Page:NIOSH Manual of Analytical Methods - 2541.pdf/1

 FORMALDEHYDE by GC

H2C=0

MW: 30.03

METHOD: 2541, Issue 2

CAS: 50-00-0

2541

RTECS: LP8925000

EVALUATION: PARTIAL

OSHA : 0.75 ppm; 2 ppm STEL NIOSH: 0.016 ppm; C 0.1 ppm; carcinogen ACGIH: C 0.3 ppm; suspected human carcinogen (1 ppm = 1.23 mg/m 3 @ NTP)

PROPERTIES:

Issue 1: 15 May 1989 Issue 2: 15 August 1994

gas; vapor density 1.067 (air = 1); BP 19.5 °C; explosive range 7 to 73% v/v in air

SYNONYMS: methanal; formalin (aqueous 30 to 60% w/v HCHO); methylene oxide

SAMPLING SAMPLER:

MEASUREMENT

SOLID SORBENT TUBE (10% (2-hydroxymethyl)piperdine on XAD-2, 120 mg/60 mg

TECHNIQUE:

GAS CHROMATOGRAPHY, FID

ANALYTE:

oxazolidine derivative of formaldehyde

FLOW RATE:

0.01 to 0.10 L/min

DESORPTION:

1 mL toluene; 60 min ultrasonic

VOL-MIN: -MAX:

1 @ 3 ppm 36 L

INJECTION VOLUME:

1 µL splitless; split vent time 30 sec

SHIPMENT:

routine

SAMPLE STABILITY:

3 weeks @ 25 °C [1]

TEMPERATURE-INJECTOR: -DETECTOR: -COLUMN:

FIELD BLANKS:

2 to 10 field blanks per set

MEDIA BLANKS:

10 per sample set

ACCURACY RANGE STUDIED:

not determined

BIAS:

not determined

ˆ ): not determined OVERALL PRECISION (S rT ACCURACY:

not determined

250 °C 300 °C 70 °C for 1 min; 15 °C/min; hold @ 240 °C for 10 min

CARRIER GAS:

He, 1 to 2 mL/min: makeup flow 29 mL/min

COLUMN:

capillary, 30 m x 0.32-mm ID, 0.5-µm film, DB-Wax or equivalent

CALIBRATION:

formalin solution spiked on sorbent

RANGE:

3 to 200 µg per sample [2,3]

ESTIMATED LOD: 1 µg per sample [2] PRECISION (Sr):

0.0052 @ 38 to 194 µg per sample [2]

APPLICABILITY: The working range is 0.24 to 16 ppm (0.3 to 20 mg/m 3) for a 10-L air sample. The method is suitable for the simultaneous determinations of acrolein and formaldehyde.

INTERFERENCES: None have been observed. Acid mists may inactivate the sorbent leading to inefficient collection of formaldehyde. A 15 m x 0.32-mm ID DB-1301 fused silica capillary column can also be used. This column will also separate the acetaldehyde and acrolein oxazolidines. A nitrogen-specific detector (NPD) can be used for improved sensitivity.

OTHER METHODS: OSHA Method 52 is similar but uses slightly larger sampling tubes [2]. This method has improved sample stability and ease of personal sampling compared to NIOSH Methods 2502 (which has been withdrawn), 3500 and 3501. However, Method 3500 (chromotropic acid) is the most sensitive.

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