Fast analysis of quaternary ammonium pesticides in food and beverages using cation‐exchange chromatography coupled with isotope‐dilution high‐resolution mass spectrometry

A fast separation based on cation‐exchange liquid chromatography coupled with high‐resolution mass spectrometry is proposed for simultaneous determination of chlormequat, difenzoquat, diquat, mepiquat and paraquat in several food and beverage commodities. Solid samples were extracted using a mixture of water/methanol/formic acid (69.6:30:0.4, v/v/v), while liquid samples were ten times diluted with the same solution. Separation was carried out on an experimental length‐modified IonPac CS17 column (2 × 15 mm²) that allowed the use of formic acid and acetonitrile as mobile phase. Detection limits for food and beverage matrices were established at 1.5 μg/L for chlormequat, difenzoquat and mepiquat, and 3 μg/L for diquat and paraquat, while for drinking water a pre‐analytical sample concentration allowed detection limits of 9 and 20 ng/L, respectively. Precision, as repeatability (RSD%), ranged from 0.2 to 24%, with a median value of 6%, and trueness, as recovery, ranged from 64 to 118%, with a median value of 96%. The method developed was successfully applied to investigate the presence of herbicide residues in commercial commodities (mineral water, orange juice, beer, tea, green coffee bean, toasted coffee powder, cocoa bean, white corn flour, rice and sugar samples).     

在线净化/固相萃取-高效液相色谱法测定饮用水和环境水体中的百草枯和敌草快

建立了在线净化/固相萃取(SPE)-高效液相色谱(HPLC)快速、准确测定饮用水和环境水体中的两种痕量除草剂百草枯和敌草快的方法。样品用大体积自动进样器注入在线净化小柱并流经固相萃取小柱,通过双梯度高效液相色谱系统中的上样泵实现净化和富集后,通过阀切换将固相萃取小柱切换至分析流路中;用分析泵将待测物从富集柱冲洗至分析柱进行测定。上样泵流速和分析泵流速分别为0.7和0.6 mL/min,采用等度洗脱方式完成两种除草剂的分离和检测。检测波长分别为260 nm (百草枯)和311 nm (敌草快),进样体积为2.5 mL,整个分析时间为16 min。该方法在1.0～20 μg/L范围内线性关系良好,两种除草剂的线性相关系数均大于0.9980,检出限分别为0.10和0.12 μg/L(S/N=3)。该方法前处理简单,快速,可用于饮用水和环境水体中痕量除草剂的测定。     

Synthesis and application of a novel solid‐phase extraction adsorbent for multiresidue analysis of insecticides in water

A new solid‐phase adsorbent was synthesized for the simultaneous enrichment of multiple classes of trace insecticides (neonicotinoids, organophosphates, fiproles, and organochlorines) in water. The adsorbent was spherical with a diameter, surface area, average pore volume, and pore size of approximately 5 μm, 341 m²/g, 0.092 m³/g, and 2.22 nm, respectively. Extraction conditions were optimized, including water pH and the type and volume of the rinsing and eluting solvents. After extraction, target insecticides were analyzed by gas chromatography with mass spectrometry and high‐performance liquid chromatography with tandem mass spectrometry. The recovery of neonicotinoids ranged from 63.0 to 124%, except for clothianidin (40.1–52.9%). Recoveries of organophosphates, fiproles, and organochlorines were in the ranges of 37.0–102, 64.0–101, and 42.0–69.3%, respectively. Relative standard deviations were <20% except for profenofos (5.1–30%) and method detection limits were 1.8–12.7 ng/L, suggesting that the precision and accuracy of the developed method were viable. At environmentally relevant concentrations, the new adsorbent achieved comparable recoveries of target insecticides to hydrophilic–lipophilic balance adsorbent while providing an additional advantage by further reducing matrix effects. Field water samples from the Pearl River in Guangzhou, China were analyzed, and the frequent detection of neonicotinoids raises concerns about their aquatic risk.     

Multiclass method for the quantification of 92 veterinary antimicrobial drugs in livestock excreta,wastewater, and surface water by liquid chromatography with tandem mass spectrometry

A simple multiresidue method was developed for detecting and quantifying 92 veterinary antimicrobial drugs from eight classes (β‐lactams, quinolones, sulfonamides, tetracyclines, lincomycins, macrolides, chloramphenicols, and pleuromutilin) in livestock excreta and water by liquid chromatography with tandem mass spectrometry. The feces samples were extracted by ultrasound‐assisted extraction with a mixture of acetonitrile/water (80:20, v/v) and edetate disodium, followed by a cleanup using solid‐phase extraction with an amino cartridge. Water samples were purified with hydrophilic–lipophilic balance solid‐phase extraction column. Urine samples were extracted with acetonitrile and edetate disodium. Detection of veterinary antimicrobial drugs was achieved by liquid chromatography with tandem mass spectrometry using both positive and negative electrospray ionization mode. The recovery values of veterinary antimicrobial drugs in feces, urine, and water samples were 75–99, 85–110, and 85–101% and associated relative standard deviations were less than 15, 10, and 8%, respectively. The limits of quantification in feces, urine, and water samples were 0.5–1, 0.5–1, and 0.01–0.05 μg/L, respectively. This method was applied to determine real samples obtained from local farms and provides reliable quantification and identification results of 92 veterinary antimicrobial drugs in livestock excreta and water.     

Development and independent laboratory validation of a simple method for the determination of paraquat and diquat in potato, cereals and pulses

A new sensitive, fast and robust method for the determination of paraquat and diquat residues in potatoes, cereals and pulses is presented. Different extraction conditions (solvent, time and temperature) have been evaluated using barley grain, potatoes and dry lentils containing incurred residues of diquat and paraquat. The finalised procedure involves extraction with a mixture of methanol/water/hydrochloric acid at 80?°C and analysis by liquid chromatography–tandem mass spectrometry. Diquat D4 and Paraquat D6 internal standards were added to the test portions prior to extraction. A small-scale inter-laboratory validation of the developed method for diquat and paraquat using potato and barley samples was conducted by three laboratories. The precision and accuracy of the method were determined from recovery experiments (five replicates) at 0.01 and 0.1?mg?kg^?1. The recoveries obtained (n?=?180) were in the range of 92–120?% with associated relative standard deviation (RSD) between 1.4–10?% for all compound/commodity/spiking concentration combinations.     

High‐throughput 96‐well solid‐phase extraction for preparation of tetracycline followed by liquid chromatography and mass spectrometry analysis

Tetracyclines abuse has frequently occurred in aquaculture against bacteria, rickettsiae, spirochetes, and mycoplasmas. In this study, a high‐throughput sample preparation method was developed using 96‐well plate solid‐phase extraction (p‐SPE) and the extract was analyzed by ultra‐performance liquid chromatography tandem mass spectrometry (UPLC‐MS/MS). The experimental conditions were optimized such that the pH is 4, the eluting solvent is methanol (2 mL), and the sorbent is hydrophilic‐lipophilic balance (HLB) microsphere. The whole protocol was validated, and it showed that the tetracyclines were linear with correlation coefficients ≥ 0.9990, precision and accuracy (RSD%) in 3.9–6.1%, and mean recoveries of 88.6–103.6%. To exhibit the potential of 96‐well p‐SPE as a routine tool for inspection and quarantine, fresh aquatic samples were tested, and among which positive samples were observed. This method was demonstrated to be promising for the purification and enrichment of tetracyclines with reduced time and labor, and indeed practically and particularly suitable for widespread tetracyclines analysis.     

Determination of trace triclosan in environmental water by microporous bamboo‐activated charcoal solid‐phase extraction combined with HPLC‐ESI‐MS

A sensitive and efficient analytical method for triclosan (TCS) determination in water, which involves enrichment with bamboo‐activated charcoal and detection with HPLC‐ESI‐MS, was developed. The influence of several operational parameters, including the eluant and its volume, the flow rate, the volume andacidity of the sample, and the amount of bamboo‐activated charcoal, were investigated and optimized. Under the optimum conditions, linearity of the method was observed in the range of 0.02–20 μg/L, with correlation coefficients (r²) >0.9990. The limit of detection was 0.002 μg/L based on the ratio of chromatographic signal to baseline noise (S/N = 3). The spiked recoveries of TCS in real water samples were achieved in the range of 97.6–112.5%. The proposed method was applied to analyze TCS in real aqueous samples. All the surface water samples collected in Xiaoqing River had detectable levels of TCS with concentrations of 42–197 ng/L.     

In‐line preconcentration capillary zone electrophoresis for the analysis of haloacetic acids in water

Two in‐line enrichment procedures (large volume sample stacking (LVSS) and field amplified sample injection (FASI)) have been evaluated for the CZE analysis of haloacetic acids (HAAs) in drinking water. For LVSS, separation on normal polarity using 20 mM acetic acid–ammonium acetate (pH 5.5) containing 20% ACN as BGE was required. For FASI, the optimum conditions were 25 s hydrodynamic injection (3.5 kPa) of a water plug followed by 25 s electrokinetic injection (?10 kV) of the sample, and 200 mM formic acid–ammonium formate buffer at pH 3.0 as BGE. For both FASI and LVSS methods, linear calibration curves (r²>0.992), limit of detection on standards prepared in Milli‐Q water (49.1–200 μg/L for LVSS and 4.2–48 μg/L for FASI), and both run‐to‐run and day‐to‐day precisions (RSD values up to 15.8% for concentration) were established. Due to the higher sensitive enhancement (up to 310‐fold) achieved with FASI‐CZE, this method was selected for the analysis of HAAs in drinking water. However, for an optimal FASI application sample salinity was removed by SPE using Oasis WAX cartridges. With SPE‐FASI‐CZE, method detection limits in the range 0.05–0.8 μg/L were obtained, with recoveries, in general, higher than 90% (around 65% for monochloroacetic and monobromoacetic acids). The applicability of the SPE‐FASI‐CZE method was evaluated by analyzing drinking tap water from Barcelona where seven HAAs were found at concentration levels between 3 and 13 μg/L.     

液相色谱–串联质谱法测定蔬菜中6种极性农药残留量

建立了百草枯、敌草快、矮壮素、缩节胺、单甲脒、灭蝇胺6种极性农药的液相色谱–串联质谱测定方法。采用SCX和C_(18)复合填料(质量比为1∶20)的Shiseido CAPCELL PAK CR色谱柱分离,用超高压液相色谱–串联质谱仪测定。利用响应面法优化得到样品的前处理条件,蔬菜样品用甲酸–乙腈溶液均质提取,三氯甲烷液–液萃取净化,在定量限的1,2,10倍浓度水平,回收率在61.7%~116.8%之间,测定结果的相对标准偏差不大于13.6%(n=6)。该法适用于蔬菜中百草枯、敌草快、矮壮素、缩节胺、单甲脒、灭蝇胺残留量的测定。     

Solid‐phase extraction coupled with ultra high performance liquid chromatography and electrospray tandem mass spectrometry for the highly sensitive determination of five iodinated X‐ray contrast media in environmental water samples

A highly sensitive method based on solid‐phase extraction and ultra high performance liquid chromatography with electrospray tandem mass spectrometry has been developed for simultaneous determination of five iodinated X‐ray contrast media in environmental water samples. Various solid‐phase extraction cartridges have been evaluated and a combination of LiChrolute EN and ENVI‐Carb solid phase extraction cartridges was selected for sample enrichment. The method was comprehensively validated on ground water, tap water, surface water, drinking water, and waste water by the conventional procedures: linearity, method detection limits, accuracy and precision, matrix effects. Good linearity (R² > 0.999), low detection limits (0.4–8.1 ng/L), satisfactory recoveries (55.1–109.5%) and precision (0.8–10.0% for intra‐day precisions and 0.6–16.5% for inter‐day precisions) were obtained for all the target compounds. Iopamidol, iohexol, and diatrizoate in some matrices were affected by matrix effects, which were slightly eased by using the isotope‐labeled internal standard. The developed method was successfully applied for real samples collected in Shanghai, China, with detected concentrations up to 2200 ± 200 and 9000 ± 1000 ng/L for iohexol and iopamidol, respectively.     

Determination of sub‐ppb epichlorohydrin levels in water by on‐line solid‐phase extraction liquid chromatography/tandem mass spectrometry

A new sensitive and selective method based on on‐line solid‐phase extraction (SPE) coupled to liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) using a triple quadrupole mass spectrometer has been developed for the determination of epichlorohydrin (ECH) in different types of water samples. ECH is not easily determined directly by ESI‐MS as it is not readily ionized, and it has a low molecular mass and high polarity. Thus, prior derivatization of ECH was necessary, employing 3,5‐difluorobenzylamine as a derivatizing agent with Fe(III) as a catalyst. In order to achieve accurate quantification, correcting for matrix effects, losses in the derivatization process and instrumental deviations, isotope labelled ECH (ECH‐d₅) was added as an internal standard (IS) to the water samples. The method was validated based on European SANCO guidelines using drinking and other types of treated water spiked at two concentration levels (0.1 and 1.0 µg/L), the lower level having been established as the limit of quantification (LOQ) of the method. Satisfactory accuracy (recoveries between 70 and 103%), precision (RSD <20%) and linearity (from 0.05 to 50 µg/L, r >0.99) were obtained. The limit of detection (LOD) was set up at 0.03 µg/L. The method was applied to different water samples (drinking water and water samples collected from a municipal treatment water plant). In order to enhance confidence, five selected reaction monitoring (SRM) transitions were acquired, thus obtaining a simultaneous reliable quantification and identification of ECH in water, even at sub‐ppb levels. Copyright © 2009 John Wiley & Sons, Ltd.     

Rapid analysis of pesticide residues in drinking water samples by dispersive solid‐phase extraction based on multiwalled carbon nanotubes and pulse glow discharge ion source ion mobility spectrometry

An analytical method based on dispersive solid‐phase extraction with a multiwalled carbon nanotubes sorbent coupled with positive pulse glow discharge ion mobility spectrometry was developed for analysis of 30 pesticide residues in drinking water samples. Reduced ion mobilities and the mass–mobility correlation of 30 pesticides were measured. The pesticides were divided into five groups to verify the separation capability of pulse glow discharge in mobility spectrometry. The extraction conditions such as desorption solvent, ionic strength, conditions of adsorption and desorption, the amounts of multiwalled carbon nanotubes, and solution pH were optimized. The enrichment factors of pesticides were 5.4‐ to 48.7‐fold (theoretical enrichment factor was 50‐fold). The detection limits of pesticides were 0.01～0.77 μg/kg. The linear range was 0.005–0.2 mg/L for pesticide standard solutions, with determination coefficients from 0.9616 to 0.9999. The method was applied for the analysis of practical and spiked drinking water samples. All results were confirmed by high‐performance liquid chromatography with tandem mass spectrometry. The proposed method was proven to be a commendably rapid screening qualitative and semiquantitative technique for the analysis of pesticide residues in drinking water samples on site.     

Analysis of microcystins using high‐performance liquid chromatography and magnetic solid‐phase extraction with silica‐coated magnetite with cetylpyridinium chloride

Microcystins (MCs), produced by freshwater cyanobacteria, can be serious water pollutants, so it is important to monitor their concentration in drinking water. We have developed a method for rapid and accurate determination of microcystin levels in environmental water, using magnetic solid‐phase extraction and high‐performance liquid chromatography with UV detection. The magnetic composite material, which was combined with cetylpyridinium chloride, was prepared by hydrothermal synthesis. The optimal extraction of microcystins in water sample was achieved by optimizing the amount of adsorbent, time of adsorption, ratio of eluting solvent, and volume of eluent. Under the optimal conditions, the limit of detection of MC‐LR was 0.001 μg/L, and the limit of quantification was 0.0028 μg/L. The limit of detection of MC‐RR was 0.001 μg/L, and the limit of quantification was 0.003 μg/L. These values are far lower than those established by the International Health Organization for the maximum concentration of microcystins in drinking water. The magnetic solid‐phase extraction adsorbent used in this method has the advantages of simple preparation, low price, and easy solid–liquid separation, and it can be used for the rapid and sensitive monitoring of trace microcystins in environmental water samples.     

An Ionophore‐Based Anion‐Selective Optode Printed on Cellulose Paper

A general anion‐sensing platform is reported based on a portable and cost‐effective ion‐selective optode and a smartphone detector equipped with a color analysis app. In contrast to traditional anion‐selective optodes using a hydrophobic polymer and/or plasticizer to dissolve hydrophobic sensing elements, the new optode relies on hydrophilic cellulose paper. The anion ionophore and a lipophilic pH indicator are inkjet‐printed and adsorbed on paper and form a “dry” hydrophobic sensing layer. Porous cellulose sheets also allow the sensing site to be modified with dried buffer that prevents any sample pH dependence of the observed color change. A highly selective fluoride optode using an Al^III‐porphyrin ionophore is examined as an initial example of this new anion sensing platform for measurements of fluoride levels in drinking water samples. Apart from Lewis acid–base recognition, hydrogen bonding recognition is also compatible with this sensing platform.     

Hydrophilic interaction chromatography/tandem mass spectrometry for the simultaneous determination of three polar non‐structurally related compounds,imipenem, cilastatin and an investigational β‐lactamase inhibitor,MK‐4698, in biological matrices

A method coupling hydrophilic interaction chromatography (HILIC) with tandem mass spectrometry (MS/MS) has been developed for the simultaneous determination of three polar non‐structurally related compounds – a carbapenem antibiotic, imipenem (IMP), a renal dehydropeptidase inhibitor, cilastatin (CIL), and an investigational β‐lactamase inhibitor, MK‐4698 (BLI), in rat plasma, monkey plasma and mouse blood. The analytes were extracted through protein precipitation, chromatographed on a Waters Atlantis HILIC column, and detected on a Sciex API4000 mass spectrometer using a Turbo‐Ion Spray ion source in positive ionization mode following multiple‐reaction monitoring (MRM). The assay dynamic range was 0.1–100 µg/mL for IMP, CIL and BLI, respectively, using a total of 20–25 µL biologic samples, and the total HPLC/MS/MS run time was 4 min/injection. The assay was found to be sensitive, selective and reproducible. The challenges, namely, sample stability, blood sample processing, matrix effect in monkey study samples, and dilution re‐assays for the limited mouse blood samples, are resolved and discussed. This technique allowed rapid analysis of polar compounds in biologic matrixes with satisfactory chromatographic retention and increased throughput. Copyright © 2009 John Wiley & Sons, Ltd.     

Influence of the polymer structure over self‐assembly and thermo‐responsive properties: The case of PEG‐b‐PCL grafted copolymers via a combination of RAFT and ROP

During the last years, the field of drug delivery has experienced a growing interest toward the so‐called thermo‐responsive polymers: synthetic materials that, due to the specific hydrophilic–lipophilic balance of their repeating units, exhibit a lower critical solution temperature (LCST) in water associated to a characteristic coil–globule transition. In this work, thermo‐responsive amphiphilic block copolymers are synthesized via reversible addition‐fragmentation transfer (RAFT) polymerization starting from thermo‐responsive monomers and a hydrophobic biodegradable macromonomer, oligo(caprolactone)methacrylate (CL₃MA), produced via ring opening polymerization (ROP). The obtained copolymers exhibit an interesting self‐assembly behavior leading to nanoparticles (NPs) as long as temperature is kept below the LCST. Otherwise, once this value is overcome, the destabilization of the NPs causes the formation of hydrophobic superstructures that enhance the release of an entrapped lipophilic drug. This characteristic behavior has been systematically studied and related to the copolymer structure. In particular, the self‐assembly behavior as well as temperature‐triggered NP destabilization have been related to the relative length of the two blocks constituting the copolymers and to their hydrophilic–lipophilic balance (HLB). Finally, the efficacy of the thermo‐responsive triggered drug release has been tested in the case of Paclitaxel (PTX). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2919–2931     

Solid‐phase microextraction of phthalate esters by a new coating based on a thermally stable polypyrrole/graphene oxide composite

A novel polypyrole/graphene oxide coating was made by the electrochemical polymerization of pyrrole in the presence of sodium dodecyl sulfate and graphene oxide on a platinum wire. The prepared fiber has shown a good thermal stability up to 300°C. The fiber was applied to the direct solid‐phase microextraction and gas chromatographic analysis of four phthalate esters. The effect of four parameters on gas chromatography peak area including extraction temperature, extraction time, injection temperature, and ionic strength were investigated. Under the optimized conditions, the detection limits were between 0.042 and 0.26 μg/L. The intraday and interday relative standard deviations obtained at 55 μg/L, using a single fiber, were 8.2–16% and 17.3–25.6%, respectively. The method was successfully applied to the analysis of phthalate esters in two real samples of boiling water in cheap disposable clear plastic drinking cups showing recoveries from 83 to 120%.     

Analysis of cocaine and benzoylecgonine in urine by using multisyringe flow injection analysis‐gas chromatography‐mass spectrometry system

In this paper, a method was described to determine cocaine (COC) and benzoylecgonine (BZE) in human urine samples by GC‐MS detection. The extraction of analytes from urine samples was achieved in an Oasis hydrophilic–lipophilic balance column (20 mm×3.9 mm id, dp=25 μm; Waters, USA), incorporated in a multisyringe flow injection system, used for the sample treatment. Finally, to improve the volatility of the BZE, an in‐line derivatization reaction with N,O‐bis (trimethylsilyl) trifluoroacetamide with 1% trimethylchlorosilane was made microwave‐assisted in order to reduce the reaction time. The results showed that the proposed method is a good alternative for the analysis of COC and BZE in urine samples because it offers advantages compared with those described in the literature, which include simplicity in the sample treatment, the sensitivity and selectivity necessary to determine the analytes of interest at low levels in the urine and high sample throughput.     

Determination of haloacetic acids in water using layered double hydroxides as a sorbent in dispersive solid‐phase extraction followed by liquid chromatography with tandem mass spectrometry

In the present study, highly efficient and simple dispersive solid‐phase extraction procedure for the determination of haloacetic acids in water samples has been established. Three different types of layered double hydroxides were synthesized and used as a sorbent in dispersive solid‐phase extraction. Due to the interesting behavior of layered double hydroxides in an acidic medium (pH?4), the analyte elution step was not needed; the layered double hydroxides are simply dissolved in acid immediately after extraction to release the analytes which are then directly introduced into a liquid chromatography with tandem mass spectrometry system for analysis. Several dispersive solid‐phase extraction parameters were optimized to increase the extraction efficiency of haloacetic acids such as temperature, extraction time and pH. Under optimum conditions, good linearity was achieved over the concentration range of 0.05–100 μg/L with detection limits in the range of 0.006–0.05 μg/L. The relative standard deviations were 0.33–3.64% (n = 6). The proposed method was applied to different water samples collected from a drinking water plant to determine the concentrations of haloacetic acids.     

Simultaneous determination of niacin and pyridoxine at trace levels by using diode array high‐performance liquid chromatography and liquid chromatography with quadrupole time‐of‐flight tandem mass spectrometry

A highly sensitive and simple diode‐array high‐performance liquid chromatography and liquid chromatography with quadrupole time‐of‐flight tandem mass spectrometry method was developed for the simultaneous determination of niacin and pyridoxine in pharmaceutical drugs, tap water, and wastewater samples. To determine the in vivo behavior of niacin and pyridoxine, analytes were subjected to simulated gastric conditions. The calibration plots of the diode‐array high‐performance liquid chromatography and liquid chromatography with quadrupole time‐of‐flight tandem mass spectrometry method showed good linearity over a wide concentration range with close to 1.0 correlation coefficients for both analytes. The limit of detection/limit of quantitation values for liquid chromatography quadrupole time‐of‐flight tandem mass spectrometry analysis were 1.98/6.59 and 1.3/4.4 μg/L for niacin and pyridoxine, respectively, while limit of detection/limit of quantitation values for niacin and pyridoxine in high‐performance liquid chromatography analysis were 3.7/12.3 and 5.7/18.9 μg/L, respectively. Recovery studies were also performed to show the applicability of the developed methods, and percentage recovery values were found to be 90–105% in tap water and 94–97% in wastewater for both analytes. The method was also successfully applied for the qualitative and quantitative determination of niacin and pyridoxine in drug samples.