GB/T 9551-2017 in English

Comparison of standard framework and analysis of technological evolution

This standard GB/T 9551-2017 replaces the original GB/T 9551-1999. The main changes include:

• Appearance: changed from “white to gray or slightly yellow powder” to “white powder”, indicating the improvement of production process and quality control.
• Cancel the classification and grading, and uniformly stipulate that the mass fraction of thiophanate-methyl shall not be less than 97.0%
• Adjust the control indicators of hexachlorobenzene and decachlorobiphenyl, and add the detection requirements of decachlorobiphenyl

Technical Indicator Interpretation

Thiophanate-methyl mass fraction/%

As the core component of pesticide technical, the mass fraction of thiophanate-methyl directly determines its bactericidal effect. The standard requires the mass fraction to be no less than 97.0%, ensuring the high efficiency and stability of the product.

Hexachlorobenzene and decachlorobiphenyl mass fraction/(g/kg) ≤

The control of these impurities is crucial to environmental safety and human health. The standard sets the limit of hexachlorobenzene at 0.04 g/kg and decachlorobiphenyl at 0.03 g/kg, reflecting the high attention paid to environmental protection and human health.

Xylene insolubles/%

The content of xylene insolubles reflects the consistency of product quality. The standard stipulates that it should not exceed 0.2%, ensuring the stability of the product during storage and use.

Test methods and implementation recommendations

Identification test and quality control

The standard uses gas chromatography and infrared spectroscopy for identification. Gas chromatography compares the retention time of the chromatographic peak of thiophanate-methyl in the sample solution with the standard sample to ensure that the relative difference is within 1.5%. Infrared spectroscopy verifies the consistency of the molecular structure by analyzing the position and intensity of the characteristic absorption peak.

Impurity detection

The determination of the mass fraction of hexachlorobenzene and decachlorobiphenyl adopts high performance liquid chromatography. This method ensures the sensitivity and accuracy of impurities by using a C18 packed column and ultraviolet detection at 217 nm. The minimum limits of quantification specified in the standard are 5×10^-8 g/mL and 1×10^-7 g/mL, respectively, reflecting the high attention paid to trace impurities.

Determination of xylene insoluble matter

This method dissolves the sample under the assistance of ultrasound and filters and weighs it through a glass sand core crucible. The standard allows the relative deviation of two parallel determination results to be no more than 30%, ensuring the reliability and consistency of the data.

Implementation suggestions

Enterprises should establish a complete quality control system and strictly produce, test and store in accordance with the standards.

• It is recommended to equip advanced gas chromatographs and high-performance liquid chromatographs to ensure data accuracy
• Maintain production equipment regularly to avoid the introduction of impurities
• Strengthen employee training, especially on the interpretation of standards and the actual operation of test methods
• Establish an information sharing mechanism with upstream and downstream companies to ensure product quality traceability

The implementation of this standard will effectively improve the quality level of chlorothalonil technical and ensure the safety of agricultural production and environmental sustainability.