Application of the Maximum Sensitivity of the Photometric Method

The method of high content determination of photometry was optimized in the way of maximum sensitivity:1) Under strictly observing the “condition of repeatable measurement”, make the “calibration curve” of the method used .The line joining its upper and lower end points is to be taken as the "calibration line" for the sample, the equation of which is the "two point form ”of the geometry, which indicating that "the change △A in the absorbance of a substance, is directly proportional to the change △C in its substance content, i.e. △A=k△C", and the sensitivity Se=△A/△C; 2) Weigh a standard sample and prepare its "mother liquor"; 3) Drop the "mother liquor" slowly and evenly with a microburette, prepare two samples with absorbance close to the upper and lower limits, and carry out the measurement; 4) On the premise that the content with the highest absorbance can appropriately cover the highest content of the sample, Select the amount of "mother liquor" of the standard sample, and determine the sample content with the lowest and highest absorbance accordingly;5) The line connecting the two points with the lowest and highest absorbance is used as the "calibration line" for the sample content, and a formula for determination is established; 6) The sample to be measured is prepared according to the standard sample preparation method, and determine its content by the "two-standard method".The method is simple, accurate and environmentally friendly. The same sample was measured 8 times repeatedly, the range was 0.4%, the uncertainty U95 was 0.09 %(k=2), and the relative standard deviation RSD was 0.08% (n=8).