Test results indicate colour speed of metabisulfite solution increases as acid valve(pH) dicreases because dicreasing acid valve leads to the solution electric potential moving negatively.

• 试验表明，焦亚硫酸盐试剂的着色速度随溶液酸度的增加而加快，这是由于酸度增加导致溶液电位的负移。但过量的酸化将使溶液急剧分解，而不能着色。