Determination of low nanogram/millilitre levels of volatile organic compounds in on‐purpose and by‐product hydrochloric acids

Abstract

Hydrochloric acid (HCl) is used in the food industry as a processing aid in the manufacture of certain foods. HCl is manufactured, either directly from inorganic sources, i.e. ‘on‐purpose’ or indirectly as a by‐product from the production of organic compounds generally intended for non‐food applications. By‐product HCl potentially may contain traces of the manufactured product, its precursors, and other reaction by‐products. Many of the potential contaminants are volatile organic compounds (VOCs) such as vinyl chloride and benzene. A study was conducted to determine whether there were differences between the levels of VOCs found in HCl samples collected from two on‐purpose HCl manufacturers and two by‐product HCl manufacturers. Process water used to manufacture the HCl also was analysed. Twenty‐nine VOCs were determined by purge‐and‐trap concentration and capillary gas chromatography/mass spectrometry. Of these, nine were found in the process water and in both the by‐product and on‐purpose HCl samples at total VOC levels of less than 116 ng/ml. The levels of total VOCs identified in the two on‐purpose HCl samples were 58 and 80 ng/ml; the levels of total VOCs identified in the two by‐product samples were 41 and 115 ng/ml. The process water appeared to be the source of most of the contaminants. These results show that the levels of VOCs found in the two types of acid are comparable.

Keywords:

• on‐purpose
• by‐product
• hydrochloric acid
• volatile organic compounds