Page:NIOSH Manual of Analytical Methods - 3505.pdf/1

 TETRAMETHYL THIOUREA

(CH3)2NC(=S)N(CH3)2

MW: 132.23

METHOD: 3505, Issue 2

3505

CAS: 2782-91-4

EVALUATION: PARTIAL

OSHA : no standard NIOSH: no recommended exposure limit ACGIH: no standard

RTECS: YU2750000 Issue 1: 15 May 1985 Issue 2: 15 August 1994

PROPERTIES: solid; MP 78 °C; BP 245 °C

SYNONYMS: 1,1,3,3-tetramethyl-2-thiourea; TMTU

SAMPLING SAMPLER:

IMPINGER (water)

MEASUREMENT TECHNIQUE:

VISIBLE ABSORPTION SPECTROPHOTOMETRY

ANALYTE:

tetramethyl thiourea-pentacyanoamineferrate coordination complex

WAVELENGTH:

590 nm

CALIBRATION:

solutions of tetramethyl thioureapentacyandamine ferrate coordination complex in water

RANGE:

15 to 150 µg per sample

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

50 L @ 0.3 mg/m 3 250 L

SHIPMENT:

ship impinger contents in vial

SAMPLE STABILITY:

unknown

BLANKS:

2 to 10 field blanks per set

BULK SAMPLE:

required; high-volume air or settled dust

ESTIMATED LOD: 3 µg per sample [1] PRECISION (Sr):

0.02 @ 15 to 150 µg per sample [1,2]

ACCURACY RANGE STUDIED:

generated atmospheres not studied

BIAS:

unknown

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

not determined

APPLICABILITY: The working range is 0.15 to 10 mg/m 3 for a 100-L air sample. Tetramethyl thiourea is used in the manufacture of adhesives and polychloroprene rubber. The method was also applied to ethylene thiourea [1].

INTERFERENCES: Compounds containing a thione (C=S) group will complex with the pentacyanoamineferrate reagent and may interfere with the analyte absorbance band at 590 nm. Other compounds that absorb at 590 nm may interfere.

OTHER METHODS: This method was originally designated P&CAM 282 [1], which it replaces.

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