Determination of sodium nifurstyrenate and nitrovin residues in edible food by liquid chromatography-tandem mass spectrometry after ultrasound-assisted extraction

A specific and sensitive method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the determination of nitrovin and sodium nifurstyrenate residues in muscle and liver of swine and chicken and in muscle of fish. Sample preparation procedure includes ultrasound-assisted extraction with acetonitrile, defatting with n-hexane and final clean-up with solid phase extraction (SPE) on Oasis HLB cartridges. The analytes were detected in multiple reaction monitoring (MRM) under negative scan mode acquiring two diagnostic product ions for sodium nifurstyrenate and under positive mode for nitrovin. The averaged decision limits (CCα; α 1%) ranged 0.09-0.26 μg/kg while the detection capability (CCβ; β 5%) was 0.33-0.97 μg/kg in the tissues. Reasonable recoveries (71-110%) spiked in muscle and liver showed excellent relative standard deviation (RSD). The validated method was simple, rapid, sensitive, and complied with the regulations for the determination of nitrovin and sodium nifurstyrenate residues in food matrices.     

Analysis of Pesticides in Soil Using Dispersive Solid Phase Extraction Coupled to GC-MS

A multi-residue method using dispersive solid phase extraction and gas chromatography with mass spectrometric detection has been developed for determination of trace levels of 103 pesticides, including organophosphate, organochlorine, carbamate, and pyrethroid compounds in agricultural soil. Dispersive solid phase extraction using 10 mL of acetonitrile for 3 min of extraction time showed satisfactory extraction efficiency. Recoveries of pesticides from fortified agricultural soil samples ranged from 65% to 117% for three different fortified levels of 50, 100, and 500 μg/kg and relative standard deviations of the recoveries are below 19%. Detection and quantification limits ranged from 1 to 13 μg/kg and from 3 to 38 μg/kg, respectively. The proposed method was less time-consuming, safer, and easy to use for routine analysis.     

Measurement of pyrethroid,organophosphorus, and carbamate insecticides in human plasma using isotope dilution gas chromatography–high resolution mass spectrometry

We have developed a gas chromatography–high resolution mass spectrometry method for measuring pyrethroid, organophosphorus, carbamate and fipronil pesticides and the synergist piperonyl butoxide in human plasma. Plasma samples were extracted using solid phase extraction and were then concentrated for injection and analysis using isotope dilution gas chromatography–high resolution mass spectrometry. The limits of detection ranged from 10 to 158 pg/mL with relative recoveries at concentrations near the LODs (e.g., 25 or 250 pg/mL) ranging from 87% to 156% (9 of the 16 compounds were within ±15% of 100%). The extraction recoveries ranged from 20% to 98% and the overall method relative standard deviations were typically less than 20% with some exceptions. Analytical characteristics were determined at 25, 250, and 1000 pg/mL.     

A Rapid Screening Method for the Determination of Seventy Pesticide Residues in Soil Using Microwave-Assisted Extraction Coupled to Gas Chromatography and Mass Spectrometry

A rapid screening method using microwave-assisted extraction (MAE) in combination with gas chromatography and mass spectrometry for the determination of 70 pesticide residues in soil was established. The pesticides included 27 organophosphorus pesticides (OPPs), 29 organochlorine pesticides (OCPs), nine pyrethroids, and five carbamates. Parameters that could affect the efficiency of extraction, such as temperature, time, and solvent, were investigated. The condition of the extraction, under which recoveries of all 70 pesticides ranged from 70% to 120%, was optimized with a 1:1 (V/V) mixture of acetone and hexane, a temperature of 100°C, and an extraction time of 10 min. All compounds studied could be recovered in good yields and with relative standard deviations (RSDs) lower than 20%. The linearity of the method for all the pesticides was greater than 0.99 over a concentration range of 0.1–5 μg/g. The detection limits varied from 0.5 to 211.25 ng/g. Interday and intraday precision analyses yielded RSDs of 1.2%–11.7% and 3.6%–15.1%, respectively. This method, which was as effective as Soxhlet extraction and accelerated solvent extraction (ASE), proved to be accurate and precise. When the proposed method was used to examine environmental samples, the obtained results were in good agreement with those obtained using Soxhlet extraction.     

分散固相萃取剂-液相色谱串联质谱法测定鸡肉和鸡蛋中氟苯尼考和氟苯尼考胺残留

建立分散固相萃取剂-液相色谱串联质谱法(HPLC-MS/MS)同时检测鸡肉及鸡蛋中氟苯尼考和氟苯尼考胺的方法.样品用乙腈提取,C18分散固相萃取填料净化,乙腈饱和的正己烷脱脂,电喷雾离子源正负模式切换,HPLC-MS/MS多反应监测(MRM),同位素内标法定量.氟苯尼考和氟苯尼考胺线性范围分别为0.1 ng/mL～2....     

Determination of benzimidazole residues in bovine milk by ultra-high performance liquid chromatography-tandem mass spectrometry

A method based on ultra-high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UHPLC–MS/MS) for the simultaneous determination of benzimidazole residues in bovine milk has been optimized and validated. Rapid chromatographic separation of 13 analytes in 8 min was obtained by means of UHPLC. The samples were subject to Oasis MCX solid-phase extraction cartridges for extraction and clean-up. Matrix-matched calibration curves were performed to compensate for the matrix effect and loss in sample preparation. Mean recoveries ranged from 80% to 101% and inter-day precision was lower than 14%. Limit of detection and limit of quantification of the method ranged from 0.01 to 0.5 μg L⁻¹ and from 0.1 to 1.0 μg L⁻¹, respectively.     

Determination of neonicotinoid insecticides residues in bovine tissues by pressurized solvent extraction and liquid chromatography-tandem mass spectrometry

A rapid, sensitive, and environmental-friendly method has been developed for the simultaneous determination of seven neonicotinoid insecticides residues in bovine muscle and liver. The sample preparation procedure was based on a high automated pressurized solvent extraction (PSE) combined with solid-phase extraction (SPE) clean-up. The target compounds were identified and quantitatively determined by liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) operated in multiple reaction monitoring mode. Average recoveries of the seven analytes from fortified samples ranged between 83.2% and 101.9%, with relative standard deviations (RSDs) lower than 10.8%. The limits of detection (LODs) and quantification (LOQs) for neonicotinoids were in the ranges of 0.8-1.5 μgkg?1 and 2.5-5.0 μgkg?1, respectively. This validated method was successively applied to the determination of neonicotinoid insecticides in real samples from markets.     

Simultaneous determination of five toxic alkaloids in body fluids by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry

A novel analytical method was developed and validated for the rapid and simultaneous analysis of five toxic alkaloids: Brucine, Strychnine, Ephedrine, Aconitine and Colchicine, in blood and urine using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry in the multiple reaction monitoring (HPLC-ESI-MRM) mode. The linear range was 0.05-50.0 ng mL(-1) for Brucine, 0.1-50.0 ng mL(-1) for Strychnine and Ephedrine, 0.01-10.0 ng mL(-1) for Aconitine and Colchicine. The limits of quantification for Brucine, Strychnine, Ephedrine, Aconitine and Colchicine were found to be 0.03, 0.05, 0.20, 0.05, 0.01 ng mL(-1), respectively. The average extraction recoveries in urine ranged from 96.0 to 114.0% and in whole blood were 94.0 to 113.0%. The intra-day and inter-day RSDs were less than 8.3 and 10.6%, respectively. The five alkaloids could be well separated within 7 min in a single run. The established method should be suitable for the determination of trace alkaloids in body fluids.     

Analysis of alkylphenol and bisphenol A in eggs and milk by matrix solid phase dispersion extraction and liquid chromatography with tandem mass spectrometry

A method based on matrix solid phase dispersion (MSPD) using C18 as dispersant, and a subsequent cleanup step with amino-propyl solid phase extraction cartridges and liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) has been developed for the simultaneous determination of nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA) in eggs and milk. Recovery studies were performed at different fortification levels. Average recoveries by MSPD varied from 79% of BPA to 98% of NP and relative standard deviations were equal or lower than 15% for egg samples. The average recoveries in milk ranged from 86 to 84% for BPA, 90 to 99% for NP and 82 to 103% for OP and relative standard deviations were equal to or lower than 8%. The limits of detection (LODs) in eggs were 0.10, 0.10 and 0.25 microg/kg for BPA, NP and OP, respectively and LODs for milk were 0.10, 0.05 and 0.10 microg/kg for BPA, NP and OP, respectively. Investigation of the levels in commercial samples indicated that NP was ubiquitous in milk and eggs at levels ranging from 4.24 to 17.60 microg/kg, and the milk samples were more heavily contaminated by NP than were the egg samples.     

Feasibility of an on-line restricted access material/liquid chromatography/tandem mass spectrometry method in the rapid and sensitive determination of organophosphorus triesters in human blood plasma

A rapid on-line solid phase extraction/liquid chromatography/tandem mass spectrometry (SPE/LC/MS/MS) method using restricted access material (RAM) was developed for the simultaneous determination of eight organophosphorus triesters in untreated human blood plasma. In a process involving column-switching techniques, the analytes were enriched on the RAM column, separated using a C-18 analytical column and detected with LC/MS. Tandem mass spectrometry was used to characterize and quantify the analytes. To elucidate the fragmentation pathway of a number of the analytes, MS3 experiments using an ion trap mass spectrometer were performed. The matrix effects associated with using APCI and ESI interfaces were investigated. The recoveries obtained were in the range 60-92% (R.S.D.<6%), with estimated detection limits between 0.2 and 1.8 ng/ml of plasma, and the total analysis time was 27 min.     

Quantification of a cytochrome P450 3A4 substrate, buspirone, in human plasma by liquid chromatography-tandem mass spectrometry

A sensitive HPLC-tandem mass spectrometry method was developed for determination of buspirone levels in human plasma. After solid phase extraction and reversed phase HPLC separation, detection of buspirone and the internal standard (prazosin) was performed using eletrospray ionization and selected reaction monitoring in the positive ion mode. Linear calibration curves were established over a concentration range of 0.025-2.5 ng/ml when 0.5 ml aliquots of plasma were used. Satisfactory results of within-day precision (RSD of 1.9-7.7%) and accuracy (% difference of 0.5-6.6%) and between-day precision (RSD of 3.7-11.1%) and accuracy (% difference of 2.2-6.8%) were obtained. The assay has been successfully applied to the analysis of buspirone levels in more than 500 human plasma samples collected from a drug interaction study.     

Unequivocal Enantiomeric Identification and Analysis of 10 Chiral Pesticides in Fruit and Vegetables by QuEChERS Method Combined With Liquid Chromatography‐Quadruple/Linear Ion Trap Mass Spectrometry Determination

In this research, 10 chiral pesticides in fruits and vegetables were simultaneously determined using chiral liquid chromatography triple quadrupole‐linear ion trap hybrid mass spectrometry (LC‐QqLIT). The QuEChERS method was applied for sample preparation, and an enhanced product ion (EPI) scan was used to acquire tandem mass spectrometry (MS/MS) spectra for the library search. Parameters including limit of detection (LOD), limit of quantification (LOQ), linearity, relative standard deviation (RSD), and matrix effects were evaluated in five representative matrices (strawberry, leek, cowpea, tomato, and eggplant). Good linearity with coefficient of determination (r²) ≥0.997 was obtained for all 20 enantiomers in these five matrices over the range from 1.0 to 250 µg L^‐1. All the recoveries at 5 and 50 µg kg^‐1 (n = 5) ranged between 70% and 120% with RSD below 20%, indicating satisfactory precision. The LOQ for the enantiomers ranged between 0.05 and 1 µg kg^‐1. Based on the proposed method, 135 commonly consumed fruits and vegetables taken from markets in Guizhou province, China, were analyzed. Enantioselective degradation for the selected chiral pesticides was observed in most of the positive samples. Chirality 27:958–964, 2015. © 2015 Wiley Periodicals, Inc.     

Human biomonitoring of pyrethrum and pyrethroid insecticides used indoors: determination of the metabolites E-cis/trans-chrysanthemumdicarboxylic acid in human urine by gas chromatography-mass spectrometry with negative chemical ionization

This work describes a gas chromatographic-mass spectrometric method employing negative chemical ionization (NCI) for the determination of E-cis/trans-chrysanthemumdicarboxylic acid (CDCA) in human urine used as a biomarker for the exposure to pyrethrum and/or certain pyrethroids in insecticide formulations applied indoors. Mixed-mode solid phase extraction was utilized for sample cleanup. Extraction recoveries ranged from 92 to 104% (2-9% R.S.D.). The acids were esterified with 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) allowing both their gas chromatographic separation and their sensitive mass spectrometric detection under NCI conditions. Detection limits of ca. 0.05 microg/l urine were achieved.     

Simultaneous determination of 6 beta-blockers, 3 calcium-channel antagonists, 4 angiotensin-II antagonists and 1 antiarrhythmic drug in post-mortem whole blood by automated solid phase extraction and liquid chromatography mass spectrometry. Method development and robustness testing by experimental design

A method for the simultaneous determination of the beta-blockers atenolol, sotalol, metoprolol, bisoprolol, propranolol and carvedilol, the calcium-channel antagonists diltiazem, amlodipine and verapamil, the angiotensin-II antagonists losartan, irbesartan, valsartan and telmisartan, and the antiarrhythmic drug flecainide, in whole blood samples from forensic autopsies was developed. Sample clean-up was achieved by precipitation and solid phase extraction (SPE) with a mixed-mode column. Quantification was performed by reversed phase high performance liquid chromatography with positive electrospray ionization mass spectrometric detection (HPLC-MS). The method has been developed and robustness tested by systematically searching for satisfactory conditions using experimental designs including factorial and response surface designs. With the exception of amlodipine, the concentration limit of quantification (cLOQ) covered low therapeutic concentration levels for all the compounds. Within assay precisions and accuracies (bias) were 3.4-21% RSD and from -24 to 21% for the concentration range 1.00-5.00 microM, respectively. Between assay precisions were 4.4-28% RSD for the concentration range from 0.1 to 5 microM and recoveries varied from 9 to 103%. The method is used for determination of cardiovascular drugs in post-mortem whole blood samples from forensic autopsy cases.     

Determination of urinary triclosan by stir bar sorptive extraction and thermal desorption-gas chromatography-mass spectrometry

We have developed an analytical method for the determination of urinary 5-chloro-2-(2,4-dichlorophenoxy)phenol (triclosan), which utilizes stir bar sorptive extraction (SBSE) and thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS). Human urine sample is de-conjugated by treatment with beta-glucuronidase and sulfatase. A stir bar coated with polydimethylsiloxane (PDMS) is added to the urine sample in a vial and the sample is stirred for 60 min at room temperature (25 degrees C). Then, the PDMS stir bar is subjected to TD-GC-MS. The detection limit of triclosan is 0.05 ng mL(-1). The method shows linearity over the calibration range (0.1-10 ng mL(-1)) and the correlation coefficient (r) is higher than 0.993 for triclosan standard solution. The average recoveries of triclosan in human urine sample are 102.8-113.1% (RSD: 2.4-6.7%). This simple, sensitive, and selective analytical method may be used in the determination of trace amounts of triclosan in human urine samples.     

Development of a liquid chromatography-tandem mass spectrometry with pressurized liquid extraction method for the determination of benzimidazole residues in edible tissues

A confirmatory and quantitative method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) combined with a pressure liquid extraction (PLE) was developed for the determination of 11 benzimidazole and 10 metabolites of albendazole, fenbendazole and mebendazole in the muscles and livers of swine, cattle, sheep and chicken. For sample preparation, we used an automated technique of PLE method. The optimum extraction conditions were obtained using an 11 ml Accelerated Solvent Extraction (ASE) cells, acetonitrile/hexane as the extraction solvent. HPLC analysis was performed on a C18 column with gradient elution using acetonitrile and 5 mmol l(-1) formic ammonium as mobile phase. The analytes were detected in the positive ion multiple reaction monitoring (MRM) mode by the LC-ESI-MS/MS analysis. The recoveries of benzimidazole (BZDs) spiked at the levels of 0.5 μg kg(-1) ranged from 70.1% to 92.7%; the between-day relative standard deviations were no more than 10%. The limits of quantification were 0.02-0.5 μg kg(-1). The optimized method was successfully applied to monitor real samples containing BZDs, demonstrating the method to be simple, fast, robust and suitable for identification and quantification of BZDs residues in animal products.     

Quantitative determination of Astragaloside IV, a natural product with cardioprotective activity, in plasma, urine and other biological samples by HPLC coupled with tandem mass spectrometry

Astragaloside IV is a novel cardioprotective agent extracted from the Chinese medical herb Astragalus membranaceus (Fisch) Bge. This agent is being developed for treatment for cardiovascular disease. Further development of Astragaloside IV will require detailed pharmacokinetic studies in preclinical animal models. Therefore, we established a sensitive and accurate high performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (LC/MS/MS) quantitative detection method for measurement of Astragaloside IV levels in plasma, urine as well as other biological samples including bile fluid, feces and various tissues. Extraction of Astragaloside IV from plasma and other biological samples was performed by Waters OASIS(trade mark) solid phase extraction column by washing with water and eluting with methanol, respectively. An aliquot of extracted residues was injected into LC/MS/MS system with separation by a Cosmosil C18 5 microm, 150 mm x 2.0 mm) column. Acetonitrile:water containing 5 microM NaAc (40:60, v/v) was used as a mobile phase. The eluted compounds were detected by tandem mass spectrometry. The average extraction recoveries were greater than 89% for Astragaloside IV and digoxin from plasma, while extraction recovery of Astragaloside IV and digoxin from tissues, bile fluid, urine and fece ranged from 61 to 85%, respectively. Good linearity (R2>0.9999) was observed throughout the range of 10-5000 ng/ml in 0.5 ml rat plasma and 5-5000 ng/ml in 0.5 ml dog plasma. In addition, good linearity (R2>0.9999) was also observed in urine, bile fluid, feces samples and various tissue samples. The overall accuracy of this method was 93-110% for both rat plasma and dog plasma. Intra-assay and inter-assay variabilities were less than 15.03% in plasma. The lowest quantitation limit of Astragaloside IV was 10 ng/ml in 0.5 ml rat plasma and 5 ng/ml in 0.5 ml dog plasma, respectively. Practical utility of this new LC/MS/MS method was confirmed in pilot pharmacokinetic studies in both rats and dogs following intravenous administration.     

Determination of Simvastatin in human plasma by liquid chromatography-mass spectrometry

A simple, sensitive and selective liquid chromatography coupled with electrospray ionization mass spectrometry (LC/ESI/MS) method for the determination of simvastatin (I) has been developed. After extraction by ethyl acetate, using lovastatin (II) as internal standard, solutes are separated on a C(18) column with a mobile phase consisting of methanol-water (9:1). Detection is performed on an atmospheric pressure ionization single quadruple mass spectrometer equipped with an ESI interface and operates in positive ionization mode. Simvastatin quantification was realized by computing peak area ratio (I/II) of the extracts analyzed in SIM mode (m/z: 441 and m/z: 427 for I and II, respectively) and comparing them with calibration curve (r=0.9997). Accuracy and precision for the assay were determined by calculating the intra-batch and inter-batch variation at three concentrations 0.1, 5.0, 10.0 ng/ml; the intra batch relative standard deviation (RSD) was less than 10% and ranged from 1.8 to 8.5%, respectively; the inter-batch RSD was less than 20% and ranged from 4.1 to 16.5%. The limit of detection was 0.05 ng/ml.     

Determination of anabolic steroids in bovine serum by liquid chromatography-tandem mass spectrometry

In the present paper we report the LC-MS/MS determination of residues of 12 anabolic steroids in bovine serum, as an expansion of our work protocols for steroids determination in biological matrices. Steroids analyzed included α-zearalanol, β-zearalanol, α-trenbolone, β-trenbolone, methyltestosterone, α-estradiol, β-estradiol, ethynylestradiol, α-boldenone, β-boldenone, α-nortestosterone and β-nortestosterone. Following protein precipitation, serum samples were cleaned up by solid-phase extraction using Oasis HLB and Amino cartridges. Atmospheric pressure chemical ionization (APCI) in both positive and negative ionization modes was used and mass spectrometry detection was carried out in multiple reaction monitoring mode following two or (in most cases) three product ions per precursor ion. The method was validated in accordance with the Commission Decision 2002/657/EC. The decision limit (CCα) values obtained, ranged from 0.01 to 0.07 ng/ml and the detection capability (CCβ) values obtained ranged from 0.02 to 0.12 ng/ml. The recoveries ranged from 70.2% to 118.2%. The developed method is suitable for routine and confirmatory purposes such as control of illegal use in livestock production.     

Determination of tiropramide in human plasma by liquid chromatography-tandem mass spectrometry

A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric (LC/MS/MS) method for the determination of tiropramide in human plasma was developed. Tiropramide and internal standard, cisapride were extracted from human plasma by liquid-liquid extraction and analyzed on a Luna C8 column with the mobile phase of acetonitrile-ammonium formate (10mM, pH 4.5) (50:50, v/v). The analytes was detected using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The standard curve was linear (r=0.998) over the concentration range of 2.0-200 ng/ml. The intra- and inter-assay coefficients of variation ranged from 2.8 to 7.8 and 6.7 to 8.9%, respectively. The recoveries of tiropramide ranged from 50.2 to 53.1%, with that of cisapride (internal standard) being 60.9+/-5.3%. The lower limit of quantification for tiropramide was 2.0 ng/ml using 100 microl plasma sample. This method was applied to the pharmacokinetic study of tiropramide in human.