The invention belongs to the technical field of chemical and
spectrum analysis and test, and particularly discloses a
spectrophotometry quantitative
analysis method of an
iodine-
starch color-developing
system. The
spectrophotometry quantitative
analysis method specifically comprises the steps of: (1) in a
volumetric flask, taking a quantitative I<->-containing solution to fully react with an excessive FeCl3 solution at
room temperature; (2) adding a certain amount of
starch solution in the
volumetric flask, shaking up; (3) immediately adding
distilled water in the
volumetric flask for diluting until the solution is close to the neck part of the volumetric flask, shaking up; (4) immediately adding a defined amount of H2O2, shaking up, metering the volume by using the
distilled water, shaking up; (5) measuring an
absorption curve at 400-700nm by using FeCl3 as a blank control to determine a measurement
wavelength; (6) preparing color-developing systems with different
iodine concentrations by using an I<->
standard solution according to the method of (1)-(4), measuring absorbancy A by using the measurement
wavelength, establishing a
standard curve by using a correspondence between the I<-> concentration c and the A value, and obtaining an equation of
linear regression and a coefficient of association; and (7) measuring the absorbancy A of a color-developing
system of an unknown I<->-containing solution according to the method of (1)-(4), and calculating the concentration of I<-> in the
system to be measured according to the equation of
linear regression in the (6). The
spectrophotometry quantitative
analysis method is stable in color-developing system, can be directly and indirectly used for
iodine amount analysis, has the advantages of convenience, accuracy, trace amount, rapidness, low cost and the like, and can be widely applied.