ISO 3899:2005

Overview

ISO 3899:2005 specifies a laboratory method for the determination of residual acrylonitrile in nitrile rubber latices with a residual acrylonitrile content of less than 0,2 % (by mass). The standard is intended for testing laboratories, quality assurance teams and manufacturers who require reliable measurement of trace acrylonitrile to support product safety and regulatory compliance.

The method combines controlled distillation, collection of the distillate in methanol and a chemical titration sequence using an n-dodecyl mercaptan reagent followed by iodine titration to quantify residual acrylonitrile.

Key practical points:

• Typical test portion: 25 g of latex
• Collection medium: methanol
• Chemical determination: mercaptan reaction followed by iodine titration
• Applicability: samples with <0.2 % residual acrylonitrile

Key Topics

• Scope and applicability: Applies to nitrile latex having residual acrylonitrile content below 0,2 % (by mass).
• Principle of the method: Distil a measured latex sample; trap acrylonitrile in methanol; react the distillate with n-dodecyl mercaptan; stop reaction with acetic acid; titrate excess mercaptan with standardized iodine solution.
• Reagents and apparatus: Uses analytical-grade methanol, propan-2-ol, mercaptan solution, potassium hydroxide in ethanol, glacial acetic acid and a standardized iodine solution. Distillation apparatus and ISO-conforming volumetric glassware are required.
• Quality control: A blank determination is carried out to correct for background consumption of titrant. Duplicate results must agree within specified limits or be repeated.
• Safety and environmental notes: The standard includes warnings about normal laboratory practice and handling of hazardous substances and waste; users must follow local safety and disposal regulations.

Applications

This ISO method is used to:

• Verify that nitrile latex batches meet internal quality specifications and regulatory thresholds for residual acrylonitrile.
• Support product safety declarations and compliance reporting where trace monomer levels are critical.
• Provide reproducible laboratory data for process control and supplier quality assurance.

Benefits:

• Provides a standardized, reproducible laboratory procedure for quantifying low-level acrylonitrile.
• Enables consistent comparison of results across laboratories when performed according to the standard.

Related Standards

Relevant referenced documents and standards include:

• ISO 123 - Rubber latex - Sampling (for correct sampling before testing)
• ISO 1042 - Laboratory glassware - One-mark volumetric flasks (for required volumetric accuracy)

For test reporting, ISO 3899:2005 requires inclusion of a reference to the standard, measured results and units, test date, any unusual observations and details of any deviations or optional operations used during the determination.