Caution on Using Tetrahydrofuran for Processing Crystalline Silica Samples From Engineered Stone for XRD Analysis

Area of Science:

• Occupational Health and Safety
• Analytical Chemistry
• Materials Science

Background:

• Engineered stone processing can generate respirable crystalline silica dust.
• Accurate quantification of crystalline silica is crucial for assessing worker exposure risks.
• Tetrahydrofuran (THF) is sometimes used for sample preparation before X-ray diffraction (XRD) analysis.

Purpose of the Study:

• To investigate the effect of tetrahydrofuran (THF) on crystalline silica quantification in engineered stone dust.
• To compare THF processing with muffle furnace ashing for crystalline silica analysis.
• To determine the optimal sample processing method for accurate silica measurement in engineered stone.

Main Methods:

• Laboratory experiments comparing THF processing and muffle furnace ashing.
• Analysis of crystalline silica content in engineered stone and granite samples.
• Testing at four levels of respirable dust loading (1-8 min grinding time).

Main Results:

• No significant difference in crystalline silica quantification between THF and muffle furnace for granite.
• THF processing resulted in significantly lower crystalline silica content for engineered stone at dust loadings < 0.5 mg.
• For engineered stone dust loadings of 0.19 mg and 0.34 mg, THF underestimated silica by 30.9% and 21.5% respectively.

Conclusions:

• THF processing can lead to artificially reduced crystalline silica values in engineered stone dust.
• Muffle furnace or radio frequency plasma ashing are recommended for sample processing when analyzing crystalline silica in engineered stone.
• Accurate quantification is vital, especially for low dust loadings common in field assessments.