Page:NIOSH Manual of Analytical Methods - 2549.pdf/1

 VOLATILE ORGANIC COMPOUNDS (SCREENING)

FORMULA

see Table 1

MW: see Table 1

METHOD: 2549, Issue 1

CAS: see Table 1

EVALUATION: PARTIAL

OSHA : NIOSH: varies with compound ACGIH:

PROPERTIES:

2549

RTECS: see Table 1

Issue 1: 15 May 1996

See Table 1

SYNONYMS: VOCs; See individual compounds in Table 1

SAMPLING SAMPLER:

THERMAL DESORPTION TUBE (multi-bed sorbent tubes containing graphitized carbons and carbon molecular sieve sorbents [See Appendix])

FLOW RATE:

0.01 to 0.05 L/min

VOL-MIN: -MAX:

1L 6L

SHIPMENT:

MEASUREMENT TECHNIQUE:

THERMAL DESORPTION, GAS CHROMATOGRAPHY, MASS SPECTROMETRY

ANALYTE:

See Table 1

DESORPTION:

Thermal desorption

INJECTION VOLUME:

Defined by desorption split flows (See Appendix)

Ambient in storage containers

SAMPLE STABILITY:

Compound dependent (store @ -10 C)

BLANKS:

1 to 3 per set

TEMPERATURE-DESORPTION: 300 C for 10 min. -DETECTOR (MS): 280 C -COLUMN: 35 C for 4 min; 8 C/min to 150 C, 15 C/min to 300 C CARRIER GAS:

Helium

COLUMN:

30 meter DB-1, 0.25-mm ID, 1.0-µm film, or equivalent

CALIBRATION:

Identification based on mass spectra interpretation and computerized library searches.

RANGE:

not applicable

ESTIMATED LOD:

100 ng per tube or less

PRECISION ( r):

not applicable

ACCURACY

RANGE STUDIED:

not applicable

BIAS:

not applicable

OVERALL PRECISION ( ACCURACY:

rT

):

not applicable not applicable

APPLICABILITY:This method has been used for the characterization of environments containing mixtures of volatile organic compounds (See Table 1). The sampling has been conducted using multi-bed thermal desorption tubes. The analysis procedure has been able to identify a wide range of organic compounds, based on operator expertise and library searching. INTERFERENCES:Compounds which coelute on the chromatographic column may present an interference in the identification of each compound. By appropriate use of background subtraction, the mass spectrometrist may be able to obtain more representative spectra of each compound and provide a tentative identity (See Table 1). OTHER METHODS: Other methods have been published for the determination of specific compounds in air by thermal desorption/gas chromatography [1-3]. One of the primary differences in these methods is the sorbents used in the thermal desorption tubes.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 5/15/96