HYDROGEN SULFIDE
H2S
MW: 34.08
CAS: 7783-06-4
METHOD: 6013, Issue 1
6013
RTECS: MX1225000
EVALUATION: FULL
OSHA : C 20 ppm; P 50 ppm/10 min NIOSH: C 10 ppm/10 min ACGIH: 10 ppm; STEL 15 ppm (1 ppm = 1.39 mg/m 3 @ NTP)
PROPERTIES:
Issue 1: 15 August 1994
gas; d (liq) 1.54 g/mL @ 0 °C; BP - 60 °C; VP 20 atm @ 25 °C; vapor density (air=1) 1.19; explosive range 4.3 to 46% v/v in air
SYNONYMS: sulfuretted hydrogen; hydrosulfuric acid; hepatic gas; stink damp
SAMPLING SAMPLER:
FILTER + SOLID SORBENT TUBE (Zefluor, 0.5 µm; coconut shell charcoal, 400 mg/200 mg)
MEASUREMENT TECHNIQUE:
ION CHROMATOGRAPHY, CONDUCTIVITY
ANALYTE:
sulfate ion
FLOW RATE-RANGE: 0.1 to 1.5 L/min -RECOMMENDED: 0.2 L/min
DESORPTION:
2 mL 0.2 M NH 4OH + 5 mL 30% H 2O 2
VOL-MIN: -MAX:
1.2 L @ 10 ppm 40 L
INJECTION VOLUME: 50 µL
SHIPMENT:
routine
ELUENT:
SAMPLE STABILITY:
at least 30 days @ 25 °C [1]
BLANKS:
2 to 10 field blanks per set
COLUMN:
40 mM NaOH, 1.5 mL/min Ion-Pac AS4A separator, AG4A guard
CALIBRATION:
SO 24- in deionized water
RANGE:
17 to 200 µg per sample
ESTIMATED LOD:
11 µg per sample
PRECISION (Sr):
0.031 [1]
ACCURACY RANGE STUDIED:
1.4 to 22.0 mg/m 3 [1] (20-L samples)
BIAS:
- 0.23% [1]
OVERALL PRECISION (SrT):
0.059 [1]
ACCURACY:
± 11.8%
APPLICABILITY: The working range is 0.6 to 14 ppm (0.9 to 20 mg/m 3) for a 20-L air sample [1]. The method is applicable to 15-min samples taken at 1 L/min and 10-min samples taken at 1.5 L/min. The upper limit of loading depends on the concentrations of hydrogen sulfide and other substances in the air, including water vapor. High relative humidity (80%) increases the capacity of the sampler four-fold, relative to dry air. Some lots of charcoal have excessively high sulfur backgroun ds and/or poor desorption efficiencies; therefore, screening of each lot should be done before field use.
INTERFERENCES: SO 2 is a positive interference, equivalent to H 2S by approximately twice the SO 2 concentration by weight. Methyl and ethyl mercaptans do not interfere [1].
OTHER METHODS: Alternate methods are S4 [2] which uses impinger collection, and P&CAM 296 [3] which uses a molecular sieve sampler but has poor stability.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
