Enhanced Detection of Arsenic in Soil, Food, and Water

Overview

That hundreds of millions of people lack access to clean drinking water on a planet with a surface that is largely covered by water is a harsh paradox. Arsenic is a plentiful and hazardous metal found in large quantities in the earth's crust, and it is one of the main causes of the contamination of drinkable and natural water sources. In more than 100 countries, arsenic is currently thought to be the main contributor to contaminated groundwater. It is also a known source of serious illnesses, particularly in underdeveloped nations, where the population is more vulnerable. Methods for detecting arsenic in soil, food, and water are therefore required to be effective and trustworthy.

The Premise of the Arsenic Test

Principle: The limit test for arsenic is based on the reaction between arsenic gas and hydrogen ions, which results in the formation of a yellow stain on mercuric chloride paper when reducing agents like potassium iodide are present. The exam, also known as the Gutzeit test, needs specialized equipment.

In order to detect and identify trace amounts of trivalent and pentavalent inorganic arsenic compounds, this study compares two different types of silver-coated SERS substrates. An electroless procedure was used to prepare the second type of substrate, whereas a traditional thermal evaporation method was used to prepare the first. Whereas As(V) could not be identified at any analyte concentration, the thermally evaporated substrates only permitted the identification of As(III) at a limit of detection of about 50 mg/l. With a LOD of 1 g/l (1 ppb), equal for each valency, and below the WHO standard, electroless substrates enable one to distinguish between As(III) and As(V). The electroless substrates exhibit extremely high sensitivity for analyte concentrations spanning up to five orders of magnitude.

The author, Dominique Vouagner, stated that because arsenic can take on several forms in water, it is crucial to be able to estimate both the species and the overall quantity. Even at the lowest concentrations of contaminants, SERS enables us to identify and detect them. Included in this is arsenic, the World Health Organization recommends that its concentration not goes above 10 ppb.

The method differs from currently used, time-consuming, and expensive reference methods for tracing arsenic speciation. Traditional approaches also call for sample pre-treatment in a lab, making them less than optimal for on-site field testing. Surface-enhanced Raman spectroscopy is used by the sensors (SERS). Arsenic-containing molecules are zapped with a laser as they stick to the surface. Arsenic compound scatters laser light, leaving a trace that can be used to detect its presence.

In addition, the new technique uses a solid substrate to facilitate optical interrogation.

Optical detection methods are far more sensitive than electronic systems because they are less "noisy," according to author Bernard Dussardier. "They are also less susceptible to parasitic electromagnetic fields. In contrast to electronic systems and some other optical systems, the SERS technique enables direct measurements of physical-chemical properties."

What are the Procedures for Finding Arsenic?

For the measurement of arsenic, inductively-coupled plasma atomic emission spectrometry (ICP-AES) and inductively-coupled plasma mass spectrometry (ICP-MS) are becoming more and more popular techniques; both may typically offer lower detection limits than absorbance detection methods.

How can Arsenic in Water be Measured?

Improved arsenic detection in food, water, and soil image result. Arsenic concentrations below 10 g L1 are easily measured using well-established laboratory procedures such as HG AAS, ICP MS, and AFS.

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