ABSTRACT
OBJECTIVE: To study the algorithm of four-parameter logistic regression and apply the model in the potency calibration of bacterial endotoxin standard. METHODS: The potency of endotoxin reference standard was estimated by a novel monocyte activation test,HL60-IL6 assay.The endotoxin national standard was set as standard, while the endotoxin working standard was set as test. The four-parameter logistic model was fitted by the method of nonlinear least squares when observations of standard or sample solutions were plotted against endotoxin concentration. The algorithm was performed by C Language, the RESULTS: of which were compared by those of softmax, R Language as well as Microsoft Office Excel. RESULTS The estimated parameters as well as estimated potency were parallel between the four statistical tools. The goodness-of-fit were all over 0.99.The variance was within 0.1%. CONCLUSION: The four-parameter logistic model can be established by the four statistical tools. Researchers can select a suitable tool according to demands.