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Med. Pr. 2005;56(1)

Free crystalline silica: a comparison of methods for its determination in total dusts

Wolna krystaliczna krzemionka (WKK) - porównanie metod jej oznaczania w pyłach całkowitych

Aleksandra Maciejewska1, Irena Szadkowska-Stańczyk1, Grzegorz Kondratowicz2 1 Z Zakładu środowiskowych Zagrożeń Zdrowia Instytutu Medycyny Pracy im. J. Nofera w Łodzi 2 Z Centrum Badawczo- Projektowego Miedzi CUPRUM Ośrodek Badawczo-Rozwojowy we Wrocławiu

Abstract

Background: The major objective of the study was to compare and investigate the usefulness of quantitative analyses of free crystalline silica (FCS) in the assessment of dust exposure in samples of total dusts of varied composition, using three methods: chemical method in common use in Poland; infrared spectrometry; and x-ray powder diffraction. Materials and Methods: Mineral composition and FCS contents were investigated in 9 laboratory samples of raw materials, materials, and industrialwastes, containing from about 2 to over 80% of crystalline silica and reduced to particles of size corresponding with that of total dust. Sample components were identified using XRD and FT-IR methods. Ten independent determinations of FCS with each of the three study methods were performed in dust samples. An analysis of linear correlation was applied to investigate interrelationship between mean FCS determinations. Results: In analyzed dust samples, along with silica dust there were numerous minerals interfering with silica during the quantitative analysis. Comparison of mean results of FCS determinations showed that the results obtained using the FT-IR method were by 12ś13% lower than those obtained with two other methods. However, the differences observed were within the limits of change ability of results associated with their precision and dependence on reference materials used. Conclusions: Assessment of occupational exposure to dusts containing crystalline silica can be performedon the basis of quantitative analysis of FCS in total dusts using each of the compared methods. The FT-IR method is most appropriate for the FCS determination in samples of small amount of silica or collected at low dust concentrations; the XRD method for the analysis of multicomponent samples; and the chemical method in the case of medium and high FCS contents in samples or high concentrations of dusts in the work environment.

Key words

free crystalline silica, quartz, FT-IR, XRD, UV/VIS spectrophotometry