An optimized bioluminescent assay for inorganic sulfate quantitation in freshwater

• Type: Article in International Scientific Journal
• Date: 2013

Authors

Simone M Marques (Author) Other; Joaquim C G E Esteves da Silva (Author) FCUP

Journal

Title: Analytical Methods

Vol. 5

Pages: 1317-1327

ISSN: 1759-9660

Publisher: Royal Society of Chemistry

Indexing

ISI Web of Knowledge - 5 Citations

Scopus - 5 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-002-1GB

DOI: 10.1039/c3ay26255c

Abstract (EN): In this paper an optimized enzymatic assay for inorganic sulfate (SO4-2) detection and quantitation in freshwater, relying on adenosine-5'-triphosphate sulfurylase catalyzed reaction coupled to bioluminescent detection by firefly luciferase, is described. Inorganic sulfate is converted, by adenosine-5'-triphosphate sulfurylase, into adenosine-5'-phosphosulfate and inorganic pyrophosphate, with consumption of adenosine-5'-triphosphate. The remaining adenosine-5'-triphosphate is used as a co-factor in the reaction catalyzed by firefly luciferase generating, as a co-product, photons of visible light. The light output is inversely proportional to the inorganic sulfate content. Using sodium sulfate as a model, the assay was optimized through a statistical experimental design methodology and validated in water samples from domestic wells from two municipalities within the Metropolitan Area of Porto plus tap water as control. The optimized method requires 20 mu L of sample in a final reaction volume of 100 mu L. It is linear in the range from 14 to 134 mg L-1 of inorganic sulfate, with limits of detection and quantitation of 10 and 34 mg L-1, respectively. Repeatability, expressed as relative standard deviation, is 7.23% at 34 mg L-1, 6.87% at 68 mg L-1 and 4.67% at 96 mg L-1. The inorganic sulfate concentration in the wells is approximately 124, 182 and 182 mg L-1, whereas it was found to be a value of about 200 mg L-1 in tap water. Samples can be quantified by calibration curves without any pre-treatment other than dilution. The optimized method is fast, simple to perform and robust.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11