气相分子吸收光谱法在海水无机氮测定中的适用性研究

Application of Gas-Phase Molecular Absorption Spectrometry in Determination of Inorganic Nitrogen in Seawater

为探究气相分子吸收光谱法在海水无机氮测定中的适用情况,在检出限的10~20倍、30~50倍、50~100倍3个浓度范围内开展了准确度、加标回收率和方法比对试验。结果表明,采用气相分子吸收光谱法测定海水亚硝酸盐氮(0~0.100 mg/L)、硝酸盐氮(0~0.400 mg/L)、氨氮(0~0.200 mg/L)时,标准曲线均具有很好的线性,线性拟合度均在0.9993以上,检出限依次为0.0008、0.004、0.004 mg/L,且该方法不具有盐效应,适用于海水样品的检测。当样品浓度太低时,气相分子吸收光谱法测定结果的准确度较低,因此,建议仅在亚硝酸盐氮浓度高于0.030 mg/L、硝酸盐氮浓度高于0.100 mg/L、氨氮浓度高于0.090 mg/L时使用该方法,对应的海域为河口及近岸等无机氮含量较高的海域。此外,为保证测定结果的准确度,每个样品需平行测定2~3次。

To explore the application of gas-phase molecular absorption spectrometry in the determination of inorganic nitrogen in seawater,the accuracy,recovery rate and method comparison experiments were carried out in three concentration ranges of 10-20 times,30-50 times and 50-100 times higher than the detection limit.The results showed that the determination of nitrite(0-0.100 mg/L),nitrate(0-0.400 mg/L)and ammonia(0-0.200 mg/L)has good linearity with the linear correlation coefficient 0.9993,and the detection limits 0.0008 mg/L,0.004 mg/L and 0.004 mg/L,respectively.This method is not effected by salt and is suitable for seawater samples.It was recommended that this method is used when the concentration of nitrite is higher than 0.030 mg/L,nitrate nitrogen is higher than 0.100 mg/L,and ammonia nitrogen is higher than 0.090 mg/L.The application area of this method is the sea with higher inorganic nitrogen concentrations such as estuary and inshore.In addition,in order to ensure the accuracy of the determination results,each sample needs to be determined in parallel for 2-3 times.