Page:NIOSH Manual of Analytical Methods - 3704.pdf/1

 PERCHLOROETHYLENE (portable GC) in exhaled breath and air C2Cl4

MW: 165.8

METHOD: 3704, Issue 1

CAS: 127-18-4

RTECS: KX3850000

EVALUATION: FULL

OSHA : 100 ppm; C 200 ppm; P 300 ppm (5 min. max peak in any 3 h) NIOSH: Ca; lowest feasible ACGIH: 25 ppm, 100 ppm STEL; 10 ppm BEI, end-exhaled air (1 ppm = 6.8 mg/m3 @ NTP)

PROPERTIES:

3704

Issue 1: 15 January 1998 colorless liquid with mild chloroform-like odor; d 1.62 g/mL @ 20 C; BP 121 C; VP 14 kPa (13 mm Hg) @ 22 C; I. P 9.32 eV

SYNONYMS: tetrachloroethylene; perc

SAMPLING ™

MEASUREMENT

SAMPLER:

AIR BAG (Tedlar ) or direct injection

TECHNIQUE:

GAS CHROMATOGRAPHY (PORTABLE) / PHOTOIONIZATION DETECTOR (PID)

FLOW RATE:

0.02 to 5 L/min sufficient volume in bag (greater than approximately 0.5 L) during sampling period of interest; fill bag 80% capacity

ANALYTE:

SAMPLE STABILITY:

8 h in Tedlar bags

BLANKS:

clean air in bag from non-work area

TEMPERATURE-INJECTION:ambient -DETECTOR: ambient -COLUMN: 40 C

INJECTION VOLUME: 0.5 mL (greater volume will increase sensitivity, smaller volume will extend upper range)

CARRIER GAS: ACCURACY RANGE STUDIED:

0.1 to 100 ppm 0.05 to 0.3 ppm field validation [1]

BIAS:

not significant

OVERALL PRECISION ( ACCURACY:

rT

):

0.115 ± 22.7%

perchloroethylene (perc)

air, ultra-pure @ 10 to 20 mL/min

COLUMN:

macrobore capillary, 10 m, 0.53-mm ID, 2-µm polymethyl siloxane film, (CPSil 5CB,™or equivalent)

CALIBRATION:

bag standards or calibrated gas mixtures

RANGE:

0.1 to 1000 ppm [1]

ESTIMATED LOD:

0.01 ppm

PRECISION ( r):

0.115

APPLICABILITY: The working range is from 0.1 to 100 ppm for both air and exhaled breath samples by direct on-site analysis or by collection into inert sampling bags. Collection of exhaled breath into sample bags requires the use of a desiccant (see SAMPLING section) to remove humidity which may condense on the bag. INTERFERENCES: Any compounds having similar retention times as perchloroethylene are potential positive interferences. The presence of a large number of compounds with retention times similar to perchloroethylene will cause a high background resulting in decreased sensitivity, possibly to the point where the LOQ approaches 1 ppm. Common human metabolites found in exhaled breath, as well as chemicals normally found in dry cleaning plants, do not interfere with the analysis of perchloroethylene. Specific compounds tested and shown not to interfere with this method include: acetone, isoprene, methanol, ethanol, acetaldehyde, carbon tetrachloride, chloroform, benzene, butane, styrene, toluene and xylenes. OTHER METHODS: NMAM method 1003 for halogenated hydrocarbons [2] calls for collection of sample on charcoal sorbent, followed by laboratory desorption with carbon disulfide, and subsequent analysis by gas chromatography with a flame ionization detector. NMAM method 2549, volatile organic compounds (screening) [3], uses a multi-bed sorbent tube for sample collection, thermal desorption, and laboratory analysis by gas chromatography / mass spectrometry. Estimated limits of detection for Methods 1003 and 2549 are 1.5 and 15 ppm, respectively, for 1-L samples, which are typical for exhaled breath analysis.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition