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An analytical method based on dispersive solid-phase extraction (d-SPE) and ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) was employed for the determination of 43 mycotoxins in chestnut flour and wheat flour. A total of 128 samples consisting of 48 chestnut samples and 80 wheat flour samples were collected randomly and subjected to analysis. Finally, five specific toxins were selected as markers to identify these two foodstuffs. Acetonitrile-water (84∶16, v/v) was used to extract mycotoxins from chestnut flour and wheat flour. After extraction, the supernatant was transferred to the d-SPE equipment, using which purification was performed with C

Nowadays, anesthetics are widely used in fishery production processes, such as fish breeding, surgery, and fresh aquatic product transportation. Because of the widespread application of anesthetic drugs in aquatic products, there is an increasing demand for the rapid and sensitive detection of anesthetic drugs in aquatic products. The complex aquatic product matrix contains a variety of interfering substances, such as proteins, fats, and phospholipids, along with anesthetic drug residues at very low concentrations; therefore, it is necessary to adopt appropriate pretreatment methods for improving the sensitivity of detection. In this study, a dispersive solid-phase extraction (DSPE) method, combined with high-performance liquid chromatography, was established for the simultaneous detection of seven anesthetic drugs in aquatic products, viz. procaine, oxybuprocaine, tricaine, eugenol, methyl eugenol, isoeugenol, and methyl isoeugenol. For the DSPE step, pretreatment conditions, such as extraction solvent, extraction time, adsorbent amount, and DMSO dosage, were optimized. Sample pretreatment is a three-step process. First, in ultrasound-assisted extraction, 2.0 g samples were extracted using 10.0 mL 1.0% formic acid in acetonitrile under ultrasound conditions for 10 min. Then, DSPE was performed with mixed adsorbents: the solvent extracts were cleaned using 20 mg poly(styrene-glycidylmethacrylate) microspheres (PS-GMA), 50 mg primary secondary amines (PSA), and 10 mg C18, followed by separation by centrifugation. Finally, DMSO-assisted concentration was applied: the organic layer was collected and was dried at 40 ℃ in a N

A method for the detection of trace 1,4-dioxane in drinking water using headspace solid-phase microextraction (HS/SPME ) with gas chromatography/flame ionization detector (FID) was presented. Both the extraction conditions (SPME fiber, extraction temperature, extraction time, pH and sample volume, et al) and the gas chromatographic conditions were optimized. The results showed that the best response was obtained with 85 µm Carboxen-PDMS above 3 mL water in a 20-mL screw capped vial containing 3 mL sodium hydroxide solution (600 g/L). The best chromatographic separation was obtained on a PTA-5 capillary column (30 m x 0.53 mm x 3.0 µm) which was modified with alkali-bonding and of large pores and thick film. The linear range for 1,4-dioxane was 0.50-50.0 µg/L with the correlation coefficient (r) of 0.9995. The limit of detection (S/N > 3) was 0.14 µg/L. The recoveries for the actual water samples at low, medium and high spiked levels were 95.5%-107%, with the relative standard deviations of 1.1%-5.3% (n = 6). The developed method is simple, accurate, reproducible and highly sensitive. It is suitable for the routine monitoring of trace amount of 1,4-dioxane in the drinking water.

A rapid, sensitive and accurate method for the simultaneous determination of six phenolic environmental estrogens, i. e., bisphenol A (BPA), diethylstilbestrol (DES), dienestrol( DE), hexestrol (HEX), 4-( tert-octyl)-phenol (4-tOP) and 4-nonylphenol (4-NP) in bullfrog blood by dispersive solid-phase extraction-ultrafast liquid chromatography-tandem mass spectrometry (dSPE-UFLC-MS/MS) was established. After protein precipitation, bullfrog blood samples were cleaned-up by dSPE method with ethylenediamine-functionalized Fe3O4, magnetic polymers (EDA-MPs) as adsorbent. The effects of precipitation solvents, adsorption time and the amount of EDA-MPs used on the recoveries of six phenolic environmental estrogens were investigated in detail. Chromatographic separation was performed on a Shim-pack XR-ODS II analytical column (100 mm x 2.0 mm, 2.2 microm). The mass spectrometer was operated by using electrospray ion (ESI) source in the multiple reaction monitoring (MRM) mode. The results showed that the linearities were in the range of 0.5-100.0 microg/L with correlation coefficients (r2) not less than 0.999 6 for all the six phenolic environmental estrogens. The lim- its of quantification (LOQs) (S/N10) in bullfrog blood samples were between 0. 075 microg/L and 0.40 microg/L. The recoveries were between 95.0% and 110.0% at three spiked levels. The precision values expressed as relative standard deviations (RSDs) were in the range of 0.6%-6.3%. The developed method can be applied to the routine analysis of the six phenolic environmental estrogens in bullfrog blood samples.

A method was developed for the determination of 11 anabolic hormones (boldenone, androstenedione, nandrolone, methandrostenolone, methyltestosterone, testosterone, testosterone acetate, trenbolone, testosterone propionate, stanozolol, fluoxymesterone) in fish by multi-function impurity adsorption solid-phase extraction-ultrafast liquid chromatography-tandem mass spectrometry. After the sample was extracted by methanol, the extract was cleaned-up quickly by C18 adsorbent, neutral alumina adsorbent and amino-functionalized nano-adsorbent. The separation was performed on a Shim-Pack XR-ODS II column (100 mm x 2.0 mm, 2.2 microm) using the mobile phases of 0.1% (v/v) formic acid in acetonitrile and 0.1% (v/v) formic acid solution in a gradient elution mode. The identification and quantification were achieved by using electrospray ionization in positive ion mode (ESI+) in multiple reaction monitoring (MRM) mode. The matrix-matched external standard calibration curves were used for quantitative determination. The results showed that the calibration curves were in good linearity for the eleven analytes with the correlation coefficients (r) more than 0.999. The limits of detection (LODs, S/N3) for the 11 anabolic hormones were from 0.03 microg/kg to 0.4 microg/kg and the limits of quantification (LOQs, S/N10) were from 0.1 microg/kg to 1.5 microg/kg. The average recoveries ranged from 80.9% to 98.1% with the relative standard deviations between 5.2% and 11.5%. The method is simple, rapid, sensitive, accurate and suitable for the quantitative determination and confirmation of the 11 anabolic hormones in fish.

A sensitive and selective analytical method based on ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) was developed for the simultaneous determination of nine preservatives and sweeteners in yellow wine and wine. After the sample was diluted by pure water, the UFLC separation was performed on a Shim-pack XR-ODS II column (100 mm x 2.0 mm, 2.2 microm) with a linear gradient elution program of acetonitrile-ammonium acetate (AmAc, 2.5 mmol/L)-trifluoroacetic acid (TFA, 0.01%, v/v) aqueous solution as the mobile phase. Electrospray ionization was applied and operated in the negative multiple reaction monitoring (MRM) mode. The results showed that the limits of detection (LODs, S/N3) for the nine analytes were in the range of 0.03 - 15.0 microg/L, and the limits of quantitation (LOQs, S/N10) were in the range of 0.1 - 50.0 microg/L. The calibration curves showed good linearity for the nine analytes in their detection ranges, and the correlation coefficients (r2) were larger than 0.998. The recoveries were between 96.2% and 100.5% with the relative standard deviations (RSDs) of 0.6% - 5.4% for yellow wine, and between 96.0% and 104.0% with the RSDs of 0.7% - 4.8% for wine. Additionally, the mass spectral characterizations of the nine food additives were studied and the fragmentation pathways were speculated. The method is sensitive, reproducible and adaptable to the simultaneous rapid determination of the nine food additives in different yellow wine and wine samples.

The influences of ion-suppressors on retention behaviors of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in reversed-phase high performance liquid chromatographic (RP-HPLC) separation were investigated. The organic modification effects of acids, i. e. , trifluoroacetic acid (TFA) and buffer salts, i. e. , TFA-ammonium acetate (AmAc) were studied emphatically. The relationships between retention factors of solutes and volume percentages of ion-suppressors in the mobile phase systems of acetonitrile-TFA aqueous solution and acetonitrile-TFA-AmAc aqueous solution were quantitatively established, separately. The separation of nine food additives was completed by a gradient elution with acetonitrile-TFA (0.01%, v/v)-AmAc (2. 5 mmol/L) aqueous solution as the mobile phases. An RP-HPLC method was established for the simultaneous determination of nine food additives in red wine. In the range of 10. 0 - 100. 0 mg/L, nine food additives showed good linearity with the correlation coefficients ( r2 ) larger than 0. 999 1. The limits of detection (LODs) were in the range of 0. 33 - 2. 36 mg/L and the limits of quantification (LOQs) were in the range of 1. 11 - 7. 80 mg/L. The spiked recoveries were between 87. 61% and 108. 4% with the relative standard deviations (RSDs) of 2. 2% -9. 4%. These results are of referential significance for the rapid establishment and accu- rate optimization of RP-HPLC separation for the simultaneous determination of food additives in other foods.

A rapid qualitative and quantitative method for the simultaneous determination of trace diphacinone and chlorophacinone in biological samples has been established. The method mainly serves for the emergent poisoning detection. The whole blood was treated with methanol-acetonitrile (50/50, v/v) and the urine was cleaned-up by Waters Oasis HLB SPE cartridges. The samples were separated on an Extend C18 column (150 mm x 4.6 mm, 5 microm) by using the mobile phase consisted of ammonium acetate-acetic acid (0.02 mol/L, pH 5.5) - methanol (15/85, v/v). The determination was performed by high performance liquid chromatography coupled with ion trap mass spectrometry (HPLC-IT-MS) using a negative electrospray ionization interface in the multiple reaction monitoring (MRM) mode. The transitions of m/z 339 --167 for diphacinone and m/z 373 --201 for chlorophacinone were selected for the quantificantions. For the whole blood samples, the calibration curves were linear within the ranges of 1.0 - 200.0 microg/L and 0.5 - 100.0 microg/L; the limits of quantification were 1.0 microg/L and 0.5 microg/L; the spike recoveries were 90.1% - 92.2% and 87.6% - 93.4%, the intra-day relative standard deviations (RSDs) were less than 6.8% and 7.4%, and the inter-day RSDs were less than 9.9% and 10.9% for diphacinone and chlorophacinone, respectively. For the urine samples, the calibration curves were linear within the ranges of 0.2 - 40.0 microg/L and 0.1 - 20.0 microg/L; the limits of quantification were 0.2 microg/L and 0.1 microg/L; the spike recoveries were 90.1% -94.5% and 90.0% -98.0%, the intra-day RSDs were less than 6.1% and 7.3%, and the inter-day RSDs were less than 8.9% and 11.2% for diphacinone and chlorophacinone, respectively. This method is simple and sensitive for the satisfactory determination of trace diphacinone and chlorophacinone residues in poisoned patients for the clinical diagnosis.

Using isotope internal standard dilution technique, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed for the identification and quantitative determination of ciprofloxacin residue in the tissues of various fishes/shellfishes. The homogenized tissue sample added with ciprofloxacin-D8 and phosphate buffer solution (pH 7.0) was extracted with acetonitrile under ultrasonication, and degreased with hexane. After solid-phase extraction (SPE) was performed on an Oasis MAX cartridge, the sample was separated on a Cloversil-C18 column (150 mm x 4.6 mm, 5 microm) by using the mobile phase consisting of CH3CN-0.05% CF3 COOH (25:75, v/v). The detection was carried out by LC-MS/MS using an electrospray ionization interface in multiple reaction monitoring (MRM) mode. The quantification using isotope-labelled internal standard was based on the peak area ratio of ciprofloxacin and deuterated internal standard in the MRM mode. The calibration curve was linear within the range of 0.1 - 50.0 microg/kg and the limit of quantification was 0.1 microg/kg (S/Nor = 10). The recovery was between 92.5% and 98.1%, and the relative standard deviation was less than 4.3%. The application of this method was further demonstrated by analyzing ten various real samples from local markets. The results show that this method is sensitive, accurate and suitable for the confirmative determination of ciprofloxacin residues.

A simple, accurate and sensitive method has been developed for the simultaneous determination of warfarin, coumatetralyl, bromadiolone, flocoumafen and brodifacoum in whole blood by high performance liquid chromatography (HPLC) with fluorescence detection. The five 4-hydroxycoumarin rodenticides in whole blood were extracted by ethyl acetate, separated on XDB C,, column( 150 mm x 2. 1 mm, 5 [microm) by using the mobile phase consisting of methanol-0. 2% acetic acid aqueous solution (88: 12, v/v) at a flow rate of 0. 5 mL/min and detected with a variational time program for fluorescence wavelength. Each analyte was qualitatively determined with its fluorescence excitation spectrum, fluorescence emission spectrum and retention time being compared with those of the reference standard, and quantified with external calibration method. The linear range was 0. 01 - 10. 00 mg/L and the limit of quantification was 0. 01 mg/L except warfarin of which the corresponding results were 0. 05 - 10. 00 mg/L and 0. 05 mg/L. The recoveries were between 81% and 98% and the relative standard deviations (RSDs) were between 3. 8% and 8. 5%. This method can be used in the diagnosis of the clinical poisoned patients.