We examined the reaction surfaces around two variables (lactate and NAD⁺) in the JSCC (Japan Society of Clinical Chemistry) method for determining Lactate dehydrogenase (LD), using 23 factorial experimentation at the reaction temperatures of 30 and 37°. Theoretical response surfaces were computed by fitting a quadratic polynomial equation to the experimental data by least-squares regression. Our response surface data showed a broad plateau over the concentration range investigated (lactate 5-210 mmol/L, NAD⁺ 1-19 mmol/L, respectively ). Response surface methodology (RSM) is a collection of statistical and mathematical techniques useful for developing, improving and optimizing processes.

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Expressing the reliability of measurement results by using uncertainty is becoming the international rule. We have reported on an uncertainty estimation method for the routine test data and assigned values of calibrator by differentiating the calibration procedures for the measurement methods into those that are performed each time and those that are performed at certain intervals. This paper discusses the measurement methods whose calibration curve are not linear and presents the methods for estimating the uncertainty of these measurements by means of examples, including specific procedures. While measurements involving non-linear calibration curve, such as immunochemical analysis methods, have recently been used on an extensive scale the fact remains that the methods of expressing the reliability of the measurement data have not been sufficiently examined. We therefore take this opportunity to present here a method for estimating uncertainty based on repeat measurement values, using as samples the reference materials employed for the preparation of the calibration curve.

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Mass spectrometry (MS) is one of powerful tools for detections and identifications of unknown molecules having their own masses and structures. Before the development of softionizations such as electro-spray (ESI) and matrixassisted laser desorption ionizations (MALDI) invented by Prof. JB. Fenn and Dr. Koichi Tanaka, respectively, the MS was a restricted instrument for the detection and identification of low molecular organic compounds by gas chromatography/MS and direct MS using electron impact ionization and chemical ionization methods. Therefore, the MS had been only an apparatus which organic and inorganic chemists used to analyze low molecules. After the developments of ESI and MALDI at 1980s, we could apply these modern MS techniques to detect and characterize unknown and interesting high molecular compounds such as protein, peptides, nucleosides and com- plex lipids in body fluids and organs. Not only researchers but also medical doctors were surprised by their big capabilities of the modern MS to detect and identify the structures of high molecules. And so we could acquire new information for the understanding of the etiology of diseases by the modern MS. In this paper, I would like to summarize the principle of MS and its ionization and explanations of special terms for understanding of MS.

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