ISO 15923-1:2013

Overview

ISO 15923-1:2013 specifies automated methods for the determination of selected water quality parameters using discrete analysis systems with photometric detection. It covers spectrophotometric and turbidimetric procedures for ammonium, nitrate, nitrite, chloride, orthophosphate, sulfate and silicate in ground, potable, surface, waste, eluates and boiler water. The standard provides principles, sample preparation, calibration and reporting requirements for routine, automated photometric analysis.

Key topics and requirements

• Principle: color-forming reactions are carried out in individual reaction cells (cuvettes) and measured by UV/VIS detectors after controlled incubation.
• Analytes: ammonium, nitrate (and nitrate+nitrite options), nitrite, chloride, orthophosphate, sulfate (turbidimetric), silicate - detailed procedures in Annexes B–H.
• Sample preparation: filtration through a 0.45 µm membrane is recommended to remove particulates (except total phosphate and certain digests); discard first 20–30 ml of filtrate. pH range applicability: 5–9 (adjust outside this range).
• Interferences: particle turbidity and inherent colour can bias photometric readings; Annex A describes sample blanking and compensation methods. Some analyte-specific interferences are addressed in respective annexes.
• Reagents and water: use analytical-grade reagents; laboratory water must meet ISO 3696 grade 1. Dry and handle solids as prescribed.
• Apparatus: discrete analysis system with sample/reagent delivery, incubator (e.g., 37 °C recommended), UV/VIS detector (typical range 340–880 nm), control/data unit and PC/software.
• Calibration & QA: establish calibration functions per ISO 8466-1/2, include zero and multi-level calibration standards, perform calibration validity checks and run control standards (recommended at least every 20 samples). Recalibrate as needed.
• Reporting: calculate concentrations per calibration line, account for dilutions, and express results up to three significant figures; units may be reported as elemental or ion forms (conversion table provided).

Applications and users

• Routine water quality monitoring in environmental laboratories, municipal drinking water and wastewater laboratories.
• Industrial process control and boiler water monitoring.
• Laboratories and organizations implementing automated discrete photometric workflows for high-throughput analysis.
• Instrument manufacturers and method developers adapting procedures for specific discrete analyzers.

Practical benefits include reduced sample/reagent volumes, flexibility to test multiple parameters on one platform, and automated dilution/blanking options for samples outside the measurement range.

Related standards

• ISO 3696 - Water for analytical laboratory use
• ISO 5667-3 - Sampling: preservation and handling of water samples
• ISO 8466-1 / ISO 8466-2 - Calibration and evaluation of analytical methods (statistical and calibration strategy)

Keywords: ISO 15923-1, water quality, discrete analysis systems, photometric detection, spectrophotometric, turbidimetric, ammonium, nitrate, nitrite, orthophosphate, sulfate, silicate, water monitoring.