ALKALINE DUSTS
NaOH, KOH, LiOH, (NaOH) and basic salts
MW : 40.00 (NaOH); 56.11 (KOH) 23.95 (LiOH)
METHOD: 7401, Issue 2
CAS: 1310-73-2
RTECS: WB490000
1310-58-3 1310-65-2
EVALUATION: FULL
OSHA : 2 mg/m 3 (NaOH) NIOSH: C 2 mg/m 3/15 min (NaOH); Group I Pesticide ACGIH: C 2 mg/m 3 (NaOH)
7401
TT2100000 (KOH) OJ6307070 (LiOH) Issue 1: 15 February 1984 Issue 2: 15 August 1994
PROPERTIES: basic, hygroscopic, caustic solids and aerosols; VP not significant
SYNONYMS: alkali; caustic soda; lye; sodium hydroxide; potassium hydroxide
SAMPLING SAMPLER:
FILTER (1-µm PTFE membrane)
MEASUREMENT TECHNIQUE:
ACID-BASE TITRATION
ANALYTE:
OH - (alkalinity)
EXTRACTION:
5.00 mL 0.01 N HCl, 15 min under nitrogen with stirring
TITRATION:
0.01 N NaOH under nitrogen, endpoint by pH electrode
CALIBRATION:
0.01 N NaOH standardized with 0.01 N HCl
RANGE:
0.14 to 1.9 mg (as NaOH) per sample [1]
FLOW RATE: 1 to 4 L/min VOL-MIN: -MAX:
70 L @ 2 mg/m 3 1000 L
SHIPMENT:
routine
SAMPLE STABILITY:
at least 7 days @ 25 °C [1,2]
BLANKS:
2 to 10 field blanks per set
ESTIMATED LOD: 0.03 mg per sample (as NaOH) [1] (7 x 10 -4 moles of alkalinity) ACCURACY RANGE STUDIED:
0.76 to 3.9 mg/m 3 [1] (360-L samples)
BIAS:
5.6%
PRECISION (Sr):
0.033 @ 0.38 to 1.5 mg NaOH per sample [1]
ˆ ): 0.062 [1] OVERALL PRECISION (S rT ACCURACY:
± 16.2%
APPLICABILITY: The working range is 0.4 to 5.4 mg/m 3 for a 360-L air sample. The method measures total alkalinity of alkali hydroxides, carbonates, borates, silicates, phosphates, and other basic salts, expressed as equivalents of NaOH.
INTERFERENCES: Carbon dioxide in the air may react with alkali on the filter to produce carbonates but does not interfere when titrated. The carbonates will produce the equivalent amount of strong alkali that was consumed on the filter [1]. Acid a erosols may neutralize the sample, if present, producing a negative interference.
OTHER METHODS: This revises Methods S381 [2] and P&CAM 241 [3].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
