Informed articles about creatine supplementation tend to mention something about creatine purity. That is, we are warned not to buy the 'cheap stuff' because it can contain several types of alarming toxins. Nikhil Rao's recent article describes this danger. What I haven't been able to find, however, is any a standard measure of purity or quality.
Some manufacturers of Creatine Monohydrate note that they test their product using an HPLC, which is short for High Performance Liquid Chromatography, and not very telling at all. Anyone with about $4000 can buy and claim to use such a device.
My question to you is how do you assess the quality of the creatine you buy, and what makes you confident that you're getting pure product with no potentially harmful byproducts?