Multiresidue determination of fluoroquinolones in eggs

A multiresidue method was developed for the determination of fluoroquinolones in eggs. Extraction of eggs with ammoniacal acetonitrile was followed by liquid-liquid defatting, solvent evaporation, and redissolution in a small volume of buffer. The fluoroquinolones were further purified by on-line microdialysis, concentrated on a trace enrichment column, and separated by reversed-phase liquid chromatography with fluorescence detection. Norfloxacin (NOR), ciprofloxacin (CIP), and sarafloxacin (SAR) were extracted from fortified eggs over a range of 2-200 microg/kg, with recoveries of 65.7-78.9%, 65.6-77.1%, and 67.6-110%, respectively. Enrofloxacin (ENRO) was extracted over a range of 1-100 microg/kg, with recoveries of 71.5-86.7%, whereas desethylene ciprofloxacin (DCIP) and danofloxacin (DANO) were extracted over a range of 0.2-20 microg/kg, with recoveries of 68.7-90.7% and 76.0-93.8%, respectively. The limits of quantitation for the 6 fluoroquinolones were as follows: DCIP and DANO, 0.3 microg/kg; ENRO, 1 microg/kg; NOR and CIP, 2 microg/kg; and SAR, 3 microg/kg. Both SAR and ENRO incurred eggs were also successfully analyzed using this method.     

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 determination of fluoroquinolones in milk by column liquid chromatography with fluorescence and ultraviolet absorbance detection

Column liquid chromatography with fluorescence (FLD) and UV-diode array detection (UV-DAD) was used for the simultaneous determination of ciprofloxacin (CIPRO), enrofloxacin (ENRO), marbofloxacin (MARBO), danofloxacin (DANO) and sarafloxacin (SARA) residues in milk, using norfloxacin (NOR) as internal standard. Two solid-phase extraction (SPE) cartridges, were evaluated for sample clean-up and preconcentration, Strata X, based on a modified styrene-divinylbenzene polymer, and Strata Screen A, a mixed anion exchanger/C8 reversed-phase sorbent. The fluoroquinolones (FQs) were separated on a polar endcapped column (AQUA C18). The recoveries for raw milk spiked with the antibiotics at three concentrations close to the maximum residue limit (MRL), were 80-103% for ENRO, CIPRO and DANO, with relative standard deviations (R.S.D.) lower than 6.6%. SARA recoveries were 70% (R.S.D. = 7%) and values in the order of 95% (R.S.D. = 1.5%) were obtained for MARBO at the MRL level. The quantification limits ranged from 2.4 to l0 ng ml(-1) and are below the MRL established for these drugs by the European Union. The method was successfully applied to the analysis of ENRO and its metabolite CIPRO in an incurred milk sample.     

Multiresidue determination of 77 pesticides in textiles by gas chromatography-mass spectrometry

A simple and efficient method for multiple determination of 77 pesticides, including one organonitrogen, eight carbamate, 12 pyrethroid, 26 organochloride, 30 organophosphorous compounds, in textiles is developed. Six representative textiles are chosen as test samples. Extraction using hexane-ethyl acetate (1:1) assisted by ultrasonic processor is carried out twice, followed by clean-up using solid-phase extraction on a florisil column. The final solution is analyzed using gas chromatography-mass spectrometry, and 77 pesticides are determined. This method is highly sensitive, selective, and reproducible, with a broad linear range and reliable accuracy. Six blank samples are spiked with 0.50 and 2.00 mg/kg of the 77 pesticides, and the corresponding recoveries are between 64.5% and 99.1%; the precisions range from 4.04% to 14.78%; and the minimum detection limits of this method are 0.02-0.20 mg/kg.     

Concurrent determination of four fluoroquinolones in catfish,shrimp, and salmon by liquid chromatography with fluorescence detection

A liquid chromatographic (LC) method with fluorescence detection was developed for concurrent determination of 4 fluoroquinolones: ciprofloxacin (CIPRO), enrofloxacin (ENRO), sarafloxacin (SARA), and difloxacin (DIFLX) in catfish, shrimp, and salmon. The procedure consists of extraction from fish tissue with acidified ethanol, isolation and retention on a cation exchange solid-phase extraction column, elution with basic methanol, and LC analysis with fluorescence detection. LC is performed by isocratic elution with acetonitrile-2% acetic acid (16 + 84) mobile phase, and a PLRP-S polymer column with fluorescence detection, excitation 278 nm and emission 450 nm. A target level of 20 ppb for each of the 4 fluoroquinolones has been established for this method. Fortified and incurred fish sample results are based on a 5-point standard curve calculation (10-160 ppb). Overall percent recoveries (% relative standard deviation) from fortified catfish were 78 (10), 80 (11), 70 (9.4), and 78 (10); from fortified shrimp, 69 (5.9), 85 (4.9), 79 (5.9), and 90 (4.5); and from fortified salmon, 56 (15), 93 (5.6), 61 (11), and 87 (5.0) for CIPRO, ENRO, SARA, and DIFLX, respectively. Data from the analysis of fluoroquinolone-incurred catfish, shrimp, and salmon are presented.     

气相色谱-质谱法分析蜂蜜中多种有机氯农药残留

建立了气相色谱-电子轰击离子化-质谱法（GC-EI-MS）同时分析蜂蜜试样中12种有机氯农药残留的分析方法.蜂蜜试样用V（正己烷）：V（乙酸乙酯）=5：1混合提取剂超声提取和Florisil硅藻土层析柱净化后,以PCB 103为内标物,采用GC-EI-MS的选择离子监测方式（SIM）分析,同时探讨了一些有机氯农药EI-MS特征离子的结构与断裂机理.当空白试样的加标浓度为10、50、200μg/kg时,加标回收率为80%～112%,相对标准偏差为0.4%～9.8%,方法检出限为0.2～4.0μg/kg,其中8种农药的MDL＜1.0μg/kg,线性范围为10～500μg/kg,相关系数皆大于0.996,此方法已用于蜂蜜试样中多种痕量有机氯农药残留的分析.     

Multiresidue determination of sulfonamides in a variety of biological matrices by supported liquid membrane with high pressure liquid chromatography-electrospray mass spectrometry detection

A high performance liquid chromatography (HPLC) coupled to a mass spectrometer (MS) was used for a simultaneous determination of 16 sulfonamide compounds spiked in water, urine, milk, and bovine liver and kidney tissues. Supported liquid membrane (SLM) made up of 5% tri-n-octylphosphine oxide (TOPO) dissolved in hexyl amine was used as a sample clean-up and/or enrichment technique. The sulfonamides mixture was made up of 5-sulfaminouracil, sulfaguanidine, sulfamethoxazole, sulfamerazine, sulfamethizole, sulfamethazine (sulfadimidine), sulfacetamide, sulfapyridine, sulfabenzamide, sulfamethoxypyridazine, sulfamonomethoxine, sulfadimethoxine sulfasalazine, sulfaquinoxaline, sulfadiazine, and sulfathiazole. Some of these compounds, such as, sulfaquinoxaline, sulfadiazine, sulfabenzamide, sulfathiazole and sulfapyridine failed to be trapped efficiently by the same liquid membrane (5% TOPO in hexylamine). The detection limits (DL) obtained were 1.8 ppb for sulfaguanidine and sulfamerazine and between 3.3 and 10 ppb in bovine liver and kidney tissues for the other sulfonamides that were successfully enriched with SLM; 2.1 ppb for sulfaguanidine and sulfamerazine and between 7.5 and 15 ppb in cow’s urine, whereas the DL values in milk were 12.4 ppb for sulfaguanidine and sulfamerazine and between 16.8 and 24.3 for the other compounds that were successfully enriched by the membrane. Several factors affecting the extraction efficiency during SLM enrichment, such as donor pH, acceptor pH, enrichment time and the membrane solvent were studied.     

高效液相色谱-电喷雾串联质谱法同时测定鸡肉中残留的磺胺类和氟喹诺酮类兽药

建立了一种同时测定鸡肉中两类共10种兽药(3种磺胺和7种氟喹诺酮类药物)残留量的高效液相色谱-电喷雾串联质谱方法(HPLC -ESI-MS2)。样品经2%醋酸-乙腈提取,正己烷脱脂,过ENVI-18固相萃取柱净化,经氮气吹干后,残余物用流动相定容到1 mL。以乙腈和 0.05%甲酸溶液作为流动相,采用梯度洗脱程序进行液相色谱分离,用质谱检测器进行定性和定量分析,并对10种药物的二级质谱碎裂方 式进行分析。10种药物在0.02～2.0 mg/L范围内线性良好,相关系数均大于0.9988。检出限(LOD)为1.10～6.85 μg/kg,定量限(LOQ) 为3.68～22.85 μg/kg,样品的平均加标回收率为68.9%～102.6%,相对标准偏差均小于8.6%(n=3)。实验结果表明,该方法灵敏度高,重 现性好,确证能力强,分析时间短,可满足动物源性食品中磺胺和氟喹诺酮类药物的残留分析。     

Simultaneous determination of fluoroquinolones,sulfonamides and tetracyclines in sewage sludge by pressurized liquid extraction and liquid chromatography electrospray ionization-mass spectrometry

A new scheme for the quantitative determination of traces of fluoroquinolones (FQs), tetracyclines (TCs) and sulfonamides (SAs) in sewage sludge was developed. The compounds were simultaneously extracted from sewage sludge by pressurized liquid extraction (PLE). A novel and effective method for PLE was developed. Solid-phase extraction was used for cleaning up the extracts. Identification and quantification of the compounds was done using high-performance liquid chromatography with electrospray ionization mass spectrometry in selected reaction monitoring mode. The best recovery of FQs and TCs was obtained by using hydrophilic–lipophilic balance cartridges, recoveries ranged 59% for norfloxacin to 82% for ofloxacin and 95% for doxycycline; for SAs strong cation-exchange cartridges were more efficient, recoveries were 96% for sulfamethoxazole and 43% for sulfadimethoxine. Limit of quantification ranged from 0.1 ng/g for SAs to 160 ng/g for tetracycline. Method precision for TCs was 5.06% and 1.12%, and for SAs 0.43% and 2.01%. FQs precision ranged from 0.77% to 1.89%.     

Comparison between a bioassay and liquid chromatography-fluorescence-mass spectrometry(n) for the determination of incurred enrofloxacin in whole eggs

The objective of this study was to compare a bioassay with a liquid chromatography-fluorescence-mass spectrometry(n) method for detection of enrofloxacin (ENRO) in incurred eggs. The bioassay developed by our laboratories involves an agar diffusion microbiological method using Klebsiella pneumoniae as an indicator organism. Results demonstrate that both methods are capable of detecting incurred fluoroquinolone residues in eggs. During the 3-day dosing period of hens (Days 1-3) and following drug withdrawal (Days 5, 7, and 9), both of these methods were able to detect incurred ENRO in eggs above the zero tolerance established by the U.S. Food and Drug Administration. The LC-fluorescence-MS(n) method has the benefit of providing confirmation for fluoroquinolones, while the bioassay may be used as an effective, rapid screening method for detection of fluoroquinolone residues in eggs.     

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.     

Multiresidue determination of pesticides in juice by solid-phase extraction and gas chromatography-mass spectrometry

A multiresidue method based on solid-phase extraction was developed for the simultaneous determination of 50 pesticides in commercial juices. The extraction procedure was carried out in C₁₈ columns preconditioned with acetonitrile and water. The subsequent elution of pesticides was performed with a mixture of hexane-ethyl acetate (1:1, v/v) prior to the determination by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM), using one target and two qualifier ions. Standards were prepared spiking blank juice samples to counteract the observed matrix effect. Average recoveries for all the pesticides studied were higher than 91% with relative standard deviations lower than 9% in the concentration range of 0.02-0.1 μg/mL and the detection limits achieved ranged from 0.1 to 4.6 μg/L. The proposed method was applied to the analysis of these compounds in commercial juices and diazinon, ethion and procymidone were the pesticides encountered, although the levels found were very low.     

Multiresidue method for fast determination of pesticides in fruit juices by ultra performance liquid chromatography coupled to tandem mass spectrometry

A new analytical method for the simultaneous determination of 90 pesticides in fruit juices by ultra performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) has been developed and validated. Extraction was performed with acetonitrile, applying QuEChERS methodology, and the extracts were analyzed without any further clean-up step, providing better results than solid phase extraction (SPE) procedure. Before chromatographic step, extracts were diluted with water (1:1) in order to obtain good peak shapes. Several chromatographic conditions were evaluated in order to achieve a fast separation in Multiple Reaction Monitoring (MRM) mode, obtaining a run time of only 11 min. Matrix effect was studied for different types of fruit juices (peach, orange, pineapple, apple and multifruit), indicating that multifruit juice can be selected as representative matrix for routine analysis of these food commodities. Pesticides were quantified using matrix-matched calibration with recoveries between 70.4 and 108.5% and relative standard deviation lower than 20%. Limits of quantification were lower than 5 microg L(-1) in all the cases. The developed procedure was applied to commercial fruit juices, detecting carbendazim, cyprodinil and thiabendazol in a few samples.     

Multiresidue analysis of avermectins in cattle liver by liquid chromatography/tandem mass spectrometry

A simple multiresidue analysis method was developed for the confirmation and quantification of eprinomectin, abamectin, doramectin, and ivermectin in cattle liver. The target analytes were extracted with acetonitrile and cleaned up with C18 and C8 solid-phase extraction cartridges before analysis by liquid chromatography combined with positive ion electrospray tandem mass spectrometry. The residue mean recoveries of the 4 drugs were 64.16-99.53%. The limit of detection was 2.5 ng/g for eprinomectin, abamectin, doramectin, and ivermectin.     

Multiresidue determination of eleven quinolones in milk by liquid chromatography with fluorescence detection

A liquid chromatographic method with fluorescence detection was developed for simultaneous determination of norfloxacin, ofloxacin, ciprofloxacin, pefloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, and flumequine in milk The samples were extracted with 10% trichloroacetic acid/acetonitrile (9 + 1, v/v) and cleaned by Strata-X reversed-phase solid-phase extraction cartridges. The 11 quinolones were separated on a reversed-phase C18 column (Hypersil BDS-C18) with mobile phase gradient elution and detected with fluorescence by means of a wavelength program. The recoveries for milk fortified with the 11 quinolones at 3 levels were 69-88% with acceptable relative standard deviations of <9% (intraday) and <14% (interday). The limits of detection were 23 microg/L for enrofloxacin, and 1-9 microg/L for the other 10 quinolones.     

高效液相色谱法检测六种氟喹诺酮类兽药残留前处理的优化

建立了一个检测动物源性食品中6种氟喹诺酮类药物残留的高效液相色谱方法。不同基质的样品前处理对检测影响较大:鱼、肉及肝脏等样品需经过乙腈-0.1 mol/L KH2PO4缓冲液提取,乙腈饱和的正己烷洗涤去除油脂;蛋及乳制品样品用正己烷饱和的乙腈提取,乙腈饱和的正己烷去脂。目标化合物采用高效液相色谱-荧光检测器检测,外标法定量。对市售鸡肉、猪肉、鸡蛋进行检测,添加10、20、50、100μg/kg浓度水平时,回收率在82%~105%之间,相对标准偏差在4%~12%之间,方法的检出限诺氟沙星、环丙沙星、沙拉沙星及单诺沙星为5.0μg/Kg,恩诺沙星、达氟沙星为3.0μg/Kg。     

Evaluation of serum as a potential matrix for multiresidue determination of fluoroquinolone antibiotics in chicken using liquid chromatography-fluorescence-mass spectrometry(n)

An efficient multiresidue method was successfully applied to the determination of fluoroquinolones (FQs) in chicken serum. In this method, FQs are extracted from matrix with ammoniacal acetonitrile, and the extracts are defatted and then evaporated. After addition of basic phosphate buffer and filtration, the samples are analyzed by liquid chromatography-fluorescence-mass spectrometry(n) (multiple mass spectrometry; MS(n)). This approach allows for simultaneous quantitation (fluorescence) and confirmation (MS(n)) of the FQs. Using this method, 8 FQs were determined in fortified chicken serum at levels of 10, 20, 50, and 100 ng/g. Recoveries ranged from 71-99%, with excellent relative standard deviations (< 10%). Limits of quantitation for the FQs ranged from 0.05-5 ng/g. Confirmation was achieved by comparison of MS2 or MS3 product ion ratios with those of standard FQ samples. These quantitative and confirmatory results were compared with those obtained for muscle using this approach. Serum and muscle samples from enrofloxacin-dosed chickens were also analyzed with this method. The results show that enrofloxacin can be determined in both serum and muscle of chickens dosed at a level formerly approved by the U.S. Food and Drug Administration, for up to at least 48 h after withdrawal from dosing, and suggest that serum can provide an efficient matrix for monitoring FQ levels in chicken.     

反相离子对液相色谱法同时测定11种氟喹诺酮类药物的研究

建立了高效液相色谱-荧光法同时测定11种氟喹诺酮类药物的分析方法.主要研究了流动相、流动相配比及流动相的pH对氟喹诺酮分离的影响.确定了液相色谱分析最佳条件.分离条件为:Xbridge Shield RP C18柱,以V(0.10%三氟乙酸)∶V(乙腈)∶V(甲醇)=89∶4∶7为流动相;检测波长为λex=280 nm和λem＝450 nm.方法检出限为:诺氟沙星、环丙沙星、培氟沙星和恩诺沙星0.007μg/mL,单诺沙星0.002 μg/mL,沙拉沙星和氧氟沙星为0.04 μg/mL,二氟沙星和奥比沙星为0.02 μg/mL,依诺沙星、麻保沙星为0.4 μg/mL,各组分回收率在97%～100.2%,相对标准偏差为0.2%～2.9%.     

Multiresidue determination of UV filters in water samples by solid‐phase extraction and liquid chromatography with tandem mass spectrometry analysis

UV filters, contained in sunscreens and other cosmetic products, as well as in some plastics and industrial products, are nowadays considered contaminants of emerging concern because their widespread and increasing use has lead to their presence in the environment. Furthermore, some UV filters are suspected to have endocrine disruption activity. In the present work, we developed an analytical method based on liquid chromatography with tandem mass spectrometry for the determination of UV filters in tap and lake waters. Sixteen UV filters were extracted from water samples by solid‐phase extraction employing graphitized carbon black as adsorbent material. Handling 200 mL of water sample, satisfactory recoveries were obtained for almost all the analytes. The limits of detection and quantification of the method were comparable to those reported in other works, and ranged between 0.7–3.5 and 1.9–11.8 ng/L, respectively; however in our case the number of investigated compounds was larger. The major encountered problem in method development was to identify the background contamination sources and reduce their contribution. UV filters were not detected in tap water samples, whereas the analyses conducted on samples collected from three different lakes showed that the swimming areas are most subject to UV filter contamination.     

Multiresidue determination of pesticides in fruit and vegetables by gas chromatography/tandem mass spectrometry

Pesticide residues in fruit and vegetables were determined by gas chromatography/tandem mass spectrometry (GC/MS/MS). Electron impact (EI)/MS/MS and chemical ionization (CI)/MS/MS were developed for 80 compounds, including organochlorine, organophosphorus, organonitrogen, and pyrethroids, providing unambiguous spectral confirmation for these complex matrixes. Residues were extracted from samples with acetone followed by a mixture of dichloromethane-petroleum ether. Two injections per sample were required for analysis of the entire pesticide list by EI/MS/MS and CI/MS/MS. Initial steps involving cleanup and concentration of extracts were eliminated. The excellent selectivity and good linearity allowed quantification and identification of low levels of pesticides in the most difficult matrixes. The method has been used for routine analysis of many vegetables.