Precious-Metal Salt Coatings for Detecting Hydrazines

Substrates coated with a precious metal salt KAuCl4 have been found to be useful for detecting hydrazine vapors in air at and above a concentration of the order of 0.01 parts per million (ppm). Upon exposure to air containing a sufficient amount of hydrazine for a sufficient time, the coating material undergoes a visible change in color. Although the color change is only a qualitative indication, it can serve as an alarm of a hazardous concentration of hydrazine or as advice of the need for a quantitative measurement of concentration. Detection of hydrazine vapors by this technique costs much less and takes less time than does laboratory analysis of sorbent tubes using high-performance liquid chromatography, which is the technique used heretofore to detect hydrazines at concentrations down to 0.01 ppm.