当表示溶液浓度时,有人常常把ppm、pphm,ppb当作计量单位使用,这是十分错误的。ppm等既不是计量单位符号,也不是数学符号(如百分符号%);事实上,它们在某些国家中是表示数量份额的一种缩写(数学上称作某数的倒数),即ppm、pphm、ppb分别是英文parts　per　million、parts　per　h When expressing solution concentrations, it is often incorrect to use ppm, pphm, ppb as units of measurement. ppm, etc. are neither symbols of units of measurement nor mathematical notation (eg percent symbols); in fact they are abbreviations (in mathematics, called the inverse of a number) that represent the quantity share in some countries, ie ppm , Pphm, ppb are English parts per million, parts per h