nonspecific adsorbent (Carbograph), and then a cation exchanger (SCX). Eluate from the SCX was evaporated to dryness under reduced pressure and redissolved in mobile phase. An aliquot was injected into the chromatograph, which was operated isocratically in the reverse-phase mode with UV detection at 225 nm. Analytical recoveries for the eight triazines ranged from 73.0 % to 92.4 %. The limit of sensitivity of this method was about 0.09 ng mL⁻¹ of milk. The method was validated and evaluated by comparison with a method reported in literature.     

Evaluation of double solid-phase extraction system for determining triazine herbicides in milk

Summary High-performance liquid chromatography with UV detection was used to determine eight triazine herbicides in milk. Solid-phase extraction was performed using a double trap; first, a nonspecific adsorbent (Carbograph), and then a cation exchanger (SCX).Eluate from the SCX was evaporated to dryness under reduced pressure and redissolved in mobile phase. An aliquot was injected into the chromatography, which was operated isocratically in the reverse-phase mode with UV detection at 225 nm.Analytical recoveries for the eight triazines ranged from 73.0% to 92.4%. The limit of sensitivity of this method was about 0.09 ng mL^–1 of milk. The method was validated and evaluated by comparison with a method reported in literature.     

Novel solid‐phase membrane tip extraction and gas chromatography with mass spectrometry methods for the rapid analysis of triazine herbicides in real waters

Novel, fast, selective, eco‐friendly and reproducible solid‐phase membrane tip extraction and gas chromatography with mass spectrometry methods were developed and validated for the analysis of triazine herbicides (atrazine and secbumeton) in stream and lake waters. The retention times of atrazine and secbumeton were 7.48 and 8.51 min. The solid‐phase membrane tip extraction was carried out in semiautomated dynamic mode on multiwall carbon nanotubes enclosed in a cone‐shaped polypropylene membrane cartridge. Acetone and methanol were found as the best preconditioning and desorption solvents, respectively. The extraction and desorption times for these herbicides were 15.0 and 10.0 min, respectively. The percentage recoveries of atrazine and secbumeton were 88.0 and 99.0%. The linearity range was 0.50–80.0 μg/L (r² > 0.994), with detection limits (<0.47 μg/L, S/N = 3) and good reproducibility (<8.0%). The ease of operation, eco‐friendly nature, and low cost of solid‐phase membrane tip extraction made these methods novel. The Solid‐phase membrane tip extraction method was optimized by considering the effect of extraction time, desorbing solvents and time.     

Determination of triazine herbicides in surface and drinking waters by off-line combination of liquid chromatography and gas chromatography-mass spectrometry

Summary Mass spectra of 12 triazines were obtained by electron impact (EI), positive-ion chemical ionization (PCI) and negative-ion chemical ionization (NCI) using methane and isobutane as reagent gases. EI mass spectrometry is more sensitive than PCI and NCI, although the chemical ionization modes increase selectivity markedly. A pre-column packed with polymer stationary phase was employed to preconcentrate surface and drinking water samples. After desorption of the analytes with ethyl acetate, an aliquot was injected directly into the GC-MS system. Atrazine and simizine were found in these samples at 10–80 ppt levels. The limits of detection for both herbicides were below 10 ppt in drinking water.     

Determination of triazine herbicides in human body fluids by solid-phase microextraction and capillary gas chromatography

Summary Eight triazine herbicides, prometon, propazine, atrazine, simazine, prometryn, ametryn, metribuzin, and cyanazine, have been extracted from human whole blood and urine samples by headspace solid-phase microextraction (SPME) with a polydimethylsiloxane-coated fiber and quantified by capillary gas chromatography with nitrogen-phosphorus detection. Extraction efficiencies for all compounds were 0.21–0.99% for whole blood, except for cyanazine (0.06%). For urine, the extraction efficiencies for prometon, propazine, atrazine, prometryn and ametryn were 13.6–38.1%, and those of simazine, metribuzin and cyanazine were 1.35–8.73%. The regression equations for the compounds extracted from whole blood were linear within the concentration ranged 0.01–1 μg (0.5 mL)⁻¹ for prometon, propazine, atrazine, prometryn, and ametryn, and 0.02–1 μg (0.5 mL)⁻¹ for simazine, metribuzin, and cyanazine. For urine, regression equations for all compounds were linear within the concentration range 0.005–0.25 μg mL⁻¹. Compound detection limits were 2.8–9.0 ng (0.5 mL)⁻¹ and 0.4–2.0 ng mL⁻¹ for whole blood and urine, respectively. The coefficients of within-day and day-to-day variation were satisfactory for all the compounds, and not greater than 10.3 and 14.2%, respectively. Data obtained from determination of atrazine in rat whole blood after oral administration of the compound are also presented.     

Quantification of intracellular homocysteine by stable isotope dilution liquid chromatography/tandem mass spectrometry

A precise and accurate stable isotope dilution liquid chromatography/tandem mass spectrometry method for the analysis of intracellular homocysteine has been developed. An internal standard, [(2)H(8)]-homocystine, was added to cell pellets from EA.hy 926 cells grown in culture under low and high folate concentrations. D,L-dithiothreitol was used to reduce cellular homocystine to homocysteine. Cellular proteins were precipitated by the addition of formic acid in acetonitrile. After centrifugation, a portion of the supernatant was analyzed by liquid chromatography/tandem mass spectrometry. Using a Supelcosil cyano column with an Applied Biosystems API 4000 triple quadrupole mass spectrometer, the SRM transitions for homocysteine (m/z 136 to m/z 90) and [(2)H(4)]-homocysteine (m/z 140 to m/z 94) were monitored. The method was validated by conducting five replicate analyses on three different days at four different concentrations (concentrations at the lower limit of quantitation and expected lower quartile, mid-range and upper quartile). The limit of detection was 2 ng/10(6) EA.hy 926 cells. Using this method, the intracellular homocysteine concentration in EA.hy 926 cells ranged from 10 to 36 ng/10(6) cells.     

Gas chromatography and gas chromatography/mass spectrometry for the characterization of complex mixtures of large oligosaccharides

High temperature gas chromatography and gas chromatography/mass spectrometry are used in the characterization of complex natural mixtures of permethylated oligosaccharides released from proteins or lipids. The high resolution allows separation of isomeric compounds and the mass range extends to oligosac-charides around molecular mass 2000 daltons or 10 sugar residues for isomalto-oligosaccharides. The mass spectra of permethylated oligosaccharide alditols from mucin glycopeptides are very informative and the approach allows a simple and rapid characterization of these complex components.     

Membrane protected conductive polymer as micro‐SPE device for the determination of triazine herbicides in aquatic media

A micro‐SPE technique was developed by fabricating a rather small package including a polypropylene membrane shield containing the appropriate sorbent. The package was used for the extraction of some triazine herbicides from aqueous samples. Solvent desorption was subsequently performed in a microvial and an aliquot of extractant was injected into GC‐MS. Various sorbents including aniline‐ortho‐phenylene diamine copolymer, newly synthesized, polypyrrole, multiwall carbon nanotube, C18 and charcoal were examined as extracting media. Among them, conductive polymers exhibited better performance. Influential parameters including extraction and desorption time, desorption solvent and the ionic strength were optimized. The developed method proved to be rather convenient and offers sufficient sensitivity and good reproducibility. The detection limits of the method under optimized conditions were in the range of 0.01–0.04 ng/mL. The RSDs at a concentration level of 0.1 ng/mL were obtained between 4.5 and 9.3% (n=5). The calibration curves of analytes showed linearity in the range of 0.05–10 ng/mL. The developed method was successfully applied to the extraction of selected triazines from real water samples. The whole procedure showed to be conveniently applicable and quite easy to manipulate.     

Development and evaluation of a candidate reference measurement procedure for the determination of testosterone in human serum using isotope dilution liquid chromatography/tandem mass spectrometry

A candidate reference measurement procedure for total testosterone in human serum involving isotope dilution (ID) coupled with liquid chromatography/tandem mass spectrometry (LC/MS/MS) has been developed and critically evaluated. The endogenous testosterone and its internal standard (testosterone-d ₃) were extracted from the serum matrix using a combination of solid-phase extraction and liquid–liquid extraction prior to reversed-phase LC/MS/MS. Accuracy of the measurements was evaluated by a recovery study using testosterone-spiked serum. The recovery of the added testosterone ranged from 100.0 to 100.3%. This method was applied to the determination of testosterone in frozen serum samples from three individual donors (one female and two males) with the testosterone concentrations ranging from 0.3 to 8.5 ng g⁻¹. Repeatability with within-set coefficients of variation (CVs) from 0.1 to 1.0% and intermediate precision with between-set CVs from 0.1 to 0.5% for both female and male serum materials were demonstrated. Excellent linearity was obtained for all linear regression lines. The detection limit at a signal-to-noise ratio of approximately 3 was 2 pg of testosterone in serum. Structural analogs as well as testosterone metabolites were tested and found to not interfere with the measurement of testosterone. This well-characterized LC/MS/MS method for serum testosterone, which demonstrates good accuracy and precision, and low susceptibility to interferences, qualifies as a reference measurement procedure that can be used to provide an accuracy base to which routine methods for testosterone can be compared and that will serve as a standard of higher order for measurement traceability.     

Determination of triazine herbicides in sheep liver by microwave-assisted extraction and high performance liquid chromatography

A multi-residue method developed for the analysis of triazine herbicides, simazine, atrazine, propazine and prometryne, in sheep liver is presented. The method is based on microwave-assisted extraction (MAE) of sheep liver using methanol as extractant and analysis of extracts by high performance liquid chromatography (HPLC) and ultraviolet detection. MAE operational parameters, the solvent type and volume, extraction temperature and time, were optimized in detail with respect to extraction efficiency of the target compounds from sheep liver. The recoveries of the method at two different spiked levels were assessed by analyzing spiked liver samples and were found to be in the range from 90 to 102% with good precision (<11%).     

High resolution gas chromatography/mass spectrometry analysis of the environmental pollutants methylnitronaphthalenes

We report the linear retention indices of the 14 methylnitro-naphthalenes on three high resolution capillary columns and their electron impact mass spectra. The analyses of the methylnitro-naphthalenes in an ambient air sample by gas chromatography/mass spectrometry with multiple ion detection utilizing 5% phenylmethylsilicone, 50% phenylmethylsilicone, and smectic columns are shown.     

Gas chromatography-tandem mass spectrometry analysis of gabapentin in serum

A new highly sensitive analytical method for determining gabapentin [1-(aminomethyl) cyclohexaneacetic acid; Neurontin] in serum using gas chromatography/tandem mass spectrometry (GC-MS/MS) was developed. GC-MS/MS was applied to determine the levels of gabapentin in serum samples of mice at 1 and 6 h after oral or intraperitoneal treatment (300 mg/kg). At 1 h, the concentrations of the drug were 4.02 +/- 0.42 and 4.32 +/- 0.28 microg/mL in mice treated orally and intraperitoneally, respectively. At 6 h, drug levels decreased by about 66% in both groups. The method, coupling two stages of mass analysis, could be very useful in identifying the drug in complex mixtures such as blood and urine. Moreover, it is easy and rapid to perform, and sensitive enough to allow the presence of the drug to be determined at very low detection limits. It is a very reliable method for both clinical and experimental monitoring of gabapentin.     

Gas chromatography/mass spectrometry and pyrolysis-gas chromatography/mass spectrometry for the chemical characterisation of modern and archaeological figs (Ficus carica)

Gas chromatography/mass spectrometry (GC/MS) after alkaline hydrolysis, solvent extraction and trimethylsilylation, and analytical pyrolysis using hexamethyldisilazane (HMDS) for in situ derivatisation followed by gas chromatographic/mass spectrometric analysis (Pyrolysis-silylation-GC/MS) were used to investigate the hydrolysable and soluble constituents, and the polymerised macromolecules of an archaeological fig (Ficus carica) recovered in Zaragoza (Spain), as well as of modern figs. The main aim was to study the compositional alterations undergone by the fig tissues in a particular archaeological environment: the fig was in a vessel and covered by a layer of a mixture of orpiment and gypsum. A comparison between the GC/MS results from modern and archaeological figs revealed that degradative reactions took place, leading to the disappearance/depletion of reactive (unsaturated fatty acids) and sensitive compounds (phytosterols and triterpenes). Py-silylation-GC/MS data provided evidence of a significant degradation of the saccharide and lipid components of the fig tissue, which left a residue enriched in polyphenols and polyesters.     

Stable isotope dilution analysis of N-acetylaspartic acid in urine by liquid chromatography electrospray ionization tandem mass spectrometry

N-acetylaspartic acid (NAA) is a specific urinary marker for Canavan disease, an autosomal recessive leukodystrophy. We developed a 'dilute and shoot' stable isotope dilution liquid chromatography tandem mass spectrometry (LC-MS/MS) method for determination of NAA in urine. Deuterated internal standard d(3)-NAA was added to untreated urine and the mixture was injected into the LC-MS/MS system operated in the negative ion mode. Chromatography was carried out on a C(8) minibore column using 50% acetonitrile solution containing 0.05% formic acid at a flow rate of 0.25 mL/min. The retention time was 1.6 min and the turnaround time was 2.2 min. NAA and d(3)-NAA were analyzed in multiple reaction monitoring mode. Calibrators and quality control samples were prepared in pooled control urine. The assay was linear up to 2000 micromol/L with limit of quantification at 1 micromol/L (S/N = 12). Interassay and intraassay coefficients of variation were less than 7% and recovery at three different concentrations was 98.9-102.5%. The LC-MS/MS method for NAA as described involves no extraction and no derivatization, showed no interference and gave excellent recovery with low variability and short analytical time. The method was successfully applied for the retrospective analysis of urine from 21 Canavan disease cases.     

加速溶剂萃取-固相萃取净化-气相色谱/质谱法测定土壤中的多环芳烃

建立了加速溶剂萃取-固相萃取净化-气相色谱/质谱法同时测定土壤中16种多环芳烃的方法。土壤样品经正己烷-丙酮提取,经无水Na₂SO₄脱水、氮吹浓缩后,弗罗里土小柱净化,采用气相色谱/质谱检测,内标法定量。结果表明:该方法在质量浓度0.4～10μg/mL范围内线性良好,相关系数(r²)大于0.9962,检出限为4.8～25μg/kg,定量限为19.2～100μg/kg;在0.05,0.15,0.40 mg/kg 3个加标水平下的平均回收率为55.4%～129.0%,相对标准偏差为1.5%～11%。采用该方法检测土壤样品,除苊烯、苊、芴3种多环芳烃未检出外,其他13种多环芳烃均有检出,其含量范围在6.6～86μg/kg。