海洋沉积物中甾醇类物质的气相色谱/质谱方法分析

应用超声提取技术,结合硅胶-中性氧化铝柱层析净化分离,BSTFA+1%TMCS衍生,及气相色谱-质谱定性定量技术,建立了海洋表层沉积物中8种甾醇类化合物的定量分析方法.实验采用正交实验优化了提取过程中提取剂种类、试剂体积和超声时间,同时对比并优化了柱层析淋洗液的配比、用量以及衍生剂的用量.结果表明,50 mL二氯甲烷/甲醇(V/V,2∶1),超声40 min,超声3次,总甾醇的萃取率可达99.6%;3 g硅胶+2 g中性氧化铝层析,35 mL二氯甲烷/甲醇(V/V,9∶1)淋洗净化回收最佳;8种甾醇在0—848μg.L-1范围内有良好的线性关系;方法检测限为1.2—2.4 ng.g-1.在3种浓度水平0.05、0.1和1.0μg.g-1下,其平均回收率为76.2%—100.9%,相对标准偏差为1.0%—10.3%.应用本方法检测大连湾的3个沉积物样品,8种甾醇的含量在0.079—6.833μg.g-1范围内.本方法的灵敏度高、准确度好,适合用于沉积物样品中甾醇物质的检测要求.     

固相萃取填料对水中脂肪族二元酸酯类增塑剂萃取效率的影响

以水中11种脂肪族二元酸酯类(ADEs)增塑剂的固相萃取-气相色谱-质谱法(SPE-GC-MS)为例,探讨了用C₁₈柱和HLB柱萃取水样时不同品牌、不同批号的SPE填料和C₁₈柱封端与否及相对应的洗脱溶剂不同配比对萃取效率的影响。实验结果表明:正己烷不可作为C₁₈柱和HLB柱的淋洗溶剂;11种ADEs用不同配比的二氯甲烷/正己烷溶剂体系洗脱,对C₁₈柱和HLB柱,不同SPE填料最佳二氯甲烷体积分数分别为0~60%和15%~20%;未经封端处理的C₁₈柱不适合作为ADEs的SPE柱;最佳溶剂洗脱体积为5 mL,样品穿透体积至少为200 mL;在优化条件下,11种ADEs方法检出限为0.2~0.5 μg/L,实际样品加标回收率为85.2%~113%,平行样相对标准偏差为5.5%~18%,各特性指标显示该方法正确度、精密度和灵敏度良好。     

在线固相萃取-液相色谱-串联质谱法直接测定水中15种全氟烷基化合物

通过优化样品保存、前处理、分析条件,建立了水中15种典型全氟烷基化合物(PFASs)在线固相萃取-液相色谱-串联质谱分析方法,并对饮用水水源地和末梢水中PFASs进行定量检测。水样过膜后,准确移取700 μL水样、300 μL甲醇至1.5 mL聚丙烯进样瓶,并加入同位素内标后直接进样800 μL至在线固相萃取流路,进行萃取富集,再通过十通阀切换将洗脱的PFASs转移至分析流路进行分离,质谱检测,内标法定量。方法分析总时长22 min,15种全氟烷基化合物的方法检出限为0.31~1.20 ng/L,纯水高、中、低浓度加标样品回收率为70%~115%,相对标准偏差为0.2%~14.0%(n=6)。经实际样品验证,该方法与传统手动固相萃取方法分析结果基本一致。结果表明,该方法操作简单、自动化程度高、有机试剂用量少、灵敏度高、方法稳定,可满足地表水和末梢水中PFASs的快速测定。     

Concentrations of chlorine, bromine and iodine in Japanese rivers

Concentrations of halogens (Cl, Br and I) in 30 Japanese rivers were measured by ion chromatography and inductively coupled plasma mass spectrometry to understand their behavior in the terrestrial environment. Concentrations of Cl, Br and I in each river, obtained at 10 sampling points from the upper stream to the river mouth, tended to increase near the river mouth. The ranges of geometric means of Cl, Br and I in each river were 1.0–19.4 mg l⁻¹, 2.5–67.9 μg l⁻¹, and 0.18–8.34 μg l⁻¹, respectively. To compare halogen behavior, the concentration ratios, Br/Cl and I/Cl, were calculated. The Br/Cl range was (2.3–7.8) × 10⁻³ (geometric mean: 3.74 × 10⁻³), and it was nearly constant except for the Yoneshiro river. It was estimated that 60–80% of total Br in the middle to lower parts of this river was the excess Br. The Br chemical form in all the rivers is generally considered to be Br⁻. The I/Cl ratios had different trends in rivers flowing into the Japan Sea and Pacific Ocean, possibly due to the different geological features in the river catchments.     

高分辨气相色谱/高分辨质谱法测定南极样品中有机氯农药

建立了同位素稀释-高分辨气相色谱/高分辨质谱法(HRGC/HRMS)测定南极土壤、苔藓和地衣样品中23种有机氯农药的分析方法.样品经冷冻干燥、研磨处理后用正己烷∶二氯甲烷(1∶1,V∶V)混合溶剂进行加速溶剂萃取(ASE),萃取液经硅胶-氧化铝层析柱和C18小柱净化后,进HRGC/HRMS检测分析.样品中目标物定量采用平均相对响应因子法,6点标准曲线响应因子的相对标准偏差(RSD)≤20%,方法的线性范围为0.4—800μg·L-1,回收率在62%—101%之间.实际样品分析结果表明,23种OCPs的加标回收率为40%—100%,在土壤、苔藓和地衣样品中的检出限(LODs)分别为0.024—5.01、0.2—12.2、0.020—13.7 pg·g-1,可以满足南极环境样品中有机氯农药的检测分析.     

Studies of Thermal Transformations of Humic and Fulvic Acids in Soils I. Infrared Spectroscopy and Temperature-Programmed Pyrolysis Mass Spectrometry

Temperature-programmed pyrolysis mass spectrometry and Fourier-transform infrared spectroscopy have been used to monitor structural changes of humic and fulvic acids isolated from soils in China, in the temperature range of 25-550°C. in this work, we found that decarboxylation is obvious as the main reaction with dehydration reaction from 150°C to 400°C, the anhydride can be identified from FT-IR spectra at temperature range from 200°C to 400°C; there are evident changes of the aromatic nucleus of humic and fulvic acids above 400°C, even remaining up to 550°C. Besides, some changes of adsorption water can be distinguished before 200°C, and the mass signal of sulphur dioxide was detected.     

Analysis of heavy metals in ecstasy tablets by electrochemical methods

Trace amounts of heavy metals have been analysed by electrochemical techniques in ecstasy tablets obtained from different police seizures in Spain. Lead, cadmium, copper and zinc were determined by differential-pulse anodic stripping voltammetry at a hanging mercury drop electrode, whereas nickel and cobalt were determined by adsorptive differential-pulse cathodic stripping voltammetry from their dimethylglyoxime complexes, M(DMG)₂. The performance of the procedure was compared with electrothermal atomic absorption spectrometry. The procedure was applied to the determination of these elements in nine ecstasy samples, finding that Zn is the element present in the highest concentration, ranging from 0.3 to 200?mg?kg^?1, Ni, Cu appear below 15?mg?kg^?1 and Pb below 8?mg?kg^?1, while Cd and Co levels were always lower than 0.51?mg?kg^?1.     

Distribution of mercury in the sediments of some freshwater bodies in Ethiopia

Sediment samples were collected from Tinishu Akaki River (TAR), Lake Awassa, and Lake Ziway, Ethiopia for determination of mercury. The air-dried samples were analyzed for mercury with a differential atomic absorption spectrometer after thermal evaporation of bound mercury converting it to its atomic form. Certified reference materials (CRMs) of sediments and soils were used to validate the method. The recovery of mercury from CRMs and sediments was in the range of 95–100%. The limit of detection for the determination of mercury was 50?ng?kg^?1. The concentration of total mercury in the sediments varied from 3.9 to 110?µg?kg^?1 for TAR, 14 to 67?µg?kg^?1 for Lake Awassa, and 17 to 110?µg?kg^?1 for Lake Ziway. It was found that the total mercury concentrations in all samples were below the United States Environmental Protection Agency guideline of 200?µg?kg^?1.     

Identification of urinary metabolites in rats administered the fluorine-containing pyrethroids metofluthrin,profluthrin, and transfluthrin

The major metabolites in urine of rats administered the fluorine-containing pyrethroids transfluthrin, profluthrin, and metofluthrin, which are used widely recently as mosquito repellents or mothproof repellents, were identified to establish biological indexes for evaluating the absorption amounts of these pyrethroids in the general population. A single dose of 300?mg?kg^?1 body weight of each pyrethroid was separately administered intraperitoneally to male Sprague-Dawley rats and urine samples were collected until 24 hours after the administration. The metabolites identified by gas chromatography-mass spectrometry were as follows: 2,3,5,6-tetrafluorobenzyl alcohol, 2,3,5,6-tetrafluorobenzoic acid, and 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (DCCA) for transfluthrin; 4-methyl-2,3,5,6-tetrafluorobenzyl alcohol, 4-methyl-2,3,5,6-tetrafluorobenzoic acid, 4-hydroxymethyl-2,3,5,6-tetrafluorobenzyl alcohol (HOCH₂–FB–Al), and 2,2-dimethyl-3-(1-propenyl)-cyclopropanecarboxylic acid (MCA) for profluthrin; 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol, HOCH₂–FB–Al and MCA for metofluthrin. In addition, several compounds estimated to be metabolites were detected as follows: hydroxylated DCCA and its lactone for transfluthrin; 4-hydroxymethyl-2,3,5,6-tetrafluorobenzoic acid (HOCH₂–FB–Ac), hydroxylated MCA and its lactone for profluthrin; 4-methoxymethyl-2,3,5,6-tetrafluorobenzoic acid, HOCH₂–FB–Ac, hydroxylated MCA, and its lactone for metofluthrin. The pyrethroids administered underwent metabolic reactions such as ester hydrolysis and oxidation, and most of the metabolites were excreted as their conjugates into urine. These findings should be useful as basic data for evaluating the health effects of exposure to pyrethroids for the general population.     

Ultrasound-assisted emulsification/microextraction based on solidification of trace amounts of thallium prior to graphite furnace atomic absorption spectrometry determination

In the present work, determination of ultratrace amounts of thallium in water samples was performed by ultrasound-assisted emulsification microextraction based on solidification of a floating organic drop as sample preparation method prior to furnace atomic absorption spectrometry. 1-(2-Pyridylazo)-2-naphthol was used as chelating agent. The factors influencing the complex formation and extraction, such as pH of the aqueous solution, the type and the volume of extraction solvent, the volume of chelating agent solution, and the extraction time were investigated. Under optimized conditions, the enrichment factor was 200. The calibration graph was linear from 0.2 to 10.0 μg L^?1 with a correlation coefficient of 0.9966, the detection limit was 0.03 μg L^?1 and reproducibility was ±3.3% (C = 5.0 μg L^?1, n = 8). The method was successfully applied for the determination of thallium in water samples.