An embodiment provides a method for measuring arsenic in a sample, showing marked increase in sensitivity over previous methods including: preparing a compound of metal-plated zinc and zinc; introducing the compound to an acidified sample, wherein the sample contains an amount of arsenic, wherein the compound reduces the amount of arsenic to produce arsine gas; wherein sufficient hydrogen gas is produced to purge the sample solution; wherein the arsine gas is completely purged from the sample and captured on a test pad, wherein the pad comprises mercuric bromide, wherein the capturing produces a color change of the pad; and measuring the amount of arsenic in the sample by measuring the color change of the pad. Other aspects are described and claimed.