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| Method | Advantages | Limitations |
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| a-Centering via normalized spectrum | (1) Measurement was done in zero order
(2) It is able to recover and determine the component of both at their λmax, so it gives maximum accuracy and reproducibility
(3) Obtaining spectra typical to that of pure components which confirm the spectral profile of each component of interest
(4) No need for special software
(5) Needs calculation of one factor
(6) Easy and accurate | (1) Four manipulation steps
(2) Calculation of two factors
(3) Presence of isopoints
(4) Preparing the normalized spectrum via spectrophotometer software |
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| a-Centering via factorized spectrum | (1) Measurement was done in zero order
(2) It is able to recover and determine the component of both at their λmax, so it gives maximum accuracy and reproducibility
(3) Obtaining spectra typical to that of pure components which confirm the spectral profile of each component of interest
(4) No need for special software
(5) Needs calculation of one factor
(6) Simple preparation of the factorized spectrum
(7) Easy and accurate | (1) Three manipulation steps
(2) Presence of isopoints
(3) Preparing the factorized spectrum via spectrophotometer software |
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| Ratio Subtraction (RS) | (1) It is able to determine the nonextended component at its λmax with maximum accuracy and reproducibility
(2) Obtaining spectra typical to that of pure components which confirm the spectral profile of each component of interest
(3) No need for special software | (1) Three manipulation steps
(2) Recovery of zero order for the less extended spectra only
(3) Availability of the pure drug of the component with extended spectrum as a divisor
(4) Optimization study for choosing the best concentration of the divisor |
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| Extended Ratio Subtraction (EXRS) | (1) It is able to determine the extended component at its λmax with maximum accuracy and reproducibility
(2) Obtaining spectra typical to that of pure components which confirm the spectral profile of each component of interest
(3) No need for special software | (1) Four manipulation steps
(2) Recovered the D0 spectra of the more extended one only
(3) Accurate measuring of a constant is required
(4) Need for the pure drug of the component with the nonextended spectrum as a divisor
(5) Optimization study was applied to choose the best concentration of the divisor |
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| Constant Multiplication (CM) | (1) No need for special software
(2) No need for isopoint
(3) No need for calculated factor | (1) Two manipulation steps
(2) Accurate measuring of a constant is required
(3) Need for the pure sample of the drug of interest as a divisor
(4) Optimization study was applied in order to choose the best concentration of the divisor |
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| Unified Constant Subtraction (UCS) | (1) Measurement was done on ratio spectra
(2) No need for isopoint
(3) No need for pure form, divisors, or calculated factors | (1) Three manipulation steps
(2) Complementary method for the RS method |
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| Spectrum Subtraction (SS) | (1) No need for isopoint
(2) No need for pure form, divisors, or calculated factors
(3) One-step manipulation | (1) Applied only as a complementary method |
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