Page:NIOSH Manual of Analytical Methods - 2535.pdf/1

 TOLUENE-2,4-DIISOCYANATE

C9H6N2O 2

MW: 174.16

METHOD: 2535, Issue 2

CAS: 584-84-9

2535

RTECS: CZ6300000

EVALUATION: FULL

OSHA : C 0.02 ppm NIOSH: lowest feasible; carcinogen ACGIH: 0.005 ppm; STEL 0.02 ppm (1 ppm = 7.12 mg/m 3 @ NTP)

PROPERTIES:

Issue 1: 15 August 1987 Issue 2: 15 August 1994

liquid; MP 19.5-21.5 °C; BP 251 °C; density 1.2244 g/mL @ 20 °C; VP ca. 1.3 Pa (0.01 mm Hg; 0.96 mg/m 3) @ 20 °C

SYNONYMS: 2,4-TDI; 2,4-bis(carbonylamino)toluene; 2,4-tolylene diisocyanate

SAMPLING SAMPLER: WOOL

TUBE

WITH

REAGENT-COATED

MEASUREMENT GLASS

(N-[(4-nitrophenyl)methyl]-propylamine on glass wool)

TECHNIQUE:

HPLC, UV DETECTION

ANALYTE:

3,3'-bis[(4-nitrophenyl)methyl]-3,3'dipropyl-1,1'-(4-methyl-1,3-phenylene) diurea (2,4-TDIU)

DESORPTION:

2 mL CH 3OH; ultrasonic bath, 3 min

INJECTION VOLUME:

50 µL

FLOW RATE: 0.2 to 1 L/min VOL-MIN: -MAX:

2 L @ 0.02 ppm 170 L

SHIPMENT:

protect from light

SAMPLE STABILITY:

MOBILE PHASE:

55:45 (v/v) CH 3CN:H 2O with 0.08% Et 3N and 0.16% H 3PO 4; 1.0 mL/min

COLUMN:

25 cm x 4.6 mm; octadecylsilylated silica, 5-µm particle size

DETECTOR:

UV @ 254 nm

CALIBRATION:

standard solutions of 2,4-TDIU in CH 3OH

RANGE:

0.3 to 25 µg 2,4-TDI per sample

at least 14 days @ 25 °C [1]

STABILITY OF REAGENT ON GLASS WOOL: ≤ 7 days @ 25 °C; ≥ 4 weeks @ -21 °C

ACCURACY RANGE STUDIED:

0.039 to 0.53 mg/m 3 [1] (67-L samples)

BIAS:

- 0.5% [1]

ˆ ): 0.033 [1] OVERALL PRECISION (S rT ACCURACY:

ESTIMATED LOD: 0.1 µg 2,4-TDI per sample PRECISION (Sr):

0.067 [1]

± 7.0%

APPLICABILITY: The working range is 0.004 to 0.35 ppm (0.03 to 2.5 mg/m 3) for a 10-L air sample. This method is applicable to isocyanate vapors (2,4-TDI vapor, 2,6-TDI vapor, and hexamethylene diisocyanate (HDI) vapor) [2,3], but not aerosols because of inefficient collection of aerosols and incomplete reaction of aerosol isocyanates with reagent.

INTERFERENCES: The reagent is slightly unstable in the dark at 25 °C. Tailing during HPLC, a result of reagent deterioration, may raise detection limits.

OTHER METHODS: This revises P&CAM 326 [4]. Sangö used similar HPLC conditions [5]. Melcher reviewed methods for isocyanates [6]. Method 5521 (Isocyanates, Monomers), using collection in an impinger, is an alternative method.

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