Determination of penconazole on personal protection equipment after field applications

A simple analytical method, validated in-house and intra-laboratory, has been developed for the determination of penconazole on personal protection equipment (PPE) used by operators during field applications of Topas 20EW. The analytical determination of penconazole was performed by GC-ECD. Sample preparation was based on a liquid extraction procedure. The possible effect of different personal protection equipment matrices on the analytical determination of penconazole was studied and evaluated with regression analysis. No evidence of significant (at 95% CI level) effect was observed at several fortification levels. The percentage recovery of penconazole from the different PPE was in the range 59-100% with adequate correlation with the level of fortification (r2>0.99). The RSD% was in the range of 1-15% and the LOD and LOQ for penconazole were 0.84 and 2.5 ng mL(-1), respectively.     

Determination of penconazole on personal protection equipment after field applications

A simple analytical method, validated in-house and intra-laboratory, has been developed for the determination of penconazole on personal protection equipment (PPE) used by operators during field applications of Topas 20EW. The analytical determination of penconazole was performed by GC–ECD. Sample preparation was based on a liquid extraction procedure. The possible effect of different personal protection equipment matrices on the analytical determination of penconazole was studied and evaluated with regression analysis. No evidence of significant (at 95% CI level) effect was observed at several fortification levels. The percentage recovery of penconazole from the different PPE was in the range 59–100% with adequate correlation with the level of fortification (r²>0.99). The RSD% was in the range of 1–15% and the LOD and LOQ for penconazole were 0.84 and 2.5 ng mL^–1, respectively.     

Multiresidue Method for the Determination of Organophosphorus Pesticides in Still Wine and Fortified Wine Using Solid-Phase Microextraction and Gas Chromatography – Tandem Mass Spectrometry

A SPME-GC-MS/MS method for the determination of eight organophosphorus pesticides (azinphos-methyl, chlorpyriphos, chlorpyriphos-methyl, diazinon, fenitrothion, fenthion, malathion, and methidathion) in still and fortified wine was developed. The extraction procedure is simple, solvent free, and without any sample pretreatment. Limits of detection (LOD) and quantitation (LOQ) values in the range 0.1–14.3 µg/L and 0.2–43.3 µg/L, respectively, were obtained. The LOQ values are below the maximum residue levels (MRLs) established by European Regulation for grapes, with the exception of methidathion. Coefficients of correlation (R²) higher than 0.99 were obtained for the majority of the pesticides, in all different wines analyzed.     

Fast quantitative determination of melamine and its derivatives by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

A simple, sensitive and fast method for the determination of melamine and its derivatives in milk powder using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was developed. Neither time-consuming sample preparation, nor special target plates, or other extra equipment are necessary. The common matrix sinapinic acid (SA) was used with a dried-droplet preparation. Detection limits (signal-to-noise (S/N) ratio = 3) for standard solutions of melamine, ammeline and cyanuric acid were 10, 25 and 10 μg/L, respectively. The limit of quantification (LOQ) for melamine was 25 μg/L and excellent linearity (R(2): 0.9990) was maintained over the range of 10-2000 μg/L. Ammeline and cyanuric acid were analyzed with an LOQ of 50 μg/L and also excellent linearity (R(2): 0.9997 and R(2): 0.9998). Good accuracy and precision were obtained for all concentrations within the range of the standard curve. The developed method was successfully used for the determination of melamine, ammeline and cyanuric acid in milk powder samples with a simple sample preparation. The LOQ of melamine was 0.5 μg/g. Ammeline and cyanuric acid were detectable at 0.5 and 5 μg/g. This method showed excellent accuracy, precision and linearity and significantly reduces the needed analysis time, as only approximately 10 s/sample measuring time is required. To the authors' knowledge, this is the first published method to quantify melamine and derivatives by MALDI-TOF-MS.     

Determination of carbamazepine and its impurities iminostilbene and iminodibenzyl in solid dosage form by column high-performance liquid chromatography

An accurate and precise RP-HPLC method was developed and validated for the determination of carbamazepine and its impurities iminostilbene and iminodibenzyl in a tablet formulation with fluphenazine as an internal standard. Buffer-methanol (50 + 50, v/v) was used as the mobile phase. During validation, specificity, linearity, precision, accuracy, LOD, LOQ, and robustness of the method were tested. The method was proven to be specific against placebo interference. Linearity was evaluated over the concentration range of 100-500, 0.05-0.25, and 0.1-0.5 microg/mL, and the r values were 0.9994, 0.9997, and 0.9979 for carbamazepine, iminostilbene, and iminodibenzyl, respectively. Intraday precision of the method was good, and RSD was below 2% for all analytes. The accuracy of the method ranged from 100.69 to 102.10, 99.76 to 102.66, and 99.26 to 100.08% for carbamazepine, iminostilbene, and iminodibenzyl, respectively. LOD was 0.0125, 0.025, and 0.05 microg/mL and LOQ was 0.05, 0.05, and 0.1 microg/mL for carbamazepine, iminostilbene, and iminodibenzyl, respectiviely. Robustness of the method was proven by using a chemometric approach. The method was successfully applied to the analysis of commercially available carbamazepine tablets and showed good repeatability, with RSD below 2%.     

Confirmatory method for the determination of volatile congeners and methanol in Turkish raki according to European Union Regulation (EEC) No. 2000R2870: single-laboratory validation

A method described by European Union Regulation (EEC) No. 2000R2870 was validated and supported by GC/MS analysis for the determination of volatile congeners and methanol in Turkish raki. The method was validated in terms of specificity, accuracy, precision, LOD, LOQ, linearity, and robustness. The specificity of the method was demonstrated, and the method showed excellent accuracy (97.5-100.1%). Linearity was checked in the ranges of 0.200-26.390 mg/100 mL for more volatile compounds and 1.155-48.00 mg/100 mL for less volatile compounds, after concentrations found in Turkish raki were taken into account. The calibration curves of all analytes showed good linearity (R2 > 0.998). The within- and between-day precision (RSD) values of 11 analytes were in the range of 0.18-4.50%. The LOD and LOQ values were in the range of 0.014-0.362 and 0.045-1.085 mg/100 mL, respectively. The method can be used as an absolute quantification method for the determination of volatile congeners and methanol in Turkish raki and for QC.     

Development and validation of a solid-phase extraction and gas chromatography-tandem mass spectrometry method for the determination of isopropyl-9H-thioxanthen-9-one in carton packaged milk

A simple and efficient method for the determination of isopropyl-9H-thioxanten-9-one (ITX) in different fat content milk samples and baby milk samples stored in packaged cartons was developed and validated. Samples were extracted using solid-phase extraction (SPE) and analysed by gas chromatography-tandem mass spectrometry operated in selected reaction monitoring mode (SRM). Validation was carried out in terms of limit of detection (LOD), limit of quantitation (LOQ), linearity, precision and trueness. LOD and LOQ values in the low microg/L were achieved, whereas linearity was established within 0.5-500 microg/L range. Good precision was obtained both in terms of intra-day repeatability and inter-day precision on two concentration levels (RSD% lower than 2%). Good percentage recoveries were obtained (92.0-102.0%) even in the presence of high amount of fat. Finally, the developed method was successfully applied to analyse a number of commercial milk samples with different fat content and baby milk samples.     

Simultaneous enantioselective determination of fenbuconazole and its main metabolites in soil and water by chiral liquid chromatography/tandem mass spectrometry

A novel and sensitive method was developed for the simultaneous determination of fenbuconazole and its main metabolites enantioselectively using chiral liquid chromatography coupled with tandem mass spectrometry. The separation and determination were performed using reversed-phase chromatography on a cellulose chiral stationary phase, a Chiralcel OD-RH (150 mm×4.6 mm) column, under isocratic conditions at 0.5 mL/min flow rate. The effects of three cellulose-based columns and three amylose-based columns on the separation were also investigated. The elution orders of the eluting enantiomers were identified by an optical rotation detector. The QuEChERS (acronym for Quick, Easy, Cheap, Effective, Rugged and Safe) method and solid-phase extraction (SPE) were used for the extraction and clean-up of the soil and water samples, respectively. Parameters including the matrix effect, linearity, precision, accuracy and stability were evaluated. Under optimal conditions, the mean recoveries for all enantiomers from the soil samples were 82.5-104.1% with 2.7-9.5% intra-day relative standard deviations (RSD) and 5.7-11.2% inter-day RSD at 5, 25 and 50 μg/kg levels; the mean enantiomer recoveries from the water samples were 81.8-104.6% with 2.6-11.4% intra-day RSD and 5.3-10.4% inter-day RSD at 0.25, 0.5 and 2.5 μg/L levels. Coefficients of determination R2≥0.9991 were achieved for each enantiomer in the soil and water matrix calibration curves within the range of 1.0-125 μg/L. The limits of detection (LOD) for all enantiomers in the soil and water were less than 0.8 μg/kg, whereas the limit of quantification (LOQ) did not exceed 2.5 μg/kg. The results of the method validation confirm that this proposed method is convenient and reliable for the enantioselective determination of the enantiomers of fenbuconazole and its main metabolites in soil and water.     

Single-laboratory validation of a method for the determination of furan in foods by using static headspace sampling and gas chromatography/mass spectrometry

A headspace gas chromatography/mass spectrometry method was developed and validated in-house for the determination of furan in foods. The method of standard additions with d4-furan as the internal standard was used to quantitate furan. The limit of detection and limit of quantitation (LOQ) values ranged from 0.2 and 0.6 nglg, respectively, in apple juice to 0.9 and 2.9 ng/g, respectively, in peanut butter. Recoveries were obtained at 0.5, 1, 2, and 3 times the LOQ. At 1, 2, and 3 times the LOQ, the recoveries ranged from 89.4 to 108%, and the relative standard deviations ranged from 3.3 to 17.3% for all the matrixes. For apple juice, chicken broth, and infant formula, the averaged coefficients of determination from the linear regression analyses were >0.99 with each food fortified at 0.5, 1, 2, and 3 times the LOQ. The coefficients of determination were >0.99 for green beans and 0.96 for peanut butter with the foods fortified at 1, 2, and 3 times the LOQ. Within-laboratory precision was determined by comparing the amounts of furan found in 18 samples by 2 analysts on different days with different instruments. For most of the foods, the difference between the amounts found by each analyst was <18%. The method was used to conduct a survey of >300 foods. The furan levels found ranged from none detected to 174 ng/g.     

Development and validation of a HPLC method for 4,7-phenanthroline-5,6-dione I and identification of its major impurity by HPLC-MS-APCI

In this study, the development and validation of an analytical method for the assay of 4,7-phenanthroline-5,6-dione I (dione I) using high-performance liquid chromatography (HPLC) and the determination of its synthetic impurities by employing the method in HPLC-mass spectrometry with atmospheric-pressure chemical ionization and photodiode-array UV detection is reported. The results show that dione I is eluted as a spectrally pure peak resolved from its impurities. 5-Bromo,4-7-phenanthroline is identified as the main impurity. This is supported by elemental analysis of the dione I, which demonstrated the presence of bromine. Validation parameters such as specificity and selectivity, linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ), ruggedness, stability, and system suitability, which are evaluated for this method. The LOD and LOQ are 2.0 microg/mL and 50 microg/mL with a 0.50% relative standard deviation (%RSD), respectively. The calibration curves showed good linearity over the concentration range of 0.05-1.50 mg/mL. The correlation coefficient is > 0.9991 in each case. The %RSD values for intra- and interday precision studies are < 0.40%.     

Development of a simple and sensitive high-performance liquid chromatography method for determination of glucosamine in pharmaceutical formulations

A column high-performance liquid chromatography (HPLC) method was developed for the determination of glucosamine in dosage forms. Glucosamine was derivatized by addition of a solution containing orthophthaldialdehyde. The HPLC separation was achieved on a Spherimage 80 ODS2 column (250 x 4 mm id, 5 microm particle size) using an isocratic mobile phase containing phosphate buffer-methanol (90 + 10, v/v, pH 6.50) and methanol-tetrahydrofuran (97 + 3, v/v) in proportions of 85 + 15 at a flow rate of 1 mL/min, followed by fluorescence detection. The method was validated for specificity, linearity, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). The detector response for glucosamine HCI was linear over the concentration range of 0.1-20 microg/mL with a correlation coefficient of 0.9980. The accuracy was between 99.4 and 100.8%. The LOD and the LOQ were 0.009 and 0.027 microg/mL, respectively. The method was applied to determination of glucosamine in solid dosage forms.     

Voltammetric study of the hydrolysis product of fenthion at the Nafion®-modified glassy carbon electrode

The differential pulse voltammetric (DPV) method is proposed for the determination of phosphorothioate insecticide (fenthion) based on the oxidation of its hydrolysis product. A single peak at +0.65 V (vs. Ag/AgCl) is observed at the Nafion®-modified glassy carbon electrode in 0.1 M Britton-Robinson buffer solution (pH 4.0) as a supporting electrolyte. The voltammetric behavior of fenthion was investigated over a wide range of pH (2.0–8.0). The effect of the solution and operational parameters on the sensitivity of the DPV peak was carefully examined in order to select the optimum conditions for the determination of fenthion. Under optimum conditions, the oxidation response gives a linear calibration plot over a concentration range of 8.41 × 10^?7?5.98 × 10^?6 M and the detection limit is found to be 7.6 × 10^?7 M. The effects of some diverse metal ions, anions, and some other organic molecules on the determination of fenthion were studied. The applicability of DPV for the determination of fenthion insecticide in a commercial sample as well as in some water samples was demonstrated.     

超高效液相色谱-串联质谱法测定牛奶中糠氨酸

采用超高效液相色谱-串联质谱法建立了检测牛奶中糠氨酸含量的分析方法。试样经10.6 mol/L盐酸水解,纯水稀释后,糠氨酸在C18色谱柱上以0.1%甲酸水溶液和乙腈为流动相,进行液相色谱分离;质谱检测采用电喷雾正离子化模式和多反应监测模式(MRM)。结果表明,糠氨酸在0.01~0.5 mg/L范围内线性关系良好,相关系数(R2)为0.9996,定量限(LOQ)为0.5 mg/100 g蛋白。在生牛乳空白样品中添加浓度为10,100,300 mg/100 g蛋白时,糠氨酸的平均回收率为93.1%~95.7%,相对标准偏差(RSDs)为1.2%~1.7%(n=6)。     

Chiral determination of a novel acaricide cyflumetofen enantiomers in cucumber,tomato, and apple by HPLC

A simple chiral analytical method was developed for the enantiomeric determination of cyflumetofen in cucumber, tomato, and apple by normal‐phase HPLC. The effects of mobile phase composition and column temperature on the enantioseparation were evaluated. Excellent separation was achieved at 25°C on a Chiralpak AD‐H column, with a mixture of n‐hexane and 2‐propanol (95:5, v/v) as mobile phase at a flow rate of 1.0 mL/min detecting at 234 nm. The resolution of cyflumetofen enantiomers was up to 5.5. The elution order of the enantiomers was determined by an online OR‐2090 detector, which was performed under the same chromatographic conditions. The first eluted enantiomer was (–)‐cyflumetofen and the second eluted one was (+)‐cyflumetofen. The method was validated for linearity, repeatability, accuracy, LOD, and LOQ. LOD ranged from 0.1 to 0.15 mg/kg, with the LOD varying from 0.33 to 0.5 mg/kg for each enantiomer, respectively. The average recoveries of the pesticide ranged from 71.4 to 102.0% at all fortification levels. The precision values associated with the analytical method, expressed as RSD values, were below 14.8% in all matrices. The method was then successfully applied to detect cyflumetofen enantiomers in real samples.     

Liquid chromatographic method for the simultaneous determination of eprosartan and hydrochlorothiazide in tablets and human plasma

A new, specific, and sensitive RP-HPLC method was developed for the simultaneous determination of eprosartan (EPR) and hydrochlorothiazide (HCT). Good chromatographic separation was achieved using a 250 x 4.6 mm id, 5 microm particle size Symmetry C18 column. The mobile phase acetonitrile-0.1 M phosphate buffer (35+65, v/v), pH 4.5, was pumped at a flow rate of 1 mL/min, with UV detection at 275 nm. The method showed good linearity in the ranges of 0.5-50 and 0.1-10 microg/mL, with LOD of 0.06 and 0.02 microg/mL and LOQ of 0.20 and 0.08 microg/mL for EPR and HCT, respectively. The proposed method was successfully applied for the analysis of the studied drugs in their synthetic mixture and co-formulated tablets. The method was further extended to the in vitro and in vivo determination of the two drugs in spiked and real human plasma. Interference likely to be encountered from the co-administered drugs was studied.     

Development and validation of an analytical method for metformin hydrochloride and its related compound (1-cyanoguanidine) in tablet formulations by HPLC-UV

A simple, and stability-indicating liquid chromatographic method was developed and validated for the analysis of metformin hydrochloride and its related compound (1-cyanoguanidine) in tablet formulations. Liquid chromatography with a UV detector at a wavelength of 232 nm using a Nova-Pak silica column was employed in this study. Isocratic elution was employed using a mixture of ammonium dihydrogen phosphate buffer and methanol (21:79, v/v). This new method was validated in accordance with USP requirements for new methods for assay determination, which include accuracy, precision, specificity, linearity and range. The current method demonstrates good linearity over the range of 0.01-0.03 mg mL⁻¹ of metformin hydrochloride. The accuracy of the method is 100.4%. The precision of this method reflected by relative standard deviation of replicates is 0.30%. Validation of the same method for 1-cyanoguanidine determination was also performed according to USP requirements for quantitative determination of impurities which include accuracy, precision, linearity and range, selectivity, and limit of quantification (LOQ). Low LOQ of 1-cyanoguanidine using this method enables the detection and quantification of this impurity at low concentration.     

气相色谱-三重四极杆质谱法快速检测鸡蛋中氟虫腈及其代谢物

建立了QuEChERS前处理技术结合气相色谱-三重四极杆质谱（GC-MS/MS）分析鸡蛋中氟虫腈及其代谢物的快速检测方法。样品由乙腈提取,然后经150 mg MgSO₄脱水和50 mg N-丙基乙二胺（PSA）、50 mg C18净化,采用农药残留专用柱（TR-Pesticide Ⅱ）进行气相色谱分离,以定时反应监测（timed-SRM）模式进行检测,基质曲线外标法定量。结果表明,氟虫腈及其代谢物在1.0~200 μg/L范围内呈良好线性,线性相关系数（R²）均大于0.999,定量限为0.5~1.0 μg/kg;氟虫腈及其代谢物在3个添加水平（2、5和10 μg/kg）下的加标回收率为87.8%~111.5%,相对标准偏差（RSD,n=3）为2.0%~9.2%,该方法能满足欧盟规定的鸡蛋中氟虫腈及其代谢物的残留检测限量要求。     

Quantification of ropivacaine and its major metabolites in human urine samples utilizing microextraction in a packed syringe automated with liquid chromatography-tandem mass spectrometry (MEPS-LC-MS/MS)

The determination of ropivacaine and its major metabolites in urine was performed using microextraction in a packed syringe as an on-line sample preparation method with LC and MS/MS. The sampling sorbent utilized was polystyrene polymer. [2H7]ropivacaine was used as the internal standard. The lower LOQ was 5.0 nmol/L. The calibration curves were obtained within the concentration range 5-2000 nmol/ L in urine. The regression correlation coefficients for urine samples were > or = 0.999 for all runs. The between-batch accuracy and precision values were determined from six replicates of quality control (QC) samples at three different concentrations in human urine. The mean accuracy values for the QC samples, reported as the percentage difference from the nominal value, were in the range of 99-115%. The precisions, given as the RSDs, were in the range 1.9-11%. The present method is miniaturized and fully automated and can be used for pharmacokinetic and pharmacodynamic studies.     

超高效液相色谱-三重四极杆质谱法测定人尿中9种邻苯二甲酸酯代谢物

建立了人尿中9种邻苯二甲酸酯（PAE）代谢物的超高效液相色谱-三重四极杆质谱（UPLC-MS/MS）测定方法。2 mL尿液样本酶解2 h后,经强阴离子固相萃取净化处理;选用Waters ACQUITY UPLC BEH Phenyl色谱柱（100 mm×2.1 mm,1.7 μ m）,以0.1%（体积分数）乙酸乙腈和0.1%（体积分数）乙酸水溶液为流动相进行梯度洗脱;在负离子电喷雾多反应监测模式（MRM）下测定9种PAE代谢物含量。8种PAE代谢物在0.39~200 μ g/L范围内、1种PAE代谢物在1.17~600 μ g/L范围内线性关系良好,相关系数均大于0.995。方法检出限为0.06~0.85 μ g/L,定量限为0.20~2.80 μ g/L。3个加标水平的加标回收率为84.1%~122%,精密度为4.5%~14.3%;日内精密度不高于9.3%,日间精密度不高于10.1%;基质效应和稳定性符合分析要求。应用该方法测定50份人尿液样本,邻苯二甲酸单环已酯（MCHP）和邻苯二甲酸单苄酯（MBZP）的检出率分别为0和44.0%,其余7种PAE代谢物的检出率为100%。该方法操作简单、定量准确、稳定性好,适用于人尿中9种PAE代谢物的定量分析。     

Determination of fipronil and its major metabolites in vegetables,fruit and soil using QuEChERS and gas chromatography-mass spectrometry

A rapid, simple and selective gas chromatography with mass spectrometric detection (GC-MS) method was developed and validated for simultaneously determining fipronil and its three major metabolites in vegetables, fruit and soil. The fipronil residues were extracted using QuEChERS technique with ethyl acetate and then were purified by dispersive solid phase extraction (d-SPE) cleanup for cabbage, cauliflower, okra, tomato, grapes and soil. The linearity of the analytical response across the studied range of concentrations (0.01–0.5?µg?mL^?1) was excellent, obtaining correlation coefficients higher than 0.999. The average recoveries of the pesticide from all matrixes ranged from 86 to 112%, for fortification levels of 0.01, 0.05 and 0.1?µg?g^?1. The precision values associated with the analytical method, expressed as RSD values, were less than 10.15% for the pesticide in all matrixes. This method can be used to evaluate environmental residues and the safety of agricultural products.