Page:NIOSH Manual of Analytical Methods - 5003.pdf/1

 PARAQUAT

C12 H14 N2Cl2 MW: 257.16 CAS: 4685-14-7 (ion) (C12 H14 N2)2+ (M.W. Paraquat = 186.26) METHOD: 5003, Issue 2

5003

RTECS: DW1960000 (ion)

EVALUATION: FULL

OSHA : 0.5 mg/m 3 (skin; respirable) NIOSH: 0.1 mg/m 3 (skin; respirable) ACGIH: 0.1 mg/m 3 (respirable; 0.5 mg/m 3 total)

Issue 1: 15 February 1984 Issue 2: 15 August 1994

PROPERTIES: (dichloride salt) solid; decomposes @ 300 °C; VP not significant

SYNONYMS: 1,1'-dimethyl-4,4'-bipyridinium dichloride; methyl viologen; CAS # 1910-42-5; 1,1'-dimethyl-4,4'-bipyridinium bis methyl sulfate (CAS #2074-50-2). SAMPLING SAMPLER:

FILTER (1-µm PTFE membrane)

FLOW RATE:

1 to 4 L/min

VOL-MIN: -MAX:

40 L @ 0.5 mg/m 3 1000 L

SHIPMENT:

routine

SAMPLE STABILITY:

at least 1 week @ 25 °C

BLANKS:

2 to 10 field blanks per set

ACCURACY RANGE STUDIED:

0.26 to 1.03 mg/m 3 [1] (90-L samples)

BIAS:

- 0.97%

ˆ ): 0.088 [1] OVERALL PRECISION (S rT ACCURACY:

MEASUREMENT TECHNIQUE:

HPLC, UV DETECTION

ANALYTE:

1,1-dimethyl-4,4'-bipyridium cation

DESORPTION:

5 mL water

INJECTION VOLUME:

20 µL

MOBILE PHASE:

25% acetonitrile; 75% 0.01 M heptanesulfonic acid, sodium salt (pH 3.2); 1.5 mL/min

COLUMN:

30 cm x 4-mm ID stainless steel packed with µ-Bondapak C 18 or equivalent

DETECTOR:

UV absorption @ 254 nm

CALIBRATION:

Paraquat dichloride in water

RANGE:

20 to 500 µg/sample [2,3]

ESTIMATED LOD: 10 µg/sample [2] PRECISION (Sr):

0.048 [1]

± 17.1%

APPLICABILITY: The working range is 0.1 to 10 mg/m 3 for a 200-L air sample. The paraquat cation is the analyte for this method; therefore, either salt, the dichloride or bismethyl sulfate, can be quantitated. The standards are prepared from a solution of the dichloride salt with appropriate stoichiometric factor applied.

INTERFERENCES: None identified.

OTHER METHODS: This revises Method S294 [2].

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