Selenium Speciation and Analysis Techniques in Environmental Samples

Selenium plays a dual role in environmental and human health, acting as an essential micronutrient at low concentrations and a toxicant when present in excess. Speciation—the determination of distinct chemical forms such as selenite (Se(IV)), selenate (Se(VI)) and various organoselenium compounds—is critical because toxicity, mobility and bioavailability depend strongly on oxidation state and molecular structure. Environmental matrices such as surface and groundwater, soils, sediments and biota present analytical challenges owing to low selenium levels, complex interferences and the need to distinguish species rather than total element content. Traditional methods include hydride generation coupled with atomic absorption or fluorescence detection, chromatographic separation paired with inductively coupled plasma mass spectrometry, and voltammetric techniques. Recent trends emphasise miniaturised, automated and green approaches: flow-injection and sequential injection analysis for high throughput, surfactant-based preconcentration such as cloud point extraction for matrix removal, and low-temperature electrochemical and spectrofluorimetric methods that offer heightened sensitivity. Advances in coupling separation and detection have improved limits of detection into the parts‐per‐trillion range, facilitating monitoring of trace selenium in drinking water, agricultural soils and foodstuffs. These methodological developments support regulatory compliance, remediation design and evaluation of selenium biotransformations on a global scale.

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Selenium Speciation and Analysis Techniques in Environmental Samples publication trend

The graph below shows the total number of articles in selenium speciation and analysis techniques in environmental samples across all publications each year (not limited to Nature Index journals).

Technical terms

Speciation: The process of identifying and quantifying the distinct chemical forms of an element in a sample, which is essential for assessing toxicological and biogeochemical behaviour.

Sequential injection analysis (SIA): An automated flow-injection technique in which sample and reagents are dispensed sequentially through a manifold to perform mixing, reaction and detection with minimal operator intervention.

Cloud point extraction (CPE): A preconcentration method using non-ionic surfactants that separate into a micelle-rich phase above a certain temperature to isolate analytes from complex matrices.

Low-temperature voltammetry: Electrochemical measurement performed at sub-ambient temperatures to enhance detection sensitivity by stabilising redox species and reducing background noise.

Molecular fluorimetry: Analytical technique that quantifies analytes by measuring characteristic fluorescence emission of specific complexes formed with target species.

References

1. Development of a sequential injection analysis method for the automatic speciation of inorganic selenium in water samples. Microchemical Journal (2024).
2. Reliable Quantification of Ultratrace Selenium in Food, Beverages, and Water Samples by Cloud Point Extraction and Spectrometric Analysis. Nutrients (2022).
3. Determination of selenium in the environment and in biological material.. Environmental Health Perspectives (1981).