Anhydrous Magnesium Sulfate Research Articles

LC-MS/MS를 이용한 축산물 중 Phorate 및 대사산물 5종 동시분석법 개발

A simultaneous official method was developed for the determination of phorate and its metabolites (phorate sulfoxide, phorate sulfone, phorate oxon, phorate oxon sulfoxide, phorate oxon sulfone) in livestock samples. The analytes were quantified and confirmed via liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). Phorate and its metabolites were extracted from beef and milk samples with acidified acetonitrile (containing 1% acetic acid) and partitioned with anhydrous magnesium sulfate. Then, the extract was purified through primary secondary amine (PSA) and C18 dispersive sorbent. Matrix matched calibration curves were linear over the calibration ranges (0.005-0.5 mg/L) for all the analytes into blank extract with r > 0.996. For validation purposes, recovery studies were carried out at three different concentration levels (beef 0.004, 0.04 and 0.2 mg/kg; milk 0.008, 0.04 and 0.2 mg/kg, n = 5). The recoveries were within 79.2-113.9% with relative standard deviations (RSDs) less than 19.2% for all analytes. All values were consistent with the criteria ranges requested in the Codex guidelines. The limit of quantification was quite lower than the maximum residue limit (MRL) set by the Ministry of Food and Drug Safety (0.05 mg/kg). The proposed analytical method was accurate, effective and sensitive for phorate and its metabolites determination and it will be used to as an official analytical method in Korea.

Analysis of 19 PCB congeners in catfish tissue using a modified QuEChERS method with GC–MS/MS

A simple approach to determine 19 PCB congeners in catfish tissue was presented. A modified QuEChERS method employing high solvent to sample ratio 10:1 was used to improve the extraction recovery of 19 PCB congeners. After salting out by shaking with anhydrous magnesium sulfate and sodium chloride, 1mL of acetonitrile extract was pipetted into a 2-mL centrifuge tube containing anhydrous magnesium sulfate, primary secondary amine sorbent, and C-18 sorbent. The tube was then shaken and centrifuged to absorb fat and fatty acid residue present in the acetonitrile extract. The acetonitrile extract was analyzed by GC–MS/MS. The excellent sensitivity of GC–MS/MS allows for the direct injection of the samples to detect the low level of the PCB congeners. The method therefore is high throughput, uses fewer consumable lab supplies, and provides excellent sensitivity with an LOQ below 1ng/g.

Determination of polycyclic aromatic hydrocarbons (PAHs) in seafood using gas chromatography-mass spectrometry: collaborative study.

A collaborative study was conducted to determine selected polycyclic aromatic hydrocarbons (PAHs) and their relevant alkyl homologs in seafood matrixes using a fast sample preparation method followed by analysis with GC/MS. The sample preparation method involves addition of (13)C-PAH surrogate mixture to homogenized samples and extraction by shaking with a water-ethyl acetate mixture. After phase separation induced by addition of anhydrous magnesium sulfate-sodium chloride (2 + 1, w/w) and centrifugation, an aliquot of the ethyl acetate layer is evaporated, reconstituted in hexane, and cleaned up using silica gel SPE. The analytes are eluted with hexane-dichloromethane (3 + 1, v/v), the clean extract is carefully evaporated, reconstituted in isooctane, and analyzed by GC/MS. To allow for the use of various GC/MS instruments, GC columns, silica SPE cartridges, and evaporation techniques and equipment, performance-based criteria were developed and implemented in the qualification phase of the collaborative study. These criteria helped laboratories optimize their GC/MS, SPE cleanup, and evaporation conditions; check and eliminate potential PAH contamination in their reagent blanks; and become familiar with the method procedure. Ten laboratories from five countries qualified and completed the collaborative study, which was conducted on three seafood matrixes (mussel, oyster, and shrimp) fortified with 19 selected PAH analytes at five different levels of benzo[a]pyrene (BaP) ranging from 2 to 50 μg/kg. Each matrix had a varying mixture of three different BaP levels. The other studied PAHs were at varying levels from 2 to 250 μg/kg to mimic typical PAH patterns. The fortified analytes in three matrixes were analyzed as blind duplicates at each level of BaP and corresponding other PAH levels. In addition, a blank with no added PAHs for each matrix was analyzed singly. Eight to 10 valid results were obtained for the majority of determinations. Mean recoveries of all tested analytes at the five different concentration levels were all in the range of 70-120%: 83.8-115% in shrimp, 77.3-107% in mussel, and 71.6-94.6% in oyster, except for a slightly lower mean recovery of 68.6% for benzo[ a ]anthracene fortified at 25 μg/kg in oyster (RSDr: 5.84%, RSDR: 21.1%) and lower mean recoveries for anthracene (Ant) and BaP in oyster at all three fortification levels (50.3-56.5% and 48.2-49.7%, respectively). The lower mean recoveries of Ant and BaP were linked to degradation of these analytes in oyster samples stored at -20°C, which also resulted in lower reproducibility (RSDR values in the range of 44.5-64.7% for Ant and 40.6-43.5% for BaP). However, the repeatability was good (RSDr of 8.78-9.96% for Ant and 6.43-11.9% for BaP), and the HorRat values were acceptable (1.56-1.94 for Ant and 1.10-1.45 for BaP). In all other cases, repeatability, reproducibility, and HorRat values were as follows: shrimp: RSDr 1.40-26.9%, RSDR 5.41-29.4%, HorRat: 0.22-1.34; mussel: RSDr 2.52-17.1%, RSDR 4.19-32.5%, HorRat: 0.17-1.13; and oyster: RSDr 3.12-22.7%, RSDR 8.41-31.8%, HorRat: 0.34-1.39. The results demonstrate that the method is fit-for-purpose to determine PAHs and their alkyl homologs in seafood samples. The method was approved by the Expert Review Panel on PAHs as the AOAC Official First Action Method 2014.08.

Determination of Niclosamide in Aquatic Animal Tissue by a Novel Extraction Procedure and High-Performance Liquid Chromatography–Heated Electrospray Ionization-Tandem Mass Spectrometry

Niclosamide is a mollusicide used for aquaculture on a large scale in China. However, it has high toxicity to aquatic animals and may cause damage to DNA. A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction procedure with high-performance liquid chromatography–heated electrospray ionization-tandem mass spectrometry method was developed for its determination. Samples were extracted with ammoniated acetonitrile, and anhydrous magnesium sulfate was added to remove moisture and precipitate proteins. The extracts were further purified with octadecylsilane. The recoveries of niclosamide in fortified muscle tissue at concentrations of 0.5 to 20 µg/kg were between 76.40% and 95.60% with relative standard deviations less than 9.54%. The limits of detection and quantification were 0.2 µg/kg and 0.5 µg/kg, respectively. The developed method was used to study the adsorption of niclosamide in channel catfish after administration.

Сочетание пробоподготовки QuEChERS и мицеллярной электрокинетической хроматографии при определении неоникотиноидных инсектицидов в овощах и фруктах

The possibility of electrophoretic separation and simultaneous determination of 7 neonicotinoids (imidacloprid, acetamiprid, thiamethoxam, thiacloprid, nitenpyram, clothianidin and dinotefuran) by micellar electrokinetic chromatography is shown. We propose a method for extracting and concentrating of neonicotinoid insecticides from vegetables and fruits using the sample preparation QuEChERS. The optimum compositions of the salting-out mixtures for extraction and sorbents for purification of the resulting extracts from vegetables and fruits were selected. Extraction of pesticides from the fruits was performed by acetonitrile using a mixture of sodium citrates (Na3C6H5O7·2H2O, Na2HC6H5O7·1,5Н2О) with the following clean-up of 2 ml of the extract with sorbent PSA (100 mg) and anhydrous magnesium sulfate (300 mg). During the analysis of vegetables ethyl acetat was used as an extractant in the presence of anhydrous magnesium sulfate and sodium chloride with the following clean-up of 2 ml of the extract with sorbent PSA (100 mg) and graphitized carbon black (10 mg). In optimal conditions the recovery of the analytes ranged from 62 to 81 % for fruits and from 38 to 76 % for vegetables. The limits of quantification of neonicotinoids with a 10.0 g weight sample were from 0.25 to 0.65 mg·kg-1 and from 0.04 to 0.13 mg·kg-1 for fruits and vegetables respectively. The relative standard deviation of the test results does not exceed 0.1. Duration of analysis is 1-1.5 hr.Key words: neonicotinoids, micellar electrokinetic chromatography, QuEChERS, vegetables, fruits(Russian)DOI:http://dx.doi.org/10.15826/analitika.2015.19.1.003 D.S. Bol’shakov1, V.G. Amelin1,2, T.B. Nikeshina1 1Federal Centre for Animals Health (ARRIAH), Yur’evets, Vladimir, Russian Federation2Vladimir State University named after Alexander and Nikolay Stoletovs, Vladimir, Russian Federation

Rapid screening and confirmation of 205 pesticide residues in rice by QuEChERS and liquid chromatography-mass spectrometry

A method for rapid screening and confirmation of 205 pesticide residues in rice was developed by combining QuEChERS and high performance liquid chromatography-triple quadrupole-linear ion trap mass spectrometry (LC-Q-TRAP/MS). The rice samples were extracted with acetonitrile, and then cleaned up with primary secondary amine (PSA), anhydrous magnesium sulfate (MgSO4) and C18 adsorbent. Finally, the samples were detected by LC-Q-TRAP/MS in multiple reaction monitoring with information-dependent acquisition of enhanced product ion (MRM-IDA-EPI) mode followed with database searching. A total of 205 pesticide residues were confirmed by retention times, ion pairs and the database searching using EPI library, and quantified by external standard method. All the pesticides showed good linearities with linear correlation coefficients all above 0.995. The limits of quantification (LOQs) for the 205 pesticides were 0.5-10.0 μg/kg. The average recoveries of the 205 pesticides ranged from 62.4% to 127.1% with the relative standard deviations (RSDs) of 1.0% - 20.0% at spiked levels of 10 μg/kg and 50 μg/kg, and only 20 min were needed for the analysis of an actual rice sample. In brief, the method is fast, accurate and highly sensitive, and is suitable for the screening and confirmation of pesticide residues in rice.

Determination of 32 sulfonylurea herbicide residues in sweet corns and green soybeans by QuEChERS-liquid chromatography-tandem mass spectrometry

A fast method based on QuEChERS methodology for the simultaneous determination of 32 sulfonylurea herbicide residues in sweet corns and green soybeans was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The clean-up effects of three dispersive sorbents were evaluated in terms of the residue mass for extracts after evaporation and recoveries. The three sorbents were C18, a mixture of two sorbents--silica coated with zirconium dioxide (Z-Sep) and C18, a bonded C18 zirconia-coated silica (Z-Sep+). As a result, the best effects were obtained from using Z-Sep/C18 sorbents. The samples were extracted with acetonitrile, and salted out with anhydrous magnesium sulphate and sodium chloride. The extracts were cleaned up with dispersive solid phase extraction using Z-Sep/C18 sorbents. Chromatographic analysis was carried out using a CSH C18 column with gradient elution. The pesticides were analyzed by negative electrospray ionization tandem mass spectrometry under scheduled multiple reaction monitoring mode. The quantification was achieved using matrix-matched standard calibrations as the external standard. The recoveries at fortification levels of 10, 20, 100 µg/kg in sweet corns and green beans ranged from 80.0% to 108.2% with the relative standard deviations of 1.2%-13.0%. The limits of quantification (S/N ≥ 10) were 0.2-5.0 µg/kg. The method has been proven to be simple, sensitive, environmental, and thus suitable for the determination of the 32 sulfonylurea herbicide residues in sweet corns and green soy- beans.

Determination of dimethyl yellow and diethyl yellow in yuba and dried beancurd by modified QuEChERS method and liquid chromatography-tandem mass spectrometry

A modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method followed by liquid chromatography-tandem mass spectrometric analysis was developed for the determination of dimethyl yellow and diethyl yellow in yuba and dried beancurd. Yuba and dried beancurd samples were soaked by deionized water, then acetonitrile was added to extract the analytes. Sodium chloride and anhydrous magnesium sulfate were added for liquid-liquid separation. The extracts were cleaned-up by dispersive solid-phase using N-propyl diethylamine. The analytes were separated by liquid chromatography and determined by mass spectrometry. External standard method was used for quantification. The recoveries of dimethyl yellow were in the range of 73.5%-84.5% at spiked levels of 0.3, 1 and 10 kg/kg and the recoveries of diethyl yellow were in range of 70.5%-81.2% at spiked levels of 0.1,1 and 10 µg/kg; relative standard deviations of the method were lower than 11%. The limit of detection and the limit of quantification of dimethyl yellow were 0.1 µg/kg and 0.3 µg/kg, respectively; the limit of detection and the limit of quantification of diethyl yellow were 0.05 µg/kg and 0.1 µg/kg, respectively. This method can be used in rapid screening and quantitative analysis of dimethyl yellow and diethyl yellow in yuba and dried beancurd.

Development of a modified QUick, Easy, CHeap, Effective, Rugged and Safe method for the determination of multi-class antimicrobials in vegetables by liquid chromatography tandem mass spectrometry

A modified quick, easy, cheap, efficient, rugged and safe (QuEChERS) method coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed for rapid determination of 26 veterinary antimicrobials in vegetables. Samples were extracted by single-phase extraction with acetonitrile-methanol (85:15, v/v) and citric buffer solution, followed by liquid–liquid partitioning with the addition of anhydrous magnesium sulfate and sodium chloride. A dispersive solid-phase extraction with primary secondary amine was applied for cleanup. Concentration and solvent exchange was performed prior to LC-MS/MS analysis. All matrix-matched calibration curves were linear with correlation coefficients (r) over 0.99. Recoveries for all the analytes spiked at 0.5 (1 or 1.5), 5 and 50ng/mL were in the range of 60.0–98.0%, except for sulfaquinoxaline, sulfaclozine and doxycycline, with relative standard deviations below 25% for the low concentration level, 20% for the medium and 15% for the high. The decision limits and the detection capabilities of the analytes ranged from 0.005 to 0.5μg/kg and from 0.02 to 1.5μg/kg, respectively. The method was developed and validated in accordance with romaine lettuce matrix, and higher recovery rates were obtained from the other five kinds of vegetables including white radish, Chinese cabbage, cucumber, string bean and green pepper. Matrix effects of different vegetables were evaluated and signal suppression effect was observed for the majority of 26 analytes. Finally, the method was applied to the analysis of real samples collected from the agricultural areas in the vicinity of local pig farms, and the phenomenon of vegetables contaminated by antimicrobials residues is provoking.

Determination of 16 phthalate esters in tea samples using a modified QuEChERS sample preparation method combined with GC-MS/MS

A modified QuEChERS method for the determination of 16 phthalate esters (PAEs) in tea samples using GC-MS/MS was developed and validated. The kinds and amounts of adsorbents were optimised, and the crude extracts were purified using primary secondary amine (PSA), graphitised carbon black (GCB) and anhydrous magnesium sulphate (MgSO4). Compared with extraction without matrix hydration, the addition of water could achieve higher extraction efficiency. The recoveries for PAEs obtained against matrix-matched standards at spiking levels of 50, 200 and 500 μg kg–1 ranged from 84.7% to 112.7% with relative standard deviations below 20% (n = 6) for all cases. Limits of detection (0.6–36.0 μg kg–1) and quantitation (2.0–120.0 μg kg–1) were achieved using the proposed method for all PAEs. A total of 105 tea samples were found to be contaminated with PAEs.

Multiresidue Analysis of Pesticides in Vegetables and Fruits by Supercritical Fluid Extraction and Liquid Chromatography-Tandem Mass Spectrometry

A multiresidue method for analyzing pesticides in vegetables and fruits by supercritical fluid extraction (SFE) and LC-MS/MS was developed. The sample preparation and SFE parameters were optimized for extracting LC-amenable polar and medium-polarity pesticides. High recoveries were achieved for most of the tested pesticides by extracting a 1 : 1 : 1 sample-Celite-anhydrous magnesium sulfate mixture with supercritical carbon dioxide at 16.4 MPa at 40℃ for 30 min with methanol added as a modifier. The recoveries of 117 pesticides fortified with 0.01 mg/kg of each pesticide were 70-120%, and the relative standard deviations were less than 25% for 112 pesticides in tomato and 103 pesticides in cucumber. No significant differences were observed in the residue concentrations determined in real samples by the SFE method and the liquid extraction method (the modified Japanese official method). Higher recoveries of polar pesticides, such as acephate and methamidophos, were achieved by the developed SFE method than by the liquid extraction method.

Rapid determination of six preservative residues in fruits and vegetables by high performance liquid chromatography using dispersive solid phase extraction

A dispersive solid phase extraction-high performance liquid chromatographic (HPLC) method was established for the simultaneous determination of 2,4-D, thiabendazole, 2-naphthol, o-phenyl phenol, diphenyl ether and biphenyl in the fruits and vegetables. The samples were vortexed for extraction with acetonitrile containing sodium chloride and anhydrous magnesium sulfate. The acetonitrile extraction was purified by acidic alumina dispersed solid phase extraction. The analysis was performed on an Agilent TC C18 column (250 mm x 4.6 mm, 5 microm) and an ultraviolet detector at 235 nm with a mobile phase of methanol-0.02 mol/L (pH 6) potassium dihydrogen phosphate solution, at a flow rate of 1.0 mL/min with gradient elution. Good linearities were observed in the range of 0.5-20 mg/L with correlation coefficients greater than 0.99. The average recoveries of the six preservatives in fruits and vegetables were in the range of 84.2% -99. 1% at three spiked levels of 1, 2 and 10 mg/kg (n = 6) and the relative standard deviations (RSDs) were in the range of 1.67%-10.3%. The limits of quantification were 1 mg/kg. This method is simple, accurate and suitable for the determination of the six preservatives in fruits and vegetables.

Simultaneous determination of six aflatoxins and sterigmatocystin in livestock and poultry tissues by QuEChERS-ultra high performance liquid chromatography-tandem mass spectrometry

A method for the simultaneous determination of six aflatoxins (AFTs) and sterigmatocystin (SMC) in livestock and poultry tissues by QuEChERS-ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. The samples were extracted with 10 mL acetonitrile-water (84:16, v/v) after enzymatic hydrolysis with 20 μL β-glucosidase. The extracts were cleaned with 1.0 g each of sodium chloride and anhydrous magnesium sulfate, and then degreased with 5 mL hexane. The residues were re-dissolved in 1 mL acetonitrile-water (80:20, v/v) containing 5 mmol/L ammonium acetate. Methanol and 5 mmol/L ammonium acetate were used as the mobile phases. Six AFTs and SMC were analyzed by multiple reaction monitoring in the positive ion mode. Matrix-matched calibration curves and external standards were used for the accurate quantification of the six AFTs and SMC. Good linear relationships were obtained, the correlation coefficients (R2) were greater than 0.99. The limits of detection (LODs, S/N=3) and the limits of quantification (LOQs, S/N=10) ranged from 0.007 to 0.30 μg/kg, and 0.02 to 0.91 μg/kg, respectively. The recoveries at different spiked levels were satisfactory, and ranged from 77.3% to 118.5%. This method is simple, easy and sensitive, and is suitable for the rapid determination of the six AFTs and SMC in different pork, pork liver and chicken samples.

Rapid Multiplug Filtration Cleanup with Multiple-Walled Carbon Nanotubes and Gas Chromatography–Triple-Quadruple Mass Spectrometry Detection for 186 Pesticide Residues in Tomato and Tomato Products

This study reports the development and validation of a novel rapid cleanup method based on multiple-walled carbon nanotubes in a packed column filtration procedure for analysis of pesticide residues followed by gas chromatography-triple-quadruple tandem mass spectrometry detection. The cleanup method was carried out by applying the streamlined procedure on a multiplug filtration cleanup column with syringes. The sorbent used for removing the interferences in the matrices is multiple-walled carbon nanotubes mixed with anhydrous magnesium sulfate. The proposed cleanup method is convenient and time-saving as it does not require any solvent evaporation, vortex, or centrifugation procedures. It was validated on 186 pesticides and 3 tomato product matrices spiked at two concentration levels of 10 and 100 μg kg(-1). Satisfactory recoveries and relative standard deviations are shown for most pesticides using the multiplug filtration cleanup method in tomato product samples. The developed method was successfully applied to the determination of pesticide residues in market samples.

Determination of 19 phthalate esters in cucumbers using QuEChERS coupled with gas chromatography-triple quadrupole mass spectrometry

An efficient method using QuEChERS equipped with triple quadrupole GC-MS/MS for the simultaneous detection of 19 phthalate acid ester residues in cucumbers was established. The phthalate acid esters were extracted from cucumber samples by ultrasonic with acetonitrile. The extracts were salted out and centrifuged with anhydrous magnesium sulfate and sodium chloride. The supernatants were enriched by vacuum distillation, and then purified by C18 adsorbent. The 19 phthalate esters were separated on an HP-5ms UI column (30 mx 0.25 mm x 0.25 μm), and determined using MS/MS in multiple reactions monitoring mode. The method showed favorable qualitative and quantitative analysis of the phthalate esters with good linearity (r ≥ 0.9995) in the linear range of 10-5,000 μg/kg and the limits of detection (LODs) were 0.2-3.5 μg/kg. With the proposed method, the recoveries were evaluated in cucumbers at the spiked levels of 10, 100 and 500 μg/kg. The results showed that the average recoveries were ranged from 63.3%-127.8% and the relative standard deviations (RSDs) were 0.5%-13.3%. In short, the proposed method with high sensitivity and good accuracy can meet the determination requirements for multi-residues. Furthermore, the method can be applied for the simultaneous determination of phthalate acid esters in cucumbers.

Validation study on a multi-residue analysis of pesticides in agricultural products by using phosphoric acid treatment and GC-MS/MS

A rapid method for multi-residue determination of pesticides in agricultural products was validated. The sample was cut into pieces and placed into a mixer cup containing half weight amount of 10% phosphoric acid in order to suppress degradation of easily degraded pesticides, represented by captan, and then homogenized. Pesticides in the phosphoric acid-treated sample were extracted with acetonitrile using a homogenizer, followed by salting out with anhydrous magnesium sulfate and sodium chloride. The extract was cleaned up on a C18 and graphite carbon black/PSA mini-cartridge column. Some pesticides gave tailing peaks, but these peaks became sharp and symmetrical when polyethylene glycol (PEG) 300 was added to the test solution. Recovery tests were performed on nine kinds of agricultural products (brown rice, soybean, spinach, cabbage, potato, orange, apple, strawberry, and Japanese pear) fortified with 170 pesticides at 0.01 and 0.1 μg/g. Each concentration of pesticide residue was extracted from 2 samples on 5 separate days. The trueness of the method for 147-164 pesticides in each sample was 70-120% with satisfactory repeatability and within-run reproducibility. This method is expected to useful for multi-residue analysis of pesticides in agricultural products.

Determination of phthalanilic acid residue in bean, fruits and vegetables using a modified QuEChERS method and ultra-performance liquid chromatography/tandem mass spectrometry

A rapid, sensitive and selective method for determining phthalanilic acid residue in bean, fruits and vegetables based on a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction procedure was developed by ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). The samples were extracted by acidified acetonitrile (0.4% (v/v) formic acid) and simultaneous liquid–liquid partitioning formed by adding anhydrous magnesium sulfate (MgSO4) and sodium chloride (NaCl). The extract was then cleaned up by dispersive-SPE using florisil and graphitized carbon black (GCB) as selective sorbent. Parameters including the matrix effect, linearity, precision, accuracy and stability were undertaken. The method showed good linearity in the concentration range of 10–1000 μg L−1, with correlation coefficients ≥0.997. Recovery studies were performed at three fortification levels of 10, 100 and 1000 μg kg−1 in soybean, apple, grape, cucumber, tomato and pepper. Further optimization of sample preparation and determination achieved recoveries ranging between 70.1% and 105.3% for the analyte with 0.7–14.9% intra-day relative standard deviations (RSD) and 0.2–8% inter-day RSD at three spiked levels (10, 100 and 1000 μg kg−1). The limits of detection (LOD) were below 1 μg kg−1, and the limits of quantification (LOQ) did not exceed 3 μg kg−1. The effects of two columns on the separation were also investigated. The method is demonstrated to be convenient and reliable for determination of phthalanilic acid in bean, fruits and vegetables. With the developed method, 60 samples of commercial fruit products (grape, apple), soybean and vegetables (pepper, tomato, cucumber) were analyzed. Phthalanilic acid was not detected in all samples.

Studies on rapid multi-residue analysis of pesticides in agricultural products by LC-MS/MS

Rapid multi-residue analysis of pesticides in agricultural products was studied by using LC-MS/MS. Pesticide residues in 10 g of homogenized agricultural products were extracted with 30 mL of acetonitrile and salted out with 4 g of anhydrous magnesium sulfate and 1 g of sodium chloride in the presence of citrate salts for buffering in a disposable tube. Co-extractives were removed by use of our original triple layered column (C18/GC/PSA; 60/30/60 mg). According to the method validation guideline of the Ministry of Health, Labour and Welfare of Japan, we conducted recovery tests in 5 kinds of agricultural products (brown rice, kiwi, cabbage, sweet potato and spinach) spiked with 60 pesticides at the level of 0.01 or 0.1 μg/g. Each concentration of pesticide spiked was extracted from 2 samples per day on 5 days. Pesticides in the test solution were determined by two types of LC-MS/MS using scheduled MRM. Using this method, 58 out of 60 pesticides satisfied the guideline criteria in brown rice, 59 in kiwi, 55 in cabbage, 55 in sweet potato and 56 in spinach. This method is applicable for routine examination of pesticide residues in agricultural products.

Determination of α-chaconine and α-solanine in commercial potato crisps by QuEChERS extraction and UPLC-MS/MS

AbstractA simple and fast analytical method for the determination of the main steroidal glycoalkaloids, α-chaconine and α-solanine, in commercial potato crisps, based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) extraction and ultra performance liquid chromatography coupled with an electrospray ionization triple-quadrupole tandem mass spectrometer (UPLC-MS/MS) in the multiple reaction monitoring mode was established and validated. The sample preparation procedure involves the extraction of the analytes with acidified acetonitrile and simultaneous liquid-liquid partitioning achieved by an addition of anhydrous magnesium sulfate and sodium acetate without any further clean-up steps. The limits of quantification (LOQs) for α-chaconine and α-solanine were 31 μg kg−1 and 16 μg kg−1 of fresh mass, respectively, at the signal-to-noise ratio (S/Ns) of 10. The method was applied in a survey of the content of α-chaconine and α-solanine in twenty commercial potato crisps from different brands. The results showed that all the products contained α-chaconine and α-solanine in widely varying concentrations. The amount of α-chaconine was higher than that of α-solanine in all samples.

Determination of trifluralin residue in aquatic products and edible oils by gas chromatography-negative chemical ionization mass spectrometry

A confirmatory method was established for the determination of trifluralin residue in aquatic products and edible oils with the technique of offline disperse solid phase extraction and gas chromatography-negative chemical ionization mass spectrometry (DSPE-GC-MS/NCI). Trifluralin was extracted from aquatic products and edible oils with acetonitrile, and liquid-liquid partitioning formed by adding anhydrous magnesium sulfate followed by a simple cleanup step known as dispersive solid-phase extraction. The aliquot was analyzed by GC-MS/NCI using isotope internal standard method. The method was reliable and stable. The recoveries of trifluralin were in the range from 80% to 100% at three spiked levels of 1.0, 2.0, and 3.0 microg/kg, and the RSDs were not more than 10.3%. The linearity of method was good from 1 to 40 microg/L, and the LOD was 0.02 microg/kg. This method can be used as a conclusive evidence method for the determination of trifluralin residue in aquatic products and edible oils.