ABSTRACT
International law (HJ636-2012) in preparation by alkaline potassium persulfate solution: 40.0 g persulfate 600 ml soluble in water; another 15.0 g sodium hydroxide dissolved in water 300 ml. Sodium hydroxide solution temperature after cooling to room temperature, mixing two solutions with constant volume to 1000 ml, deposited in polyethylene bottles, you can save a week.[1] Yi Tan[2] studies have shown that new storage with good alkaline potassium persulfate solution within 3 days, no impact on total nitrogen determination results almost; for more than 3 days, negative deviation of the measurement results will appear smaller; more than 7 d, there will be serious negative deviation. Table 1 according to the new store with good alkaline potassium persulfate solution blank absorbance within 3 days to meet the requirements HJ636-2012 blank absorbance values in, but when the storage time in the determination of relative error for 3 days 7.2% has already surpassed that total nitrogen content of the sample in the HJ6362012 when >1.00 mg/L, determination of relative deviation of ≤5% quality control requirements. Yi Fang[3] believes that about 15 °C for more than
National standard method (HJ636-2012) used in determination of total nitrogen potassium persulfate oxidation-ultraviolet Spectrophotometric method, this method is simple, high sensitivity.[1] But in practice potassium found itself outside the significant impact on test blank absorbance, alkaline potassium persulfate solution length of storage time, reaction time of digestion time controls, selection of cooling length after digestion, and what additional cooling cooling experimental data will cause an exception. Start with several links in this article from the comparative analysis of the impact of these factors on the determination of total nitrogen, and put forward appropriate recommendations for improvement.
