Page:NIOSH Manual of Analytical Methods - 9000.pdf/1

 ASBESTOS, CHRYSOTILE by XRD

Mg3Si2O5(OH)4

MW: ca. 283

METHOD: 9000, Issue 2

EPA Standard (Bulk):

CAS: 12001-29-5

9000

RTECS: CI6478500

EVALUATION: FULL

1% by weight

PROPERTIES:

Issue 1: 15 May 1989 Issue 2: 15 August 1994

solid, fibrous mineral; conversion to Forsterite at 580 °C; attacked by acids; loses water above 300 °C

SYNONYMS: Chrysotile

SAMPLING BULK SAMPLE:

1 to 10 grams

SHIPMENT:

seal securely to prevent escape of asbestos

SAMPLE STABILITY:

indefinitely

BLANKS:

none required

ACCURACY RANGE STUDIED: 1 to 100% in talc [1] BIAS:

negligible if standards and samples are matched in particle size [1]

ˆ ): OVERALL PRECISION (S rT

unknown; depends on matrix and concentration

ACCURACY:

± 14% to ± 25%

MEASUREMENT TECHNIQUE:

X-RAY POWDER DIFFRACTION

ANALYTE:

chrysotile

PREPARATION:

grind under liquid N 2; wet-sieve through 10-µm sieve

DEPOSIT:

5 mg dust on 0.45-µm Ag membrane filter

XRD:

Cu target X-ray tube; Optimize for intensity; 1° slit; Integrated intensity with background subtraction

CALIBRATION:

suspensions of asbestos in 2-propanol

RANGE:

1 to 100% (w/w) asbestos

ESTIMATED LOD: 0.2% asbestos in talc and calcite; 0.4% in heavy X-ray absorbers such as Fe 2O 3 PRECISION (Sr):

0.07 (5 to 100%); 0.10 (@ 3%); 0.125 (@ 1%)

APPLICABILITY: Analysis of percent chrysotile asbestos in bulk samples.

INTERFERENCES: Antigorite (massive serpentine), Chlorite, Kaolinite, Bementite, and Brushite interfere. X-ray fluorescence and absorption is a problem with some elements; fluorescence can be circumvented with a diffracted beam monochromator, a nd absorption is corrected for in this method.

OTHER METHODS: This is P&CAM 309 [2] applied to bulk samples only, since the sensitivity is not adequate for personal air samples. The EPA Test Method for the determination of asbestos in bulk insulation samples is similar to this one [3]. Me thod 7400 is an optical counting procedure for airborne fibers in personal samples. Methods 7402 (Asbestos by Transmission El ectron Microscopy) and 9002 (Asbestos by Polarized Light Microscopy) are also useful for positive identification of asbestos.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94