Here’s a lesson for those who don’t keep careful track of their lab supplies. A medical lab at Pfizer’s Research and Development Center in Chesterfield, Missouri, has allegedly lost up to US$700,000 worth of gold dust bought last year, the St Louis Post–Dispatch reports. According to the newspaper, a keen-eyed Pfizer auditor was unable to account for some or all of the stash while conducting an inventory; police aren’t sure whether the missing amount was lost, stolen or used in experiments without a record being kept.

Pfizer hasn’t commented on why it purchased the gold, but some researchers at its Chesterfield centre have co-authored studies researching the possibility of  gold-particle-mediated vaccines. In such experiments, DNA capable of prompting an immune response might be adsorbed onto a microscopic gold particle, which is then blown through the skin using compressed gas — an approach that would trigger a reaction using less DNA than an injection. One Pfizer paper from 2010 describes protocols for experiments aimed at developing that particular concept that used several hundred micrograms of gold powder per sample (pictured, from Analytical and Bioanalytical Chemistry 398, 527–539). Although dozens of samples were tested, the amount of gold used was substantially less than the 10-plus kilograms police say are missing.