出版社：National Institute of Occupational Safety and Health
摘要：An accurate and simple procedure for determining the quantity of freesilica in respirable dust samples by the pyrophosphoric acid method was achievedby employing a closed vessel dissolution technique using microwave heating. Dissolution conditions were optimized by using quartz particles less than 10 μm in diameter as representative respirable-size free silica and potassium feldspar (K-feldspar) of the same size as the matrix. The technique enabled dissolution of 100 mg of K-feldspar by pyrophosphoric acid in 3 min. Quartz recovery was 97% under these conditions. The technique was also tested on mixtures of quartz and K-feldspar in various ratios with reproducible and accurate results. These data satisfy the requirements for analysis of small amounts of respirable dust samples in work environments.
