Page:NIOSH Manual of Analytical Methods - 2000.pdf/1

 METHANOL

CH3OH

MW: 32.04

METHOD: 2000, Issue 3

2000

CAS: 67-56-1

RTECS: PC1400000

EVALUATION: FULL

OSHA : 200 ppm NIOSH: 200 ppm (skin); STEL 250 ppm (skin) ACGIH: 200 ppm (skin); STEL 250 ppm (skin) (1 ppm = 1.310 mg/m3 @ NTP)

PROPERTIES:

Issue 1: 15 August 1984 Issue 3: 15 January 1998 liquid; d = 0.792 g/ml @ 20 C; BP = 64.5 C; VP = 15.3 kPa (115 mm Hg; 15.1% v/v) @ 20 C; explosive range is 6 to 36% (v/v) in air

SYNONYMS: Methyl alcohol, wood alcohol, carbinol, wood naphtha, wood spirit

SAMPLING SAMPLER:

SOLID SORBENT TUBE (silica gel, 100/50 mg)

FLOW RATE:

0.02 to 0.2 L/min

VOL-MIN: -MAX:

1 L @ 200 ppm 5L

SHIPMENT:

pack securely for shipment; store at 5 C.

SAMPLE STABILITY :

at least 30 days at 5 C [1]

BLANKS:

2 to 10 field blanks per set

MEASUREMENT TECHNIQUE:

GAS CHROMATOGRAPHY, FID

ANALYTE:

methanol

DESORPTION:

1 mL water/isopropanol (95:5) [1]

INJECTION VOLUME:

1 µL

TEMPERATURE- INJECTION: -DETECTOR: -COLUMN:

250 C 300 C 50 to 90 C (8 C/min) [1] (Split Ratio 10:1)

CARRIER GAS:

He, 2.6 mL/min

COLUMN:

capillary, 30 m x 0.53-mm ID; 3-µm film 35% diphenyl-65% dimethyl polysilozane, Rtx™-35 or equivalent [1]

CALIBRATION:

standard solutions of water/isopropanol (95:5)

RANGE:

2.2 to 6000 µg per sample [1,2]

ACCURACY RANGE STUDIED:

140 to 540 mg/m3 [2]

BIAS:

-4.4%

OVERALL PRECISION ( ACCURACY:

rT

): 0.074 [1, 2] ±16.2%

methanol

in

ESTIMATED LOD: 0.7 µg per sample [1] PRECISION ( r):

0.030 [1]

APPLICABILITY: Under the GC parameters stated in the method, methanol may be identified based upon retention time and quantified. The working range is 0.4 to 1200 mg/m3 (0.3 to 916.0 ppm) for a 5-L air sample [1]. At high concentrations of methanol or under conditions of high relative humidity, a large silica gel tube (700 mg) is required [2].

INTERFERENCES: No specific interferences were identified. However, any compound with a similiar retention time may interfere. Positive identification can be confirmed by dual column chromatography with a 100% PEG capillary column. Mass spectrometry can also be used as a confirmation aid.

OTHER METHODS: This method updates and replaces NMAM 2000 (August 15, 1994), which combined and replaced Method S59 [3] and P&CAM 247 [4].

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition