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

A new miniaturized microextraction HS-LPME-OIP procedure for ammonium determination based on Nessler's method

Arina Skok, Yaroslav Bazel, and Andriy Vishnikin

Department of Analytical Chemistry, Institute of Chemistry, Faculty of Science, Pavol Jozef Šafárik University in Košice, Kosice, Slovak Republic

E-mail: arina.skok@student.upjs.sk

Received: 9 September 2022  Accepted: 31 May 2023

Abstract:

A recently proposed combination of headspace liquid-phase microextraction with an optical immersion probe (HS-LPME-OIP) was adapted for the spectrophotometric determination of ammonium. The developed method is based on the conversion of ammonium ions to ammonia in a 0.15 M sodium hydroxide solution, followed by the absorption of ammonia by 200 µL of Nessler's reagent solution preliminary diluted with distilled water (1:16.7). The extracting phase, in which OIP was immersed, was placed into vial fixed in the headspace above the sample solution in a hermetically sealed vessel. The analytical signal was monitored for 30 min at 400 nm. The duration of the analysis can be flexibly adjusted and, if necessary, reduced to 5 min. The level of permissible concentrations of some interfering substances, including calcium, magnesium, iron and some organic compounds, was significantly reduced. The LOD was equal to 0.20 mg L⁻¹, and the linear calibration range was from 0.70 to 15 mg L⁻¹. The RSD ranged from 2.5 to 5.2%. The developed method was successfully applied to the analysis of natural waters, fertilizers and CRM samples.

Graphical abstract

Keywords: Nessler's reagent; Ammonium determination; Microextraction; Optical immersion probe

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-02903-3

Chemical Papers 77 (12) 7303–7309 (2023)