Overview
ISO 2199:1972 specifies a titrimetric (volumetric) method for the determination of sodium hydrogen carbonate (sodium bicarbonate) content in materials intended for industrial use. The first edition (1972) describes a simple acid–base titration using a standard hydrochloric acid solution and methyl orange as the indicator. The result is reported as percentage by mass of sodium hydrogen carbonate, expressed to one decimal place.
Key topics and requirements
- Scope: Determination of sodium hydrogen carbonate content in industrial-grade sodium hydrogen carbonate.
- Principle: Titration of total alkalinity with a standard normal (N) hydrochloric acid solution in the presence of methyl orange; correction is made for any sodium carbonate present.
- Test portion: Weigh 4.0 g ± 0.1 mg of sample.
- Sample preparation: Dissolve the test portion in about 100 mL of distilled (or equivalent) water in a 500 mL conical flask.
- Indicator and titration:
- Use methyl orange (0.5 g/L solution), adding five drops to the sample solution.
- Titrate with the standard volumetric hydrochloric acid solution until the indicator changes from yellow to pinkish orange.
- Burette: 50 mL capacity, 0.1 mL graduations (specified 30 drops/mL).
- Calculation: The standard gives a formula that uses the volume of hydrochloric acid consumed (V), the mass of the test portion (m), and the sodium carbonate content (A, determined per ISO 2198). A conversion factor (1.585) is used to convert Na2CO3 alkalinity to the NaHCO3 equivalent. Results are reported to one decimal place.
- Test report must include method reference, results and expression, any unusual features, and any optional operations not covered by the standard.
Applications and users
ISO 2199 is useful for:
- Quality control laboratories in chemical manufacturers producing sodium bicarbonate for industrial processes.
- Industrial users who require verification of raw-material composition (e.g., for pH buffering, neutralization, or cleaning applications).
- Third‑party testing labs and regulatory bodies conducting compliance testing of industrial-grade sodium bicarbonate.
Practical benefits include a reproducible, low‑cost titrimetric procedure that requires routine laboratory glassware and standard reagents.
Related standards
- ISO 2198 - referenced in ISO 2199 for the separate determination of sodium carbonate content (used to correct the titration result).
Keywords: ISO 2199, sodium hydrogen carbonate, sodium bicarbonate, titrimetric method, methyl orange, hydrochloric acid titration, industrial use, volumetric analysis, sodium carbonate.