Page:NIOSH Manual of Analytical Methods - 7901.pdf/1

 ARSENIC TRIOXIDE, as As

As2O3

MW: 197.84

METHOD: 7901, Issue 2

CAS: 1327-53-3

7901

RTECS: CG3325000

EVALUATION: FULL

OSHA : 0.01 mg/m 3 (As) NIOSH: C 0.002 mg/m 3 (As)/15 min; carcinogen ACGIH: 0.01 mg/m 3; carcinogen

PROPERTIES:

Issue 1: 15 February 1984 Issue 2: 15 August 1994

solid; MP 275 °C or 313 °C (sublimes); VP 0.0075 Pa (5.6 x 10 -5 mm Hg; 0.45 µg As/m 3 ) @ 25 °C

SYNONYMS: arsenous acid anhydride; arsenous sesquioxide; arsenolite; claudetite

SAMPLING SAMPLER:

FILTER (Na 2 CO 3 -impregnated, 0.8-µm cellulose ester membrane + backup pad)

MEASUREMENT TECHNIQUE:

ATOMIC ABSORPTION, GRAPHITE FURNACE

ANALYTE:

arsenic

FLOW RATE: 1 to 3 L/min VOL-MIN: -MAX:

30 L @ 0.01 mg/m 3 1000 L

SHIPMENT:

routine

ASHING:

15 mL HNO

FINAL SOLUTION:

10 mL 1% HNO 3, 0.1% Ni 2+

WAVELENGTH:

193.7 nm; D 2 or H 2 correction

SAMPLE STABILITY:

stable

GRAPHITE TUBE: pyrolytic

BLANKS:

2 to 10 field blanks per set

GRAPHITE FURNACE:

ACCURACY

3 + 6 mL H 2O 2; 150 °C

DRY: 100 °C, 70 sec; CHAR: 1300 °C, 30 sec; ATOMIZE: 2700 °C, 10 sec

INJECTION:

25 µL

RANGE STUDIED:

0.67 to 32 µg/m 3 [1,2] (400-L samples)

CALIBRATION:

As in 1% HNO 3, 0.1% Ni 2+

BIAS:

- 0.55%

RANGE:

0.3 to 13 µg per sample

ˆ ): 0.075 [1,2] OVERALL PRECISION (S rT ACCURACY:

ESTIMATED LOD: 0.06 µg per sample

± 11.9% PRECISION (Sr):

0.029 [3,4]

APPLICABILITY: The working range is 0.001 to 0.06 mg/m 3 for a 200-L air sample. This method collects particulate arsenic compounds as well as arsenic trioxide vapor. If only total particulate arsenic is of interest, the use of the treated filter and analysis of the backup pad is not required. Arsine is not collected by this sampling method.

INTERFERENCES: Background absorption is overcome by the use of a deuterium background corrector. Matrix modification with Ni 2+ solution allows the use of a higher char temperature in the graphite furnace. Other particulate arsenic compounds will interfere.

OTHER METHODS: This method combines and replaces P&CAM 346 [3], S309 [4], and P&CAM 286 [5]. Method 7300 (ICP-AES) and arsine generation (Method 7900 and the criteria document method [1]) are for particulate arsenic compounds. Other me thods (P&CAM 173 [7], P&CAM 180 [8], and P&CAM 188 [9]) have not been revised because of interferences or poor sensitivity.

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