Exact chemicals EZTEST uses in its test-system obviously only EZTEST knows. It's EZTEST know-how )))
IMHO, they use analysis based on color and specific reactions of some d-metal complexes with different organic substances with further extraction complexes in organic layer.
Probably in early years they used Travnikoff reagent (copper thiocyanate) and chloroform. The DEA says it's semiquantitative analysis although it's truly quantitative in lab conditions. The reagent gives brown color with cocaine in organic layer.
As far as I know EZTEST made several upgrades of its cocaine purity test. Probably now they use some advance modifications (may be molybdenum catheholat – it gives very similar to copper brown color with cocaine - or another). In general, it seems that EZTEST did its best to learn its product work with illegal cocaine sample but…
The problem however is that the technology is not suitable to test real cocaine samples. For example, EZTEST says that its test-system does not react to any of -caines. Yes it does if you make analysis with every substance separately. But what if you mix cocaine and other substances? Or if you use their commercial analogs (for instance, not pure caffeine but caffeine sodium benzoate which available in farmacia) or part of your substances are decayed? EZTEST cocaine purity test gives no color with levamisole. But it does give color in reaction with products of levamisole degradation (some which included a group -SH). This color is a bit different and has absolutely different nature but anyway it affects analysis result.
Thus, if there's one more substance in a sample (in addition to cocaine) which is able to color solution the result will be affected too much to believe it.
Unfortunately or not but it's limitation of all EZTEST products for cocaine testing. And this is the reason why EZTEST cocaine cut test doesn't work at all.
All is IMHO
Bale