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Determination of Inorganic Arsenic in a Wide Range of Food Matrices using Hydride Generation - Atomic Absorption Spectrometry.
Published on: September 1, 2017
Novel colorimetric method overcoming phosphorus interference during trace arsenic analysis in soil solution
Konstantinos C Makris1, Pravin Punamiya, Dibyendu Sarkar
1Earth and Environmental Science Department, University of Texas at San Antonio, TX, USA. konstantinos.makris@utsa.edu
The Analyst
|January 30, 2008
Summary
This study presents a new colorimetric method for accurately measuring arsenic (As) in soil and water, even with high phosphorus levels. The technique modifies the malachite green method, enabling field-deployable arsenic testing.
Area of Science:
- Environmental Chemistry
- Analytical Chemistry
- Soil Science
Background:
- Arsenic (As) contamination in soil and water poses significant environmental and health risks.
- Accurate quantification of As, particularly in the presence of interfering substances like phosphorus (P), is crucial for environmental monitoring.
- Existing methods for As detection can be complex, expensive, or not suitable for field applications.
Purpose of the Study:
- To develop a sensitive and accurate colorimetric method for determining trace arsenic (As(v) and As(iii)) concentrations.
- To adapt the malachite green (MG) method for simultaneous analysis of As and P in soil/water extracts.
- To create a miniaturized, field-deployable method for As quantification.
Main Methods:
- Modification of the malachite green (MG) colorimetric method to differentiate between As and P.
- Utilizing ascorbic acid (AA) to equalize absorbance contributions from As(v) and P.
- Miniaturization of the assay using a 96-well microplate UV-VIS reader for reduced reagent and sample volumes.
- Validation against high-resolution inductively-coupled plasma mass-spectrometry (HR-ICP-MS).
Main Results:
- Achieved a method detection limit of 2.0 microg As L(-1) for trace As determination.
- Successfully quantified As and P in soil water extracts and total digests from As-contaminated soils.
- Demonstrated high As recovery rates (84-117%) and robustness in the presence of common soil matrix elements (Cu, Zn, Pb, Ni, Fe, Al, Si, Cr) and across a pH range (neutral to acidic).
Conclusions:
- The proposed colorimetric method offers a sensitive, selective, and robust approach for As determination in complex environmental samples.
- The miniaturized, field-adaptable design provides a proof of concept for a portable As testing kit.
- This method facilitates accurate environmental monitoring of arsenic contamination in soil and water resources.
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