Development of analytical methods for multiresidue determination of quinolones in pig muscle samples by liquid chromatography with ultraviolet detection, liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry

This paper presents a comparison between liquid chromatography with ultraviolet detection (LC-UV), liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods developed for the multiresidue determination of 8 quinolones, around their maximum residue levels (MRLs) in pig muscle. The procedure involves common extraction of the quinolones from the tissues by traditional extraction, a step for clean-up and preconcentration of the analytes by solid-phase extraction (SPE) and a subsequent liquid chromatographic analysis. The methods present satisfactory results of linearity, precision and limits of quantification much lower than the MRLs established by the European Union for quinolones in pig tissues.     

Confirmatory and quantitative analysis using experimental design for the extraction and liquid chromatography-UV, liquid chromatography-mass spectrometry and liquid chromatography-mass spectrometry/mass spectrometry determination of quinolones in turkey muscle

The aim of this work is to established methods for determination of quinolones (ciprofloxacin, danofloxacin, enrofloxacin, difloxacin and flumequine), regulated by European Union, and sarafloxacin in turkey muscle. An experimental design has been applied for the optimization of the factors that influence the extraction of quinolones from turkey muscle in order to determine the experimental conditions for their extraction with high recoveries. Liquid chromatography with ultraviolet detection (LC-UV), liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS) have been used for the simultaneous quantification of quinolones antibiotics in turkey muscle. The proposed methods have been validated according to the Food Drugs Administration guideline and presents the limit of quantification below the maximum residue limits established by the European Union for quinolones in turkey muscle. The methods developed have been applied to quantification of enrofloxacin and its main metabolite ciprofloxacin in samples of turkey muscle obtained from animals treated with enrofloxacin.     

Determination of selected non-authorized insecticides in peppers by liquid chromatography time-of-flight mass spectrometry and tandem mass spectrometry

In this work, two analytical methods based on liquid chromatography coupled to electrospray time-of-flight mass spectrometry (LC/ESI-TOFMS) and tandem mass spectrometry (LC/ESI-MS/MS) are described for the identification, confirmation and quantitation of three insecticides non-authorized in the European Union (nitenpyram, isocarbophos and isofenphos-methyl) but detected in recent monitoring programmes in pepper samples. The proposed methodologies involved a sample extraction procedure using liquid-liquid partition with acetonitrile followed by a cleanup step based on dispersive solid-phase extraction. Recovery studies performed on peppers spiked at different fortification levels (10 and 50 microg kg(-1)) yielded average recoveries in the range 76-100% with relative standard deviation (RSD) (%) values below 10%. Identification, confirmation and quantitation were carried out by LC/TOFMS and LC/MS/MS using a hybrid triple quadrupole linear ion trap (QqLIT) instrument in multiple-reaction monitoring (MRM) mode. The obtained limits of quantitation (LOQs) were in the range 0.1-5 microg kg(-1), depending on each individual technique. Finally, the proposed methods were successfully applied to the analysis of suspected pepper samples.     

Determination of lipid mediators in breast cancer cells using lyophilization‒supercritical fluid extraction online coupled with supercritical fluid chromatography‒quadrupole tandem mass spectrometry

A lyophilization?supercritical fluid extraction coupled with supercritical fluid chromatography?quadrupole tandem mass spectrometry online method was developed for the determination of lipid mediators in breast cancer cells. Supercritical fluid extraction was applied to the cell samples for the first time due to the use of lyophilization. The conditions of supercritical fluid extraction and supercritical fluid chromatography?quadrupole tandem mass spectrometry were investigated systematically. Under the optimized conditions, all the calibration curves for the lipid mediators showed good linearity (correlation coefficient > 0.99). The limits of detection and the limits of quantification were in the range of 0.190?5.36 pg and 0.560?16.2 pg, respectively. The recoveries were in the range of 70.3?125%. The relative standard deviations of the precision ranged from 1.49?18.7% and the accuracies were higher than 84%. Compared with liquid?liquid extraction coupled with liquid chromatography and tandem mass spectrometry method, the present approach reduced the manual labor and obtained higher sensitivity as well as higher extraction recoveries for all 15 lipid mediators. Finally, the online method was applied to the quantification of lipid mediators in breast cancer cells and normal mammary epithelial cells. On the basis of the results, this lyophilization?supercritical fluid extraction online coupled with supercritical fluid chromatography?quadrupole tandem mass spectrometry method showed great promise in the analysis of lipid mediators in complex biological samples.     

Validation of a gas chromatography/triple quadrupole mass spectrometry based method for the quantification of pesticides in food commodities

A new multiresidue method has been validated in cucumber matrix for the routine analysis of 130 multiclass pesticide residues by gas chromatography/triple quadrupole mass spectrometry. The pesticides were extracted with ethyl acetate. A first identification of the pesticides was based on a tandem mass spectrometric (MS/MS) screening method, which monitors a single transition for each target compound, in less than 12 min. After that, potentially non-negative samples were analyzed again by the MS/MS confirmation/quantification method, which monitors two or three MS/MS transitions for each compound, also in less than 12 min. Performance characteristics, such as trueness, precision, linear range, detection limit (LOD) and quantification limit (LOQ), for each pesticide were calculated. The average recoveries obtained ranged between 70 and 120% at three different fortification levels (25, 200 and 500 microg/kg) with precision, expressed as relative standard deviation (RSD), values lower than 15%. The calculated LOD and LOQ were typically <3.2 and 9.6 microg/kg, respectively. Such limits were much lower than the maximum residue levels (MRLs) established by European legislation. The proposed methodology was applied to the determination of pesticides in real vegetable samples from Almería (Spain).     

Identification of unknown pesticides in fruits using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Imazalil as a case study of quantification

Ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QqTOF-MS) is an emerging technique offering more rapid and efficient separation, as well as the possibility to obtain accurate mass measurement and tandem mass spectrometry (MS/MS). This paper deals with the use of UPLC-QqTOF-MS to identify the pesticide residues present in complex pear extracts. Carbendazim, imazalil, and ethoxyquin were successfully identified because of the accurate mass determination of their protonated molecule and their major fragments in the product ion mass spectra. A few plastic and latex additives were also found, most of them probably coming from the packaging transfer to the fruits. The potential of the UPLC-QqTOF-MS and UPLC-QqTOF-MS/MS techniques as a quantification tool is also discussed taking imazalil as example. For quantification, calibration curves were linear over a dynamic range of 2 orders of magnitude, whereas higher calibration ranges are better adjusted to polynomial curves of second and third order. Quantification using different mass windows was also assessed. Accurate quantification required mass windows as wide as 20 mDa, narrower mass windows of 5 mDa provided erroneous quantification, probably because the low ion abundance. The mean recoveries and percentage relative standard deviation (RSD) of 35 determinations for imazalil were 76% (13% RSD) by MS and 77% (14% RSD) by MS/MS. The theoretical limit of detection was 0.4 microg kg(-1), with a validated limit of quantification of 2 microg kg(-1). The quantitative data obtained using UPLC-QqTOF-MS were compared with those obtained using conventional liquid chromatography (LC)-MS/MS with a triple quadrupole (QqQ). It was concluded that UPLC-QqTOF-MS might become a powerful analytical tool for both, unknown's identification and quantification of target pesticides.     

Determination of heterocyclic amines by liquid chromatography-quadrupole time-of-flight mass spectrometry

This paper discusses the applicability of coupling liquid chromatography (LC) to mass spectrometry (MS) using a time-of-flight (TOF) mass analyzer for the analysis of heterocyclic amines (HAs). Accurate mass measurement (<2 mDa) with both MS-MS and in-source CID MS-MS was carried out to confirm the elemental composition of some fragments previously reported. Some isobaric assignments (fragments containing N versus CH2 and NH3 versus CD2H) were distinguished by taking advantage of the resolution provided by the TOF mass analyzer. On the other hand, the LC-MS analysis of HAs in MS acquisition mode was also performed. Quality parameters of the method were established. The linearity range extended over three orders of magnitude, limits of detection were in the pg level and good short-term precision values (R.S.D., 1.2-8.0%) were obtained. The LC-ESI-TOF method was applied to the determination of HAs in a lyophilized meat extract and the results obtained were comparable to those given by MS-MS with triple quadrupole and ion trap instruments.     

Simultaneous determination of toxins in algae and water samples by high-performance liquid chromatography with triple quadrupole mass spectrometry

A facile method based on liquid chromatography coupled with electrospray ionization tandem triple quadrupole mass spectrometry working in selected reaction monitoring mode has been established to analyze toxins in the algae and water samples. Twelve types of toxins (anatoxin, cylindrospermopsin, dinophysistoxin-1, nodularin, okadaic acid, microcystins) were efficiently separated under optimized liquid chromatography coupled with mass spectrometry conditions in the selected reaction monitoring mode. Correlation coefficients of the calibration curves, all felt in the range of 0.9958-0.9998, indicated good linearity. The detection limits of toxins in this method were all lower than 0.20 ng/mL and the quantification limits were in the range from 0.04 to 0.60 ng/mL. Except for anatoxin, cylindrospermopsin, and nodularin, the other toxins' recoveries varied from 55.45 to 140.85%. And the relative standard deviations of interday and intraday precision were at 8.61% (n = 5). The high-performance liquid chromatography (HPLC)/electrospray ionization (ESI)-mass spectrometery (MS) method was also successfully applied to analyze the algae and water samples. Owing to its exclusive selectivity and excellent sensitivity, the developed method is a tool for comprehensive analyses of the 12 types of toxins at nanogram levels.     

液相色谱-电喷雾串联质谱法测定生姜中的215种农药残留

建立了生姜中215种农药多残留测定的液相色谱-电喷雾串联质谱(LC-ESI-MS/MS)方法。样品用1%醋酸-乙腈溶液均质提取,经Sep-Pak Vac固相萃取柱净化,乙腈-甲苯(3:1, v/v)洗脱,旋转蒸发浓缩至约0.5 mL后,于室温氮气吹干,用乙腈-水(3:2, v/v)溶解,以电喷雾电离串联质谱在正离子多反应监测(MRM)模式下进行测定。在定量限水平进行添加回收率实验,方法的回收率范围为68.1%～132.6%,其中回收率在70%～120%的占94.4%,相对标准偏差(RSD)范围为0.4%～25.0%。方法的检出限(S/N=3)和定量限(S/N=10)范围分别为0.01～70.45 μg/L和0.04～234.84 μg/L。该方法操作简便,灵敏度、准确度和精密度均符合农药多残留检测技术要求,适用于生姜中215种农药多残留的快速测定。     

Stereoselective separation and determination of triadimefon and triadimenol in wheat, straw, and soil by liquid chromatography-tandem mass spectrometry

A sensitive and rapid analytical method was developed for simultaneous determination of triadimefon (TF) and triadimenol (TN) stereoisomers in wheat, straw, and soil by liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS). The direct enantioseparation of TF and TN was performed on a Lux cellulose-1 column packed with cellulose-tris-(3,5-dimethylphenylcarbamate). The effects of mobile-phase composition on the separation were investigated and stereoisomeric elution orders were confirmed with a polarimeter detector. The pesticides were extracted from samples with acetonitrile and cleaned up by solid-phase extraction or activated carbon. Based on the developed stereoselective LC-MS/MS method, for TF and TN stereoisomers, good linearities were obtained over the concentration range of 0.003-4 mg/L; recoveries were 84.2-102.7% in wheat, 84.0-104.0% in straw, and 85.2-106.8% in soil at spiked concentrations of 0.007-2.0 mg/kg; intra-day and inter-day assay precisions were below 12.2%. Limits of detection (LODs) and limits of quantification (LOQs) in wheat, straw, and soil were 0.001-0.005 mg/kg and 0.007-0.02 mg/kg, respectively. Finally, the method was successfully applied to detect TF and TN stereoisomers in wheat, straw, and soil samples from residual trials in farm.     

High-throughput bioanalysis with simultaneous acquisition of metabolic route data using ultra performance liquid chromatography coupled with time-of-flight mass spectrometry

The capability of ultra performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC/TOFMS) in the high-throughput quantitative analysis of a drug candidate in plasma has been investigated. Data obtained were compared with results from conventional analysis by high-performance liquid chromatography with tandem mass spectrometric detection on a triple quadrupole instrument (HPLC/MS/MS). The accuracies and precisions of the two approaches were comparable. The UPLC/TOFMS system displayed excellent robustness over the course of 276 injections of protein-precipitated plasma samples. With the instrumentation used, the limits of detection and quantification were approximately five-fold higher with UPLC/TOFMS than for HPLC/MS/MS. Nevertheless, the UPLC/TOFMS system proved adequate to quantify plasma concentrations of a drug molecule administered orally to rats at a pharmacologically relevant dose of 4 mg/kg. As well as providing quantitative data on the test compound, it was also possible to extract data for eight different metabolites, including several isomeric species (three +O and three +2O) from the UPLC/TOFMS data sets, using an analytical method with a 2.5-minute run time. Selectivity for the test compound and its metabolites was derived from the accurate mass capabilities of the TOF instrument, and no MS method development was required.     

Determination of beta-agonist residues in bovine urine using liquid chromatography-tandem mass spectrometry

A multiresidue method was developed and validated to screen bovine urine samples for 10 beta-2-adrenergic agonistic drugs--brombuterol, cimaterol, clenbuterol, clenpenterol, isoxsuprine, mabuterol, ractopamine, ritodrine, salbutamol, and tulobuterol--at the 2 microg/L level. The method is also quantitative in the range of 1 to 4 microg/L for all analytes except salbutamol. The procedure uses enzymatic digestion, liquid-liquid extraction, and cleanup on solid-phase extraction columns, followed by detection using a liquid chromatograph-tandem quadrupole mass spectrometer operated in the positive-ion atmospheric pressure chemical ionization multiple-reaction monitoring mode. Method validation included assessment of recoveries, repeatabilities, linearity of responses, decision limits, and detection capabilities. Overall average recoveries ranged from 70-91%; recoveries were generally lower for salbutamol. The decision limits ranged from 0.4-1.0 microg/L, and detection capabilities from 0.6-1.7 microg/L.     

Determination of 48 pesticides and their main metabolites in water samples by employing sonication and liquid chromatography-tandem mass spectrometry

In this work, a rapid and sensitive analytical multiresidue method has been developed for the simultaneous determination of 48 pesticides and 19 metabolites in waters (tap, leaching and sewage), using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with triple quadrupole in selected reaction monitoring (SRM) mode. The procedure involves initial single phase extraction of samples with acetonitrile by sonication, followed by liquid-liquid partition aided by “salting out” process using NaCl. Matrix influence on recoveries was evaluated for the three waters. More than 50% of the compound presented very low signal suppression. The method presents good linearity over the range assayed 10-500 μg L⁻¹ and the most frequent detection limits was 0.05 ng mL⁻¹. The average recovery by the LC-MS/MS method obtained for these compounds varied from 74.6 to 111.2% with a relative standard deviation between 2.5 and 8.9%. The proposed method was used to determine pesticides levels in leaching water samples from 5 lysimeters from an experimental greenhouse located in Murcia.     

Application of gas chromatography-triple quadrupole mass spectrometry in the quantification-confirmation of pesticides and polychlorinated biphenyls in eggs at trace levels

A new multiresidue method has been developed and validated for the simultaneous analysis of 57 compounds, including organochlorine and organophosphorus pesticide residues (OCPs and OPPs) and polychlorinated biphenyls (PCBs), in eggs at trace levels by gas chromatography coupled to triple quadrupole mass spectrometry (GC-QqQ-MS/MS). Egg samples were extracted by a simple and fast matrix solid phase dispersion (MSPD) procedure using C18 as sorbent, and ethyl acetate and acetonitrile saturated in n-hexane (85:15, v/v) as elution solvent with a simultaneous clean up with Florisil in-line. The QqQ analyzer acquired data in selected reaction monitoring (SRM) mode, permitting both quantification and confirmation in a single injection with a running time reduced up to 17.70 min. Recovery was in the range of 70-110% and 70-106% at 15 and 50 microg/kg, respectively. Precision values expressed as relative standard deviation (RSD) were lower than 20%. Linearity in the range of 10-150 microg/kg provided determination coefficients (R(2)) higher than 0.98 for all compounds. Limits of detection (LODs) for pesticides were < or =2.25 microg/kg and limits of quantification (LOQs) ranged from 0.02 to 7.78 microg/kg. LODs for PCBs were < or =0.41 microg/kg and LOQ were < or =0.71 microg/kg. The method was applied to real samples. Endosulfan sulphate and p,p'-DDE were found in two samples at concentrations below the first calibration level.     

高效液相色谱串联质谱法检测腰果中黄曲霉毒素

建立了腰果中4种黄曲霉毒素的高效液相色谱-串联质谱检测方法(HPLC-MS/MS)。样品用甲醇-水(8:2, v/v)溶液提取后用弗罗里硅土柱净化,5 mL丙酮-水-甲酸溶液(96:3.5:0.5, v/v/v)洗脱,氮吹至干,1 mL甲醇定容;在资生堂MG C18色谱柱(100 mm×3.0 mm, 3 μm)上梯度洗脱分离,然后采用电喷雾离子化三重四极杆串联质谱测定。实验结果表明,4种黄曲霉毒素在各自的线性范围内峰面积与其质量浓度线性关系良好,相关系数(r2)大于0.997;检出限(信噪比为3)为0.009～0.04 μg/kg,定量限(信噪比为10)为0.03～0.12 μg/kg;平均回收率为63.0%～78.5%,相对标准偏差为2.8%～9.1%,均符合痕量分析的要求。评价了基质效应,信号抑制/增强值为88.8%～99.4%,说明净化后的基质效应较小。该方法简单快速、准确可靠,可用于腰果中黄曲霉毒素的检测。     

Comparison of triple quadrupole mass spectrometry and Orbitrap high‐resolution mass spectrometry in ultrahigh performance liquid chromatography for the determination of veterinary drugs in sewage: benefits and drawbacks

This paper presents a comparison of triple quadrupole tandem mass spectrometry (MS/MS) and Orbitrap high‐resolution mass spectrometry (HRMS) combined to ultrahigh performance liquid chromatography for the determination of glucocorticoids and polyether ionophores in sewage, in order to show the major benefits and drawbacks for each mass spectrometry analyser. Overall, HRMS measurements have enhanced performance in terms of confirmatory capabilities than MS/MS measurements. Moreover, similar limits of quantification, limits of detection, linear range and repeatability for glucocorticoids with both the MS/MS and HRMS methods were compared, but in the case of polyether ionophores, slightly better limits of detection and limits of quantification were obtained with the HRMS method because of the high sensitivity obtained when diagnostic ions are used for quantification instead of selected reaction monitoring transitions for these compounds. The two methods have been applied to the analysis of several influent and effluent sewage samples from sewage treatment plants located in the Tarragona region (Catalonia, Spain), showing an excellent correlation between the two methods. Copyright © 2014 John Wiley & Sons, Ltd.     

Multiresidue determination of quinolone and fluoroquinolone antibiotics in fish and shrimp by liquid chromatography/tandem mass spectrometry

A multiresidue method was developed to measure low levels of 8 fluoroquinolones (norfloxacin, ofloxacin, danofloxacin, ciprofloxacin, desethylene ciprofloxacin, enrofloxacin, sarafloxacin, and difloxacin) and 4 quinolones (oxolinic acid, flumequine, nalidixic acid, and piromidic acid). Method detection limits range from 0.1 ng/g for quinolones to 0.4 ng/g for fluoroquinolones. Average recoveries range from 57 to 96%, depending on analyte and commodity; relative standard deviations are all less than 18%. The drugs are extracted from tissues using a mixture of ethanol and 1% acetic acid, diluted in aqueous HCI, and defatted by extraction with hexane. The compounds are further isolated using cation-exchange solid-phase extraction and measured using liquid chromatography with electrospray tandem mass spectrometry detection. The method has been evaluated and applied to the analysis of salmon, trout, and shrimp. Detectable residues were observed in 10 out of 73 samples, at concentrations ranging from 0.28 to 16 ng/g.     

Multiresidue analysis of quinolones in water by ultra‐high perfomance liquid chromatography with tandem mass spectrometry using a simple and effective sample treatment

A rapid and simple analytical method has been developed for the determination of 19 quinolones in environmental water samples using ultra high performance liquid chromatography with tandem mass spectrometry. Chromatographic and detection conditions have been optimized and the separation was achieved in less than 4 min. The separation was carried out using a new‐generation column filled with superficially porous particles, resulting in lower backpressure and better resolution than totally porous particle columns. The quinolones were detected by electrospray ionization in positive mode using multiple‐reaction monitoring mode for acquisition. A sample treatment based on liquid–liquid extraction and phase separation via salting‐out was employed to achieve a fast and simple extraction that enables the multiresidue analysis. The method has been validated for an environmental well water sample from a mountain area. Very low limits of detection (between 10 and 90 ng/L) with relative standard deviations lower than 16.5% and recoveries higher than 73% were achieved. Moreover, well waters from different origins (mountain and coast areas and irrigated land) have been evaluated and similar results were obtained.     

Ultra-performance liquid chromatography coupled to time-of-flight mass spectrometry for robust, high-throughput quantitative analysis of an automated metabolic stability assay, with simultaneous determination of metabolic data

The application of ultra-performance liquid chromatography coupled to time-of-flight mass spectrometry (UPLC/TOFMS) for high-throughput analysis of a 96-well plate based metabolic stability assay has been investigated. Full-scan data were acquired, with run times of 2.5-3.5 min, from which narrow window extracted ion chromatograms were generated, producing quantitative data for the test compound equivalent to that obtained by high-performance liquid chromatography with tandem mass spectrometric detection on a triple quadrupole instrument (HPLC/MS/MS). Sensitivity and mass accuracy were maintained over the analysis of >300 samples. Additionally, the UPLC/TOFMS datasets obtained gave access to metabolic route information, at no cost in terms of sensitivity for the test compound.     

固相萃取-三重串联四极杆气相色谱/质谱联用分析蔬菜中43种农药残留留

建立了气相色谱/三重四极杆串联质谱同时分析蔬菜中43种农药残留的方法。采用乙腈提取样品中待测组分,经固相萃取法(SPE)净化后采用气相色谱/三重四极杆串联质谱在多反应监测(MRM)模式下进行外标法定量测定。分别对青菜进行3个水平(10、80、200 μg/kg)的加标回收试验,其回收率为62.2%～170.0%,其中36种农药的回收率为70.0%～120.0%。方法的相对标准偏差(RSD)小于18%,定量限(LOQ)为0.3～4.4 μg/kg。该分析方法背景干扰低,灵敏度高,适合蔬菜中多种农药及杀虫剂残留的测定。