Hiskey和Reilley等提出的三种差示分光光度法-高吸收度法、低吸收度法、最精密法-都是使用一份或二份已知浓度的有色溶液作参比溶液以达到扩展分光光度计标尺、提高分析测定精度的目的.除高吸收度法外,这些方法在应用时都要预先用绝对法测量参比溶液的透光率,求出标尺扩展的总 Hiskey and Reilley proposed three kinds of differential spectrophotometry - high absorption method, low absorption method, the most sophisticated method - is the use of one or two of the known concentration of the colored solution as a reference solution to achieve extended spectroscopy Photometer scale to improve the accuracy of analytical purposes.In addition to the high absorption method, these methods should be used in advance when the absolute reference to measure the transmittance of the reference solution to determine the total ruler expansion