Analytical Method for Quantification of Airborne Respirable Crystalline Silica Using Raman Spectroscopy

Details

• Personal Author:
  Vogiazi, Vasileia ; Wang, Chen ; Kulkarni, Pramod
• Description:
  Inhalation exposure to crystalline silica aerosol poses significant health risks in many workplaces. There is a need for laboratory analytical methods as well field-portable methods for onsite analysis of trace level exposures, capable of measuring a few µg/m3. To address these needs, a standardized method using a portable probe-based Raman and an analytical confocal Raman microscope has been developed for the measurement of trace quantities of airborne respirable crystalline silica (RCS). This method is particularly useful to quantify trace level RCS exposures that can't be achieved with X-ray Diffraction (XRD) or Infrared (IR) methods. The method implements a microconcentration technique with point-measurement as well as a rastering scheme that covers a large sample spot area and provides detection limits much below the RCS exposure limit of 50 µg/m3. The method can quantify both a-quartz and cristobalite polymorphs in the range of 2 (+/- 0.1) - 50 (+/-2.8) µg per filter using point-measurement with a field-portable probe-based Raman spectrometer. The relative standard deviation of the probe-based method is in the range of 1- 11%. Using a rastering scheme with a confocal Raman microscope the limit of detection as low as 0.1 µg could be achieved. Relative standard deviations of triplicate measurements were in the range 10-23% and the limit of quantification was estimated to be 0.5 (+/- 0.08) µg RCS per filter. The uncertainty of the method was better than that of the XRD method (NIOSH method 7500). The potential interferent materials, such as iron oxide and TiO2, can affect the quantification and measurement uncertainty, particularly at trace concentrations of RCS. The method is currently being extended to quantify RCS in field samples; the results will be compared with XRD measurements. Description provided by NIOSH
• Subjects:
  • Dust
  • Occupational Health
  • Safety
  • Silicon Dioxide
• Keywords:
  • Crystalline silica; Aerosols; Analytical methods; Microscopy; Air sampling equipment; Spectroscopes
• Source:
  Abstracts from the AAAR 42nd Annual Conference, October 21-25, 2024, Albuquerque, New Mexico. Reston, VA: American Association for Aerosol Research, 2024 Oct; :82
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  Philadelphia Region OSHA ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1 pdf page
• NIOSHTIC Number:
  nn:20071695
• CAS Registry Number:
  • Quartz (SiO2) (CAS RN 14808-60-7)
• Federal Fiscal Year:
  2025
• Peer Reviewed:
  False
• Download URL:
  https://stacks.cdc.gov/view/cdc/259466/cdc_259466_DS1.pdf
• File Type:
  [PDF - 649.96 KB]
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:56d62661ae69dae02870908209b9fd62a4dd7bc183fd478b317f2b1063e80c51ab3f92b365260d039dddb9971523552cda88c4569e7c55b8036ec92fd3aed537