File(s) under permanent embargo
On-line solid phase extraction and spectrophotometric detection with flow technique for the determination of nanomolar level ammonium in seawater samples
journal contribution
posted on 2023-05-18, 14:33 authored by Chen, G, Zhang, M, Zhang, Z, Huang, Y, Yuan, DThe determination of low-level ammonium in seawaters suffers from low sensitivity and high contamination; therefore, it is desirable to develop highly sensitive methods for automatic measurements. A highly sensitive and automated flow technique system for nanomolar level ammonium measurement is described. Reagents for Berthelot reaction were automatically added into seawater samples. After a 10 min reaction at 40°C, the formed indophenol blue compound was on-line extracted onto an Hydrophilic-Lipophilic Balance (HLB) cartridge. The enriched compound was rinsed with water and ethanol solution (30%, v/v) and, in turn, eluted with an eluent containing 30% (v/v) ethanol and 5.0 mM of NaOH, and determined with a spectrophotometer at 640 nm. Parameter, including extraction conditions, reagent concentrations, pH, temperature, and reaction time, were optimized. Under the optimized conditions, the detection limit was 3.5 nM and the linear range was 0–428 nM. The relative standard deviations were 5.7% (n = 8) for 44.6 nM standard solution and less than 6.0% (n = 3–5) for samples within concentrations of about 52.4–288.7 nM; the recovery was in the range 93.6 to 108.5%. The sample throughput was 3 h−1. The proposed method provides a simple, cheap, and automatic way to determine ammonium in seawater samples without complicated sample treatment.
History
Publication title
Analytical LettersVolume
44Issue
1-3Pagination
310-326ISSN
0003-2719Department/School
School of Natural SciencesPublisher
Marcel Dekker IncPlace of publication
270 Madison Ave, New York, USA, Ny, 10016Rights statement
Copyright 2011 Taylor & Francis Group, LLCRepository Status
- Restricted