Instruments and equipment
Weighing bottle: φ60mm x 30mm, Constant temperature oven.
Weigh about 0.8g liquid humic acid sample, accurate to 0.0002g, put into weighing bottle, shake carefully.Put the weighing bottle into constant temperature oven, gradually heat to 120 ℃, at (120 ± 2 ℃) dry for 20 minutes.Then remove and put into a desiccator to cool to room temperature and weigh again.
Using the weight percentage X to express the solids conten:
ml – the weight of the weighing bottle;
m2 – the weight of the sample and weighing bottles after drying;
m – the weight of the sample.
Take the arithmetic mean of parallel determination results as the test results,the absolute difference of two parallel determination results is less than 0.30%.