ASBESTOS by TEM
FORMULA: Various
MW: Various
METHOD: 7402
7402
CAS: Various
EVALUATION: PARTIAL
OSHA : 0.1 asbestos fibers (>5 µm long)/cc; 1 f/cc/30 min excursion; carcinogen MSHA: 2 asbestos fibers/cc NIOSH: 0.1 f/cc (fibers > 5 µm long)/400 L; carcinogen ACGIH: 0.2 crocidolite; 0.5 amosite; 2 chrysotile and other asbestos, fibers/cc; carcinogen
RTECS: Various Issue 1: 15 May 1989 Issue 2: 15 August 1994
PROPERTIES: solid, fibrous, crystalline, anistropic
SYNONYMS [CAS#]: actinolite [77536-66-4] or ferroactinolite [15669-07-5]; amosite [12172-73-5]; anthophyllite [77536-67-5]; chrysotile [12001-29-5]; serpentine [18786-24-8]; crocidolite [12001-28-4]; tremolite [77536-68-6]; amphibole asbestos [ 1332-21-4]. SAMPLING SAMPLER:
MEASUREMENT
FILTER (0.45- to 1.2-µm cellulose ester membrane, 25-mm diameter; conductive cassette)
TECHNIQUE:
MICROSCOPY, TRANSMISSION ELECTRON (TEM)
ANALYTE:
asbestos fibers
SAMPLE PREPARATION:
modified Jaffe wick
FLOW RATE: 0.5 to 16 L/min VOL-MIN*: -MAX*:
SHIPMENT: SAMPLE STABILITY: BLANKS:
400 L @ 0.1 fiber/cc (step 4, sampling)
- Adjust for 100 to 1300 fibers/mm 2
EQUIPMENT:
transmission electron microscope; energy dispersive X-ray system (EDX) analyzer
CALIBRATION:
qualitative electron diffraction; calibration of TEM magnification and EDX system
RANGE:
100 to 1300 fibers/mm 2 filter area [1]
routine (pack to reduce shock)
stable 2 to 10 field blanks per set ESTIMATED LOD: 1 confirmed asbestos fiber above 95% of expected mean blank value ACCURACY PRECISION (Sr):
RANGE STUDIED:
80 to 100 fibers counted
BIAS:
not determined
ˆ ): OVERALL PRECISION (S rT METHOD ACCURACY:
0.28 when 65% of fibers are asbestos; 0.20 when adjusted fiber count is applied to PCM count [2].
see EVALUATION OF not determined
APPLICABILITY: The quantitative working range is 0.04 to 0.5 fiber/cc for a 1000-L air sample. The LOD depends on sample volume and quantity of interfering dust, and is <0.01 fiber/cc for atmospheres free of interferences. This method is use d to determine asbestos fibers in the optically visible range and is intended to complement the results obtained by phase con trast microscopy (Method 7400).
INTERFERENCES: Other amphibole particles that have aspect ratios greater than 3:1 and elemental compositions similar to the asbestos minerals may interfere in the TEM analysis. Some non-amphibole minerals may give electron diffraction patterns similar to amphiboles. High concentrations of background dust interfere with fiber identification. Some non-asbestos amphibole m inerals may give electron diffraction patterns similar to asbestos amphiboles.
OTHER METHODS: This method is designed for use with Method 7400 (phase contrast microscopy).
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
