次溴酸盐氧化法是一种海水或高盐度水质氨氮的常用检测方法,但实验发现该方法在亚硝酸盐氮存在时氨氮测定结果有较大误差.研究了次溴酸盐氧化法中亚硝酸盐氮对氨氮测定结果的影响.结果显示,氨氮的测量误差随着水样中亚硝酸盐氮含量的升高而变大,且具有明显的正相关性;探讨误差产生的机理发现,误差可能是次溴酸盐不能将氨氮完全氧化为亚硝酸盐氮导致的;研究了氧化率的影响因素发现,氧化时间对氧化率的影响可忽略,温度对氧化率有很大影响.在室温为(23±1)℃时,拟制出亚硝酸盐氮浓度对氨氮测量绝对误差的影响曲线,曲线方程为y=1.834x+0.018,r=0.996 7.利用修订的氨氮测定计算公式,可大大提高亚硝酸盐氮存在时水中氨氮的测量精度.%Hypobromite oxidation is a common method used to detect ammonia nitrogen in seawater or high-salinity water.But the existence of nitrite nitrogen may lead to great error for the measurement of ammonia nitrogen.This study investigated the effect of nitrite nitrogen on the measurement of ammonia nitrogen with the method of hypobromite oxidation.The results showed that error of ammonia nitrogen became greater with the increasing concentration of nitrite nitrogen in sample and measurement error had a significant positive correlation with nitrite nitrogen concentration.This study also investigated the mechanism of error production,and it was found that incomplete oxidation of nitrite nitrogen by hypobromite may be the reason lead to the error.It was found that reaction time had no effect on the result while the temperature had effect to the result.The influence curve ammonia nitrogen error affected by nitrite nitrogen's concentration in (23 ± 1) °C was traced in this study.The curve equation is y =1.834x + 0.018,r =0.9967.The measurement accuracy of ammonia nitrogen could be greatly increased by this formula when nitrite nitrogen existed.
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