Simultaneous Determination of Furostanol, Pennogenyl, and Diosgenyl Glycosides in Taiwanese Rhizoma Paridis ( Paris formosana Hayata) by high-performance liquid chromatography with evaporative light scattering detection

A high-performance liquid chromatographic method with an evaporative light scattering detector (HPLC-ELSD) was developed to simultaneously determine 10 steroidal saponins, including 3 furostanol glycosides, 3 pennogenyl glycosides, and 4 diosgenyl glycosides in Taiwanese rhizoma paridis ( Paris formosana Hayata). The condition was a Cosmosil C18 column kept at 35 °C and a step-gradient solvent system consisting of acetonitrile and water (25:75, v/v) in the first 30 min, 45:55 (v/v) from 31 to 45 min, and 50:50 (v/v) from 45 to 65 min, at a flow rate of 1 mL/min. The separation factors (α) and resolutions (Rs) were better than 1, and the limits of detection (LODs) and limits of quantification (LOQs) were 0.01-0.27 and 0.04-0.90 μg, respectively, for these saponins. Moreover, 203 nm UV detection was also used for comparison. The saponins in P. formosana Hayata gathered from various areas of Taiwan were determined by applying the established method.     

Simultaneous determination of chloramphenicol and aflatoxin M1 residues in milk by triple quadrupole liquid chromatography-tandem mass spectrometry

A reliable, rapid, and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of chloramphenicol and aflatoxin M(1) in milk has been developed. This method includes simple extraction of sample with acetonitrile, separation on a MGIII-C(18) column using 5 mM ammonium acetate aqueous solution/methanol (60:40, v/v) as mobile phase, and MS/MS detection using multiple reaction monitoring mode. The method was validated according to Commission Decision 2002/657/EC. The limits of detection (LODs) were 0.05 μg/kg for chloramphenicol and 0.005 μg/kg for aflatoxin M(1.) The limits of quantification (LOQs) were 0.2 μg/kg for chloramphenicol and 0.02 μg/kg for aflatoxin M(1). The recovery values ranged from 88.8% to 100.6%, with relative standard deviation lower than 15% in all cases, when samples were fortified at three different concentrations. The decision limits (CCα) and detection capability (CCβ) of the method were also reported. This method has been successfully applied for simultaneous analysis of chloramphenicol and aflatoxin M(1) residues in milk from local supermarkets in China.     

A validated multianalyte LC-MS/MS method for quantification of 25 mycotoxins in cassava flour, peanut cake and maize samples

This study was designed to develop a sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous detection and quantification of 25 mycotoxins in cassava flour, peanut cake and maize samples with particular focus on the optimization of the sample preparation protocol and method validation. All 25 mycotoxins were extracted in a single step with a mixture of methanol/ethyl acetate/water (70:20:10, v/v/v). The method limits of quantification (LOQ) varied from 0.3 μg/kg to 106 μg/kg. Good precision and linearity were observed for most of the mycotoxins. The method was applied for the analysis of naturally contaminated peanut cake, cassava flour and maize samples from the Republic of Benin. All samples analyzed (fifteen peanut cakes, four maize flour and four cassava flour samples) tested positive for one or more mycotoxins. Aflatoxins (total aflatoxins; 10-346 μg/kg) and ochratoxin A (相似文献   

Development of a method for the simultaneous determination of six sulfonylurea herbicides in wheat, rice, and corn by liquid chromatography-tandem mass spectrometry

A sensitive and reliable method was developed and validated for trace determination of sulfonylurea herbicides residues in cereals (wheat, rice, and corn) by liquid chromatography-tandem mass spectrometry. The selected analytes were ethoxysulfuron, ethametsulfuron-methyl, bensulfuron-methyl, chlorimuron-ethyl, pyrazosulfuron-ethyl, and cyclosulfamuron. In this work, the extraction procedure was performed by using a mixture solvent of phosphate buffer (pH 9.5)/acetonitrile (8:2, v/v) as the extraction solvent and then was cleaned up by using Spe-ed C18/18% SPE cartridges, providing good recoveries for all of the tested analytes and with no matrix effects affecting method accuracy. The limits of detection for the studied analytes in cereal samples were between 0.043 and 0.23 μg kg(-1), and the limits of quantification were between 0.14 and 0.77 μg kg(-1), lower in all cases than the maximum residue limits permitted by the European Union for this kind of food. The developed methodology has demonstrated its suitability for the monitoring of these residues in cereal samples with high sensitivity, precision, and satisfactory recoveries.     

Development of a lateral flow colloidal gold immunoassay strip for the rapid detection of olaquindox residues

A rapid immunochromatographic lateral flow test strip of competitive format has been developed for the specific determination of olaquindox (OLA) residues in pig urine and muscle tissues. The sensitivity of the test strip was found to be 1.58 ± 0.27 μg/kg and 1.70 ± 0.26 μg/kg of OLA in pig urine and muscle tissues, and the lower detection limit was 0.27 ± 0.08 μg/kg and 0.31 ± 0.07 μg/kg respectively. For negative pig urine and muscle samples spiked with 4, 12, and 36 μg/kg, the recovery range was 83.0-94.0% and 78.8-87.4% and the coefficient of variation scope [CV (%)] was 3.17-7.41% and 4.66-7.64% respectively. Parallel analysis of OLA samples from pig urine and muscle tissue showed comparable results from the test strip and HPLC. Each test requires 5-8 min, and the test strip can provide a useful screening method for quantitative, semiquantitative, or qualitative detection of OLA residues.     

Direct liquid chromatography method for the simultaneous quantification of hydroxytyrosol and tyrosol in red wines

A validated HPLC method with fluorescence detection for the simultaneous quantification of hydroxytyrosol and tyrosol in red wines is described. Detection conditions for both compounds were optimized (excitation at 279 and 278 and emission at 631 and 598 nm for hydroxytyrosol and tyrosol, respectively). The validation of the analytical method was based on selectivity, linearity, robustness, detection and quantification limits, repeatability, and recovery. The detection and quantification limits in red wines were set at 0.023 and 0.076 mg L(-1) for hydroxytyrosol and at 0.007 and 0.024 mg L(-1) for tyrosol determination, respectively. Precision values, both within-day and between-day (n = 5), remained below 3% for both compounds. In addition, a fractional factorial experimental design was developed to analyze the influence of six different conditions on analysis. The final optimized HPLC-fluorescence method allowed the analysis of 30 nonpretreated Spanish red wines to evaluate their hydroxytyrosol and tyrosol contents.     

Simultaneous determination of ethidimuron, methabenzthiazuron, and their two major degradation products in soil

An analytical method has been developed for the quantification of two herbicides (ethidimuron and methabenzthiazuron) and their two main soil derivatives. This method involves fluidized-bed extraction (FBE) prior to cleanup and analysis by reverse-phase liquid chromatography with UV detection at 282 nm. FBE conditions were established to provide efficient extraction without degradation of the four analytes. (14)C-labeled compounds were used for the optimization of extraction and purification steps and for the determination of related efficiencies. Extraction was optimal using a fexIKA extractor operating at 110 degrees C for three cycles (total time = 95 min) with 75 g of soil and 150 mL of a 60:40 v/v acetone/water mixture. Extracts were further purified on a 500 mg silica SPE cartridge. Separation was performed on a C18 Purosphere column (250 mm x 4 mm i.d.), at 0.8 mL min(-1) and 30 degrees C with an elution gradient made up of phosphoric acid aqueous solution (pH 2.2) and acetonitrile. Calibration curves were found to be linear in the 0.5-50 mg L(-1) concentration range. Besides freshly spiked soil samples, method validation included the analysis of samples with aged residues. Recovery values, determined from spiked samples, were close to 100%. Limits of detection ranged between 2 and 3 microg kg(-1) of dry soil and limits of quantification between 8 and 10 microg kg(-1) of dry soil. An attempt to improve these performances by using fluorescence detection following postcolumn derivatization by orthophthalaldehyde-mercaptoethanol reagent was unsuccessful.     

Portable surface plasmon resonance immunosensor for the detection of fluoroquinolone antibiotic residues in milk

An inexpensive and portable surface plasmon resonance (SPR) sensor, SPReeta Evaluation Kit SPR3, has been used to develop a biosensor for the determination of fluoroquinolone antibiotics (FQs) and to demonstrate its performance analyzing FQ residues in milk samples. The SPReeta three-channel gold chips were activated with a mixed self-assembled monolayer (m-SAM) and functionalized with a FQ haptenized protein. Binding of the antibody produced a concentration-dependent increase of the SPR signal as a result of the change in the refraction index. Similarly, the presence of the FQ produced a dose-dependent decrease of the response, which allowed a good limit of detection (LOD) to be obtained (1.0 ± 0.4 μg L(-1) for enrofloxacin in buffer). The response was reproducible in all three channels, on different injections and days, and also between chips. Milk samples could be analyzed after a simple sample treatment involving fat removal by centrifugation and dilution with water. Under these conditions calibration curves were obtained showing that FQ residues can be analyzed in milk samples with an IC(50) value of 26.4 ± 7.2 μg L(-1) and a LOD of 2.0 ± 0.2 μg L(-1) (for enrofloxacin), far below the European Union regulations for this antibiotic family in this matrix. Finally, the paper also demonstrates that the biosensor is able to selectively detect the presence of FQs in milk samples, even in the presence of other antibiotics. Enrofloxacin, ciprofloxacin, and norfloxacin residues were detected in blind samples supplied by Nestle? Co.     

Synchronous fluorescence as a rapid method for the simultaneous determination of folic acid and riboflavin in nutritional beverages

A rapid synchronous spectrofluorimetric method was first developed for the simultaneous determination of folic acid and riboflavin in nutrimental beverages. Folic acid could be detected by using H(2)O(2) plus Cu(II) as oxidation system to produce pterine-6-carboxylic acid, which had strong fluorescence in aqueous solution, and riboflavin itself was obviously fluorescent. Various operational parameters were thoroughly discussed in terms of their effects on the fluorescence signals, including instrumental parameters, concentration of the oxidation system, and pH. Under optimum conditions, the calibration curves were linear in the ranges of 100-250 μg/L for folic acid and 1-250 μg/L for riboflavin, and the detection limits were 2.0 and 0.014 μg/L, respectively. In addition, this method was applied to the determination of folic acid and riboflavin in nutrimental beverages with satisfactory results.     

Development of an immunoaffinity chromatography purification and ultra performance liquid chromatography tandem mass spectrometry method for determination of 12 sulfonamides in beef and milk

A highly selective and sensitive method was developed for the simultaneous determination of 12 sulfonamides in beef and milk by immunoaffinity chromatography purification coupled to ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The MS/MS conditions, UPLC mobile phase, injection solution, sample purification process, and matrix effect were studied to optimize the operating conditions. The limits of detection (LODs) of the instrument for the studied sulfonamides ranged from 0.4 to 2.0 μg L(-1), being 1.6-8.0 μg kg(-1) for beef and 1.8-6.4 μg kg(-1) for milk. The standard solution was diluted with blank beef or milk matrix for the construction of calibration curves, which had a linear range from 10 to 200 μg kg(-1) and regression coefficients higher than 0.990 (n=10) for all the studied sulfonamides. Samples spiked at 10, 20, and 100 μg kg(-1) showed recoveries above 70% and relative standard deviations below 10%.     

Rapid and sensitive determination of sulfonamide residues in milk and chicken muscle by microfluidic chip electrophoresis

A new, rapid, and sensitive method was proposed for the determination of sulfonamide residues in milk and chicken muscle samples by microchip electrophoresis with laser-induced fluorescence detection. Separation of fluorescamine-labeled sulfonamides was accomplished by using a buffer containing 5 mmol/L boric acid and 1% (w/v) polyvinyl alcohol (PVA). The pH, amount of PVA, and concentration of boric acid in the running buffer were found to have great influence on the separation. By optimizing these conditions, the separation of four sulfonamides, sulfamethazine, sulfamethoxazole, sulfaquinoxaline, and sulfanilamide, was achieved within 1 min with limits of detection (S/N = 3) of 0.2-2.3 μg/L, which are well below the maximum residue limit. The proposed method also exhibited very good repeatability; the relative standard deviations for both within-day and between-day measurements were ≤3.0%. With a simplified sample pretreatment protocol, fast determination of sulfonamides in real samples was successfully performed with standard addition recoveries of 93.3-100.8 and 82.9-92.3%, respectively.     

Determination of polymer additives-antioxidants and ultraviolet (UV) absorbers by high-performance liquid chromatography coupled with UV photodiode array detection in food simulants

An analytical method for the quantitative determination of migration levels of polymer additives such as antioxidants and UV absorbers in food packages by high-performance liquid chromatography coupled with UV-vis photodiode array detection has been developed. The pretreatment step involved solid-phase extraction with silica C18 cartridges. The analytical method showed good linearity, presenting regression coefficients (R(2)) ≥ 0.9990 for all compounds. This optimized method was also validated with respect to precision, reproducibility, stability, and accuracy. The limits of detection and quantification were between 0.09 and 1.72 μg mL(-1) and between 0.20 and 5.64 μg mL(-1) for 12 analytes, respectively. Recoveries were in the range of 67.48 and 108.55%, with relative standard deviations between 2.76 and 9.81%. Migration levels of antioxidants and UV absorbers were determined. Butylated hydroxyanisole, 2,6-di-tert-butyl-4-methylphenol (BHT), 2,4-di-tert-butylphenol, Cyanox 2246, Irganox 1035, Tinuvin 326, Tinuvin 328, Irganox 1010, and Irganox 1330 were detected; BHT and Cyanox 2246 were at higher levels than the specific migration levels in some food simulants.     

Development of an enzyme-linked immunosorbent assay based a monoclonal antibody for the detection of pyrethroids with phenoxybenzene multiresidue in river water

A sensitive and broad class selective direct competitive enzyme-linked immunosorbent assay (ELISA) using monoclonal antibody (McAb) has been described for the detection of pyrethroids with phenoxybenzene group. One monoclonal antibody, 2G(2)E(7), was obtained and characterized after fusion of myeloma cells with spleen cells isolated from BALB/c mice. The assay with the most selectivity for the family pyrethroids with phenoxybenzene group was optimized. The IC(50) values of the optimized immunoassay were 1.8 μg L(-1) for deltamethrin, 1.5 μg L(-1) for cypermethrin, 2.0 μg L(-1) for fluvalinate and fenvalerate, 2.2 μg L(-1) for phenothrin, 2.4 μg L(-1) for flucythrinate, 3.0 μg L(-1) for fenpropathrin, and 5.0 μg L(-1) for permethrin. River water samples fortified with pyrethroids were analyzed with the ELISA to evaluate the accuracy of the assay. The recoveries of pyrethroids in spiked water samples ranged from 74 to 108%. The results indicate that the ELISA developed can accurately simultaneously determine pyrethroids with phenoxybenzene group in water samples.     

Development of multiresidue analysis for twenty phthalate esters in edible vegetable oils by microwave-assisted extraction-gel permeation chromatography-solid phase extraction-gas chromatography-tandem mass spectrometry

A novel multiresidue analysis method is developed for the determination of twenty phthalate esters at the μg/kg level in edible vegetable oils by microwave-assisted extraction-gel permeation chromatography-solid phase extraction-high resolution gas chromatography-tandem mass spectrometry (MAE-GPC-SPE-HRGC-MS/MS). The samples were extracted with methanol under microwave incubation. Cleanup was carried out with GPC followed by a further C18 SPE column and then separated by the HP-5MS capillary column under a temperature program. The eluents were qualitatively and quantitatively determined by tandem mass analyzer with selected reaction monitoring (SRM) type and positive ion mode. The calibration curves showed good linearity in the range 5 μg/kg to 2.50 mg/kg with correlation coefficients larger than 0.999. Low detection limits (LODs) of 0.218-1.367 μg/kg and quantification limits (LOQ) of 0.72-4.51 μg/kg were achieved. The mean recoveries were in the range from 93.04% to 104.6% at 5, 15, and 40 μg/kg spiked levels, and the relative standard deviations (RSDs) were in the range of 1.01% and 5.26% (n = 7). This method could potentially overcome the interference from large amounts of lipids and pigment. The real sample test showed this method can be used for sensitive and accurate determination and confirmation of phthalate ester residues in high-fat and complex samples.     

土壤微量节肢动物组织中镉测定方法的改进

Highly precise and reliable determination of heavy metals in soil micro-arthropod tissues remains a challenge because of the small size of the animals and their typical low abundance in metal-contaminated agricultural soils. The present study sought to develop a method for cadmium(Cd) determination in soil micro-arthropods by optimizing the sample digestion procedure, reducing sample weight, modifying sample pre-treatment and validating the methodology with field samples. The optimized digestion conditions comprised a sample mass of 50–150 μg, digestion reagent of nitric acid:hydrogen peroxide(3:1), digestion temperature of 105℃,digestion period of 3 h and digestion volume of 30 μL. Defecation of the standard Collembola Folsomia candida(92 h) and the indigenous Collembola Onychiurus yodai(42 h) and ultrasonic cleaning of F. candida increased the accuracy of Cd determination.The recovery of Cd using the refined procedure was 98.9% and the limits of detection and quantification were 0.002 and 0.008 μg L~(-1), respectively. The within-batch precision values were 3%. The Cd concentrations in the tissues of the Collembola Isotoma sp.collected from a range of metal-contaminated fields determined by the improved method were consistent with the Cd concentrations in the field soils. The results indicate that the optimized method can be used for more accurate or reliable determination of Cd concentrations in soil micro-arthropod tissues.     

Analysis of pesticides in honey by solid-phase extraction and gas chromatography-mass spectrometry

An analytical method for the simultaneous determination of 51 pesticides in commercial honeys was developed. Honey (10 g) was dissolved in water/methanol (70:30; 10 mL) and transferred to a C(18) column (1 g) preconditioned with acetonitrile and water. Pesticides were subsequently eluted with a hexane/ethyl acetate mixture (50:50) and determined by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM). Spiked blank samples were used as standards to counteract the matrix effect observed in the chromatographic determination. Pesticides were confirmed by their retention times, their qualifier and target ions, and their qualifier/target abundance ratios. Recovery studies were performed at 0.1, 0.05, and 0.025 microg/g fortification levels for each pesticide, and the recoveries obtained were >86% with relative standard deviations of <10%. Good resolution of the pesticide mixture was achieved in approximately 41 min. The detection limits of the method ranged from 0.1 to 6.1 microg/kg for the different pesticides studied. The developed method is linear over the range assayed, 25-200 microg/L, with determination coefficients of >0.996. The proposed method was applied to the analysis of pesticides in honey samples, and low levels of a few pesticides (dichlofluanid, ethalfluralin, and triallate) were detected in some samples.     

Development and validation of an indirect competitive enzyme-linked immunosorbent assay for the screening of tylosin and tilmicosin in muscle, liver, milk, honey and eggs

Incorrect use of tylosin and tilmicosin could result in allergy and select resistance. To monitor the illegal use of these antibiotics in animals, a monoclonal-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) has been established. Several haptens were synthesized and conjugated to carrier protein. Female Balb/c mice were inoculated with the four different conjugates to produce monoclonal antibodies according to the schemes of immunization. Aftercell fusion and culture several times, nine hybridoma cell lines were isolated. Only one, 3C4 that has isotype IgG2a, was selected for detailed study. The cross-reactivity of the monoclonal antibody 3C4 to tylosin and tilmicosin was 100% and 51% respectively. The standard curves based on the tylosin and tilmicosin matrix calibration ranged from 2.5 to 40 μg L(-1), with an IC(50) value of 6.1 μg L(-1) and 12.1 μg L(-1), respectively. The limits of detection of the ic-ELISA ranged from 5.1 μg kg(-1) to 13.8 μg kg(-1) in edible animal tissues. The recoveries were 74.1% to 120.7% with less than 18.6% of the coefficient of variation when tylosin and tilmicosin were spiked in various biological matrices with the concentrations of 25.0-200.0 μg kg(-1). Good correlations between the results of the ic-ELISA and high performance liquid chromatography were observed in the incurred tissues. These results suggest that the ic-ELISA is a sensitive, accurate and low-cost method that would be a useful tool for the screening of the residues of tylosin and tilmicosin in muscle, liver, milk, honey and eggs.     

LC-MS/MS analysis of neonicotinoid insecticides in honey: methodology and residue findings in Austrian honeys

An analytical method for the simultaneous determination of residues of eight neonicotinoid insecticides and two metabolites in honey using LC-MS/MS was developed and validated. Two approaches of sample preparation were investigated, with the final method involving acetonitrile extraction and subsequent cleanup by dispersive solid-phase extraction (QuEChERS type). Validation was based on quintuplicate analysis at three fortification levels and showed satisfactory recoveries (60-114%) and high precision (RSDs between 2.7 and 12.8%). Low limits of detection and quantification could be achieved for all analytes ranging from 0.6 to 5 μg/kg and from 2 to 10 μg/kg, respectively. Investigations of Austrian honey samples revealed the presence of acetamiprid, thiacloprid, and thiamethoxam residues in honey; however, no sample exceeded the maximum residue limits. On average, flower honey samples contained neonicotinoid residues in higher quantities compared to forest honey samples.     

Quantification of soy isoflavones, genistein and daidzein, and conjugates in rat blood using LC/ES-MS.

Genistein is the principal soy isoflavone to which the putative beneficial effects of soy consumption have been attributed; however, the possibility of adverse biological effects (e.g., estrogenic, antithyroid) has also been raised. This paper describes development and validation of a simple and sensitive analytical method for the determination of genistein in the blood of rats receiving dietary genistein (<0.5-1250 microg of genistein aglycone/g of chow). The method uses serum/plasma deproteination, liquid-liquid extraction, deuterated genistein and daidzein internal standards, isocratic LC separation, and electrospray mass spectrometric quantification using selected ion monitoring. Extraction efficiency is approximately 85%, the detection limits for genistein and daidzein from 50 microL of rat blood are approximately 5 nM, and the limit of quantification is approximately 15 nM. Interassay precision (relative standard deviation 4.5-4.6%) and intraassay precision (3.3-6.7%) were determined from replicate analysis of a spiked control and an incurred serum sample. The distribution of conjugated and unconjugated forms of genistein in the blood of rats was determined using selective enzyme hydrolysis. The glucuronide was the predominant metabolite (>90%), and only small amounts of the sulfate conjugate and the aglycone were observed at all dose levels. No evidence for additional metabolites was obtained. The 7- and 4'-glucuronide conjugates of genistein were identified using electrospray mass spectrometry and (1)H NMR. Total blood genistein ranged from <15 nM in animals fed soy-free control diet to as high as 8.9 microM in male rats fed 1250 microg of genistein/g of chow and encompasses blood isoflavone levels observed in humans consuming a typical Asian diet and nutritional supplements (0.1-1 microM) and infants consuming soy formulas (2-7 microM).     

Synthesis of a novel composite imprinted material based on multiwalled carbon nanotubes as a selective melamine absorbent

A novel composite imprinted material, on the basis of a multiwalled carbon nanotube (CNT)-incorporated layer using melamine as a template, methacrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a cross-linker, was synthesized by a surface imprinting technique. The imprinted/CNT sorbent was characterized by a scanning electron microscope (SEM). Adsorption dynamics and a Scatchard adsorption model were employed to evaluate the adsorption process. The results showed that the imprinted/CNT sorbent displayed a rapid dynamic adsorption and a high adsorption capacity of 79.9 μmol g(-1) toward melamine. Applied as a sorbent, the imprinted/CNT sorbent was used for the determination of melamine in a real sample by online solid-phase extraction-high-performance liquid chromatography (SPE-HPLC). An enrichment ratio of 563-fold, detection limit (S/N = 3) of 0.3 μg L(-1), and quantification limit of 4.5 μg L(-1) were achieved.