As per the initial report of DOH there were no traces of cyanide, nitrite, nitrate, or arsenic. They are now testing the sample for other substances like Oxalic acid, Nitrobenzene, Organophosphate, and Organochlorine. Aside from these DOH also will expand their test to included biological like blood, gastric , content and tissue.
On a personal note, i believe that most toxicologist would suspect cyanide poisoning is the most probable culprit. Cyanide is a very potent poison that could kill a person in just a couple of minutes and at the same time it is a commonly used jewelry cleaning material so access to this substance is not that rare. But as per DOH report there is no trace of cyanide. Although, it is possible that due to the fact that the substance was extremely diluted then testing it “might” shows false negative results.
If i would make a wild guest i would say it is sodium monoflouroacetate although this chemical is ban in the Philippines it is possible that their is a black market for this pesticide. I based my guest on the taste that the victim told the news reporters. According to the male victim, the milk tea tasted salty, and sodium monoflouroacetate has a similar taste to sodium chloride