复合肥料中总氮含量测定的能力验证研究

为提升北京市周边地区复合肥料生产企业产品质量,提高企业出厂检验能力,开展生产企业测定复合肥料中总氮含量的能力验证研究.能力验证样品符合均匀性和稳定性要求,总氮含量测定结果采用频率分布统计和稳健Z比分数统计方法进行分析研究.研究结果表明,18家参与能力验证单位的数据集中分布在中位值17.12附近,仅有低频数偏离,本次测定...

Study on proficiency testing of determination of total nitrogen content in the compound fertilizer

In order to improve the product quality of compound fertilizer manufacturers in the surrounding areas of Beijing and improve their ex-factory inspection ability,a study is carried out to verify the ability of the manufacturers to determine the total nitrogen content of compound fertilizer.The samples of capability verification meet the requirements of uniformity and stability,and the results of total nitrogen content determination are analyzed by frequency distribution statistics and robust Z-score statistics.The results show that the data of 18 participating capability verification units are distributed in the vicinity of the median value of 17.12,with only a low frequency deviation.The frequency distribution of the measured results is approximately normal.The satisfactory rate of the Z-score judgment is 83.3%,indicating that more than 80% of the compound fertilizer manufacturers’ inspection ability for the determination of total nitrogen content in the compound fertilizer conforms to the national standard GB/T 8573-2010 for ‘Determination of Total Nitrogen Content for Compound Fertilizers Titrimetric Method after Distillation’.Nearly 20% of the compound fertilizer manufacturers still have shortcomings in quality control,so the enterprises should improve the inspection ability and professional technical level of the inspectors,and finally achieve the goal of improving the quality of the products.