Multi-residue analytical methods using LC-tandem MS for the determination of pharmaceuticals in environmental and wastewater samples: a review

Multi-residue analytical methodologies are becoming the preferred and required tools against single group analysis, as they provide wider knowledge about the occurrence of pharmaceuticals in the environment necessary for further study of their removal, partition and ultimate fate. However, simultaneous analysis of compounds from different groups with quite different physico-chemical characteristics requires a compromise in the selection of experimental conditions, which in some cases are not the best conditions for all the analytes studied. In this article, an overview of analytical methodologies focusing on the simultaneous determination of acidic, neutral and basic compounds belonging to different therapeutical classes is presented. The state-of-the-art of LC-MS/MS for multi-class analysis is reviewed, highlighting the specific requirements for such analysis.     

Multi-residue analysis of pesticides in tea by online SEC-GC/MS

A multi-residue method for the analysis of pesticides in tea was developed by online size exclusion chromatography (SEC)-GC/MS with full scan mode. The sample was fortified with chlorpyrifos-d(10) isotope internal standard and extracted by acetonitrile. After purification by primary secondary amine sorbent and solvent exchange by SEC mobile phase, the sample was detected by online SEC-GC/MS. The purification result of the online system was evaluated by comparing the correlation between Chinese cabbage and tea matrix. The factors for method optimization included sample preparation, matrix effects and the instrument parameters of each online component. Scatter plot was introduced in this study to directly illustrate the results of the condition optimization and matrix effects in the online system. For most of the pesticides, the average recoveries ranged from 70 to 130% and the RSD were below 15%. The feasibility of the application of full scan mode in multi-residue determination of trace amounts of pesticides (LODs below 0.01 mg/kg) in a complex matrix was discussed.     

Fast multiresidue screening of 300 pesticides in water for human consumption by LC-MS/MS

The study tested the determination of 300 pesticides in mineral water at levels of 0.1 and 1.0 μg/L. Measurements were conducted by direct sample injection into a liquid chromatograph coupled to a tandem mass spectrometer without any sample enrichment and/or cleanup. Two separate injections enabled the recording of two transitions per analyte (600 selected reaction monitoring transitions in total). For 285 analytes the sensitivity of direct sample injection (100 μL) was sufficient to quantify residues at 0.1 μg/L. All remaining pesticides were detected at 1.0 μg/L. Calibration functions were linear for more than 80% of analytes. Signal suppression or enhancement compared with signals in high-performance liquid chromatography water was equal to or smaller than 20% for 240 analytes. Even the largest matrix-induced suppression did not result in the disappearance of peaks. Combining the results of seven mineral waters, the relative standard deviation of “recovery” was 20% or less for 87% of the substances. A second transition for confirmatory purposes was often available. Consequently, the proposed direct injection of samples without any sample enrichment and/or cleanup is suitable for screening of many pesticides in mineral and drinking water.     

Two new methods of synthesis for the perbromate ion: chemistry and determination by LC-MS/MS

Historically, the synthesis of perbromate ion through conventional oxidation routes has proven elusive. Herein, we report perbromate ion formation through the reaction of hypobromite and bromate ions in an alkaline sodium hypobromite solution. Formation was established via LC-MS/MS analysis of the bromate and perbromate ions in the reaction solutions over a 13-day period. Furthermore, it was discovered that the perbromate ion was also formed as a result of the electrospray ionization process. Selective reduction of the bromate ion prior to analysis was used to confirm the two formation pathways.     

Sensitive analytical methods for 22 relevant insecticides of 3 chemical families in honey by GC-MS/MS and LC-MS/MS

Several methods for analyzing pesticides in honey have been developed. However, they do not always reach the sufficiently low limits of quantification (LOQ) needed to quantify pesticides toxic to honey bees at low doses. To properly evaluate the toxicity of pesticides, LOQ have to reach at least 1 ng/g. In this context, we developed extraction and analytical methods for the simultaneous detection of 22 relevant insecticides belonging to three chemical families (neonicotinoids, pyrethroids, and pyrazoles) in honey. The insecticides were extracted with the QuEChERS method that consists in an extraction and a purification with mixtures of salts adapted to the matrix and the substances to be extracted. Analyses were performed by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) for the pyrazoles and the pyrethroids and by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) for the neonicotinoids and ethiprole. Calibration curves were built from various honey types fortified at different concentrations. Linear responses were obtained between 0.2 and 5 ng/g. Limits of detection (LOD) ranged between 0.07 and 0.2 ng/g, and LOQ ranged between 0.2 and 0.5 ng/g. The mean extraction yields ranged between 63 % and 139 % with RSD <25 %. A complete validation of the methods also examined recovery rates and specificity. These methods were applied to 90 honey samples collected during a 2009–2010 field study in two apiaries placed in different anthropic contexts.

Multi-residue analysis of emerging pollutants in sediment using QuEChERS-based extraction followed by LC-MS/MS analysis

Emerging contaminants are suspected to cause adverse effects in humans and wildlife. Aquatic ecosystems are continuously contaminated by agricultural and industrial sources. To establish a causality relationship between the occurrence of contaminants in the environment and disease, experiments including all environmental matrices must be performed. Consequently, the current analytical tools must be improved. A new multi-residue method for analysing 15 emerging pollutants in sediments based on the Quick, Easy, Cheap, Effective, Rugged and Safe approach is reported. The development of such a multirisque, inter-family method for sediment including pharmaceuticals, pesticides, personal care products and plasticizers is reported for the first time. The procedure involves salting-out liquid–liquid extraction using acetonitrile and clean-up with dispersive solid phase extraction, followed by liquid chromatography coupled with tandem mass spectrometry. The validated analytical procedure exhibited recoveries between 40 and 98 % for every target compound. This methodology facilitated the determination of pollutant contents at nanogram-per-gram concentrations.

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).     

液相色谱-串联四极杆质谱法对动物源基质中β2-受体激动剂的检测

β2-受体激动剂苯乙胺类药物(phenethylamines,PEAs)具有苯乙醇胺结构骨架,苯环上连接有碱性的β-羟胺侧链.目前使用的β2-受体激动剂已有30多种,我国禁止所有β2-受体激动剂用于养殖业.农业部235号公告<动物性食品中兽药最高残留限量>规定在所有食用动物的可食组织中不得检出此类药物.本文在已有方法的基础上进行了改进,利用Agilent 6410A串联四极杆质谱同时测定了11种β2-受体激动剂.实验结果表明该方法快速、简单、灵敏度高,可达到出口欧盟和日本的检测要求.     

Evaluation of various QuEChERS based methods for the analysis of herbicides and other commonly used pesticides in polished rice by LC-MS/MS

Four different extraction and clean-up protocols based on the QuEChERS method were compared for the development of an optimized sample preparation procedure for the multiresidue analysis of 16 commonly applied herbicides in rice crops using LC-QqQ/MS. Additionally the methods were evaluated for the analysis of 26 insecticides and fungicides currently used in rice crops. The methods comprise, in general, the hydratation of the sample with water followed by the extraction with acetonitrile, phase separation with the addition of different salts and finally a clean-up step with various sorbents.Matrix effects were evaluated for the 4 studied methods using LC-QqQ/MS. Additionally LC-TOF/MS was used to compare the co-extractants obtained with the four assayed methodologies. Thirty-six pesticides presented good performance with recoveries in the range 70-120% and relative standard deviations below 20% using 7.5 g of milled polished rice and the buffered acetate QuEChERS method without clean-up at both fortification levels: 10 and 300 μg kg⁻¹. The other six pesticides presented low recovery rates, nevertheless all these analytes could be analyzed with at least one of the other three studied procedures.     

LC-MS/MS methods for determination of unstable pivmecillinam and mecillinam in acidified human plasma: Application to a pharmacokinetic study

Pivmecillinam, the ester of biologically active antibiotic mecillinam, is an effective oral preparation to treat urinary tract infections. To study pharmacokinetics in humans, LC-MS/MS methods were developed to quantify pivmecillinam and mecillinam in human plasma, respectively. Considering cephalexin as internal standard, analytes were separated on UltimateXB-C18 columns after protein precipitation by acetonitrile. The mobile phase was composed of water containing 0.1% formic acid and methanol. The multiple reactions monitoring transitions of m/z 440.2→167.1, 326.1→167.1, and 348.1→158.1 were selected to inspect pivmecillinam, mecillinam, and the internal standard in positive ion mode. No apparent matrix effect was perceived. Linearities were obtained over calibration ranges of 0.0500–12.0 and 10.0–15,000 ng/mL, respectively. The intraday precisions were below 5.5%, the interday precisions were below 6.1%, and accuracies were within –8.1 to 13.0%. Stability tests were conducted and an acidification step was explored to enhance the stability of pivmecillinam and mecillinam. Further stability was validated under various storage and processing conditions. Both methods were applied to a pharmacokinetic study of pivmecillinam and mecillinam after oral administration of 400 mg pivmecillinam hydrochloride tablets in healthy Chinese subjects.     

溶剂转移-气相色谱-质谱法和选择洗脱-气相色谱法测定大蒜中289种农药多残留

以溶剂转移净化为核心步骤,建立了一种适用于大蒜样品中农药多残留分析的前处理方法(方法I),配以一个辅助方法(方法II),构成大蒜中常见289种农药多残留的分析体系(方法I283种,方法II6种)。方法I中,样品用乙腈-水溶液提取,盐析分配,溶剂转移和固相萃取(SPE)净化后进行气相色谱-质谱(GC-MS)分析;方法II中,样品用无水Na2SO4配合乙酸乙酯均质研磨,超声波辅助提取,提取液经Primary Secondary Amine (PSA)粉末分散固相萃取和LC-Si柱选择洗脱净化后进行GC分析。GC-MS采用选择离子监测(SIM)方式,GC采用火焰光度检测器(FPD)检测,外标法定量。方法简便、快速,通过优化前处理和上机条件,在最优条件下进行测试,方法的定量限(S/N≥10)为0.01～0.05 mg/kg。方法I中,在加标水平为0.02、0.20 mg/kg时,回收率为52%～163%,其中回收率在70%～120%之间的占88%,相对标准偏差为2.4%～18%;方法II中,在加标水平为0.01、0.02、0.10、0.20 mg/kg时,回收率为70%～111%,相对标准偏差为3.2%～9.3%。详细描述了实验模型的构建,并对GC-MS灵敏度的提高提出了新的见解。该方法准确、灵敏、快速,可满足大蒜中多种农药残留的检测要求。     

A SDME/GC–MS methodology for determination of organophosphate and pyrethroid pesticides in water

A rapid and simultaneous method for identification and quantification of pesticides residues in water samples have been developed and applied to the analysis of real samples. Tap and San Francisco River water samples were collected from Propria town and Aracaju city in the state of Sergipe, Brazil. A new single-drop microextraction (SDME) followed by gas chromatography–mass spectrometry techniques were used to determine the dimethoate, methyl parathion, ethion (organophosphates) and permethrin (pyrethroid) pesticides in water samples. The parameters linearity, linear range, precision, accuracy, sensitivity and robustness were studied for validation of the SDME/GC–MS method. An important point to this study is that plots of relative response and logarithmic concentrations were used to verify that the measurements were within the linear dynamic range of the method. In order to enhance high linearity of analytical curve, points that do not belong to 95 to 105% of linear range were excluded. Recovery tests of pesticides in different water samples (tap water and river water) were between 76.2 and 107% and this evaluation was used to demonstrate the reliability of the method. For all pesticides the method showed the limits of detection (LOD) in a range between 0.05 and 0.38 μg L^{− 1} and the limit of quantification (LOQ) between 0.15 and 1.1 μg L^{− 1}. All these parameters demonstrate high sensitivity of the developed method and the capability for detecting and quantifying of low levels of pesticides in water samples.     

Multi-residue methods for confirmatory determination of antibiotics in milk

The prevalent use of antibiotics, e. g. sulphonamides, tetracyclines, beta-lactams, macrolides, aminoglycosides, etc., in dairy farming to prevent and treat microbial infections e. g. mastitis, can be a potential source of veterinary drug residues in milk. Antibiotic residues constitute a risk to human health, since they can cause allergic reactions in hypersensitive individuals or they may lead to the appearance of drug-resistant bacteria. Analysis of these residues plays a key role in ensuring food safety. Regulatory agencies in the European Union and in other countries have established maximum residue limits and requirements concerning the performance of analytical methods and the interpretation of the results. This review describes the state of the art in the analytical strategies concerning the multi-class as well as the multi-residue analysis of antibiotics in milk. Since milk is a complex matrix due to its high protein and fat content, which often interfere in analytical procedures, special focus has been placed on sample preparation: extraction and clean-up. Confirmation of antibiotic residues according to European Decision 657/2002/EC has been also discussed.     

Multi-residue analysis of free and conjugated hormones and endocrine disruptors in rat testis by QuEChERS-based extraction and LC-MS/MS

Endocrine disrupting compounds (EDCs) are suspected to be responsible for many disorders of the human reproductive system. To establish a causality relationship between exposure to endocrine disruptors and disease, experiments on animals must be performed with improved or new analytical tools. Therefore, a simple, rapid, and effective multi-residue method was developed for the determination of four steroid hormones (i.e., testosterone, androstenedione, estrone, and estradiol), glucuronide and sulfate conjugates of estrone and estradiol and four endocrine disruptors in rat testis (i.e., bisphenol A, atrazine, and active metabolites of methoxychlor and vinclozolin). The sample preparation procedure was based on the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) approach. An analytical method was then developed to quantify these compounds at ultra-trace levels by liquid chromatography coupled to tandem mass spectrometry. The QuEChERS extraction was optimized with regard to the acetonitrile/water ratio used in the extraction step, the choice of the cleanup method and the acetonitrile/hexane ratio used in the cleanup step. The optimized extraction method exhibited recoveries between 89% and 108% for all tested compounds except the conjugates (31% to 58%). The detection limits of all compounds were below 20 ng g⁻¹ of wet weight of testis. The method was subsequently applied to determine the levels of hormones and EDCs in seven rat testis samples.     

LC-MS/MS method for the determination of organophosphorus pesticides and their metabolites in salmon and zebrafish fed with plant-based feed ingredients

Analytical and Bioanalytical Chemistry - The composition of Atlantic salmon feed has changed considerably over the last two decades from being marine-based (fishmeal and fish oil) to mainly...     

Multi-residue determination of pesticides in water using multi-walled carbon nanotubes solid-phase extraction and gas chromatography-mass spectrometry

A reliable multi-residue method which was based on solid-phase extraction (SPE) with multi-walled carbon nanotubes (MWCNTs) as adsorbent was developed for determination and quantitation of 12 pesticides (carbofuran, iprobenfos, parathion-methyl, prometryn, fenitrothion, parathion-ethyl, isocarbofos, phenthoate, methidathion, endrin, ethion, methoxychlor) in surface water by gas chromatography-mass spectrometry (GC-MS). Parameters that might influence the extraction efficiency such as the eluent volume, the sample flow rate and the sample loading volume were optimized. The experimental results showed the excellent linearity of 12 pesticides (R(2)>0.99) over the range of 0.04-4 microg L(-1), and the precisions (RSD) were 3.1-15.1% under the optimal conditions. The detection limits of proposed method could reach 0.01-0.03 microg L(-1) based on the ratio of chromatographic signal to base line noise (S/N=3). Good recoveries achieved with spiked water samples were in the range of 82.0-103.7%. The results indicated that MWCNTs have good adsorbability to the 12 pesticides tested in this study. With less cost, less analytical time and less solvent-consuming, the developed multi-residue method could be used to determine multi-class pesticides in water simultaneously.     

Multiresidue method to quantify pesticides in fish muscle by QuEChERS-based extraction and LC-MS/MS

Pesticide residues in fish muscle are an environmental and a health safety concern which requires analytical methods presenting high sensitivity and low limits of quantification. In this study, adapted QuEChERS method, coupled to liquid chromatography tandem mass spectrometry (Scheduled MRM-5500 QTRAP), was developed to quantify 13 pesticides (azoxystrobin, clomazone, diflufenican, dimethachlor, carbendazim, iprodion, isoproturon, mesosulfuron-methyl, metazachlor, napropamid, quizalofop and thifensulfuron-methyl) in muscle of fish. Quantification limits were below 1 ng g⁻¹ except for clomazone (1.8 ng g⁻¹) and quizalofop (7.4 ng g⁻¹). Best recoveries were observed for perch (>80%) and roach (>68%), except for thifensulfuron-methyl. Lower recoveries had been observed for carp (6% to 86%). Relative standard deviation was lower than 28% for intra-day and 29% for inter-day analysis, respectively. This method was successfully tested on three fish species, naturally or orally exposed: roach (Rutilus rutilus), perch (Perca fluviatilis) and carp (Cyprinus carpio). Few levels were observed in fish naturally exposed, but carp and perch orally contaminated showed measurable levels in their muscles.     

Validation of a multi-residue method for the determination of several antibiotic groups in honey by LC-MS/MS

The presented multi-method was developed for the confirmation of 37 antibiotic substances from the six antibiotic groups: macrolides, lincosamides, quinolones, tetracyclines, pleuromutilines and diamino-pyrimidine derivatives. All substances were analysed simultaneously in a single analytical run with the same procedure, including an extraction with buffer, a clean-up by solid-phase extraction, and the measurement by liquid chromatography tandem mass spectrometry in ESI+ mode. The method was validated on the basis of an in-house validation concept with factorial design by combination of seven factors to check the robustness in a concentration range of 5-50 μg kg(-1). The honeys used were of different types with regard to colour and origin. The values calculated for the validation parameters-decision limit CCα (range, 7.5-12.9 μg kg(-1)), detection capability CCβ (range, 9.4-19.9 μg kg(-1)), within-laboratory reproducibility RSD(wR) (<20% except for tulathromycin with 23.5% and tylvalosin with 21.4 %), repeatability RSD(r) (<20% except for tylvalosin with 21.1%), and recovery (range, 92-106%)-were acceptable and in agreement with the criteria of Commission Decision 2002/657/EC. The validation results showed that the method was applicable for the residue analysis of antibiotics in honey to substances with and without recommended concentrations, although some changes had been tested during validation to determine the robustness of the method.     

Quaternary ammonium pesticides: A review of chromatography and non-chromatography methods for determination of pesticide residues in water samples

The monitoring of pesticide residues in water sources is essential because of their increased worldwide demand in agriculture and their subsequent detection in waters. Pesticide residues in water matrices are traditionally determined by multiresidue methodologies based on chromatography coupled to mass spectrometry. However, for quaternary ammonium pesticide residues, as highly polar compounds, the chromatographic approach frequently fails, requiring modifications in the separation method, or even an alternative technique for analyte quantification. Therefore, to solve this analytical limitation for these residues, several authors proposed unusual methodologies, such as those based on spectroscopic or electroanalytical approaches. This review intends to offer an overview of the analysis of quaternary ammonium pesticide residues in different water sources, focusing on advances in sample preparation before chromatographic separations and alternative analytical techniques, such as spectroscopy and electroanalytical methods.     

Study of different atmospheric-pressure interfaces for LC-MS/MS determination of acrylamide in water at sub-ppb levels

A rapid, sensitive and selective method based on LC-MS/MS has been developed for the direct determination of acrylamide residues in water in compliance with the current European Union (EU) 98/83 Drinking Water Directive. Given the high polarity of acrylamide, the application of a rapid on-line solid phase extraction step, commonly used for preconcentrating low analyte levels, was not found to be completely satisfactory. Therefore, an alternative approach based on the use of direct large-volume injection into the LC-MS/MS system has been used. Three atmospheric-pressure interfaces (ESI, APCI and Ion Sabre APCI) were checked to reach the required sensitivity (0.1 microg/l). All three interfaces were tested by analysis of six different water samples (surface water, groundwater, drinking water and three treated water samples) spiked at three concentration levels each (0.1, 1 and 10 microg/l). When using ESI, poor sensitivity and high matrix effects were observed. This situation improved when APCI was used as the interface because no matrix effect was found, although sensitivity was not completely satisfactory. The best results were obtained by interfacing the Ion Sabre APCI; its higher sensitivity for acrylamide (LOD 0.03 microg/l) and the absence of matrix effects recommended its selection. Using this approach, satisfactory recoveries (90-97%) and precision (<12%) were obtained for all water samples studied. Besides, the acquisition of two different MS/MS transitions allowed not only the quantification but also the confirmation of acrylamide in water at concentration levels around 0.1 microg/l.