ISO 10136-5:1993

Overview

ISO 10136-5:1993 is an international standard developed by the International Organization for Standardization (ISO), focusing on the quantitative determination of iron(III) oxide (Fe2O3) in glass and glassware extract solutions. This part of the ISO 10136 series specifies detailed analytical methods utilizing molecular absorption spectrometry and flame atomic absorption spectrometry to accurately measure iron released from glass materials during hydrolytic resistance tests or long-term storage.

The standard is applicable to analyzing extract solutions obtained from all types of glass and glassware, including borosilicate glass, neutral glass, and soda-lime-silica glass used in laboratory, pharmaceutical, food packaging, and domestic applications.

Key Topics

• Principle of Measurement

  • Molecular absorption spectrometry (SAM): Reduction of ferric iron (Fe³⁺) to ferrous iron (Fe²⁺), complexation with bathophenanthroline, extraction of the colored complex into chloroform, and measurement of optical density at 533 nm.
  • Flame atomic absorption spectrometry (SAAF): Evaporation of extract solutions with hydrofluoric and perchloric acids, dissolution in hydrochloric acid, and quantification of iron via atomic absorption at 248.3 nm.

• Scope and Application

  • Applicable to extract solutions from any glass or glassware types during hydrolytic resistance tests.
  • Measures iron concentration expressed as iron(III) oxide, detecting trace levels released from glass matrices.

• Reagents and Equipment

  • Use of analytical grade reagents including ascorbic acid, bathophenanthroline, chloroform, acids (HCl, HClO4, HF), and solutions of ferric ammonium sulfate for calibration.
  • Required apparatus includes molecular and atomic absorption spectrometers, spectroscopic cuvettes, volumetric flasks, and classical laboratory glassware conforming to ISO standards.

• Operating Procedures

  • Detailed sample preparation involving acidification, complexation, extraction (for SAM), or evaporation and dissolution (for SAAF).
  • Calibration curves prepared with iron standard solutions for precise quantification.
  • Careful control of pH and solution conditions to avoid interferences and ensure linearity in measurements.

Applications

• Quality Control in Glass Manufacturing
  Monitoring iron content released from glass to ensure product quality, especially in pharmaceutical and food-contact glassware where iron leachates can affect chemical stability.

• Hydrolytic Resistance Testing
  Application in testing the durability of glass materials in contact with aqueous solutions, particularly when iron release may impact safety or product performance.

• Research and Development
  Support for R&D activities assessing glass composition effects, interaction of glass with stored substances, and improvements in glass formulations to reduce iron leaching.

• Regulatory Compliance
  Ensuring conformity with international standards for glassware safety and material specifications related to iron content.

Related Standards

ISO 10136 is a multipart standard dealing with different elements extracted from glass; other relevant parts include:

• ISO 10136-1: Determination of silicon dioxide by molecular absorption spectrometry.
• ISO 10136-2: Determination of sodium oxide and potassium oxide by flame emission or flame absorption spectrometry.
• ISO 10136-3: Determination of calcium oxide and magnesium oxide by flame atomic absorption spectrometry.
• ISO 10136-4: Determination of aluminum oxide by molecular absorption spectrometry.
• ISO 10136-6: Determination of boron oxide by molecular absorption spectrometry.

Complementary ISO standards provide specifications for laboratory glassware and analytical equipment, such as:

• ISO 3585: Borosilicate glass 3.3 properties.
• ISO 3696: Laboratory water specification for analytical use.
• ISO 835 series: Specifications for laboratory pipettes.
• ISO 3819, 1042, 1773: Specifications for laboratory beakers and flasks.

By adhering to ISO 10136-5:1993, laboratories and manufacturers can achieve reliable, sensitive, and standardized measurement of iron oxides in glass extract solutions, reinforcing quality assurance and safety in glass products used globally.