酚试剂法测定甲醛含量中吸收液保存条件及稳定性探讨

Research of Preservation Condition and Stability for MBTH Absorbent in Determination of Formaldehyde by Spectrophotometric

研究不同保存温度和形式下甲醛溶液吸光度的变化情况。结果表明,在吸光度相对偏差不超过±10%时,避光条件下,采样前酚试剂吸收液,常温(25℃)下可保存8天,低温(4℃)下可稳定11天以上。采样后甲醛溶液,常温可稳定4天,低温(4℃)至少可稳定6天。在实际应用中,采样前后可将溶液低温保存不超过5天,既能满足测试要求,又能兼顾时效。

To research the changes of absorbance for formaldehyde solution which preserved under different temperatures and ways.The result shows that,in case of the relative deviation of absorbance was not more than±10%,under dark conditions,the MBTH absorbent before sampling can stable in 8 days under normal temperature(25℃)while 11 days at least under low temperature(4℃).After sampling,the formaldehyde solution can stable in 4 days under normal temperature(25℃)while 6 days under low temperature(4℃).In practical situation,before or after sampling,the solution could be preserved not more than 5 days under low temperature,which both well suited for testing application and prescription.