Photometric Determination of pH with a Single Standard and Calculation by Nomogram

[摘要] A method is described for construction of a nomogram, based on the Henderson Hasselbalch equation, with which photometric pH values can be calculated from the absorbance of an indicator in a sample and the absorbance of the indicator in a single standard solution. Thereby the necessity of preparing calibration curves from a series of standard solutions is avoided. The procedure is particularly convenient when the stock solution of the indicator is subject to slow fading, as in the case of phenol red.An application of the procedure to the photometric determination of the pH of human plasma is detailed and the results are compared with those obtained with a glass electrode.

[学科分类] 过敏症与临床免疫学