Note: This is an old certificate that was listed here when the site was first created. We get restocked with DCA every month and it is difficult to keep posting the most current certificate. The DCA arrives at the bottling facility vacuum packed and sealed in thick mylar bags. The bags do no allow any air or light in. As indicated, the purity is a minimum 99% pure. The CAS number is a unique chemical number that designates only ONE substance. The white paper is a scan of the labs test results showing the method of testing and the resulting purity results for each test.