ISO 9964-1:1993

Overview

ISO 9964-1:1993 - "Water quality - Determination of sodium and potassium - Part 1: Determination of sodium by atomic absorption spectrometry" specifies a validated flame atomic absorption spectrometry (AAS) method for measuring dissolved sodium in water. The method uses cesium chloride as an ionization suppressant, direct aspiration into an air/acetylene flame and absorbance measurement at 589.0 nm. It is suitable for routine analysis of raw and potable waters; the working concentration interval given in the standard is 5 mg/L to 50 mg/L (the range can be extended by applying different dilution factors).

Key Topics and Requirements

• Principle: addition of cesium chloride (CsCl) to suppress ionization, direct aspiration into an air/acetylene flame and measurement at 589.0 nm using flame AAS.
• Reagents: analytical-grade acids (HCl or HNO3), prepared CsCl solution, sodium primary and working standards.
• Instrumentation: flame atomic absorption spectrometer with a hollow-cathode sodium lamp, photomultiplier sensitive to the red region, recommended spectral bandwidth < 0.3 nm.
• Sample preparation:
  • Filter samples with a 0.45 µm acid-washed filter or centrifuge to remove particulates.
  • If required, preserve samples by acidification (use same acid and concentration for samples, standards and blanks).
  • Typical preparation uses a small aliquot (e.g., 2 mL) of sample diluted to a defined flask volume after addition of CsCl.
• Calibration and quality control:
  • Prepare a calibration series (example series in the standard yields 0.1–1.0 mg/L Na on the calibration curve).
  • Run blanks with each batch and periodically check calibration slope (good practice: every ~10 samples).
  • Use the specified calculation procedure to convert absorbance to mg/L sodium; report method reference and any deviations.

Applications and Users

• Intended for environmental and drinking-water laboratories, water utilities, regulatory agencies and contract testing labs performing routine sodium analysis.
• Practical uses:
  • Monitoring sodium in raw and treated potable waters.
  • Compliance testing, process control and baseline environmental assessments.
  • Laboratories requiring a standardized, traceable AAS method for sodium determination.

Related Standards

• ISO 5667-1 and ISO 5667-2 (water sampling guides) are cited for sampling practice and sample handling.
• ISO 9964 series includes Part 2 (potassium by AAS) and Part 3 (flame emission methods) - consult these for complementary procedures.

Keywords: ISO 9964-1:1993, water quality, sodium determination, flame AAS, atomic absorption spectrometry, cesium chloride, 589.0 nm, calibration, water testing.