Overview
ISO 12243:2003 defines a laboratory method for determining water-extractable protein in medical gloves made from natural rubber latex (NR). The standard specifies the modified Lowry assay workflow - extraction, protein precipitation/concentration and colorimetric measurement against an ovalbumin standard - to quantify proteins that can be removed from gloves by aqueous extraction. ISO 12243:2003 covers the analytical assay only; it does not define sampling, safety limits or labelling requirements.
Key topics and technical requirements
- Analytical principle: water-soluble proteins are extracted, precipitated/isolated to remove interfering substances, redissolved and quantified by the modified Lowry method using a calibration curve.
- Extraction conditions: whole-glove extraction at 25 °C ± 5 °C for 120 min ± 5 min; two permitted extraction procedures (“cut‑glove” or “glove‑in‑glove”) are specified.
- Buffer and pH: extractant must maintain pH 7.4 ± 0.4 (examples: PBS or TES buffers).
- Protein concentration and cleanup: precipitation agents (e.g., TCA and phosphotungstic acid) are used to concentrate proteins before assay.
- Standard and calibration: ovalbumin is recommended as the protein stock standard and must be processed the same way as test extracts.
- Apparatus and materials: use low-protein-binding plastics (polypropylene or polyethylene) to minimize adsorption; spectrophotometer or microplate reader for colorimetric measurement.
- Performance checks: the method requires verification of the analyst’s technique (Annex A) and describes considerations like protein adsorption to tubes (Annex B) and alternative methods (Annex C).
- Reporting: results can be expressed per glove, per gram or per unit area; the chosen extraction procedure must be recorded.
- Scope limits: method is validated for NR medical gloves; applicability to other NR-latex articles may vary (extraction details not validated).
Applications and who uses it
- Glove manufacturers - quality control and process monitoring to quantify extractable protein in production lots.
- Independent testing laboratories - routine compliance testing, method verification, inter-lab comparisons.
- Regulatory or procurement teams - evaluate analytical data submitted for product assessment (note: ISO 12243 does not set safety thresholds).
- Research groups studying latex proteins, glove formulations or hypoallergenic manufacturing processes.
This standard is particularly relevant where water‑extractable protein levels are monitored as part of allergy risk-reduction programs or product quality specifications.
Related standards
- ISO 10282:2002 - Single-use sterile rubber surgical gloves - Specification
- ISO 11193-1:2002 - Single-use medical examination gloves - Part 1: Specification for gloves made from rubber latex or rubber solution
Keywords: ISO 12243:2003, medical gloves, natural rubber latex, water-extractable protein, modified Lowry method, protein assay, glove testing, extractable protein.