There may not be a noticeable difference between ≥99% and ≥95% pure products. However, this difference in purity can be a problem if you don’t know what’s in the impurity. Raw ingredients are produced by synthesis or extraction. So the impurities could contain residual solvents, byproducts or side products from production. In some cases impurities can be toxic, so it’s important than any relevant toxic residuals are tested, including heavy metals, pesticides, mycotoxins, microbes, etc. However impurities cannot be fully eliminated, it is impossible to make something 100% pure, even tap water has low levels of toxic heavy metals. It is also difficult to characterize every byproduct and side product of production and some impurities are just too small to measure. But impurities can be minimized. For that reason the highest standard of chromatographic purity in the pharmaceutical and nutraceutical industries is ≥99%. Whenever possible we use ≥99% raw materials, if this is not possible at production scale we use the next best option (e.g. ≥98%, ≥95%) and make this publicly known on our COAs. Where appropriate we test for specific toxins, contaminants and byproducts.