Method 7401

Alkaline Dust by Titration

The method measures total alkalinity of alkali hydroxides, carbonates, borates, silicates, phosphates, and other basic salts, expressed as equivalents of NaOH. The sample is collected on a filter, dissolved in dilute HCl, and titrated with dilute NaOH to an endpoint measured using a pH electrode. The working range is 0.4 to 5.4 mg/m³ for a 360-L air sample. NOTE: This revises Methods S381 and P&CAM 241.

(NIOSH Issue 2: 15 August 1994)


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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   At least 7 days @ 25 °C
Preservatives:   25 °C
Required Preps:   1 um PTFE membrane filter, 37 mm
Collection Method:   Filter, 70-1000 L @ 2mg/m³ @ 1-4 L/min
Analytical Methodology:   Acid-base titration
Documentation:   7401

Analyte List*

Analyte Formula CAS Number Detection Limit
Potassium hydroxide
Lithium hydroxide
Sodium hydroxide

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.