title: A comparison of international silica (alpha-quartz) calibration standards by Fourier transform-infrared spectrophotometry.
abstract: Seven international silica (alpha-quartz) standards were examined for relative purity to the US National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1878 Respirable alpha-quartz by Fourier Transform-Infrared Spectrophotometry (FT-IR). The standards examined have been used in North America, the UK, Australia and Germany. The 189 samples analyzed included NIST-SRM 1878, Min-U-Sil 5, Ottawa Silica Sand, Sikron F-600, A9950 (AUST 1), DQ12-Robock, DQ12-Bergbau. Size distributions of the standards were determined by Coulter Counter to be broadly similar with equivalent spherical volume median diameter ranging between 1.2 and 3 microm. The results showed the standards to differ by as much as 30% in relative purity. Consequently, an internationally agreed upon calibration standard is urgently needed. Min-U-Sil 5 based NIST-SRM 1878 or Sikron F-600 are the two most likely candidates. Any agreed standard must have a well characterized size distribution and closely match the respirable dust criteria. It should also be studied by both infrared spectrophotometry and X-ray diffraction techniques.
authors.affiliation: Occupational and Environmental Health Laboratory, McMaster University, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada. vermadk@mcmaster.ca
authors.forename: D K
authors.initials: DK
authors.lastname: Verma
authors.forename: D S
authors.initials: DS
authors.lastname: Shaw
mesh_terms: D002138:Calibration / Q000592:standards; D002170:Canada; D004784:Environmental Monitoring / Q000592:standards*; D005060:Europe; D006801:Humans; D010316:Particle Size; D011791:Quartz / Q000032:analysis* / Q000592:standards*; D017550:Spectroscopy, Fourier Transform Infrared; D014481:United States
chemical_list: D011791:Quartz