ISO 3696 (Water for analytical laboratory use) specifies a purity of ten parts per billion, or 10×10−9 ― this water cannot be kept in glass or plastic containers as they leach impurities into the water, and glassware must be washed with hydrofluoric acid before use.
ISO3696（分析实验用所的水的规范）规定亿分之一的纯度，或1×10-8——这样的水不能被保存在玻璃或塑料容器中，因为它们会将杂质渗入水中，玻璃仪器使用之前必须用氢氟酸洗涤。