Objective To investigate an automated pretreatment technology for detecting levels of free silica in workplace dust. Methods An fully automated pretreatment workstation for detecting free silica levels in workplace dust was developed by integrating graphite-controlled digestion temperature, online-controlled dilution of digestion solutions, and filtration endpoint recognition based on monitoring technology, combined with multi-channel synchronous measurements. Results The fully automatic pretreatment workstation was used to digest and filter 14 standard samples of free silica produced by three institutions, and then detected by pyrophosphate method. The result range of high-, medium-, and low-level free silica standard samples detection was 66.5%-84.8%, 40.0%-44.5%, and 2.1%-24.8%, respectively. The mean relative standard deviations were 3.9%, 1.4% and 1.5%. Conclusion The fully automated pretreatment workstation produced results that met relevant requirements. It can effectively replace the manual digestion and filtration steps of the pyrophosphate method to measure free silica levels in workplace dust and enable rapid detection of free silica in dust samples.

Backgroud At present, there is no unified standard for the detection of glufosinate ammonium and three metabolites in urine, which affects the accurate assessment of occupational exposure risk to a certain extent. It is of great significance to establish a rapid and effective inspection method to ensure occupational safety and public health. Objective To establish an ultra performance liquid chromatography-tandem mass spectrometry for simultaneous determination of glufosinate ammonium and three metabolites in urine. Methods The effects of dilution solvents and dilution ratios on the response values of glufosinate ammonium and three metabolites were compared, and the retention capacities of solid phase extraction columns for targets as well as the effects of chromatographic columns and mobile phase systems on chromatographic peaks were analyzed. Samples were quantified by matrix effect matching external standard method. Accuracy of the method was evaluated by recovery rate of standard addition, and precision of the method was evaluated by relative standard deviation of intra-day and inter-day measurements. Urine samples of 30 health individuals were collected to evaluate the application of the method. Results The urine samples were diluted with 0.2 mL water and 0.6 mL acetonitrile, purified by HLB solid phase extraction columns, and separated by Dikma Polyamino HILIC columns, and gradient elution was carried out with 0.5 mmol·L⁻¹ ammonium acetate and 0.1% ammonia water as mobile phase, which achieved a good peak shape and mass spectrum response. The linearities of the four target compounds were good in the range of 0.5-50 ng·mL⁻¹, and the correlation coefficients (r) were all greater than 0.998. The detection limits were 0.56-2.86 μg·L⁻¹, the quantification limits were 1.87-29.54 μg·L⁻¹, and the recovery rates of standard addition ranged from 75.0% to 103.6%, The relative standard deviations of intra-batch and inter-batch were from 2.5% to 8.1% and from 4.3% to 9.3% respectively. The method was applied to detect 30 urine samples of subjects, and no target was detected. Conclusion The method is simple, rapid, sensitive, and accurate. It is suitable for the determination of glufosinate ammonium and its metabolites in human urine without derivatization.

AstudyofPt-metabolitesfromanewanti-hepatomadrugmiriplatinwasimportanttomiriplatin's pharmacology research. Therefore, a method based on size exclusion chromatography-inductively coupled plasma mass spectrometry ( SEC-ICP-MS) was developed to study miriplatin and its Pt-metabolites in Beagle dog plasma. This method could be used to study total platinum concentration half-quantitatively. Compared with traditional ICP-MS direct determination, data acquired from this SEC-ICP-MS method were almost the same. By using BioSep-s2000 column, 25 mmol/L of pH 7. 2 phosphate buffer as eluent, and Pt-195 as detecting isotope, we discovered miriplatin with its four Pt-metabolites in dog plasma after intra-hepatic artery administration. The main Pt-metabolite was m2 , which associated with plasma proteins. Miriplatin in plasma did not bind with plasma proteins. According to calculation, the ratio of miriplatin/m2 first decreased rapidly, and then slowly increased to its second climax, finally slowly decreased.