Scope:

Inorganic acids in the workplace can cause skin, eye, and respiratory tract irritations. There are exposure limits for hydrochloric acid, hydrobromic acid, and nitric acid in the air that have been established to limit the danger exposure to workers who may be affected. Analytical and sampling techniques are needed for risk assessment and mitigation objectives.

Procedure:

To gather volatile inorganic acids for ASTM D7773 testing, a known volume of air is pulled through a pre-filter, and an alkali-impregnated quartz fiber filter is installed in an inhalable sampler. The acids are collected on the impregnated quartz fiber filter. To extract the acids collected on the sample filter to solubilize the analytes of interest, water or eluent is used. Ionization of the sample solution is performed on aliquots. Chromatography is used on additional anions, such as nitrate or bromide, to separate the extracted chloride. As a result, the anions are separated and measured using a conductivity or density meter.

Video 01: Determination of volatile fatty acid number

Results:

The results obtained in ASTM D7773 testing are plotted on the UV-vis detector, and the analytical results are a function of the measured conductivity or absorbance concentration.

Conclusion:

This test method, ASTM D7773, determines the average mass concentration of hydrogen chloride gas and hydrochloric acid mist, hydrogen bromide vapor and hydrobromic acid mist, nitric acid vapor, and nitric acid mist.