Overview
ISO/TS 17379-2:2013 specifies a trace analytical method for the determination of selenium in water using hydride generation atomic absorption spectrometry (HG‑AAS). The procedure applies to drinking water, surface water, ground water and rainwater, with a practical dynamic range of approximately 0.5 µg/L to 20 µg/L. The method requires conversion of selenium species to Se(IV) prior to hydride generation and is unlikely to detect organoselenium compounds. Sensitivity depends on selected operating conditions and the use of high‑purity reagents.
Key topics and technical requirements
- Principle: Pre‑reduction of Se(VI) to Se(IV) (e.g., reflux in 6 mol/L HCl for 1 h), generation of SeH2 using sodium tetrahydroborate (NaBH4) and atomization/measurement at λ = 196.0 nm.
- Analytical range & sample handling: Dynamic range ~0.5–20 µg/L; samples above this range require dilution. Digestion is necessary when selenium species will not form hydrides directly.
- Reagents & blanks: Use grade‑1 water (ISO 3696); NaBH4 solutions prepared fresh; reagent blanks prepared with HCl. Reagents must have selenium levels below the method’s lowest level of interest.
- Interferences:
- Hydride‑forming/volatile elements tolerated up to specified limits (As 1 mg/L, Sb 1 mg/L, Sn 0.1 mg/L, Te 1 mg/L, Hg 0.1 mg/L).
- Readily reduced metals can suppress signal (Cr 500 mg/L, Fe 500 mg/L, Cu 500 mg/L, Ni 250 mg/L, Pb 100 mg/L - values for flow systems; batch systems may be more sensitive).
- Standard addition or dilution recommended when interferences are present.
- Calibration & data analysis: Supports external calibration and standard addition; includes procedures for enrichment and performance evaluation.
- Instrumentation: Continuous or batch hydride generators, gas/liquid separators, heated silica atomization cells and auto‑sampler control.
Applications
- Routine monitoring of selenium in municipal and environmental water quality programs.
- Compliance testing where trace selenium measurement is required.
- Environmental impact assessments and discharge monitoring when selenium is a contaminant of concern.
- Research labs and water testing laboratories validating trace element methodologies.
Who should use this standard
- Environmental and analytical chemists experienced in trace‑level elemental analysis.
- Accredited water testing laboratories implementing ISO‑based methods.
- Regulatory bodies and consultants specifying validated procedures for selenium monitoring.
Related standards
Keywords: ISO/TS 17379-2:2013, selenium determination, HG‑AAS, hydride generation, water quality, trace selenium, analytical method, drinking water monitoring.