ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

A method of the determination nitrate nitrogen (NO₃⁻-N) in high-salinity water samples

Jing Hu, Zhi Zhuang, Mengyan Pan, Tianhao Han, Yuliang Li, and Weiguo Liu

State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, China

E-mail: yulianglee@hotmail.com

Received: 17 September 2021  Accepted: 4 December 2021

Abstract:

The determination of nitrate nitrogen (NO₃⁻-N) is a key step in the pretreatment of nitrogen isotope determination, but how to determine NO₃⁻-N in high-salinity water samples simply and efficiently is always a difficult problem. A spectrophotometric method for the determination of nitrate is presented and verified in this paper. Samples with different salinity were added to determine the known concentration gradient of NO₃⁻-N. The results show that the nitrate content can be determined between 0.2 ~ 2.8 mg/L by ultraviolet–visible spectrophotometer (hereafter as UVS), and the relative error is about 10%. A standard curve of the same salinity should be attempted for a water sample with known salinity. Precon-Isotope Mass Spectrometry (hereafter as Precon-MS) was used to verify the determination of sample concentration by UVS, and the relative error was less than 8%. This paper presents a simple and efficient method for the determination of NO₃⁻-N in high-salinity water samples, which has made great progress in the determination of nitrate nitrogen in samples and provides a theoretical basis for the determination of nitrogen isotopes in the pretreatment process of water samples.

Keywords: Ultraviolet–visible spectrophotometer; NO3 −-N; Nitrogen isotope δ15N-NO3 −

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-02007-w

Chemical Papers 76 (3) 1739–1744 (2022)