Determining of Crystalline Silica in Respirable Dust Samples by Infrared Spectrophotometry in the Presence of Interferences

Abstract

Determining of Crystalline Silica in Respirable Dust Samples by Infrared Spectrophotometry in the Presence of Interferences: Jun Ojima. National Institute of Industrial Health—Infrared Spectrophotometry (IR) is now widely used to determine crystalline silica in industrial dust samples. Though the IR method has many advantages when dealing with respirable dust samples, some serious analytical errors are often caused by interference minerals contamination. These minerals have a characteristic absorption band corresponding in position to the analytical peak for crystalline silica. In this paper, six typical interference minerals (Kaolinite, Mullite, Muscovite, Pyrophyllite, Montmorillonite and Amorphous silica) were pre‐size controlled to respirable range and their infrared spectra were measured by means of an FT‐IR with the well known potassium bromide tablet technique. The effects of these interference minerals on the Japanese OEL or the administrative control level for respirable dust which depend on the silica content were calculated and expressed in figures. The measured absorption coefficients of the interference minerals and quartz were 1.36–6.98 Abs/mg and 24.46 Abs/mg, respectively. The absorption band height ratios of each interference minerals were also measured. Then the efficiency and applicability of two spectrum correction methods for the interference minerals, absorbance ratio method and difference spectrum method were examined by using artificially mixed samples (standard interference mineral + standard quartz). By comparing the quantifying results for the mixture samples, it was revealed that the interfered spectra were almost corrected successfully when using the difference spectrum method, whereas correction by the absorbance ratio method resulted in apparent negative errors. Furthermore, the difference spectrum method was proven to be superior to the absorbance ratio method in applicability.

Occupational Exposure Assessment for Crystalline Silica Dust: Approach in Poland and Worldwide

“…In IR spectrophotometry, the interference is limited by computerized development of the curves correcting their infl uence, e.g. by scaled subtraction of interferent spectra and forming higher-order derivative spectra [93,96,99,100,102,106,107]. Irrespective of the method used, it is possible to carry out a procedure of removing some sample components by ashing or chemically dissolving them, prior to the analytical measurements [96,99,102].…”

Fourier Transform Infrared Spectroscopy of Clay Size Fraction of Cretaceous-Tertiary Kaolins in the Douala Sub-Basin, Cameroon

“…DBB CN 01 showed an additional doublet at 1412 and 1467 cm −1 . This doublet can be attributed to the interference of smectite [31].…”

Spectroscopic and ancient geomagnetic field intensity studies on archaeological pottery samples, India

“…Quartz and feldspar are often present in pottery clays either because they are present already in the raw clay, or because they are added as temper. The bands occurring at 462 and 514 cm −1 are assigned to mixed Si-O-Si and O-Si-O bending mode [17]. The band at 470 cm −1 due to Si-O band is free from any temperature effects.…”