分子荧光法对水中氨氮含量的测定

Determination of ammonia nitrogen in water by molecular fluorescence spectrometry

采用分子荧光法对水中氨氮含量进行了测定,在硼酸缓冲液作用下,邻苯二甲醛(OPA)与氨氮反应,生成具有荧光性的物质,在一定的pH、反应温度和静置时间条件下,以362 nm为激发波长,在425 nm发射波长处测定荧光物质的荧光强度,探究了四硼酸钠、亚硫酸钠和OPA混合溶液配比、反应温度、静置时间对衍生物荧光值的影响。结果表明,在一定浓度范围内,衍生物的量与荧光强度有良好的线性关系,该方法灵敏度高,适用于氨氮浓度较低水样的测定,对于高浓度水样也可进行简单稀释后测定。

Ammonia nitrogen in water was determined by molecular fluorescence method.Fluorescent substances were formed based on the reaction of phthalaldehyde(OPA)with ammonia nitrogen in boric acid buffer.Under certain pH value,suitable temperature and static time,fluorescence of fluorescent substances was were determined at 425 nm with 362 nm as excitation wavelength.The effects of the ratio of sodium tetraborate,sodium sulfite and OPA,temperature and time on the fluorescence value of the derivatives were investigated.The results showed that there was a good linear relationship between the amount of derivatives and the fluorescence intensity in a certain concentration range.This method has high sensitivity and is suitable for the determination of ammonia nitrogen in low concentration water samples.It could also be used for the determination of high concentration water samples after simple dilution.