ISO 3693-1977 PDF

Full title and description

ISO 3693:1977 — Nitric acid for industrial use — Determination of chloride ions content — Potentiometric method. This International Standard specifies a potentiometric titration procedure for quantifying chloride (Cl−) in industrial-grade nitric acid using silver nitrate titrant in a nitric acid–acetone–water medium with a silver measurement electrode and a calomel reference electrode.

Abstract

The standard defines a potentiometric titration technique applicable to nitric acid samples with chloride contents equal to or greater than 0.0002 % (m/m). It covers required reagents (including specified strengths of silver nitrate solutions), electrode arrangement (silver measurement electrode and calomel reference), sample preparation, titration procedure, calculation of chloride content and reporting. The document is a short procedural standard (4 pages) published as the first edition in 1977 and subsequently withdrawn.

General information

• Status: Withdrawn (registered withdrawal date: 12 June 2002).
• Publication date: December 1977 (first edition; foreword dated 15 December 1977).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 71.060.30 (Acids).
• Edition / version: Edition 1 (1977).
• Number of pages: 4.

Scope

Specifies a potentiometric titration method for the determination of chloride ions in nitric acid intended for industrial use. The procedure is intended for samples with chloride contents, expressed as chloride (Cl−), equal to or greater than 0.0002 % (m/m). The scope covers reagents, instrument/electrode arrangement, titration technique, calculation and limits of applicability; it does not cover broader sampling protocols beyond basic sample preparation for analysis.

Key topics and requirements

• Analytical principle: potentiometric titration of chloride with silver nitrate (AgNO3) in a nitric acid–acetone–water medium.
• Required electrodes: silver measurement electrode and calomel reference electrode; details on electrode conditioning and setup.
• Reagents and solutions: preparation and approximate normalities for silver nitrate titrant (examples: ≈0.004 N and ≈0.001 N) and standard reference solutions (e.g., potassium chloride standard).
• Sample size and preparation: recommended aliquot volumes and dilution practice to bring chloride concentration into the effective titration range.
• Detection limit and applicability: method applicable down to about 0.0002 % (m/m) chloride; use weaker titrant or modified procedure to extend lower range if required.
• Calculation and expression of results: conversion to percent (m/m) chloride and reporting conventions.
• Quality and performance: basic guidance on precision, reagent standards and verification using reference materials or standard additions.
• Safety and handling notes: precautions for working with concentrated nitric acid, acetone and silver compounds; proper waste handling and neutralization.

Typical use and users

Used historically by producers of industrial nitric acid, quality control and analytical laboratories, reagent manufacturers and regulatory or inspection bodies that monitored acid purity. Typical users included QC analysts in chemical plants, contract testing laboratories and research groups needing trace-level chloride determinations in acidic media.

Related standards

ISO 3693 is part of a cluster of ISO methods for industrial chemicals and salts. Closely related or contemporaneous standards include ISO 3694 (ammonium sulphate — chloride determination, potentiometric), ISO 3695 (ammonium nitrate — chloride determination), ISO 3708 (phosphoric acid — potentiometric chloride determination) and other ISO/TC 47 documents covering analytical methods for industrial acids and laboratory water (for example ISO 3696). Many of these historical methods have since been withdrawn or superseded by newer analytical standards or national methods; users should check current, active standards for contemporary compliance.

Keywords

nitric acid; chloride; chloride ions; potentiometric titration; silver nitrate titration; AgNO3; silver electrode; calomel reference electrode; analytical method; industrial acid; trace chloride determination.

FAQ

Q: What is this standard?

A: ISO 3693:1977 is an ISO International Standard that specified a potentiometric titration method to determine chloride ion content in industrial nitric acid.

Q: What does it cover?

A: It covers the potentiometric titration procedure (reagents, electrode setup, titration steps), calculation of chloride concentration (expressed as % m/m), and the method's applicable concentration range (down to about 0.0002 % m/m chloride).

Q: Who typically uses it?

A: Analytical chemists in industrial quality control, contract testing laboratories, acid manufacturers and regulatory testing bodies historically used this procedure to verify chloride impurities in nitric acid.

Q: Is it current or superseded?

A: ISO 3693:1977 has been withdrawn (withdrawal registered 12 June 2002). It is not an active ISO standard; laboratories should consult current ISO standards or up-to-date national methods and accredited laboratory procedures for chloride determination in nitric acid.

Q: Is it part of a series?

A: Yes — it formed part of a set of ISO analytical methods for industrial chemicals and acids (neighboring numbers ISO 3694, ISO 3695, ISO 3708, etc.) that specified comparable potentiometric chloride-determination techniques for different substances.

Q: What are the key keywords?

A: Key keywords are nitric acid, chloride, potentiometric titration, silver nitrate, silver electrode, calomel electrode, trace analysis, industrial acid, analytical method.