Application Research of Shewhart Control Chart in Determination of the Stability of Total Nitrogen Content in Compound Fertilizer
LI Honglei;DOU Xingxia;HAN Qingxia;FENG Wei;Linyi Inspection and Testing Center;
The application of Shewhart control chart in laboratory internal quality control is discussed. The total nitrogen content in the compound fertilizer is measured, 50 sets of data are used to calculate the mean, range, center line, upper and lower control limits, draw a control chart, get the mean(■) graph, range(R) graph, and the stability of the determination process of total nitrogen content in compound fertilizers is analyzed in combination with ■-R diagram. The results show that the Shewhardt control chart can be used to evaluate the stability of the determination process and is simple and easy to implement.