Copper sulfate, commonly known as “blue glutinous rice”, is a commonly used pesticide in fruit industry production. In recent years, due to insufficient drug sources, some low-quality products have appeared on the market. These products often contain a lot of harmful impurities such as ferrous sulfate, which often cause harm to fruit tree production after use. Therefore, it is best to perform the test when using it. Its simple identification method is as follows:
1. Appearance identification. A sample of copper sulfate was taken by multi-point sampling to observe the crystal color. Pure copper sulfate is a triclinic crystal, and its ingot should be blue. If it contains impurities such as sodium and magnesium, the color of the ingot will gradually become lighter as the impurity content increases. If it contains iron, its crystal color is often blue-green, yellow-green or light green, and the color is not equal. When viewed, a better quality copper sulfate can be used as a reference.
2. Chemical identification. 1 Take about 1 gram of the sample to be tested and the pure copper sulfate (peanut size), put them into two water cups, add 100 ml of clean water, shake for a few minutes, and let the crystal blocks completely dissolve. 2 Take about 5 ml of each of the above turbid liquids, place them in two glass cups, add about 0.5 g of ammonium bicarbonate, shake for 1 to 2 minutes, make them fully react, develop color, and let stand for 10 minutes. Comparison. If the two solutions have the same color, no precipitation and few precipitates, the sample quality is qualified; if the blue color of the sample solution to be tested is significantly lighter than the pure product, the active ingredient content is low and may contain some sodium. Impurities such as magnesium and potassium; if a large amount of precipitates appear in the sample, it indicates that the sample contains more impurities such as iron, aluminum, zinc or calcium, and the more the precipitate, the lower the active ingredient.