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A method is proposed for the simultaneous determination of nine benzimidazole and neonicotinoid pesticides present in honey by employing automatic solid-phase extraction with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). A honey sample was dissolved in a phosphate buffer (pH=7.8) followed by ultrasonic extraction. The extracts were then purified through solid-phase extraction (SPE) with hydrophilic-lipophilic balance (HLB) cartridges. Finally, nitrogen was blown on the obtained mixture, and the mixture was subsequently filtered for conducting HPLC-MS/MS analysis. Nine compounds were detected under the multiple reaction monitoring (MRM) mode, and the corresponding quantification was performed by employing the method of internal standards. The nine detected pesticides demonstrated good linearity in the range of 0.002-0.05 mg/L, with the correlation coefficient values ( r 2 ) being higher than 0.99. The limits of detection (LODs) ( S/N =3) and limits of quantification (LOQs) ( S/N =10) were found to be in the ranges of 0.1-1.0 μg/kg and 0.3-2.0 μg/kg, respectively. Furthermore, the results indicated that the recoveries of the nine detected pesticides range from 78.2%-101.2% at three spiked levels of 5.0, 10.0, and 20.0 μg/kg with a relative standard deviation (RSD) range of 1.3%-14.3% ( n =6). Hence, the proposed method is rapid and can be employed for accurate determination of pesticide residues in large quantities of honey samples.

A method for the determination of three coriaria lactone residues in honey was developed using ultra high performance liquid chromatography-high resolution mass spectrometry. The honey samples were extracted with 0.2 mol/L phosphate buffer solution (pH = 7.5), and the extracts were cleaned up with Waters HLB solid phase extraction cartridges. The extracted components were separated on a Phenomenex C18 column by gradient elution. The qualitative and quantitative analyses were operated under t-MS2 by high resolution mass spectrometry. The results showed that the limits of detection and quantification for the three coriaria lactones in a spiked blank honey were 0.05 mg/kg and 0.1 mg/kg, respectively. The recoveries of the three coriaria lactones spiked in blank honey samples at the levels of 0.1 to 0.5 mg/kg were 86.3%-95.6% with the RSDs of 3.0%-8.4%. The method was applied for the determination of the manuka honey from New Zealand, and tutin was detected in one of the samples. The results showed that the method is suitable for the determination of the three coriaria lactone residues in honey.

A method was established for the determination of streptomycin (STR) and dihydrostreptomycin (DHS) in pollens based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was extracted and cleaned-up by a C18 solid phase extraction cartridge. The separation was carried out on a Protemix WCX-NP5 column (100 mm x 2.1 mm, 5 microm) with a gradient elution using 5% (v/v) formic acid, 20 mmol/L ammonium acetate and methanol as mobile phases. The analysis of streptomycin and dihydrostreptomycin was performed under electrospray positive ionization mode. The limits of detection (LOD, S/N = 3) and limits of quantification (LOQ, S/N = 10) for the both were 5 microg/kg and 10 microg/kg, respectively. Good linearities (r > 0.99) were achieved for the target compounds over the range of 10-200 microg/L. The recoveries at three spiked levels (10, 20, 50 microg/kg) in the blank matrices, such as pollen pini, corn pollen, camellia pollen, sunflower pollen, rape pollen and bee pollen, were from 76.8% to 100.3% with the relative standard deviations varied from 3.70% to 12.6%. The method is accurate, practical, and can be applied to most of the contaminated matrices. With this method, heptafluorobutyric acid is not required as mobile phase which is harmful to MS spectrometer.

A high-throughput method for the determination of 96 pesticides in six kinds of agricultural products by liquid chromatography-quadrupole/electrostatic field orbit trap high-resolution mass spectrometry was developed. After extraction with 0.1% acetic acid in acetonitrile solution and concentration, dispersive solid-phase extraction was further utilized to reduce the matrix interference. The chromatographic analysis was performed on a C18 column with methanol and 5 mmol/L ammonium acetate solution as the mobile phases with a gradient elution program. The 96 pesticide residues were analyzed in switching positive and negative modes at the same time. With the optimized mass resolution, accurate mass-to-charge ratio extraction of the target pesticide compounds in full scan mode could eliminate matrix interference effectively. Two-stage threshold-triggered full mass scan mode was utilized to further improve the accuracy of qualitative analysis. The linear ranges of all the 96 pesticides were from 1 microg/L to 200 microg/L with correlation coefficients greater than 0.99. By detecting spiked samples, the detection limits were 5 microg/kg for all the residues and the recoveries were in the range of 58% - 105% with the relative standard deviations (RSDs) between 8.8% and 18.3%.

A method was established for the determination of deoxynivalenol (vomitoxin) in grain and its products based on solid-phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was firstly extracted by acetonitrile-water (84:16, v/v). The extract was then cleaned-up by an HLB solid phase extraction cartridge. The separation was carried out on a Phenomenex Kinetex C18 column (100 mm x4. 6 mm, 2.6 microm) with a gradient elution using 0.3% per hundred ammonia solution-acetonitrile as mobile phases. The analysis of deoxynivalenol was performed under electrospray negative ionization mode. The limit of detection (LOD, S/N= 3) and the limit of quantification (LOQ, S/N = 10) were 20 microg/kg and 50 microg/kg, respectively. A good linearity (r > 0.99) was achieved for the target compound over the range of 20-1000 pg/L. The recoveries at the three spiked levels (50, 100, 500 microg/kg) in the blank matrices such as flour, barley, soybean, rice, cornmeal, cassava and wheat, were varied from 75.6% to 111.0% with the relative standard deviations no more than 13. 0%. The method is accurate, efficient, sensitive and practical. The cost of pretreatment is obviously reduced by replacing immunoaffinity columns and Mycosep columns with HLB columns which have the same purification effect.

A method for the determination of amoxicillin in honey by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established. The samples were dissolved by phosphate buffer and cleaned-up by solid phase extraction (SPE) cartridge. The analytes were determined by HPLC-MS/MS on a C18 column with methanol and 0.1% (v/v) formic acid solution as mobile phases with gradient elution. The analysis of amoxicillin was performed under selected reaction monitoring mode by selecting one parent ion and two daughter ions as qualitative ions and the most abundant daughter ion as quantitative ion. The external standard was used for quantitative analysis in this method. The calibration curve showed good linearity in the range of 2.0-100.0 microg/L with good precision and accuracy (r2 > 0.99). The limit of detection (LOD) and limit of quantitation (LOQ) were 2.0 microg/kg and 5.0 microg/kg, respectively. The average recoveries of amoxicillin in spiked honey ranged from 74.2% to 81.7% with the intra-day precisions (relative standard deviations, RSDs) from 2.8% to 7.8% and the inter-day precisions (RSDs) from 9.1% to 11.3%. This method is convenient and suitable for the determination of amoxicillin in honey.

The quantification method for the determination of kojic acid in foods using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. For solid samples, the kojic acid was extracted with acetonitrile; for liquid samples, they were diluted with water, then deproteinized by the deposition with zinc acetate and potassium ferrocyanide. The analytes were determined by HPLC-MS/MS on a C18 column with 5 mmol/L ammonium acetate/formic acid solution as mobile phases. The analysis of kojic acid was performed under selected reaction monitoring (SRM) mode by selecting one parent ion and two daughter ions as qualitative ions with [13C6]-kojic acid as the internal standard, and the most abundant daughter ion as quantitative ion. The limits of quantification (S/N > 10) were 0.1 mg/kg for the solid samples, and 2.5 mg/kg for the liquid samples. The good linearity (r > 0.99) was achieved for the target compound over the range of 0.1 - 2.0 mg/L. The recoveries at three levels for kojic acid were from 72.6% to 114% with the relative standard deviations no more than 11.4%. The method is simple and practical, and can be applied to most of matrices which may contain kojic acid as food additives. It can meet the qualitative and quantitative requirements for import and export foods.

A method for the determination of chloramphenicol in propolis was developed by high performance liquid chromatography-tandem mass spectrometry. The flavones were removed with lead acetate solution after the extraction of the sample with water. The extract was cleaned up by liquid-liquid extraction. Internal standard method was used for quantitative analysis. The linear range was 0.05 - 2.0 microg/L and the correlation coefficient (r2) was 0.9996. The limit of detection (LOD, S/N = 3) and limit of quantitation (LOQ, S/N = 10) were 0.1 microg/kg and 0.3 microg/kg, respectively. The recoveries ranged from 70.1% to 94.0% while the intra-day precision lower than 10% and inter-day precision lower than 15%. The method reduced the interference by removing most of the flavones and was suitable for the determination of chloramphenicol in propolis.

A method for the simultaneous analysis of 19 quinolone residues, enrofloxacin, ciprofloxacin, norfloxacin, ofloxacin, difloxacin, oxolinic acid, flumequine, sarafloxacin, sparfloxacin, danofloxacin, fleroxacin, marbofloxacin, enofloxacin, orbifloxacin, pipemidic acid, pefloxacin, lomefloxacin, cinofloxacin, and nalidixic acid in honey was developed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). In comparison of the three different extraction methods, i.e. acid solution coupled with cation-exchange solid-phase extraction cartridge (PCX), neutral buffer solution coupled with a reversed-phase extraction cartridge (HLB) and alkali solution coupled with a strong anion-exchange solid-phase extraction cartridge (PAX), the third method was finally used. The cartridge was then applied to accumulate and purify the target analytes from the sample matrices in one step. The HPLC separation was performed on a C18 column with a linear gradient elution program of methanol and 0.1% formic acid solution as the mobile phase. Selective reaction monitoring (SRM) was used for the selective detection of 19 quinolones. The linearity of all the 19 quinolones in the range from 1 microg/L to 100 microg/L had correlation coefficient greater than 0.991. In the detection of spiked samples, the detection limit of the method was 1.0 microg/kg for all the 19 quinolones, and the recoveries were 71% - 118% with the relative standard deviations of 4.2% - 6.7%. Internal standard calibration was used for the quantitative analysis.

A reliable and sensitive method was introduced for the analysis of streptomycin in royal jelly. The method was based on a separation by a C8 analytical column with beta-naphthoquinone-4-sulfonate post-column derivatization and fluorescence detection. The clean-up of the extract was done by solid-phase extraction, firstly with an octadecyl cartridge and secondly with a cation-exchange cartridge. The linear range was 0.02 - 0.5 mg/L and the correlation coefficient was 0.995 8. The limits of detection (S/N = 3) and quantitation (S/N = 10) of streptomycin were 0.005 mg/kg and 0.01 mg/kg, respectively. The recoveries ranged from 84.0% to 104.0% with the relative standard deviations not larger than 7.9%. The method reduced the possibility of the false positive, and it could meet the need of the current work.

A method for the determination of melamine residue in plant origin protein powders was developed using high performance liquid chromatography-diode array detection (HPLC-DAD) and HPLC-electrospray ionization tandem mass spectrometry (ESI-MS/MS). HPL-DAD was used in preliminary screening of the samples for melamine, and HPLC-MS/MS was used in the confirmatory of melamine. Trichloroacetic acid solution was used to precipitate proteins and to dissociate the target analyte from the sample matrix. The supernatant was cleaned up with strong cation exchange column for HPLC-MS/MS. The HPLC-DAD separation was carried out on a C18 column (250 mm x 4.6 mm, 5 microm) with 0.01 mol/L sodium n-heptanesulfate (pH adjusted to 4.5 with citric acid)-acetonitrile (90:10, v/v) as mobile phase at a flow rate of 1.0 mL/min, and detected at 240 nm. HPLC-MS/MS was performed in selected ion monitoring mode with trichloroacetic acid solution as ion pair reagent. The limits of detection were 10 mg/kg and 0.5 mg/kg for HPLC-DAD and HPLC-MS/MS, respectively. The mean recoveries were 76%-88% for HPLC-DAD and 72%-82% (matrix match calibration curve) for HPLC-MS/MS and the relative standard deviations were 3.4%-6.4% for both HPLC-DAD and HPLC-MS/MS.

A confirmatory method is presented for the determination of acrylamide in different food products by gas chromatography-mass spectrometry (GC-MS). The method is based on the extraction of acrylamide with and methanol, and purification with Carrez I zinc sulfate) and Carrez II (potassium hexacyanoferrate) solution, followed by bromination onto the acrylamide double bond. The derivative was extracted with ethyl acetate/hexane (4: 1, v/v), and converted to the stable 2-bromopropenamide by dehydrobromination using 10% triethylamine, then analyzed by GC-MS, employing 13C3-acrylamide as internal standard. In-house validation data for flour and bread showed good accuracy and precision of the method. The recoveries of acrylamide in the French fries and bread were all in the range from 80% to 110% after correction of analyte loss by the internal standard at three spike levels of 0.02, 0.05 and 0.2 mg/kg, and relative standard deviations (RSDs) no more than 12.7%. The limits of detection for flour and bread were estimated at 5 microg/kg.

Nitrofurans are a group of widely used veterinary antibiotics that have been banned in many countries. This has generated a great deal of interests and demands for assay of nitrofurans in animal food products. To our knowledge, this is the first time that a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been successfully developed for simultaneously analyzing the metabolites of four nitrofuran antibiotics (furazolidone, furaltadone, nitrofurazone and nitrofurantoin) in royal jelly. Trichloroacetic acid solution was used both to precipitate proteins and to provide acidic reaction condition. Four isotope internal standards were utilized to improve the quantitative precision. The limits of detection (LODs) were 0.03 microg/kg for the metabolite of furaltadone and 0.05 microg/kg for the other three metabolites. The limits of quantitation were 0.20 microg/kg for the metabolite of furaltadone and 0.25 microg/kg for the other three metabolites. The linear range was 0.4-20 ng/mL for all the target analytes. The recoveries calibrated by internal standard were in the range of 97.7%-104.8 with the relative standard deviations (RSDs) of 2.7-9.7. It showed that this method could meet the requirements of national monitoring plan in China and the Minimum Required Performance Limits (MRPL) set by the European Union.

An analytical method for the determination of lincosamide antibiotic residues in honey was developed. In the procedure a solid-phase extraction for the isolation of lincomycin and clindamycin from diluted honey samples was employed. The residues of lincomycin and clindamycin were subsequently analyzed by reversed-phase high performance liquid chromatography (RP-HPLC) coupled with electrospray tandem mass spectrometry. Mass spectral acquisition was applied with selective reaction monitoring of two diagnostic transition reactions. The qualitative analysis was based on the retention time, the precursor ion and two product ions, and the quantitation was carried out with intension of the characteristic ion m/z 126. The linear ranges were from 1.0 microg/L to 200 microg/L for lincomycin and clindamycin and the correlation coefficients (r2) were all greater than 0.996. The average recoveries for lincomycin and clindamycin ranged from 80% to 110% in replicate sets of honey samples spiked with the drug concentrations of 1.0, 5.0 and 20.0 microg/kg, and the relative standard deviations (RSDs) were less than 8% for intra-day and 15% for inter-day determinations. The method detection limit and quantitation limit were 0.1 micro/kg and 0.5 microg/kg, respectively. The method is simple and suitable for routine analysis.

A method for analysis of trace metronidazole (MTZ), dimetridazole (DMZ) and ronidazole (RNZ) residues in royal jelly was developed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). After samples were dissolved in sodium hydroxide solution to disassociate target analytes from matrix, liquid-liquid extraction methods by ethyl acetate solvent were used. Matrix effects were minimized and good quantitation results were obtained by using highly-selective reaction monitoring (H-SRM) technology when deuterated dimetridazole (dimetridazole-D3) was selected as internal standard. Limits of detection (LODs) were 1.0 microg/kg for DMZ, 0.5 microg/kg for MTZ and RNZ (S/N > 5). Limits of quantitation (LOQs) were 2.0 microg/kg for DMZ, 1.0 microg/kg for MTZ and RNZ (S/N > 10). The linear ranges were 2.0 - 200 microg/L for all target analytes. Recoveries and relative standard deviations (RSDs) were in the ranges of 96.6% - 110.6% and 2.1% -7.4%, respectively. This method is suitable for statutory residue testing in the National Residue Surveillance Plan in China and meets the requirement for export.