Purity testing of industrial sodium persulfate is mainly implemented in accordance with the current valid national standard GB/T 26519.1-2021 Industrial Persulfates — Part 1: Industrial Sodium Persulfate, together with the referenced standard GB/T 23940-2021 Test Methods for Industrial Persulfate Products for full-process inspection. As a strongly oxidizing basic chemical raw material, sodium persulfate is widely used in industrial scenarios including polymerization synthesis, metal surface treatment, environmental remediation and textile bleaching. Its purity directly determines application efficiency, production safety and finished product quality of downstream users. Establishing a standardized purity testing system constitutes a core link of product quality control.

Ⅰ Core Testing Items (Purity-Related Indicators)

1. Main Content (Purity)

Main content is the decisive core indicator for grading industrial sodium persulfate, directly reflecting the proportion of effective ingredients. It is a mandatory item for factory delivery inspection, warehouse incoming acceptance and third-party sampling inspection. The industry universally adopts the iodometric redox titration method to quantitatively determine effective components in samples, which serves as the fundamental basis for product grading, commercial settlement and process selection. Every production batch must undergo this test without exemption.

2. Active Oxygen Content

Active oxygen content characterizes the oxidation capacity of sodium persulfate, with a fixed stoichiometric relationship against the main content theoretical value. The industrial value of sodium persulfate relies on its oxidizing property. Testing active oxygen can verify whether the oxidation performance meets process requirements, and assist in checking decomposition loss during storage and transportation. Product grade classification takes main content as the statutory criterion, while active oxygen mainly functions as cross-check data to identify abnormalities such as product decomposition or adulteration.

3. Impurities and Physicochemical Indicators

Impurity limits and supporting physicochemical parameters are supplementary specification items, covering heavy metals, iron and manganese metallic impurities, moisture, pH value, ammonium salts, chlorides and others. Various impurities will inhibit the oxidation activity of sodium persulfate; certain metallic impurities can even accelerate spontaneous decomposition of the product and raise safety risks in storage, transportation and application. Physicochemical factors such as moisture and pH affect long-term storage stability. All above indicators are incorporated into the comprehensive product evaluation system. Any out-of-limit impurity or physicochemical parameter will result in disqualification of the batch from release.

Ⅱ Testing Error Control and Avoidance of Common Problems

Testing error control runs through the whole procedure of sample collection, reagent preparation, instrument operation and environmental condition management. During sampling, dry and clean utensils shall be used with uniform split sampling to avoid non-representative samples caused by concentrated sampling points. Standard titrants and chromogenic reagents shall be prepared freshly, stored away from light, and verified periodically for validity. Measuring equipment including analytical balances and titration devices shall be calibrated regularly per operational regulations.

Laboratory temperature and humidity must remain stable. Fluctuations will alter reagent properties and lead to sample deliquescence and decomposition. Operators shall strictly comply with standard reaction conditions and light-shielding requirements to reduce result deviation triggered by premature decomposition and loss of active ingredients. Parallel tests shall be arranged for each batch of samples; standard reference materials can be introduced for comparison if conditions permit to continuously correct systematic errors.

For frequent practical problems such as misjudgment of titration endpoints, impurity interference and sample decomposition, standardized operational rules shall be formulated. Detailed parameters including reagent adding sequence, acidification conditions and standing time shall be specified. Original testing records shall be fully archived to realize full data traceability and minimize purity judgment distortion arising from human operational errors.

Ⅲ Enterprise Quality Control Practice Case

Supported by large-scale continuous production technology, Fujian Zhanhua Chemical has built a full-process dynamic quality control system covering raw material refining, synthetic reaction, crystallization purification and finished product packaging. Graded testing nodes are set at each production stage to guarantee product purity from the source. The company is equipped with a standardized professional quality inspection laboratory that fully follows national standard testing specifications, implementing closed-loop quality management with full-item batch testing and whole-process data recording. Refined control enables product quality exceeding general industrial benchmarks.

The company delivers excellent purity performance: the main content of sodium persulfate is stably ≥ 99.0%, and active oxygen content ≥ 6.65%. Stringent control is enforced on key indicators including metallic impurities, inorganic salts, moisture and pH value, effectively preventing quality risks such as excessive impurities, component fluctuation and product decomposition. Benefiting from consistent high purity, the products fully satisfy strict requirements on raw material purity, stability and safety from high-end sectors such as electronics manufacturing, premium daily chemicals and precision metal treatment.

Purity testing of industrial sodium persulfate is fundamental for chemical raw material quality management. It requires strict implementation of national standards, full coverage of core indicators, reasonable selection of test methods and full-chain error prevention. A standardized testing system not only ensures compliant factory quality, but also avoids process fluctuations and hidden safety hazards for downstream industrial production, acting as solid technical support for high-quality industrial development.

This document is compiled based on current national standards and common industrial practices. All specific testing operations shall be subject to the latest official standard texts.