Validation of a method for the analysis of quinolones residues in bovine muscle by liquid chromatography with electrospray ionisation tandem mass spectrometry detection

A liquid chromatography-tandem mass spectrometry method for the determination and confirmation of nine quinolones was optimised and validated according to Commission Decision 2002/657/EC. Analytes were extracted from veal muscle with water and extracts purified with 96-well plates Oasis HLB cartridges. Separation was carried out in a silica-based C₁₈ column (50 mm × 2.1 mm) with mobile phases consisting of water/acetonitrile mixtures containing acetic acid. Linear calibration curves in the ranges 4-400 and 50-800 ng g⁻¹, with correlation coefficients at least 0.995, were obtained for all the analytes. At concentration levels above 10 ng g⁻¹, quantification errors were lower than 10% and repeatability and within-laboratory reproducibility standard deviations below 6% and 10%, respectively. Decision limits and detection capabilities are reported.     

Quantitative analysis of polypeptide antibiotic residues in a variety of food matrices by liquid chromatography coupled to tandem mass spectrometry

A quantitative LC–MS/MS method was developed for the determination of five polypeptide antibiotics (bacitracin, colistin A, colistin B, polymyxin B1 and polymyxin B2) in a variety of food matrices (muscle, liver, kidney, egg and milk). The described method is sufficiently sensitive, selective and provides acceptable recoveries for all compounds. The extraction is based on acidified methanolic solvent. This is followed by a reversed phase solid phase extraction step to clean-up and concentrate the extracts. The use of a modern core shell column in combination with an eluent consisting of trifluoroacetic acid, formic acid and acetonitrile provides chromatographically well resolved analyte peaks The single-step clean-up is fast and produces a sufficiently clean extract in order to control matrix-related signal suppression in the electrospray interface.     

Determination of antimicrobial residues and metabolites in the aquatic environment by liquid chromatography tandem mass spectrometry

Antimicrobials are used in large quantities in human and veterinary medicine. Their environmental occurrence is of particular concern due to the potential spread and maintenance of bacterial resistance. After intake by the organisms, the unchanged drug and its metabolized forms are excreted and enter wastewater treatment plants where they are mostly incompletely eliminated, and are therefore eventually released into the aquatic environment. The reliable detection of several antimicrobials in different environmental aqueous compartments is the result of great improvements achieved in analytical chemistry. This article provides an overview of the more outstanding analytical methods based on liquid chromatography tandem mass spectrometry, developed and applied to determine antimicrobial residues and metabolites present in surface, waste, and ground waters.      

Detection of tetracycline and oxytetracycline residues in pig and calf hair by ultra-high-performance liquid chromatography tandem mass spectrometry

An ultra-high-performance liquid chromatography tandem mass spectrometry method to detect residues of tetracycline (TC), epi-tetracycline (eTC) and oxytetracycline (OTC) in animal hair was developed. Hair samples were washed with water, extracted with NH₄OH 0.1 M, purified by SPE-C₁₈ cartridge and analyzed by tandem mass spectrometry (ESI⁺, MRM mode) with satisfactory results. For the first time, accumulation of TC, eTC and OTC was confirmed in livestock hairs after a therapeutic treatment with TC and OTC, respectively. Administered drug residues were detectable in hair samples up to 2 months after the last treatment, providing a retrospective evidence of TC and OTC administration. Hair analysis seems to offer a wider window of detection than edible tissues.     

Determination of aminoglycoside residues by liquid chromatography and tandem mass spectrometry in a variety of matrices

A quantitative LC–MS/MS method was developed for the determination of 13 commonly used aminoglycoside antibiotics in meat (pork muscle, fish, and veal livers and kidneys). The proposed method is sufficiently sensitive and highly selective. Unlike other previously reported methods, it uses a simple clean-up procedure based on a strong cation-exchange solid-phase cartridge that permits high sample extract loading volumes. A unique elution regime based on a volatile buffer at intermediately high pH value in combination with an organic solvent provides quantitative elution of the various aminoglycosides. This methodology ensured that neither a breakthrough of weakly retained aminoglycosides (e.g. spectinomycin) nor the incomplete elution of strongly retained analytes (e.g. neo- and gentamycin) is observed. The single-step clean-up is fast and produces clean extracts that minimize matrix-related signal suppression in the electrospray interface.     

On-line solid-phase extraction-thermal desorption-gas chromatography with ion trap detection tandem mass spectrometry for the analysis of microcontaminants in water

An improved set-up for solid-phase extraction with thermal desorption coupled on-line to gas chromatography (SPETD-GC) is presented. It includes a newly designed liner for a programmable temperature vaporizer (PTV) and an improved water elimination system. The SPETD procedure now includes a washing step with HPLC-grade water to prevent degradation of analytes due to interaction with remaining sample constituents. The system was used to analyze surface and tap water samples over a 4-month period. No decrease of chromatographic or trace-enrichment performance was observed, and a liner packed with Tenax GR could be used for at least 150 analyses. The SPETD module was coupled to GC with ion-trap detection for mass spectrometric (MS) and MS/MS detection. The linearity and repeatability of the procedure for several pesticides which were tested in the 0.5–10 μg/1 range were fully satisfactory (1 μg/1, RSD range 5–11%; n = 5). When using sample volumes of 0.1 ml only, detection limits were as low as 0. 1-0.2 μg/1. As an example, the confirmation and quantification of a suspected pesticide in a real-life sample using electron impact and positive chemical ionization in both the MS and MS/MS mode is shown.     

Quantification of anthelmintic drug residues in milk and muscle tissues by liquid chromatography coupled to Orbitrap and liquid chromatography coupled to tandem mass spectrometry

A simple method for the determination of some anthelmintic drugs and phenylbutazone residues in milk and muscle was developed. Following a fast and easy extraction and evaporation procedure, the extract was injected into an ultra performance liquid chromatography system coupled to a single stage Orbitrap detector. The high mass resolution of 50,000 full width at half maximum and corresponding narrow mass windows permitted a very selective and sensitive detection of analytes without requiring fragmentation of the observed [M+H]⁺ or [M+Na]⁺ ions. This eliminated some difficulties which have plagued the analysis of compounds belonging to the group of avermectins. The analytical method was validated according to the EU commission decision for Orbitrap based, but also for more traditional tandem mass spectrometry based detection and quantification. Equal repeatability but significantly higher sensitivity for critical compounds (avermectins) was obtained for the Orbitrap based detection. A result of this study was the conclusion that analytes with poor fragmentation properties (e.g. sodium-cationized molecules) can be more easily quantified by single stage high resolution mass spectrometry than by tandem mass spectrometry.     

Determination of polar organic compounds in atmospheric aerosols by gas chromatography with ion trap tandem mass spectrometry

A gas chromatography with ion trap mass spectrometry method has been developed and validated for the analysis of 27 polar organic compounds in atmospheric aerosols. The target analytes were low‐molecular‐weight carboxylic acids and methoxyphenols, as relevant markers of source emissions and photochemical processes of organic aerosols. The operative parameters were optimized in order to achieve the best sensitivity and selectivity for the analysis. In comparison with the previous gas chromatography with mass spectrometry procedure based on single ion monitoring detection, the tandem mass spectrometry technique increased the analytical sensitivity by reducing detection limits for standard solutions from 1–2.6 to 0.1–0.4 ng/μL ranges (concentrations in the injected solution). In addition, it enhanced selectivity by reducing matrix interferences and chemical noise in the chromatogram. The applicability of the developed method in air quality monitoring campaigns was effectively checked by analyzing environmental samples collected in the Po Valley (Northern Italy) in different seasons. The obtained results indicate that the ion trap mass spectrometer may be an ideal alternative to high‐resolution mass spectrometers for the user‐friendly and cost‐effective determination of a wide range of molecular tracers in airborne particulate matter.     

Multiresidue pesticide analysis of fruits by ultra-performance liquid chromatography tandem mass spectrometry

Ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC–MS–MS) has been used for screening and quantification of 32 pesticides and metabolites in two fruit matrices. The compounds investigated belonged to different chemical families of insecticides, acaricides, fungicides, and herbicides; several metabolites were also included. Quantification was conducted using matrix-matched standards calibration; response was a linear function of concentration in the range tested (10–500 ng mL⁻¹). The method was validated with blank samples of lemon and raisin spiked at 0.01 and 0.1 mg kg⁻¹, and recoveries were satisfactory, between 70 and 110%, for most of the pesticides tested and relative standard deviations were below 15% (n = 5 at each spiking level). Excellent sensitivity resulted in limits of detection for all compounds well below 0.01 mg kg⁻¹, with the limit of quantification being validated at 0.01 mg kg⁻¹. The UPLC system generates narrow peaks (approx. 5 s), thus increasing peak height and improving sensitivity. This improved separation efficiency facilitates adequate resolution not only of the analytes but also of matrix interferences compared with conventional HPLC. The method developed could also resolve some geometric isomers. The main advantage of this approach is the high sample throughput achieved because of the short analysis time, which enables satisfactory separation of all the compounds in less than 5 min per sample.     

Development and validation of a multiclass method for the analysis of antibiotic residues in eggs by liquid chromatography-tandem mass spectrometry

A multiclass method for the analysis of residues, in egg matrices, of 41 antimicrobial agents belonging to seven families (sulfonamides, diaminopyridine derivates, quinolones, tetracyclines, macrolides, penicillins and lincosamides) was developed and validated according to the requirements of European Commission Decision 2002/657. Compounds were extracted with a pressurized liquid extraction (PLE) technique using a 1:1 mixture of acetonitrile and a succinic acid buffer (pH 6.0) at 70 °C. As this resulted in clear extracts, no further clean-up was necessary. Analytes were determined by ultra-high-pressure liquid chromatography–tandem mass spectrometry (UHPL–MS/MS) in a chromatographic run of 13 min. Calibration was carried out with spiked blank samples subjected to the entire analytical procedure. Five compounds, two of them isotopically labelled, were used as internal standards. Most analytes were quantified with errors below 10%. Precision in terms of reproducibility standard deviation was between 10% and 20% in most cases. CCα values were in the range 0.5–3.8 μg kg⁻¹ for the non-authorized compounds. The proposed method would enable an experienced analyst to process about 25 samples per day.     

Environmentally friendly method for the determination of acrylamide and trimethylolpropane in paper packaging materials by liquid chromatography with tandem mass spectrometry

A simple, rapid, and environmentally friendly method was developed for the determination of acrylamide and trimethylolpropane in paper packaging materials. No organic solvent was used and the matrix effect was investigated. The extract was directly analyzed by liquid chromatography with tandem mass chromatography for quantification and confirmation. The chromatographic separations were performed on a ZORBAX HILIC Plus (2.1 mm × 150 mm, 3μm; Agilent, USA) column with only one mobile phase (100% water). Calibration curves for acrylamide and trimethylopropane were achieved with concentrations ranging from 0.4 to 20 mg/kg and the corresponding r² values were 0.998 and 0.999, respectively. The recoveries were >85% with relative standard deviations <10%. The validated method was applied to the analysis of 50 real samples, and positive results were obtained for 30 samples. The result indicated that trimethylolpropane is associated with inks and printing activity and acrylamide is widely used as a papermaking additive in many paper packages. The concentrations of acrylamide and trimethylolpropane ranged from 0.41 to 7.5 and 0.50 to 8.8 mg/kg, respectively. The results of this study revealed that this method could be used accurately and precisely.     

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.     

Ultra-high performance liquid chromatography tandem mass spectrometry for comprehensive analysis of urinary acylcarnitines

We report an enabling mass spectrometric method for the analysis of lipid metabolites in order to define better the lipid metabolome in terms of chemical diversity and generate fragment ion spectra of these metabolites as a potential resource for unknown metabolite identification. This work focuses on the analysis of one important class of lipid metabolites, the acylcarnitines. Current analytical methods have only detected and identified a limited number of these metabolites. The method described herein provides the most comprehensive acylcarnitine profile in urine of healthy individuals up to date. It involves an optimized solid phase extraction technique for selective analyte extraction using cartridges containing both lipophilic and cation-exchange properties. The captured analytes are then subjected to ultra-high performance liquid chromatography (UPLC) separation, followed by tandem mass spectrometry (MS/MS) analysis using information-dependent acquisitions and selected reaction monitoring (SRM). The urine of six healthy individuals was analyzed using this method. A total of 355 acylcarnitines were detected; only 43 of them have been previously reported in the urine of healthy individuals. Detection of this large number of acylcarnitines illustrates the great diversity of the lipid metabolome as well as the usefulness of the method for profiling acylcarnitines. Furthermore, the MS/MS spectra of the 355 acylcarnitines will be uploaded to a public human metabolome database as a mass spectrometric resource for unknown metabolite identification.     

Single‐step multiresidue determination of ten multiclass veterinary drugs in pork,milk, and eggs using liquid chromatography with tandem mass spectrometry

A multiclass, multiresidue determination method is reported for the detection of ten veterinary drugs, including scopolamine, metoclopramide, acriflavine, berberine, tripelennamine, diphenhydramine, acrinol, triamcinolone, loperamide, and roxithromycin in pork, milk, and eggs. The method involves a simple extraction using 0.1% formic acid in acetonitrile, followed by defatting with n‐hexane, centrifugation, and filtration prior to liquid chromatography with tandem mass spectrometric analysis. As ion suppression and enhancement effects are reported, matrix‐matched calibrations are used for quantification, with determination coefficients ≥0.9765. For the majority of the tested analytes, the intra‐ and interday accuracy (expressed as recovery %) range from 70.6 to 94.6% and from 70.1 to 93.3%, respectively, and the precision (expressed as relative standard deviation) ranges from 0.5 to 19.8% and from 2.8 to 18.4% in all matrices. The limits of quantification range between 0.5 and 10 ng/g. The validated tandem mass spectrometry method is successfully applied to market samples; the target analytes are not detected in any of the tested samples. In terms of accuracy, no extract cleanup is deemed necessary. The developed method is feasible for the simultaneous detection of the tested analytes in pork, milk, and eggs.     

Combination of liquid chromatography/tandem mass spectrometry and gas chromatography/mass spectrometry for the detection of 21 anabolic steroid residues in bovine urine

For the detection of anabolic steroid residues in bovine urine, a highly sensitive liquid chromatographic/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method was developed using both positive and negative ionization. For four compounds the ESI mode was not sensitive enough and gas chromatographic/mass spectrometric GC/MS detection was therefore still necessary as a complementary method. The sample clean-up consisted of solid-phase extraction (SPE) on a C(18) column followed by enzymatic hydrolysis and a second solid-phase extraction on a combination of a C(18) and a NH(2) column. After this last SPE clean-up, the eluate was split into two equal aliquots. One aliquot was further purified and after derivatization used for GC/MS analysis. The other aliquot was analyzed with LC/MS/MS in both ESI+ and ESI- modes. The method was validated according to the European Commission Decision 2002/657/EC. Decision limits (CCalpha) were between 0.16 and 1 ng ml(-1) for the compounds detected with the LC/MS/MS method. The developed method is used in routine analysis in our laboratory.     

Comparison of extraction solvents and sorbents in the quick,easy, cheap,effective, rugged,and safe method for the determination of pesticide multiresidue in fruits by ultra high performance liquid chromatography with tandem mass spectrometry

An improved analytical method was developed for the simultaneous quantification of several plant growth regulators and fungicides (carbendazim, pyrimethanil, metalaxyl, triadimefon, paclobutrazol, thiophanate, prochloraz, dimethomorph, difenoconazole, (4‐chlorophenoxy)‐acetic acid, (2,4‐dichlorophenoxy)‐acetic acid, thiadiazuron, forchlorfenuron and gibberellins) in fruits followed by ultra high performance liquid chromatography with tandem mass spectrometry. Samples were extracted and purified using a modified QuEChERS method. Different extraction solvents and sorbents in the QuEChERS method were compared. Optimum results were followed by the addition of 1% acetic acid in acetonitrile; C₁₈ sorbent was added due to the acidic nature of several pesticides. The recoveries of the pesticides were in the range 73.7–118.4%, with relative standard deviations lower than 16.63%. Limits of detection ranged from 0.1–1.0 μg/kg. The method presented here is simple, rapid, sensitive and can be applied to large‐scale monitoring programs to screen the presences of pesticides in fruits.     

Analysis of catecholamines and their metabolites in adrenal gland by liquid chromatography tandem mass spectrometry

Two simple, rapid and specific analytical methods for 13 catecholamines and their metabolites have been developed based on liquid chromatography tandem mass spectrometry in a multiple reaction monitoring mode. Tyrosine, dopamine, dihydroxyphenylalanine, epinephrine, norepinephrine, 3-methoxytyramine, normetanephrine, metanephrine and isoproterenol (internal standard) were separated on a Kromasil™ Cyano analytical column by a mobile phase consisting of 60% (v/v) acetonitrile and 40% (v/v) water adjusted with formic acid to pH 3.0, and detected by positive ionization electrospray tandem mass spectrometry. While vanillymandelic acid, 3,4-dihydroxymandelic acid, homovanillic acid, 3,4-dihydroxyphenylacetic acid, 4-hydroxy-3-methoxyphenylglycol and 5-hydroxy-2-indolecarboxylic acid (internal standard) were separated on a reversed-phase Shim-Pak VP-ODS column with the mobile phase of 60% (v/v) acetonitrile, and 40% (v/v) water adjusted with formic acid to pH 4.5 and detected in the negative ionization electrospray tandem mass spectrometry. The influence of various parameters such as column type and mobile phase composition on separation and sensitivity were investigated. The limits of detection were in the range of 0.5-20 ng mL⁻¹. The mean recoveries determined from three different concentrations of each analyte were above 85.4%. The precision of the method calculated as relative standard deviation was lower than 5.3%. Deduced from the results of real sample analysis, adrenal gland synthesizes and stores the catecholamine hormones norepinephrine and epinephrine.     

超高效液相-串联质谱法同时测定蜂蜜中15种喹诺酮类药物残留

建立了蜂蜜样品中15种喹诺酮类兽药残留的超高效液相色谱-串联质谱检测方法。蜂蜜样品用磷酸盐缓冲溶液溶解提取后,用Oasis HLB固相萃取柱净化,超高效液相-电喷雾串联四级杆质谱检测,外标法定量。测定时用Acquity UPLC BEHC18色谱柱(50 mm×2.1 mm,1.7μm)分离,体积分数0.1%甲酸溶液-乙腈系统梯度洗脱,质谱测定采用多重反应监测(MRM)模式。15种喹诺酮类兽药的检出限均低于或等于1.0 ng/mL,回收率均在78.6%～112.9%范围内,相对标准偏差均在10%范围内。该方法各项指标均能满足国内外各项法规的要求,可用于蜂蜜样品中喹诺酮类药物残留的定量和定性检测。     

高效液相色谱串联质谱法测定牛奶中林可酰胺类和大环内酯类抗生素残留量的研究

建立了牛奶样品中洁霉素、氯洁霉素、红霉素、螺旋霉素、交沙霉素、泰乐菌素、竹桃霉素等7种林可酰胺类及大环内酯类药物残留量的确证方法。用乙腈萃取样品中7种林可酰胺类及大环内酯类抗生素,然后用正己烷脱脂,旋转蒸发仪浓缩,以Luna C18(2)色谱柱分离,在正离子模式下以电喷雾电离串联质谱仪进行测定。在20、50、200μg/kg 3个浓度水平进行验证试验,方法的线性范围为20~200μg/kg,总体平均回收率为74.5%~97.5%,相对标准偏差为2.7%~11.3%。该方法各项技术指标满足国内外法规的要求,可用于牛奶样品中林可酰胺类及大环内酯类抗生素残留量的确证检测。     

Determination of quinolone residues in shrimp using liquid chromatography with fluorescence detection and residue confirmation by mass spectrometry

The quinolones, oxolinic acid (OXO), flumequine (FLU), and nalidixic acid (NAL), are antibacterial drugs effective against Gram-negative bacteria. Quinolones are used in both human and veterinary medicine, but are currently not approved by the U.S. Food and Drug Administration for use in food fish. A liquid chromatography-fluorescence (LC-FL) method was developed to determine OXO, FLU, and NAL residues in shrimp. An additional liquid chromatography-mass spectrometry (LC-MSⁿ) method was created to confirm these residues using the same sample extract. Samples were prepared with a simple ethyl acetate extraction followed by solvent exchange into 0.2% formic acid and cleaned-up with hexane. Reverse phase chromatography was used to separate the three compounds in both procedures. For the LC-FL determinative method, fluorescence emission was monitored at 369 nm with excitation at 327 nm. With electrospray ionization, the three most abundant ions from the MS³ product ion spectrum were used to identify OXO, FLU, and NAL in the confirmation procedure. Shrimp samples fortified at levels ranging from 7.5 to 100 ng g⁻¹ were used to validate both methods.