ABSTRACT
Objective To establish a method for the determination of 10 organophosphorus flame retardants in drinking water by on-line solid phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry (On-line SPE-UPLC-MS/MS). Methods After adding the internal standard, the water sample was filtered by Millipore filtration, and then concentrated and detected by Online SPE-UPLC-MS/MS. Samples were concentrated by C8 SPE column and separated by C18 column with acetonitrile-water-formic acid as the mobile phases gradient elution，and were detected by multiple reaction monitoring (MRM) acquisition under anion mode. Results The 10 organophosphorus flame retardants all displayed good linear relationships within a certain range of concentrations, with the correlation coefficients being more than 0.990. The method detection limits were 0.60-5.50 ng/L, and the spiked recoveries of low, medium and high concentrations were 64%-106% , 83%-104% and 85%-99%, respectively. Conclusion The method is simple, sensitive, rapid, accurate and reliable, so it is applicable for the determination of 10 organophosphorus flame retardants in drinking water.
ABSTRACT
In this study,we developed a novel on-line solid phase extraction (SPE)-ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS)-based analytical method for simulta-neously quantifying 12 illicit drugs and metabolites (methamphetamine,amphetamine,morphine,co-deine,6-monoacetylmorphine,benzoylecgonine,3,4-methylenedioxymethamphetamine,3,4-methylenedioxyamphetamine,cocaine,ketamine,norketamine,and methcathinone) and cotinine(COT) in wastewater samples.The analysis was performed by loading 2 mL of the sample onto an Oasis hydrophilic-lipophilic balance cartridge and using a cleanup step (5％ methanol) to eliminate interference with a total run time of 13 min.The isotope-labeled internal standard method was used to quantify the target substances and correct for unavoidable losses and matrix effects during the on-line SPE process.Typical analytical characteristics used for method validation were sensitivity,linearity,precision,repeatability,recovery,and matrix effects.The limit of detection (LOD) and limit of quantification (LOQ)of each target were set at 0.20 ng/L and 0.50 ng/L,respectively.The linearity was between 0.5 ng/L and 250 ng/L,except for that of COT.The intra-and inter-day precisions were ＜10.45％ and 25.64％,respec-tively,and the relative recovery ranged from 83.74％ to 162.26％.The method was used to analyze various wastewater samples from 33 cities in China,and the results were compared with the experimental re-suits of identical samples analyzed using off-line SPE.The difference rate was between 19.91％and-20.44％,and the error range could be considered acceptable.These findings showed that on-line SPE is a suitable alternative to off-line SPE for the analysis of illicit drugs in samples.
ABSTRACT
An automated on-line solid phase extraction-liquid chromatography-tandem mass spectrometry ( on-line SPE-LC-MS/MS ) method for the simultaneous quantification of six endogenous phytohormones including abscisic acid ( ABA ) , indole-3-acetic acid ( IAA ) , salicylic acid ( SA ) , jasmonic acid ( JA ) , indole-3-propionic acid ( IPA) and indole-3-butyric acid ( IBA) in rice tissues was described. Plant samples were extracted with methanol and on-line SPE procedure was performed with C18 SPE cartridges. Analytes were eluted to C18 analytical column with mobile phase and further analyzed by LC-MS/MS. The performance of the method was fully validated. Linearity showed good correlation (R2≥0. 99). Limits of detections (S/N=3) were in the range of 0. 1-0. 8 μg/kg. Recoveries varied between 71. 2% and 126%. The method was rapid and sensitive to determine multiple phytohormones in rice young panicles and the results were cross-validated with the off-line SPE-LC-MS/MS phytohormone analytical method. Finally, the method was applied to monitor the changes of ABA, IAA, SA and JA in wounded rice leaves. The trends were in accord with plant physiological processes.
ABSTRACT
An on-line solid phase extraction-high performance liquid chromatography ( SPE-HPLC ) system was applied in the plasma pharmacokinetic study of highly active anti-cancer compound tyrosine kinase inhibitors (TEB-415) in mouse. The on-line SPE-HPLC method associated with Ultimate3000 system which was applied to the determination of the blood drug level of TEB-415 in mouse plasma. C18 column ( Venusil MP, 150 mm × 4. 6 mm, 5μm) was used as analytical column and the mobile phase consisted of acetonitrile-5 mmol/L monopotassium phosphate buffer ( pH 3 . 5 ) at a flow rate of 1 . 0 mL/min was used as the isocratic elution. An MF Ph-1 column (10 mm×4 mm, 5 μm) was used as on-line SPE column, and water and water-acetonitrile were used as the washing solvent and elution solvent respectively. The detection wavelength was set at 262 nm. The pharmacokinetic parameters were calculated by WinNonlin 5. 2 software. The linear range of the calibration curve was between 100 and 20000 μg/L, and the limit of qualification was 20 μg/L. The extraction recovery was between 90 . 5% and 94 . 6%. The RSD of intra-day and inter-day precision was less than 3. 5%. The accuracy of short-term stability, freeze-thaw stability and long-term stability were between 91. 49% and 101. 96%. After oral medication, the mean peak time (Tmax) of TEB-415 in mice was 5. 29 h, and the mean maximum concentration ( Cmax) was 3403μg/L. The area under the curve ( AUC) of TEB-415 was 24600 μg/L·h. This drug's mean half-life was 3. 84 h, and its mean retention time (MRT) was 6. 56 h. These parameters suggested that TEB-415 had appropriate rate of absorption and elimination with preferable bioavailability.
ABSTRACT
To determine the residue of 14 sulfonamides in milk, a high performance liquid chromatography-tandem mass spectrometry ( HPLC-MS/MS ) method with on-line soild phase extraction ( SPE ) in cation exchange mode was established. 5 g of milk was extracted with 15 mL acetonitrile. Then the extraction was evaporated by 50 ℃ nitrogen and dissolved by 1. 00 mL 0. 2% formic acid. The dissolution was enriched and purified by MS/MS cation exchange on-line SPE column on a double ternary liquid chromatography, and eluted by the mixed solution of 2% ammonia methanol and 0. 2% formic acid (50:50, V/V). The compounds were separated by an octadecyl silica bonded column and determined by the tandem mass spectrometry. The results showed that the linearity of 14 sulfonamides was good in the range of 0 . 1–10 μg/kg ( r≥0 . 9995 ) . The LOD of the method was 0. 05 μg/kg, while the LOQ was 0. 1 μg/kg. The recoveries of the 14 sulfonamides were in the range of 60 %-90 %, while the inter-batch and intra-batch RSDs were all lower than 10%. The method was proved to be more convenient, economical and stable than the traditional SPE column method.
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A method of on-line solid phase extraction ( SPE )-two dimensional liquid chromatography electrospary-tandem mass spectrometric method was established for the determination of Teicoplanin concentrations in human cerebrospinal fluid. Cerebrospinal fluid samples were treated by the on-line SPE treatment, and analyzed by LC-MS/MS. The chromatographic separation was performed on a Shiseido CAPCALL-PAK C18 column with gradient elution by using 25 mmol/L ammonium acetate ( pH 6. 0 )-acetonitrile as mobile phases, and the flow rate of 1 mL/min. Detection was carried out under the selected reaction monitoring ( SRM) in positive ionization mode with scopolamine hydrobromide as internal standard. Matrix-matched calibration curves with good correlation coefficients (R2=0. 9993, n=6) were obtained in the concentration range of 25-5000 μg/L. The average recoveries varied from 100. 8% to 109. 9%. The intra-and inter-day precisions were less than 6%. The method is proved to be rapid, sensitive, accurate, and suitable to determine Teicoplanin concentrations in human cerebrospinal fluid.
ABSTRACT
A simple analytical method by means of on-line solid phase extraction followed liquid chromatography-tandem mass spectrometry ( SPE-LC-MS/MS) was developed for the simultaneous quantitation of 4 endocrine disruptors ( triclosan, triclocarban, bisphenol A and nonylphenol) in dairy products. Infant formula and milk samples were dissolved in acetic acid buffer and hydrolyzed by β-glucuronidase/arylsulfatase. Acetonitrile was used as the extract. Then, the mixture was freeze-centrifuged for 10 min and the supernatant was diluted with water, and analyzed via on-line SPE-LC-MS/MS. The sample extracts were concentrated by an Xbridge C8 cartridge and separated on a BEH C18 column with a gradient mobile phase of methanol and water; then analyzed by triple quadrupole mass spectrometry. Mass acquisition was conducted under negative electrospray ionization mode. Quantification was performed by isotopic internal standard calibration. Acceptable linearity (R2>0. 99) was achieved over the range of 0. 005-5. 0 μg/L, with limits of quantification of 0. 03-1. 0μg/kg. Average recoveries of four target compounds (spiked at three concentration levels) ranged from 80. 2%-106. 7%,with relative standard deviation less than 15%. Due to its rapidity, simplicity, and high sensitivity, the method is suitable for the analysis of endocrine disruptors in dairy products. It has been applied in the analysis of raw milk and milk products collected in Beijing. As a result, nonylphenol was found with a high detectable frequency.
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An on-line solid phase extraction ( SPE ) coupled with HPLC-MS/MS method was developed to determine S-ammuxetine and R-ammuxetine in rat plasma. The sample preparation consisted of the following steps:A protein precipitation extraction used methanol and acetonitrile ( 50:50 , V/V ); an on-line SPE treatment to remove most matrixes in plasma;an enrichment and separation step used a C18 analytical column. S-and R-ammuxetine were determined by tandem mass spectrometry. The SPE column was a Retain PEP Javelin (10 mm × 2. 1 mm × 5 μm), while the chromatographic separation was achieved using a ZORBAX SB-C18 (50 mm × 2. 1 mm × 3. 5 μm) analytical column with an isocratic mobile phase composed of acetonitrile-water-formic acid (40:60:0. 1, V/V/V, 0. 3 mL/min). The selected reaction monitoring mode of the positive ion was performed and the precursor to the product ion transitions of m/z 292 . 1/154 . 0 and m/z 260. 4/116. 2 were used to measure S-ammuxetine, R-ammuxetine and internal standard (propranolol). The method was linear over a concentration range from 0 . 2 to 1000 μg/L with the correlation coefficients of 0 . 9903 and 0 . 9951 . The average intra-day precision values were 1 . 2% -12 . 0% for S-ammuxetine and 0. 4%-11. 2% for R-ammuxetine, respectively. The average recoveries were 94. 2%-101. 6% for S-ammuxetine and 94. 3% -109. 4% for R-ammuxetine. Compared to the literature, the sensitivity of this method increased dramatically. The present method has been successfully applied to the preclinical rat research of ammuxetine isomers following intragastric administration.
ABSTRACT
There are some common analysis challenges in the hormone detection in agriculture science, including matrix interference, complicated sample preparation, poor reproducibility, trace analyte content. An automated on-line SPE and innovative fast polarity switch analysis method employing dual-gradient liquid chromatography ( DGLC ) coupled with tandem mass spectrometry ( DGLC-MS/MS ) was established and validated for the simultaneous determination of gibberellic acid ( GA3 ) , indole acetic acid ( IAA ) , zeatin ( ZT) and abscisic acid ( ABA) in the soybean plant ( leaf, grain and pod) . The method was applied in the actual sample detection successfully. In order to acquire higher sensitivity, recovery, stability and precision, some conditions including SPE column, analytical column, mobile phase, additive etc were optimized according to the selection and retain of hormone. Beans were cryogenically grinded by liquid nitrogen, extracted by 80% methanol, certrifugatel and dilluted with water, and then injected directly. Samples were transported and gradient eluted on the analytical column Acclaim PA2 by 0 . 1% formic acid in water and methanol, after retaining and separation on the SPE column Hypersep Retain AX. All analytes were detected in selection reaction monitoring ( SRM) mode in both positive and negative channels. The quantification was based on linear regression. The linear ranges of GA3, IAA and ZT were 0. 1-50 μg/L with the LOQ of 0. 0002 μg/g, and the linear of ABA was 0. 5-50 μg/L with the LOQ of 0. 0010μg/g. The recoveries of four kinds of plants hormones were 76 . 1%-93 . 5%, and RSDs were 0 . 82%-6 . 02% at low ( 0 . 8 μg/L ) , medium (4. 0μg/L) and high (40μg/L). The results noted that the content of ABA in seeds was apparently higher than others. This method could be used for the rapid and accurate detection of hormone in different parts of soya beans.
ABSTRACT
An automated analytical method for simultaneous determination of vitamin A and E in livers, fortified infant formulae and eggs has been developed based on on-line solid phase extraction (SPE) coupled with a dual gradient high performance liquid chromatography system with column-switching. Firstly, food samples were centrifuged after saponified in mixture solution of anhydrous alcohol, potassium hydroxide and ascorbic acid at 80 ℃ for 30 min. Secondly, the saponified sample was loaded and washed on the first dimension extraction column using methanol-water (60∶40, V/V). Afterwards, the targeted analytes were trapped and enriched on the SPE column. Finally, the trapped analytes were transferred to the second dimension analysis column by valve-switching technique for the following separation and determination. Several key factors such as the type of SPE columns, elution buffer as well as pH of washing solution were optimized. The results showed that the calibration curves of vitamin A and E were linear in the range of 0 . 02-20 mg/L with correlation coefficient (R2) more than 0. 9998. In addition, the limits of detection (S/N=3) were found in the range of 3. 0-30. 0 μg/L. The spiked recoveries of the vitamin A and E from livers, eggs and fortified infant formulae ranged from 87 . 3% to 115 . 0% with the relative standard deviations ( RSDs ) of 1 . 8% -4 . 6%. The developed method is simple, sensitive and rapid to determine vitamins A and E in animal derived food.