Abstract
Objectives: The purpose of this study is to establish a method for the production of standard samples of crystalline silica and to assess its feasibility for the future application in non-mandatory quality control. Methods: We dispersed crystalline silica in 2-propanol to prepare a 1 mg/mL dispersion solution. Between 50-200 uL of the dispersion solution was taken with a pipette, injected onto PVC filters, air-dried, and used as samples. The variation and homogeneity of the quartz concentrations were confirmed by FTIR analysis. Analytical proficiency testing was conducted across 30 voluntary participants. Results: The coefficient of variation was lower for samples prepared using supernatant (settled for 16 hours) compared to those made with dispersion solution. The contamination level after using the pipette tip one to five times was 8.13-9.89% of the solution's concentration. Homogeneity was confirmed within the concentration of 0.0223-0.0431 mg/mL, but it was not at the higher concentration of 0.0553 mg/mL. In the analytical proficiency testing, the coefficient of variation for each level ranged from 24.6% to 28.3%, with a compliance rate of 90.0% to 96.7%. Conclusions: This study was conducted to produce standard samples of crystalline silica. The homogeneity of the samples was confirmed at low concentrations. However, further investigations on the applicability of wider range of concentrations are needed.
