络合萃取-在线衍生土壤酸性除草剂条件选择与优化

以Na4EDTA为络合剂,以五氟苄基溴为衍生试剂,采用快速溶剂萃取仪萃取,同时实现土壤酸性除草剂的络合萃取在线衍生,并以气相色谱-质谱(NCI源)进行检测。对络合条件、衍生条件、萃取条件、离子源选择进行了优化。方法的回收率为75%～95%、相对标准偏差为6.7%～13%、检测限2.8～8.4μg/Kg。     

Gas‐phase Smiles Rearrangement of Sulfonylurea Herbicides in Electrospray Ionization Mass Spectrometry

In the negative ion mode of electrospray ionization tandem mass spectrometry (ESI‐MS/MS) of four sulfonylurea herbicides, Smiles rearrangements were observed in rimsulfuron and nicosulfuron. In the case of rimsulfuron, two competitive gas‐phase Smiles rearrangements initiated by nitrogen anion and oxygen anion respectively were witnessed. The ion‐neutral complex was proposed as the reactive intermediate in the course of this unimolecular dissociation reaction of the oxygen attack Smiles rearrangement route. The density functional theory (DFT) was carried out to elucidate the mechanism as well as to show the possible transition states and the intermediates.     

Multi-residue analytical method for the determination of emerging pollutants in water by solid-phase extraction and liquid chromatography-tandem mass spectrometry

This paper describes the development and validation of a method for the simultaneous determination of 53 multi-class emerging organic pollutants in water samples using solid-phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), using electrospray ionisation (ESI) in both positive and negative modes. Target compounds include acidic herbicides, UV filters, insect repellents, organophosphorous flame retardants, a bactericide, pharmaceuticals and metabolites. A single SPE consisting on the loading of 200-500 mL of sample adjusted to pH 7 on Oasis HLB 200mg cartridges and elution with methanol, permitted obtaining good recoveries: higher than 60% for tap, surface and wastewater in most cases. The 7 isotopically labelled internal standards effectively compensated losses during sample preparation and matrix effects at LC-MS/MS determination. The precision of the method, calculated as relative standard deviation (RSD) was below 15% for all compounds and all tested matrices. Detection limits (LODs) based on the confirmation, less intense, MRM (multiple reaction monitoring) transition and considering blanks varied between 0.3 and 30 ngL(-1). Finally, the developed method was applied to the determination of target analytes in various samples, including tap, surface and waste water. Among the tested emerging pollutants, 31 were found in wastewater in concentrations reaching up to 10 microgL(-1) in the case of ibuprofen. Also, 13 species were detected in tap water with concentrations up to 0.13 microgL(-1) for tri(chloropropyl) phosphate (TCPP).     

特丁二甲硅烷基衍生化气相色谱-质谱法检测尿中4种苯氧羧酸类除草剂

建立了尿中2,4-滴(2,4-D)、2,4-滴丙酸(2,4-DP)2、甲4氯(MCPA)和2甲4氯丙酸(MCPP)4种苯氧羧酸类除草剂的气相色谱-质谱(GC-MS)分析方法。尿样加氯化钠饱和,酸化后用乙醚萃取,萃取物进行特丁二甲硅烷基(TBDMS)衍生化后分析。尿中4种除草剂的浓度在3~3 000 ng/mL范围内工作曲线的线性关系良好,检出限在1 ng/mL以下,3、100和1 000 ng/mL水平加标回收率在97.0%~102.2%之间,精密度在6.2%~14.2%之间。该法灵敏,可用于中毒者和职业接触者尿中苯氧羧酸类除草剂的分析。     

Enrichment and low‐level determination of glyphosate,aminomethylphosphonic acid and glufosinate in drinking water after cleanup by cation exchange resin

For the determination of glyphosate, aminomethylphosphonic acid and glufosinate in drinking water, different procedures of enrichment and cleanup were examined using anion exchange or SPE. In many cases interactions of, e.g. alkaline earth metal ions especially calcium could be observed during enrichment and cleanup resulting in loss of analytes. For that reason, a novel cleanup and enrichment procedure for the determination of these phosphonic acid herbicides has been developed in drinking water using cation‐exchange resin. In summary, the cleanup procedure with cation‐exchange resin developed in this study avoids interactions as described above and is applicable to calcium‐rich drinking water samples. After derivatization with 9‐fluorenylmethylchloroformate followed by LC with fluorescence detection, LOD of 12, 14 and 12 ng/L and mean recoveries from real‐world drinking water samples of 98±9, 100±16 and 101±11% were obtained for glyphosate, aminomethylphosphonic acid and glufosinate, respectively. The low LODs and the high precision permit the analysis of these phosphonic acid herbicides according to the guidelines of the European Commission.     

Stereoselective quantitation of mecoprop and dichlorprop in natural waters by supramolecular solvent-based microextraction,chiral liquid chromatography and tandem mass spectrometry

Liquid chromatography (LC)/tandem mass spectrometry (MS/MS) after supramolecular solvent-based microextraction (SUSME) was firstly used in this work for the enantioselective determination of chiral pesticides in natural waters. The method developed for the quantitation of the R- and S-enantiomers of mecoprop (MCPP) and dichlorprop (DCPP) involved the extraction of the herbicides in a supramolecular solvent (SUPRAS) made up of reverse aggregates of dodecanoic acid (DoA), analyte re-extraction in acetate buffer (pH = 5.0), separation of the target enantiomers on a chiral column of permethylated α-cyclodextrin under isocratic conditions, and detection of the daughter ions (m/z = 140.9 and 160.6 for MCPP and DCPP, respectively) using a hybrid triple quadrupole mass spectrometer equipped with an electrospray source operating in the negative ion mode. Similar recoveries (ca. 75%) and actual concentration factors (ca. 94) were obtained for both phenoxypropanoic acids (PPAs). The quantitation limits were 1 ng L⁻¹ for R- and S-MCPP, and 4 ng L⁻¹ for R- and S-DCPP, and the precision, expressed as relative standard deviation (n = 6) was in the ranges 2.4–2.7% ([R-MCPP] = [S-MCPP] = 5 ng L⁻¹ and [R-DCPP] = [S-DCPP] = 15 ng L⁻¹) and 1.6–1.8% (100 ng L⁻¹ of each enantiomer). The SUSME-LC–MS/MS method was successfully applied to the determination of the enantiomers of MCPP and DCPP in river and underground waters, fortified at concentrations between 15 and 180 ng L⁻¹ at variable enantiomeric ratios (ER = 1–9).     

Hollow‐fiber liquid‐phase microextraction combined with capillary HPLC for the selective determination of six sulfonylurea herbicides in environmental waters

A three‐phase hollow‐fiber liquid‐phase microextraction combined with a capillary LC method using diode array detection was proposed for the determination of six sulfonylurea herbicides, triasulfuron, metsulfuron‐methyl, chlorsulfuron, flazasulfuron, chlorimuron‐ethyl, and primisulfuron‐methyl, in environmental water samples. Different factors that can affect the extraction process such as extraction solvent, acidity of the donor phase, composition and pH of the acceptor phase, salt addition, stirring speed, and extraction time were optimized. Under the optimum conditions, detection and quantitation limits between 0.1 – 1.7 and 0.3 – 5.7 μg/L, respectively, and enrichment factors ranging from 71 to 548 were obtained. The calibration curves were linear within the range of 0.3 – 40 μg/L. Intra‐ and interday RSDs were <6.3 and 8.4%, respectively. The relative recoveries of the spiked ground and river water samples were in the range of 69.4 – 119.2 and 77.4 – 111.7%, respectively. The results of the study revealed that the developed methodology involves an efficient sample pretreatment allowing the preconcentration of analytes, combined with the use of a miniaturized separation technique, suitable for the accurate determination of sulfonylurea herbicides in water.