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
