Selection of Operating Conditions for UV - Vis Spectrophotometer
- Apr 25, 2018 -
(1) measuring the wavelength
In the quantitative analysis, in order to improve the sensitivity of the measurement, the wavelength of the incident light should select the maximum absorption wavelength λmax of the measured object. If λmax is disturbed, another spectrum with less sensitivity can be selected but the interference line can be avoided. Selecting the wavelength of the incident light not only improves the sensitivity of the measurement, but also improves the accuracy of the measurement.
(2) slit width
Slit width is too large, the incident light of the monochromatic difference; slit width is too small, the intensity of the incident light weakened. If the width of the slit is too large or too small, the sensitivity will be reduced. The best choice is to produce the largest slit under the minimum error. The width of the slit width should be less than the half width of the absorption band of the sample to be measured. Otherwise, the measured absorbance value will be low and the slit width should be chosen to reduce the slit width. Plus for the most tested varieties, you can use 2nm seam width.
(3) control the appropriate range of absorbance
The range of absorbance can be achieved by controlling the concentration of the measured object or changing the thickness of the absorption cell to minimize the measurement error. General absorbance as far as possible in the control range of 0.1-0.8.
(4) the choice of blank solution
The blank solution is used to adjust the absorbance measurement working zero, that is, A = 0, T = 100% of the solution to eliminate the solution of other matrix components and the absorption pool and solvent on the incident light reflection and absorption of the error. According to different circumstances, commonly used blank solution has the following options.
① solvent blank when the solution only components in the measured wavelength of absorption, while the other components without absorption, the pure solvent can be used as blank.
② reagent blank If the color reagent or other reagents are absorbed, and the sample solution to be measured without absorption, with no other components of the test reagent blank.
③ sample blank If the sample matrix is absorbed, and the color reagent or other reagents without absorption, then with no color reagent sample solution for blank.
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