Overview
ISO 10136-3:1993 specifies a standardized analytical method for measuring calcium oxide (CaO) and magnesium oxide (MgO) released from glass and glassware into extract solutions. The method uses flame atomic absorption spectrometry (FAAS) - measuring absorption at the characteristic lines 422.7 nm (Ca) and 285.2 nm (Mg) - and compares sample absorption with calibration (reference) solutions. It applies to extract solutions from any kind of glass or glassware (laboratory and pharmaceutical ware, food and drink packaging, tableware, kitchenware) and is part of the ISO 10136 series on analysis of extract solutions.
Key topics and requirements
- Analytical principle: FAAS measurement of elemental Ca and Mg, results reported as their oxides (CaO, MgO).
- Instrumentation: FAAS with hollow-cathode lamps for Ca and Mg; suitable burners and gas mixtures (air/acetylene or N2O/acetylene).
- Calibration and reference solutions: preparation of stock and standard solutions, sets of calibration solutions and plotting calibration graphs; blank test solution required.
- Sample preparation: use of extract solution produced by hydrolytic resistance tests; addition of spectrochemical buffer (lanthanum oxide solution or strongly acidic buffer) and acidification when necessary to dissolve hydroxides/carbonates; filtration of turbid solutions.
- Reagents and standards: specified use of analytical-grade reagents (e.g., hydrochloric acid, CaCO3/CaO and MgO standards, La2O3 buffer); preparation of fresh standard solutions before use.
- Quality procedure: repeat measurements (multiple spray/read cycles), use of blank corrections, and calculation of mean values; concentrations expressed as µg of CaO/MgO per mL of extract solution.
- Reporting: test report to reference ISO 10136-3, identify samples, hydrolytic resistance method used, measurement method (gas mixture), and results.
Practical applications and users
- Quality control and compliance: used by glass manufacturers, QC laboratories and testing houses to assess hydrolytic resistance and chemical durability of glass and glassware.
- Regulatory and pharmacopoeial testing: applicable to pharmaceutical and laboratory ware where leachable Ca and Mg affect product safety or performance.
- Packaging and food safety: testing food and drink packaging glass for element release.
- Research and development: materials scientists and analytical chemists studying glass composition, leaching behavior, or process changes.
- Typical users: analytical laboratories, glass producers, pharmaceutical QC, food-packaging testing labs, and standards bodies.
Related standards
- ISO 10136 (other parts): Part 1 (SiO2), Part 2 (Na2O, K2O), Part 4 (Al2O3), Part 5 (Fe2O3), Part 6 (Boron).
- Supporting ISO references cited in the method: ISO 3696 (water for analytical use), ISO 648 (one-mark pipettes), ISO 3585 (borosilicate glass 3.3), ISO 3819 (beakers).
Keywords: ISO 10136-3:1993, glass and glassware, analysis of extract solutions, calcium oxide, magnesium oxide, flame atomic absorption spectrometry, FAAS, hydrolytic resistance, spectrochemical buffer, calibration.
Open preview (PDF)Glass and glasssware — Analysis of extract solutions — Part 3: Determination of calcium oxide and magnesium oxide by flame atomic absorption spectrometry