A new method for determination of trace Cu, Cr, Mn, Co, Ni, Cd, Fe and Pb impurities in high pure tin oxide material was proposed. 0. 1 g of sample was successfully digested at 230℃ in 3 h when autoclaves with high pressure and high temperature were used. After that, over 99. 9% of the matrix Sn was removed by chloride volatilization at 150℃ for 1. 5 h, which eliminated the matrix effect and spectra interference in the following ICP-MS detection. The recoveries for all the analytes of the spiked test were 100%±5%, the RSDs for 6 runs of sample analysis were from 0. 09% to 3. 68%, and the limits of detection (LOD, 3σ) were from 0. 002 mg/kg to 0. 034 mg/kg, which indicated that the established method were of both accuracy and high sensitivity, and could be applied for the analysis of samples with purity up to 6N. Finally, three samples specified with 4N purity were analyzed by this method.

Objective To analyze the influencing factors of frailty in elderly patients with lower extremity osteoarthritis,and to construct and validate the risk assessment model.Methods Convenient sampling method was used to select 535 elderly patients with lower extremity osteoarthritis from tertiary hospitals and community health service centers in Hangzhou from January to September 2022 as the survey subjects including 357 in the modeling group and 178 in the validation group.Univariate and multivariate logistic regression analysis were used to determine the risk factors of frailty,construct a risk assessment model and draw a nomogram.The discrimination and calibration of the model were evaluated by the area under the receiver operating characteristic curve and the Hosmer-Lemeshow test.The Bootstrap method was used for intemal validation of the model,and the time verification method was used for external validation.Results The model variables included the number of affected joints,age-adjusted Charlson comorbidity index,pain,nutritional status,sedentary time,activity of daily living,osteoarthritis index,lower limb muscle strength,and Social Support Rating Scale score.The Hosmer-Lemeshow test results of the model showed that P=0.202,the area under the receiver operating characteristic curve was 0.942,the optimal critical value was 0.392,the sensitivity was 0.914,the specificity was 0.893,and the accuracy rate was 0.902.The internal and external validation showed that the C-statistics were 0.935 and 0.919,respectively,and the calibration curve showed good fitting.Conclusion The risk assessment model has a good degree of discrimination and calibration,which can more intuitively and easily screen elderly patients with lower extremity osteoarthritis at high risk of frailty,and provide references for early monitoring,identification,prevention and control.