To develop a method for the determination of 13 antibiotics in 8 classes for desinfection products by ulta-high perfomance chromatography-tandem mass spectrometry(UPLC-MS/MS).
 
  Samples were extracted by methanol or acetonitrile. The target compouds were separated on a Waters HSS T3 column(100 mm×2. 1 mm, 1. 8 μm), and detected by triple quadrupole tandem mass spectrometer.
 
  The 13 selected antibiotics showed good linear relationships in the range of 4-100 μg/L and the correlation coefficients(r~2) were all above 0. 991. The limits of detection ranged from 2 to 25 μg/kg. The recovery rates at three spiked levels(low, medium and high) in three dosage forms of disinfection products were in the range of 71. 2%-130. 4%, and the relative standard deviations(RSD) were all less than 11. 3%, which could meet the detection requirements of illegal addition of antibiotics in disinfection products. Ofloxacin at a concentration of 21. 1 mg/kg was found in a cream disinfection product by the developed method, and no related drugs were detected in other samples.
 
  This method is simple, reliable, reproducible, which covers a wide range of antibiotics, and provides technical support for monitoring the illegal addition of antibiotics in disinfection products.
 This method is simple, reliable, reproducible, which covers a wide range of antibiotics, and provides technical support for monitoring the illegal addition of antibiotics in disinfection products.
  A method utilizing liquid chromatography-tandem mass spectrometry(LC-MS/MS) coupled with dispersive solid phase extraction for quantitative analysis of domoic acid in four kinds of shellfish was established.
 
  The sample of 0. 1 g was extracted with 25% methanol aqueous solution, the extract was purified by dispersive solid phase extraction with 50 mg HLB and 5 mg GCB, and then filtered through a PTFE membrane. The analytes were separated on a C_(18) column(100 mm×2. 1 mm, 1. 9 μm), and detected in selected reaction monitoring(SRM) mode via positive electrospray ionization. The matrix matching and external standard method was used for quantitation.
 
  Domoic acid showed good linearity in the concentration range between 1. 0 ng/mL and 50. 0 ng/mL with correlation coefficients higher than 0. 9994. The detection limits of domoic acid in shellfish was 5 μg/kg. The inter-and intra-day recoveries were 91. 6%-109. 2% and 90. 9%-109. 3%, respectively. The inter-and intra-day ralitive standard deviations(RSDs) were lower than 8. 2% at spiked concentrations of 20, 50 and 100 μg/kg.
 
  The method is accurate, fast, easy to operate, which can satisfy the requirements of public health emergency testing or routine testing.
 The method is accurate, fast, easy to operate, which can satisfy the requirements of public health emergency testing or routine testing.
  To compare the result of serum folate determined by improved microbial assay and electrochemiluminescence method, and to look for the relationship between them, so as to provide basis for the assessment of nutrition status of folate in population.
 
  A total of 258 serum samples were examined by improved microbial assay and electrochemiluminescence method. The correlation and consistence of the two method were analyzed.
 
  The result showed that the correlation coefficient of the two method was 0. 885, which indicated that the result of two method were highly correlated. Results of Bland-Altman method showed that 94. 5% of the values were within the consistency limit, and the Kappa value of Kappa test was 0. 665. The result of consistency analysis showed that there were some differences between the two methods, and the result of serum folate tested by improved microbial assay were higher than that of electrochemiluminescence method in general.
 
  The result of serum folate tested by electrochemiluminescence were highly correlated with the improved microbial assay, yet there are some differences in the consistency result between the two methods. Evaluating the nutrition status of folate by electrochemiluminescence may lead to a higher number of folate deficiency.
 The result of serum folate tested by electrochemiluminescence were highly correlated with the improved microbial assay, yet there are some differences in the consistency result between the two methods. Evaluating the nutrition status of folate by electrochemiluminescence may lead to a higher number of folate deficiency.
  To establish the determination method for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans(PCDD/Fs) in human serum, and further to provide an operable and scientific determination protocal and basis for conducting human health risk assessment for PCDD/Fs.
 
  The serum samples were pretreated by C18 column solid phase extraction, acid silica gel column and activated carbon column purification, separated by DB-5 MS capillary column(60 m×0. 25 mm×0. 25 μm), and PCDD/Fs was quantitative analyzed by high resolution mass spectrometry.
 
  The method detection limit was in the range of 0. 35-3. 26 pg/g lipid. This method was further validated using international serum standard reference material sample SRM 1958. According to the reference mass fraction values given for SRM 1958, the concentrations of 17 PCDD/Fs monomers were all in the range of reference mass fraction values, and the relative standard deviation was 2%-19%(n=3). This method was further applied to determination PCDD/Fs in actual serum of human body. The result showed that the recovery rate of isotope labeled PCDD/Fs internal standards were in the range of 61%-135%.
 
  The performance of the method is highly sensitive, stable and highly accurate, which meets the requirements for the determination of PCDD/Fs in human serum and the method can be applied to human health risk assessment for PCDD/Fs in the future.
 The performance of the method is highly sensitive, stable and highly accurate, which meets the requirements for the determination of PCDD/Fs in human serum and the method can be applied to human health risk assessment for PCDD/Fs in the future.
  To observe the effect of selenomethionine(SeMet)on the selenoproteins expression in hepatocyte L02 and the synergistic effect of serine.
 
  The L02 cells were cultured and divided into SeMet group and Serine+SeMet group. SeMet dose was set as 0. 001, 0. 01, 0. 1, 1 and 10 μmol/L.  https://www.selleckchem.com/products/nx-1607.html  Serine and SeMet were mixed according to 2∶1 molar ratio(Serine∶SeMet=2∶1). The L02 cells were cultured for 48 h after SeMet and Serine added. Finally, the cell culture supernatants and homogenates were collected for the selenoprotein P(SEPP)and glutathione peroxidase 1(GPx1)concentrations detection by a double-antibody sandwich enzyme-linked immuno-sorbent assay(ELISA). The expression of SEPP and GPx1 in cell homogenates was detected by western blot(WB).
 
  ELISA and WB results showed that GPx1 and SEPP expressions were dose dependent in a low SeMet concentration range, reached their inflection points when SeMet concentration was 1 μmol/L and 0. 1 μmol/L respectively, and began to decrease when SeMet concentration was further increased to 10 μmol/L.