2010 Volume 18 Issue 2 Pages 72-78
A simple method of lead analysis is spectrophotometry, which makes use of absorption changes that occur when lead forms complexes with porphyrin in an aqueous solution. Actual sample solutions, however, contain unknown amounts of various components that affect the calibration curve. An attempt was made to alleviate this interference by the use of masking agents that bind to the interfering components. A measuring reagent containing several masking agents in addition to porphyrin was prepared and reacted with a lead solution to create a calibration curve, in which concentration of the masking agent solution was used as a control factor, concentration of lead in the sample solution was used as a signal factor, and the presence or absence of interfering substances in samples was used as noise factors N1 and N2. The levels of the control factors that maximized the S/N ratio were taken as the optimal conditions, and a confirmatory test was carried out. The gain was 4.1 db, which was 2.1 db larger than the estimated value. Although the reproducibility of the gain was poor, an improvement effect was observed. A simple detection method that can detect traces of lead without being affected by interfering components was developed (detection limit: 36μg/L).
