T/ZYNY 008-2023 Active

Scope: This document specifies the method for determining the mass fraction of juglone in plant-based herbicides used in traditional Chinese agriculture. This document is applicable to the determination of the mass fraction of juglone in plant-based herbicides used in traditional Chinese agriculture. Main technical content: 1. Test method: The sample is dissolved in methanol, with juglone used as the internal standard. The juglone in the sample is separated and measured by gas chromatography using an ultraviolet-visible detector. 2. Determination steps: - Preparation of standard solution: Precisely weigh 2.5 mg of juglone standard and dissolve it in methanol. Transfer the solution to a 25 ml volumetric flask and adjust the volume to obtain a juglone stock solution with a concentration of 0.1 mg/ml. - Precisely pipette 0.1 ml, 1 ml, and 2 ml of the juglone stock solution into a 10 ml volumetric flask and adjust the volume to the mark with methanol to obtain standard solutions with concentrations of 0.001 mg/ml, 0.01 mg/ml, and 20 mg/ml, respectively. 3. Determination: Under the above-mentioned operating conditions, after the instrument baseline stabilizes, successively inject several standard solutions until the area of the juglone peak in two adjacent injections is less than 2.0%. Then, determine the juglone peak area in the sample solution according to the order of standard solution, sample solution, sample solution, and standard solution. 4. Calculation: Calculate the average peak area of juglone in two adjacent sample solutions and the two adjacent standard solutions. Plot the standard curve y=Ax+B with the concentration of the standard solution as the horizontal axis and the peak area of juglone as the vertical axis. The content of juglone in the sample, expressed as a mass fraction, X, is calculated according to Equation (1): - X0: The mass fraction of juglone in the sample solution, expressed as a percentage; - Y0: The average peak area of juglone