Page:NIOSH Manual of Analytical Methods - 2542.pdf/1



MERCAPTANS, METHYL-, ETHYL-, and n-BUTYL-	2542 CH3SH CH3CH2SH CH3CH2CH2CH2SH

MW: 48.11 MW: 62.13 MW: 90.19

METHOD: 2542, Issue 1

CAS: 74-93-1 CAS: 75-08-1 CAS: 109-79-5

RTECS: PB4375000 RTECS: KI9625000 RTECS: EK6300000

EVALUATION: PARTIAL

OSHA:	 Table 1 NIOSH:	Table 1 ACGIH:	 Table 1

Issue 1: 15 August 1994

PROPERTIES: Table 1

SYNONYMS:	Methyl mercaptan: methanethiol; mercaptomethane; methyl sulfhydrate Ethyl mercaptan: ethanethiol; mercaptoethane; ethyl sulfhydrate n-Butyl mercaptan: butanethiol; 1-mercaptobutane; 1-butanethiol

SAMPLING SAMPLER:	 FILTER (glass fiber, 37-mm, impregnated with mercuric acetate)

MEASUREMENT TECHNIQUE:

GAS CHROMATOGRAPHY, FPD SULFUR MODE

ANALYTE:

methyl, ethyl, and n-butyl mercaptans

EXTRACTION:

20 mL HCl (25% v/v) plus 5 mL 1,2dichloroethane, 2 min

FLOW RATE:	 0.1 to 0.2 L/min VOL-MIN: -MAX:

10 L @ 0.5 ppm 150 L

SHIPMENT:	 protect samples from light [1,2] SAMPLE STABILITY:	 at least 3 weeks @ 25 °C BLANKS:

1 µL

TEMPERATURE-INJECTION:	250 °C -DETECTOR:	250 °C -COLUMN:	30 °C 2 min, 15 °C/min, 200 °C

2 to 10 field blanks per set ACCURACY

RANGE STUDIED:

Table 2

BIAS:

not determined

OVERALL PRECISION :	Table 2 ACCURACY:

INJECTION VOLUME:

not determined

COLUMN:

narrow-bore, fused-silica capillary, 30 cm × 0.25-mm ID, 1 µm DB-1

CARRIER GAS:

He, 1.0 mL/min; makeup gas: N2, 20 mL/ min

CALIBRATION:

standard solutions of mixed mercaptans in 1,2-dichloroethane

RANGE:

Table 2

ESTIMATED LOD:	 Table 2 PRECISION :

Table 2

APPLICABILITY: The working ranges are 0.2 to 10 ppm for a 20-L air sample for all three mercaptans [1–4]. INTERFERENCES: Dimethyl disulfide, diethyl disulfide, and dibutyl disulfide may interfere [2–4]. OTHER METHODS: This is a modification of OSHA Method 26 for methyl mercaptan with the addition of ethyl- and n-butyl mercaptan [2].

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition