Page:NIOSH Manual of Analytical Methods - 5521.pdf/1

 ISOCYANATES, MONOMERIC 2,4-TDI: 2,6-TDI: MDI: HDI: NDI:

CH3C6H3(NCO)2 CH3C6H3(NCO)2 CH2(C6H4NCO)2 OCN(CH2)6NCO C10H6(NCO)2

MW: 174.16 174.16 250.26 168.20 210.20

METHOD: 5521, Issue 2

5521

CAS: 584-84-9 91-08-7 101-68-8 822-06-0 3173-72-6

EVALUATION: UNRATED

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

RTECS:

CZ6300000 CZ6310000 NQ9350000 MO1740000 NQ9600000

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

PROPERTIES: Table 1

SYNONYMS: Table 1 SAMPLING SAMPLER:

MEASUREMENT

IMPINGER (solution of 1-(2-methoxyphenyl)-piperazine in toluene)

TECHNIQUE:

HPLC, ELECTROCHEMICAL AND UV DETECTION

ANALYTE:

urea derivatives of isocyanates

SAMPLE PREP:

acetylate excess reagent, evaporate toluene, redissolve in 5 mL CH3OH

FLOW RATE: 1 L/min VOL-MIN: -MAX:

5 L @ 35 µg TDI/m3 500 L

SHIPMENT:

ship in screw-cap vial refrigerated @ 4 °C or lower

MOBILE PHASE:

acetonitrile (20% to 40%)/pH 6.0 methanolic buffer (80% to 60%) 1 mL/min; ambient temperature

may be unstable; perform steps 7 & 8 as soon as possible

COLUMN:

Supelcosil, LC-8-DB, 3-µm particle size, 7.5 cm x 4.6-mm; 2-cm guard column, 10-µm particle size

DETECTOR:

242 nm; ECHD, + 0.80 V vs. Ag/AgCl

CALIBRATION:

standard solutions of ureas in methanol

RANGE:

2,4-TDI: 0.5 to 8 µg per sample [1] 2,6-TDI: 0.7 to 10 µg per sample [1] MDI: 0.3 to 4 µg per sample [1] HDI: 1 to 15 µg per sample [1] NDI: 0.2 to 13 µg per sample

INJECTION VOLUME:

SAMPLE STABILITY:

BLANKS:

2 to 10 field blanks per set

ACCURACY RANGE STUDIED:

not studied

BIAS:

not known

ˆ ): OVERALL PRECISION (S rT ACCURACY:

not known not determined

10 µL

ESTIMATED LOD: ca. 0.1 µg diisocyanate per sample [1] PRECISION (Sr):

not determined

APPLICABILITY: The working range is from 5 µg/m3 2,4-TDI, 7 µg/m3 2,6-TDI, 3 µg/m3 MDI, 1 µg/m3 HDI, and 2 µg/m3 NDI to more than 1 mg/m3 for 100-L air samples. This method determines the air concentration of specific diisocyanates. The method has been applied to samples from general foaming, spray- or dip-painting industries [1].

INTERFERENCES: Any substance which elutes with the ureas and is electroactive will interfere with the analysis. Mobile phase conditions can be adjusted to separate most co-eluting peaks, however, ureas of HDI and TDI are difficult to separate.

OTHER METHODS: This method is a modification of Method MDHS 25 published by the Health and Safety Executive of Great Britain [2,3]. Method 2535 is an alternate method for TDI vapor, employing collection on glass wool impregnated with N-(4-nitrophenylmethyl)propylamine.

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