Determination of polycyclic aromatic hydrocarbons and substitutes (Nitro-, Oxy-PAHs) in urban soil and airborne particulate by GC-MS and NCI-MS/MS

A method involving high resolution gas chromatography combined with ion trap (HRGC-MS/MS) and negative chemical ionisation (NCI) was developed for the determination of nitrated or oxygenated polycyclic aromatic hydrocarbons (nitro-PAHs, oxy-PAHs) and other electrophilic substitutes in soil samples. Efficient clean-up was achieved by a combination of methods for the determination of PAHs in soil and nitro-PAHs in aerosol using solid phase extraction (SPE) and semipreparative high performance liquid chromatography (HPLC). In samples of surface soil from the city of Basle (Switzerland), nitro-PAHs (mainly 3-nitrofluoranthene and 1-nitropyrene) were found in concentrations between 30 and 800 ng/kg dry weight. Oxy-PAHs and parent PAHs revealed 10²-10⁴-fold higher levels. Nitro-PAHs which are up to 10⁵ times more mutagenic seem to be less persistent in soil than the parent forms, although their entire mutagenic potential has to be estimated as being on the same order of magnitude. In urban air particulate matter, the amounts of nitro-PAHs (2–62 pg/m³) were 10–100 times lower than oxyPAHs and parent PAHs which were both found in a similar range. 3-nitrobenzanthrone, a recently described suspected human carcinogen has not yet been detected. Using multivariate statistical analysis, it was possible to elucidate similarities or special characteristics of substances in a given matrix reflecting their chemical properties or specific emission sources.     

Evaluation of the impact of matrix effects in LC/MS measurement on the accurate quantification of neonicotinoid pesticides in food by isotope-dilution mass spectrometry

The use of isotope-labeled internal standards is the most widely accepted approach to overcome the matrix effects on quantification of pesticides in food by LC/MS. We evaluated the impact of the matrix effects on quantification of six neonicotinoid pesticides, acetamiprid, clothianidin, dinotefuran, imidacloprid, thiacloprid, and thiamethoxam, in food by using deuterated internal standards. The calibration curves for each pesticide were obtained by using matrix-free and matrix-matched calibration solutions with blank brown rice, carrot, and green onion extracts. For brown rice and carrot, the matrix effects were not observed. In contrast, the slopes of calibration curves for each pesticide were influenced by presence of green onion extracts in calibration solutions (variability of the slopes was 4–9%), because the ratios of peak area for native pesticide to those for internal standards were influenced by matrix. The spike-and-recovery test with green onion was also performed. The analytical values obtained by using matrix-free calibration solution were biased from the spiked concentration, whereas those obtained by using matrix-matched calibration solution were comparable to the spiked concentration. These results indicate that matrix-matched calibration solution should be used for accurate quantification of neonicotinoid pesticides in food by LC/MS using deuterated internal standards.     

Ultra trace simultaneous determination of 50 polycyclic aromatic hydrocarbons in biota using pMRM GC-MS/MS

Abstract

A saponification extraction method with gas chromatography pseudo-MRM (pMRM) mass spectrometry detection was developed for the determination of 50 total polycyclic aromatic hydrocarbons (TPAH50, a combination of parent and alkylated homologues) in biota. The method was aimed at monitoring and identification of potential TPAH contaminants in bitumen impacted environments. Alkylated PAHs were determined by multi-level, quantitative calibration using parent PAHs. The developed and thoroughly validated method required only one injection for TPAH50 analysis which represents significant saving of time and expensive authentic alkylated standards. The current method was tested with certified reference mussel tissue NIST 1974c and performed well. In a comparison study, the method reached a limit of quantitation (LOQ) for the TPAH50 between 0.1 and 0.2?ng g^?1, while the QuEChERs enhanced matrix removal – lipid (EMR) kit produced by Agilent showed an LOQ of 5–10?ng g^?1. The current method relied on response factors (RF) for the quantitation of alkylated PAHs determined against parent PAHs. These RFs were shown to be stable and consistent over the course of 1 year, during which over 200 routine environmental biota monitoring samples were analyzed. The environmental biota monitoring samples analyzed include muscle, carcass and liver, with an average total PAH50 concentration of 13, 90 and 135?ng g^?1, respectively. Results show significant differences in the distributions of 1 ringed, 2 ringed, 3 ringed, 4 ringed, and 5+ ringed TPAHs between the types of biota samples.     

Urinary analysis reveals high Alternaria mycotoxins exposure in the general population from Beijing, China

Alternaria mycotoxins are of concern due to its adverse health effect, they affect various cereal crops and grain-based food along with modified forms that contribute to overall exposure. This study aimed to determine the frequency and level of exposure to Alternaria mycotoxins (tenuazonic acid, TeA; alternariol, AOH; alternariol monomethyl ether, AME; tentoxin, TEN; and altenuene, ALT) in human urine from Beijing adults. A total of 2212 urine samples were collected and analyzed for five mycotoxins using LC–ESI–MS/MS. More than 98% of the samples had at least one Alternaria mycotoxin detected. Among the mycotoxins, AME had the highest detection rate (96.0%), followed by TeA (70.5%). The calculated average daily intake values of AME (12.5 ng/kg b.w.) was 5 times the TTC value (2.5 ng/kg b.w.) set by the EFSA, indicating the potential health risks associated with mycotoxins. Immediate attention and subsequent actions should be taken to identify the sources of mycotoxins and the corresponding exposure pathways to humans in the investigated regions.     

单液滴微萃取—气相色谱/质谱法检测水中多环芳烃

采用单液滴微萃取-气相色谱/质谱(GC/MS)法建立了检测水中多环芳烃(PAHs)的方法,研究了萃取溶剂种类、萃取时间、搅拌速度对萃取效率的影响,确定了最佳单液滴微萃取条件,该法用于水中PAHs的检测,16种PAHs的线性范围为0.2～7.0μg/mL,相关系数≥0.9784,检出限为0.002～0.190μg/mL,相对标准偏差为7.1%～15.1%,加标回收率在81%～122%.     

磺胺抗性消长与堆肥进程的交互特征

基于添加和不添加磺胺药[m(磺胺二甲嘧啶SM2)∶m(磺胺-6-甲氧嘧啶SMM)=1∶1]的好氧堆肥试验,分析堆肥过程中鸡粪理化性质、微生物群落代谢特征、磺胺抗生素以及5种抗性基因变化,探明磺胺抗性消长与堆肥过程的交互特征.结果表明,磺胺药添加抑制了堆肥基础呼吸,延长了堆体达到高温的时间,减缓了养分转化速度,显著影响堆肥中期微生物群落结构特征.鸡粪中SMM和SM2在堆肥14 d内即可完全降解,且SMM降解速率高于SM2.随堆肥进行,sul1和sul2呈先下降后轻微回升的趋势,磺胺药添加对sul1和Int I1丰度无明显提高作用,但可促进sul2扩散.堆肥过程中,tet Q和tet W变化与磺胺抗性基因不同,但磺胺药添加亦增加tet Q和tet W相对丰度.冗余分析结果显示,温度与sul1、sul2和Int I1明显负相关,与tet Q和tet W无明显相关性;5种抗性基因相对丰度均与碳氮比和硝态氮含量负相关,与p H、含水率和铵态氮含量正相关.     

仲辛醇吸收NOx尾气的GC／MS研究

本文采用GC/MS法研究了仲辛醇氧化还原法吸收NO_x尾气后的化学组成,鉴定出的组份达37种,并且对一些主要组份的生成机理进行了简单的探讨。     

北黄海辽宁近岸水环境中壬基酚污染状况调查及生态风险评估

利用固相萃取气质连用(SPE-GC/MS)法对1月辽宁近岸19个站位水体中壬基酚污染状况进行了调查,结果显示水体中壬基酚浓度为15.13～762.73 ng/L,整体呈现出近岸高于远海,西部海域高于东部的特点,高值区多出现在河流入海口或港口附近.与国内外相关报道比较,调查海域壬基酚处于中等污染水平.以风险熵(RQ)为标准对壬基酚的污染状况的初步评估表明,调查海域壬基酚风险熵为0.05～2.25,某些站位熵值高于阈值,可能造成一定的风险,需要采取相应措施减少污染.     

吹扫捕集—气相色谱／质谱联用测定饮用水中59种挥发性有机物

建立了吹扫捕集一气相色谱／质谱联用测定饮用水中59种挥发性有机物的方法,方法检出限为0．004～0．085μg/L,可满足饮用水中特定有机分析项目的检测要求。     

Diverse molecular compositions of dissolved organic matter derived from different composts using ESI FT-ICR MS

Dissolved organic matter (DOM) derived from various composts can promote significant changes of soil properties. However, little is known about the DOM compositions and their similarities and differences at the molecular level. In this study, the molecular compositions of DOM derived from kitchen waste compost (KWC), green waste compost (GWC), manure waste compost (MWC), and sewage sludge compost (SSC) were characterized by electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). The molecular formulas were classified into four subcategories: CHO, CHON, CHOS, and CHONS. The KWC, MWC, and SSC DOM represented the highest fraction (35.8%-47.4%) of CHON subcategory, while the GWC DOM represented the highest fraction (68.4%) of CHO subcategory. The GWC DOM was recognized as the nitrogen- and sulfur-deficient compounds that were less saturated, more aromatic, and more oxidized compared with other samples. Further analysis of the oxygen, nitrogen-containing (N-containing), and sulfur-containing (S-containing) functional groups in the four subcategories revealed higher organic molecular complexity. Comparison of the similarities and differences of the four samples revealed 22.8% ubiquitous formulas and 17.4%, 11.1%, 10.7%, and 6.3% unique formulas of GWC, KWC, SSC, and MWC DOM, respectively, suggesting a large proportion of ubiquitous DOM as well as unique, source-specific molecular signatures. The findings presented herein provide new insight into the molecular characterization of DOM derived from various composts and demonstrated the potential role of these different compounds for agricultural utilization.