Mass spectrometric identification of polychlorinated dibenzothiophenes (PCDBTs) in surface sediments of the River Elbe

HRGC/MS was applied to six sediment samples from River Elbe for the determination of polychlorinated dibenzothiophenes (PCDBTs). Among the studied tri-, tetra- and octa-chlorinated isomers, trichlorinated species were found to be the dominating ones. The estimated concentration levels of the compounds were in the range of approximately 0.02–2 μg/kg dry weight for trichlorinated and 0.1–0.3 μg/kg for octachlorinated species. Tetrachlorinated dibenzothiophenes could not be detected. Received: 7 October 1997 / Revised: 4 February 1998 / Accepted: 9 February 1998     

Fast ultrasound‐assisted extraction followed by capillary gas chromatography combined with nitrogen–phosphorous selective detector for the trace determination of tebuconazole in garlic,soil and water samples

A fast and an efficient ultrasound‐assisted extraction technique using a lower density extraction solvent than water was developed for the trace‐level determination of tebuconazole in garlic, soil and water samples followed by capillary gas chromatography combined with nitrogen–phosphorous selective detector (GC–NPD). In this approach, ultrasound radiation was applied to accelerate the emulsification of the ethyl acetate in aqueous samples to enhance the extraction efficiency of tebuconazole without requiring extra partitioning or cleaning, and the use of capillary GC–NPD was a more sensitive detection technique for organonitrogen pesticides. The experimental results indicate an excellent linear relationship between peak area and concentration obtained in the range 1–50 μg/kg or μg/L. The limit of detection (S/N, 3 ± 0.5) and limit of quantification (S/N, 7.5 ± 2.5) were obtained in the range 0.2–3 and 1–10 μg/kg or μg/L. Good spiked recoveries were achieved from ranges 95.55–101.26%, 96.28–99.33% and 95.04–105.15% in garlic, Nanivaliyal soil and Par River water, respectively, at levels 5 and 20 μg/kg or μg/L, and the method precision (% RSD) was ≤5%. Our results demonstrate that the proposed technique is a viable alternative for the determination of tebuconazole in complex samples.     

Qualitative-quantitative analysis of multi-mycotoxin in milk using the high-performance liquid chromatography-tandem mass spectrometry coupled with the quick,easy, cheap,effective, rugged and safe method

High-performance liquid chromatography-tandem mass spectrometry coupled with the quick, easy, cheap, effective, rugged and safe method was established for the qualitative and quantitative detections of 20 mycotoxins in milk. The linear range of this method was 0.01–10 μg/L and the correlation coefficients were all greater than or equal to 0.9933. At three levels of addition, the spiked recoveries ranged from 80.00 to 112.50%, relative standard deviations were 2.67–14.97%, limits of quantitation were 0.02–4.00 μg/kg, and limits of detection were 0.007–1.300 μg/kg. This developed procedure for the identification and quantitation of mycotoxins provided prospective support for quality regulation.     

Innovative mixture of salts in the quick,easy, cheap,effective, rugged,and safe method for the extraction of residual macrolides in milk followed by analysis with liquid chromatography and tandem mass spectrometry

A simple extraction technique has been developed for seven macrolide antibiotics in milk. The procedure involves a modified quick, easy, cheap, effective, rugged, and safe method based on acetonitrile extraction, followed by the addition of a mixture of salts (sodium sulfate, sodium chloride, and potassium carbonate) not yet reported in literature. The method was validated for tylosin and was selective, free of matrix effect, and linear in the range of 0.78–18.75 ng/mL in the final extract, corresponding to 0.125–3 times the maximum residue limit. The limit of detection, limit of quantification, decision limit, and detection capability were, respectively, 0.84, 2.79, 58.4, and 71.7 μg/kg. The overall average recovery at 25, 50, and 75 μg/kg ranged from 89–97%. Repeatability and intermediate precision expressed by relative standard deviations were below 10.5 and 12%, respectively. The extension of the validation for spiramycin, throleandomycin, oleandomycin, roxithromycin, erythromycin, and clarithromycin is under consideration since the procedure proved to be able to efficiently extract all studied macrolides, with recoveries from 74–104% at 50 μg/kg for tylosin, erythromycin, spiramycin, and oleandomycin and 20 μg/kg for throleandomycin, roxithromycin, and clarithromycin.     

Multiresidue analysis of 36 pesticides in soil using a modified quick,easy, cheap,effective, rugged,and safe method by liquid chromatography with tandem quadruple linear ion trap mass spectrometry

A new method for simultaneous determination of 36 pesticides, including 15 organophosphorus, six carbamate, and some other pesticides in soil was developed by liquid chromatography with tandem quadruple linear ion trap mass spectrometry. The extraction and clean‐up steps were optimized based on the quick, easy, cheap, effective, rugged, and safe method. The data were acquired in multiple reaction monitoring mode combined with enhanced product ion to increase confidence of the analytical results. Validation experiments were performed in soil samples. The average recoveries of pesticides at four spiking levels (1, 5, 50, and 100 μg/kg) ranged from 63 to 126% with relative standard deviation below 20%. The limits of detection of pesticides were 0.04–0.8 μg/kg, and the limits of quantification were 0.1–2.6 μg/kg. The correlation coefficients (r²) were higher than 0.990 in the linearity range of 0.5–200 μg/L for most of the pesticides. The method allowed for the analysis of the target pesticides in the lower μg/kg concentration range. The optimized method was then applied to the test of real soil samples obtained from several areas in China, confirming the feasibility of the method.     

Dispersive liquid-liquid microextraction followed by gas chromatography–electron capture detection for determination of polychlorinated biphenyls in fish

A new method of dispersive liquid-liquid microextraction (DLLME) combined with GC-electron capture detection (GC-ECD) was proposed for the extraction and determination of four polychlorinated biphenyls (PCBs) congeners in fish samples. Acetone was used as extraction solvent for the extraction of PCBs from fish samples. The target analytes in the acetone solvent were rapidly transferred to chlorobenzene, which was used as extraction solvent in DLLME procedures. Under the optimum conditions, linearity was obtained in the concentration range from 1.25 to 1250 μg/kg for PCB 52, and 0.25 to 250 μg/kg for PCB 101, 138 and 153. Coefficients of correlation (r²) ranged from 0.9993 to 0.9999. The repeatability was tested by spiking fish samples at 10 μg/kg PCBs, and RSD% (n = 8) varied between 2.2 and 8.4%. The LODs were between 0.12 and 0.35 μg/kg. The enrichment factors of PCBs were from 87 to 123. The relative recoveries of the four PCB congeners for the perch, pomfret and yellow-fin tuna at spiking levels of 10, 20 and 50 μg/kg were in the range of 81.20–100.6%, 85.00–102.7% and 87.80–108.4%, respectively. The results demonstrated that DLLME combined with GC-ECD was a simple, rapid, and efficient technique for the extraction and determination of PCBs in fish samples.     

A new solid-phase extraction and HPLC method for determination of patulin in apple products and hawthorn juice in China

A new solid‐phase extraction (SPE) pretreatment method using a home‐made polyvinylpolypyrrolidone‐florisil (PVPP‐F) column was developed for the analysis of patulin in apple and hawthorn products in China. Fifty samples (25 apple juices, 12 apple jams, and 13 hawthorn juices) were prepared using the new method and then analyzed by high performance liquid chromatography with diode array detection (HPLC‐DAD) on an Agela Venusil MP C₁₈ reversed‐phase column (4.6 mm × 250 mm, 5 μm). The cleanup results for all samples using home‐made PVPP‐F column were compared with those obtained using a MycoSep®228 AflaPat column. The correlation coefficient R (0.9998) fulfilled the requirement of linearity for patulin in the concentration range of 2.5–250 μg/kg. The limits of detection (LODs) and quantification (LOQs) of patulin were 3.99 and 9.64 μg/kg for PVPP‐F column, and 3.56 and 8.07 μg/kg for MycoSep®228 AflaPat column, respectively. Samples were spiked with patulin at levels ranging from 25 to 250 μg/kg, and recoveries using PVPP‐F and MycoSep®228 AflaPat columns were in the range of 81.9–100.9% and 86.4–103.9%, respectively. Naturally occurring patulin was found in 2 of 25 apple juice samples (8.0%) and 1 of 13 hawthorn juice samples (7.7%) at concentrations ranging from 12.26 to 36.81 μg/kg. The positive results were further confirmed by liquid chromatography electrospray ionization mass spectrometry (LC‐ESI‐MS).     

Trace analysis of some organophosphorus pesticides in rice samples using ultrasound‐assisted dispersive liquid–liquid microextraction and high‐performance liquid chromatography

An ultrasound‐assisted dispersive liquid–liquid microextraction based on solidification of a floating organic drop method followed by high‐performance liquid chromatography was developed for the extraction, preconcentration, and determination of trace amounts of organophosphorus pesticides in rice samples. Variables affecting the performance of both steps were thoroughly investigated. Some effective parameters on extraction were studied and optimized. Under the optimum conditions, recoveries for rice sample are in the range of 58.0–66.0%. The calibration graphs are linear in the range of 4–800 μg/kg and, limits of detection and limits of quantification are in the range of 1.5–3 and 4.2–8.5 μg/kg, respectively. The relative standard deviation for 50.0 μg/kg of organophosphorus pesticides in rice sample are in the range of 4.4–5.1% (n = 5). The obtained results show that proposed method is a fast and simple method for the determination of pesticides in cereals.     

Enantioselective determination of triazole fungicide tebuconazole in vegetables,fruits, soil and water by chiral liquid chromatography/tandem mass spectrometry

A novel and sensitive method was developed for the determination of tebuconazole enantioselectively using reversed‐phase LC‐MS/MS. The separation and determination were performed using on an amylose‐based chiral stationary phase, a Lux 3u Amylose‐2 column (150 mm×2.0 mm), under isocratic conditions at 0.3 mL/min flow rate. A series of chiral stationary phases were investigated and the effect of mobile phase composition on the enantioseparation was discussed. Parameters including the matrix effect, linearity, precision, accuracy and stability were evaluated. Under optimal conditions, the overall mean recoveries for two enantiomers from the soil, tomato, cucumber, pear and apple samples were 79.3–101.1% with 2.8–11.5% intra‐day relative standard deviations (RSDs) and 4.1–8.6% inter‐day RSDs at 5, 25 and 50 μg/kg levels; the mean enantiomer recoveries from the water samples were 89.6–101.9% with 3.3–10.2% intra‐day RSDs and 5.1–7.7% inter‐day RSDs at 0.25, 0.5 and 2.5 μg/kg levels. The limits of detection (LODs) for all enantiomers in tomato, cucumber, pear, apple, soil and water were less than 0.6 μg/kg, whereas the limit of quantification (LOQ) did not exceed 2.0 μg/kg. The results indicate that this proposed method is convenient and reliable for the enantioselective determination of tebuconazole enantiomers in foods and environment samples.     

LC of sulfonamide residues in poultry muscle and eggs extracts using fluorescence pre‐column derivatization and monolithic silica column

A new, rapid, sensitive and selective HPLC method with fluorescence detection is described for the simultaneous determination of 12 sulfonamides, in the presence of putrescine as internal standard, after pre‐column derivatization with fluorescamine. The drugs were separated on a Chromolith Performance RP‐18 column (100×4.6 mm), using a gradient elution with a binary mobile phase of methanol/0.05 M acetate buffer (pH 3.4). Linearity of derivatization was obtained for concentrations from 3.0 to 300 μg/L in standard solutions. The whole procedure was evaluated and fully validated, according to the European Union Decision 2002/657/EC, for the determination of sulfonamides in turkey muscle and hen eggs following SPE. The LODs varied from 2 to 17 μg/kg in turkey and 2 to 15 μg/kg in egg samples. The average recoveries ranged between 96.9–108.6% in turkey muscle and 96.0–108.4% in egg samples, respectively.     

化学浸提-电感耦合等离子体发射光谱法测定粉条中活性铝的化学形态

采用化学浸提-电感耦合等离子体发射光谱法(ICP-OES)测定粉条中溶出铝的化学形态及其含量.实验结果显示,粉条溶出铝中,Al3+为135 μg/g,Al(OH)2+和Al(OH)2-未检出,胶态Al(OH)3o为143 μg/g,有机铝为460 μg/g.各化学形态铝含量的回收率在88.3％～105％范围,精密度(RSD)为1.14％,方法检出限为0.74 mg/kg.该方法准确度高,精密度好,检出限低,线性关系好,是一种简便实用的食品、药物中活性铝化学形态的检测方法.     

Simultaneous determination of pyflubumide and its metabolite in vegetables and fruits by ultrahigh performance liquid chromatography-tandem mass spectrometry

A rapid and cost-effective analytical method based on ultrahigh-performance liquid chromatography-tandem mass spectrometry was designed and verified for simultaneously monitoring the novel acaricide pyflubumide and its metabolite (pyflubumide-des(2-methyl-1oxopropyl)) in vegetables and fruits. After the extraction with acetonitrile, the samples were purified by dispersive solid-phase extraction with multi-walled carbon nanotubes. Detection of the two target analytes was achieved within 3.0 min using a positive electrospray ionization mode. The average recovery, intra-day precision, and inter-day precision of the two analytes at three spiked levels (2, 20, and 100 μg/kg) were 75.0–101.0, 0.4–4.4, and 0.6–5.3%, respectively. The limit of quantification of two compounds was 2 μg/kg, which was far below the maximum residue limits of pyflubumide in foods established by Japan and South Korea. Finally, the concentrations of pyflubumide and its metabolite in the samples were 16.6 and 7.8 μg/kg respectively, which verified the practicability and reliability of the method. The method was used to efficiently detect pyflubumide and its metabolite in real samples and was confirmed to be robust and effective for routinely analyzing both pyflubumide and its metabolite in vegetable and fruit samples.     

Development of a single‐run analytical method for the detection of ten multiclass emerging contaminants in agricultural soil using an acetate‐buffered QuEChERS method coupled with LC–MS/MS

This study was undertaken to develop and validate a single multiresidue method for the monitoring of ten multiclass emerging contaminants, viz. ceftiofur, clopidol, florfenicol, monensin, salinomycin, sulfamethazine, sulfathiazole, sulfamethoxazole, tiamulin, and tylosin in agricultural soil. Samples were extracted using an acetate‐buffered, modified quick, easy, cheap, effective, rugged, and safe method followed by liquid chromatography with tandem mass spectrometric analysis in positive ion mode. Separation on an Eclipse Plus C₁₈ column was conducted in gradient elution mode using a mobile phase of methanol (A) and distilled water (B), each containing 0.1% formic acid and 5 mM ammonium formate. The linearity of the matrix‐matched calibrations, expressed as determination coefficients, was good, with R ² ≥ 0.9908. The limits of quantification were in the range 0.05–10 μg/kg. Blank soil samples spiked with 4 × and 20 × the limit of quantification provided recovery rates of 60.2–120.3% (except sulfamethoxazole spiked at 4 × the limit of quantification, which gave 131.9%) with a relative standard deviation < 13% (except clopidol spiked at 20 × the limit of quantification, which gave 25.2%). This method was successfully applied to the monitoring of 51 field‐incurred agricultural loamy‐sand soil samples collected from 17 provincial areas throughout the Korean Peninsula. The detected and quantified drugs were clopidol (≤ 4.8 μg/kg), sulfathiazole (≤ 7.7 μg/kg), sulfamethazine (≤ 6.6 μg/kg), tiamulin (≤ 10.0 μg/kg), and tylosin (≤ 5.3 μg/kg). The developed method is simple and versatile, and can be used to monitor various classes of veterinary drugs in soil.     

Study of the packing density and molecular orientation of bimolecular self-assembled monolayers of aromatic and aliphatic organosilanes on silica

Bimolecular self-assembled monolayers (SAMs) of aromatic and aliphatic chlorosilanes were self-assembled onto silica, and their characteristics were established by contact angle measurement, near-edge X-ray absorption fine structure spectroscopy, and Fourier transform infrared spectroscopy. Three aromatic constituents (phenyltrichlorosilane, benzyltrichlorosilane, and phenethyltrichlorosilane) were studied in combination with four aliphatic coadsorbates (butyltrichlorosilane, butyldimethylchlorosilane, octadecyltrichlorosilane, and octadecyldimethylchlorosilane). Our results demonstrate that whereas SAMs made of trichlorinated organosilanes are densely packed, SAMs prepared from monochlorinated species are less dense and poorly ordered. In mixed systems, trichlorinated aromatics and trichlorinated aliphatics formed SAMs with highly tunable compositions; their surfaces were compositionally homogeneous with no large-scale domain separation. The homogeneous nature of the resulting SAM was a consequence of the formation of in-plane siloxane linkages among neighboring molecules. In contrast, when mixing monochlorinated aliphatics with trichlorinated aromatics, molecular segregation occurred. Although the two shortest aromatic species did not display significant changes in orientation upon mixing with aliphatics, the aromatic species with the longest polymethylene spacer, phenethyltrichlorosilane, displayed markedly different orientation behavior in mixtures of short- and long-chain aliphatics.     

A MSALL quantitative method for the determination of Poloxamer 188 in rat plasma by UHPLC–Q-TOF/MS and its application to pharmacokinetic study

Poloxamer (PL)188 is a commonly used pharmaceutical excipient with unique physicochemical properties. In this study, an MS^ALL quantitative method for the determination of PL188 in rat plasma by UHPLC–Q-TOF/MS was developed and validated. PL188 was analyzed on PLRP-S reversed-phase column (50 × 4.6 mm, 8 μm, 1,000 Å) with mobile phase 0.1% formic acid–water and 0.1% formic acid in acetonitrile–isopropanol (2:3, v/v). The liner range was 0.1–10.0 μg/ml. A pharmacokinetic study was performed on rats at a dose of 5 mg/kg by intravenous injection. The pharmacokinetic parameters of intravenous injection were as follows: half-life was 2.0 ± 1.1 h, volume of distribution was 5.1 ± 3.2 L/kg, area under the concentration–time curve was 3.0 ± 0.6 μg/L h and clearance was 1.7 ± 0.3 L/h/kg. The results indicated that PL188 could be rapidly distributed to tissues with a high clearance rate. This study can provide a good reference for the further study of PL188.     

液相色谱-串联质谱法测定甲壳类水产品中氨基脲的含量

利用液相色谱-串联质谱技术测定了甲壳类水产品中氨基脲的含量。样品用HCl水解、2-硝基苯甲醛衍生、乙酸乙酯萃取,液相色谱分离,串联质谱检测,内标法定量。方法检出限为0.25μg/kg(S/N>3);定量限为0.5μg/kg(S/N>10)。甲壳类水产品的品种涉及青虾、斑节对虾、罗氏沼虾、南美白对虾、小龙虾、青蟹、珍宝蟹、三疣梭子蟹、中华绒螯蟹和鲎等。虾类样品中氨基脲的含量在未检出～370.4μg/kg之间,蟹类样品中氨基脲的含量在未检出～87.5μg/kg之间。氨基脲在甲壳中含量最高,在肌肉中含量最低。结果表明:氨基脲作为内源性物质普遍存在于甲壳类水产品中。     

Immuno-affinity columns versus conventional clean-up: a method-comparison study for the determination of zearalenone in corn

The efficiency of a modern analytical method employing immuno-affinity columns (IACs) is compared to a well established traditional technique with respect to the determination of zearalenone (ZON) in corn in the μg/kg range. Despite of a constant error of about 4 μg/kg in the examined working range of 10–200 μg/kg, analytical data obtained from the analysis of spiked and naturally contaminated samples showed good correspondence for the compared methods. The performance characteristics of immuno-affinity-chromatography as a new clean-up technique for the determination of ZON in corn is reported for the first time and compared to a conventional clean-up procedure     

An enzyme linked immunoassay for the determination of deoxynivalenol in wheat based on chicken egg yolk antibodies

An indirect competitive enzyme linked immunoassay (ELISA) for the detection of the Fusarium mycotoxin deoxynivalenol (DON) in wheat was developed. Instead of the much more common antibody isolation from mammal serum, DON specific antibodies were, for the first time, isolated from the eggs of previously immunized hens. The limit of detection was 2 μg/L for standard curves and spiked wheat extracts. Recoveries for naturally contaminated samples (200–525 μg/kg) were between 80 and 125% compared with GC-ECD data. Concentrations for naturally contaminated samples were chosen with regard to current Austrian guidelines concerning DON levels in produce intended for human consumption, recommending a maximum of 500 μg DON/kg.     

Development of a procedure for the multiresidue analysis of pesticides in vineyard soils and its application to real samples

A procedure for multiresidue analysis was developed for the extraction and determination of 17 pesticides, including herbicides, fungicides, and insecticides, as well as certain degradation products, in vineyard soils from La Rioja region (Spain). Different solvents and mixtures were tested in spiked pesticide‐free soils, and pesticides were comparatively evaluated by gas chromatography with mass spectrometry and liquid chromatography with mass spectrometry. Recoveries >70%, with relative standard deviations <9%, were obtained when a mixture of methanol/acetone or a mixture of methanol/CaCl₂ 0.01 M for the most polar compounds was selected as the extraction solvent. Method validation was accomplished with acceptable linearity (r² ≥ 0.987) within the concentration range of 0.005–1 μg/mL corresponding to 1.667–333.4 μg/kg and 0.835–167.1 μg/kg for liquid chromatography with mass spectrometry and gas chromatography with mass spectrometry, respectively, and detection limits <0.4 μg/kg for the compounds were studied. The extraction method was applied to 17 real vineyard soil samples, and terbuthylazine and its metabolite desethylterbuthylazine were the most ubiquitous compounds, as they were detected in the 100% of the soils analyzed. The presence of fungicides was also high, and the presence of insecticides was lower than other pesticides. The results confirm the usefulness of the optimized procedure for monitoring residues in vineyard soils.     

Core-shell magnetic porous organic polymer for magnetic solid-phase extraction of fluoroquinolone antibiotics in honey samples followed by high-performance liquid chromatography with fluorescence detection

By monomer-mediated in-situ growth synthesis strategy, with hydroquinone and 1,3,5-tris(4-aminophenyl)benzene as monomers, a core-shell magnetic porous organic polymer was synthesized through a simple azo reaction. Based on this, a magnetic solid-phase extraction–high-performance liquid chromatography–fluorescence detection method was proposed for the analysis of fluoroquinolones in a honey sample. With ofloxacin, ciprofloxacin, enrofloxacin, lomefloxacin, and difloxacin as target analytes, factors affecting the extraction efficiency had been optimized. The LODs were 1.5–5.4 ng/L (corresponding to 0.23–0.81 μg/kg in honey). The linear range was 0.005–20 μg/L for difloxacin, 0.01–20 μg/L for ofloxacin, ciprofloxacin and lomefloxacin, and 0.02–20 μg/L for enrofloxacin. The enrichment factor was 84.4–91.7-fold with a high extraction efficiency of 84.4–91.7%. The method was assessed by the analysis of target fluoroquinolones in honey samples, and the recoveries for the spiked samples were 79.3–95.8%. The results indicated that the established magnetic solid-phase extraction–high-performance liquid chromatography–fluorescence detection method is efficient for the analysis of trace fluoroquinolones in honey.