Page:NIOSH Manual of Analytical Methods - 1005.pdf/1

 METHYLENE CHLORIDE CH2Cl2 METHOD:

MW: 84.94

1005, Issue 3

CAS: 75-09-2 EVALUATION: FULL

OSHA : 25 ppm; STEL 125 ppm NIOSH: lowest feasible; carcinogen ACGIH: 50 ppm; suspect carcinogen (1 ppm = 3.47 mg/m3)

PROPERTIES:

1005 RTECS: PA8050000 Issue 1: 15 August 1984 Issue 3: 15 January 1998

liquids, d 1.323 g/mL @ 20 C; BP 40 C; MP -95 C; VP 47 kPa ( 349 mm Hg) @ 25 C, nonflammable

SYNONYMS: dichloromethane, methylene dichloride

SAMPLING SAMPLER:

SOLID SORBENT (2 coconut shell charcoal tubes, 100/50 mg)

MEASUREMENT TECHNIQUE:

GAS CHROMATOGRAPHY, FID

ANALYTE:

methylene chloride

FLOW RATE:

0.01 to 0.2 L/min

DESORPTION:

1 mL CS2

VOL-MIN: -MAX:

0.5 L @ 500 ppm 2.5 L

INJECTION VOLUME:

1 µL

SHIPMENT:

separate front and back tubes

TEMPERATURE-INJECTION: 250 C -DETECTOR: 300 C -COLUMN: 80 to150 C at 10 C/min

SAMPLE STABILITY:

ca. 30 days @ 5 C [1]

CARRIER GAS:

Helium, 2.4 mL/min

COLUMN:

capillary, 30 m x 0.32-mm ID, 0.25-µm film polyethylene glycol, Stabilwax, or equivalent

CALIBRATION:

solutions of methylene chloride in CS2 1.4 to 2600 µg per sample [1]

BLANKS:

2 to 10 field blanks per set

ACCURACY RANGE STUDIED:

1700 to 7097 mg/m3 [2]

RANGE:

BIAS:

- 4.1%

ESTIMATED LOD: 0.4 µg per sample [1]

OVERALL PRECISION ( ACCURACY:

rT

): 0.076 [1, 2]

PRECISION ( r):

0.026 [1]

±15.8%

APPLICABILITY: The working range for GC-FID analysis is 0.4 to 749 ppm (1.4 to 2600 mg/m3) for a 1-L air sample [1]. An electron capture detector (ECD) also may be used to obtain lowest feasible level of detection and quantitation [3]. Conditions for using an ECD are listed in the APPENDIX. INTERFERENCES:No specific interferences were identified. However, any compound with a similar retention time may interfere. Alternate chromatographic columns are Carbowax-PEG and DB-1 fused silica capillary columns. The capacity of the charcoal is greatly reduced when sampling in high humidity [4].

OTHER METHODS:This revises NMAM 1005 (dated 8/15/94) [5]. If sampling in an atmosphere with high relative humidity ( 80%), a tube with larger bed of charcoal is recommended. OSHA Method 59 uses a sampler with three sorbent sections, each containing 350 mg of charcoal, and has been evaluated for a 10-L air sample at 1 ppm of methylene chloride with 80% relative humidity [4]. OSHA Method 80 uses a carbon molecular sieve sampler and GC-FID analysis, and has been evaluated at 10 ppm and 500 ppm [6].

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition