ISO 1389-7-1977 PDF

Full title and description

ISO 1389-7:1977 — Phthalic anhydride for industrial use — Methods of test — Part 7: Determination of maleic anhydride content — Polarographic method. This part specifies a polarographic analytical procedure for quantifying maleic anhydride in samples of phthalic anhydride intended for industrial use.

Abstract

The method is based on dissolving a test portion in acetone, removing interfering 1,4‑naphthoquinone by extraction with benzene, and measuring the analyte by polarography of the aqueous solution. The maleic anhydride mass is determined from a calibration graph. ISO 1389 (Parts 1–11) collectively replaced the earlier ISO Recommendation R 1389‑1970.

General information

• Status: Withdrawn
• Publication date: February 1977 (1977‑02)
• Publisher: International Organization for Standardization (ISO)
• ICS / categories: 71.080.50 (Chemical analysis of industrial chemicals)
• Edition / version: Edition 1 (1977)
• Number of pages: 3

Scope

This part of ISO 1389 defines a laboratory polarographic test method for determining the content of maleic anhydride as an impurity in phthalic anhydride produced for industrial applications. It covers sample dissolution, removal of a specific interfering substance (1,4‑naphthoquinone), measurement by polarography and calculation against a calibration graph; it is intended for routine quality control or specification testing where this technique is appropriate.

Key topics and requirements

• Analytical principle: polarographic measurement of maleic anhydride after sample preparation and extraction.
• Sample preparation: dissolution in acetone and selective extraction to remove 1,4‑naphthoquinone interferences.
• Reagents and solvents: specified use of acetone and benzene for extraction (user must follow current safety guidance when handling solvents).
• Calibration: determination of maleic anhydride mass by reference calibration graph (method requires suitable standards and calibration practice).
• Applicability: intended for industrial phthalic anhydride quality control laboratories equipped for polarographic analysis.

Typical use and users

Primary users are chemical manufacturers and independent testing laboratories performing quality control on phthalic anhydride shipments or production batches. Secondary users include regulatory laboratories and purchasers who need specification testing for impurities such as maleic anhydride. The method is suitable where polarographic instrumentation and trained analysts are available.

Related standards

ISO 1389 is a multipart standard (Parts 1–11) covering various test methods for phthalic anhydride (colour, acidity, ester content, ash, iron, etc.). Many parts of ISO 1389 (including Part 7) have been withdrawn. Related items include historical ISO Recommendation R 1389‑1970 that was replaced by the multipart ISO 1389 series; nearby standards addressing maleic anhydride test methods (e.g., ISO 1390 series) cover analogous analyses for that substance.

Keywords

phthalic anhydride, maleic anhydride, polarographic method, analytical chemistry, test method, quality control, acetone, 1,4‑naphthoquinone, ISO 1389

FAQ

Q: What is this standard?

A: ISO 1389‑7:1977 is Part 7 of the multipart ISO 1389 series; it specifies a polarographic method for determining maleic anhydride content in industrial phthalic anhydride samples.

Q: What does it cover?

A: It covers sample dissolution in acetone, removal of interfering 1,4‑naphthoquinone by extraction, polarographic measurement of the aqueous solution, and calculation of maleic anhydride mass using a calibration graph.

Q: Who typically uses it?

A: Chemical manufacturers, production quality control laboratories, independent testing labs and other analytical labs dealing with phthalic anhydride quality assessment and impurity determination.

Q: Is it current or superseded?

A: ISO 1389‑7:1977 has been withdrawn (the ISO catalogue shows the standard as withdrawn, with withdrawal actions recorded in ISO’s lifecycle). Users should check current national or international standards or alternative methods for routine use and regulatory compliance.

Q: Is it part of a series?

A: Yes — it is one part of the ISO 1389 multipart series (Parts 1–11) that together addressed methods of test for phthalic anhydride; the series replaced ISO Recommendation R 1389‑1970. Many parts of the series have been withdrawn.

Q: What are the key keywords?

A: Phthalic anhydride; maleic anhydride; polarography; analytical method; quality control; 1,4‑naphthoquinone; acetone; benzene; ISO 1389.