Page:NIOSH Manual of Analytical Methods - 8322.pdf/1

 TRICHLOROACETIC ACID IN URINE FORMULA: C2HCl3O2

MW: 163.39

METHOD: 8322, Issue 1

CAS: 76-03-9

EVALUATION: FULL

EXPOSURE LIMITS: OSHA & NIOSH:	 N/A Because data on exposure limits and guidelines may change over time, NIOSH recommends referring to the following sources for updated limits and guidelines concerning trichloroacetic acid as well as its use as a marker for other compounds [1-4].

8322 RTECS: AJ7875000

Issue 1: 17 April 2015 PROPERTIES: BIOLOGICAL INDICATOR OF:

White solid; mp 59.1 °C; bp 198.2 °C; d = 1.61 g/cm3 [5] Exposure to trichloroethylene, trichloro- acetic acid, methyl chloroform, tetra- chloroethene, chloral hydrate

SYNONYMS:	 Trichloroethanoic acid, Aceto-caustin SAMPLING SPECIMEN:	 Urine VOLUME:

At least 10 mL

PRESERVATIVE:

MEASUREMENT TECHNIQUE

GAS CHROMATOGRAPHY with ELECTRON CAPTURE DETECTOR (GC-ECD)

ANALYTES:

Trichloroacetic acid (determined as the methyl ester)

PROCEDURE:

Methylation of an aliquot with BF3·methanol to form the methyl ester followed by extraction into toluene

INJECTION:

1 µL, splitless for 0.5 min

None

SHIPMENT:	 Freeze urine; ship in dry ice in an insulated container. SAMPLE STABILITY:	 Stable at least 30 days at -17 ºC [6] CONTROLS:	 Urine specimens from matched population of non-exposed persons ACCURACY

TEMPERATURES -INJECTION: 250 ºC -DETECTOR: 300 ºC -OVEN: 80 ºC (hold for 0.5 min), 80 to 180 ºC at 20 ºC/min, hold for 7 min

RANGE STUDIED:	 0.9 to 100 µg/mL (as trichloroacetic acid)

CARRIER GAS:

Helium, ~3.5 mL/min

BIAS:

MAKEUP GAS:

Nitrogen, 40 mL/min

COLUMN:

Capillary, fused silica, 6% cyanopropylphenyl-94% dimethylpolysiloxane, 75 m x 0.53 mm ID, 3 µm film

CALIBRATION:

Trichloroacetic acid prepared in water to cover range and derivatized with the samples

0.0113

OVERALL PRECISION (ŜrT):

0.03656

ACCURACY:	 	7.5%

ESTIMATED LOD:	 0.08 µg/mL (as trichloroacetic acid) [6] APPLICABILITY: This method can be used for the determination of trichloroacetic acid (TCAA) in urine specimens. TCAA is one of several metabolites detected after exposure to a variety of chlorinated compounds (representative compounds listed above) or from contaminated drinking water [7-11]. INTERFERENCES:	 None observed in the analytical method apart from some carryover issues (see Evaluation of Method section.) TCAA is a non-specific metabolite of several compounds. Urinary TCAA levels reflect exposure to any and all of these precursors. Background TCAA was detected in 76% of urine samples in a US general population sample, with a median concentration of 3.3 µg/L, approximately 300 times lower than the range of this method [12]. OTHER METHODS:  There are numerous literature methods for the determination of TCAA in urine [13]. The National Center for Environmental Health/Centers for Disease Control and Prevention (NCEH/CDC) has a method that is more expensive but also significantly more sensitive [11]. This method is based on the procedure used by O’Donnell [7] with some modifications. NIOSH Manual of Analytical Methods (NMAM), Fifth Edition