Table 1: Comparison of the performance characteristics of the proposed methods with the existing visible spectrophotometric methods.

Serial
number
Reagent(s) usedMethodology (nm)Linear range (µg/mL)
( = L/mol/cm)
RemarksReference

1(a) Molybdenum thiocyanate
(b) DDQ
Methylene chloride extractable ion-pair complex measured469.5
588
5–37.5
10–80
Employs unstable oxidant, narrow linear range[24]

2(a) F-C reagent
(b) NBS-celestine blue
(c) Sulphanilamide
(d) Azocarmine G
Measurement of the absorbance of blue colored chromogen
Unreacted NBS measured using celestine blue in acid medium
Measurement of pink colored coupled product of drug with diazotized sulphanilamide with drug
Chloroform extractable 1 : 1 ion-pair complex was measured
720
540
520
540
4–28
2–12
1–10
2.5–25
Multistep, unstable oxidant, strict pH control, and tedious extraction procedure[25]

3(a) Bromophenol blue
(b) Bromothymol green
(c) Bromothymol blue
(d) Bromocresol purple
Chloroform extractable 1 : 1 ion-pair complex was measured0Required close pH control and narrow linear range and involved tedious time consuming extraction steps[26]

4Bromocresol greenChloroform extractable 1 : 1 ion-pair complex was measured4235.15–61.91Required close pH control and narrow linear range and involved tedious time consuming extraction steps[27]

5Ce(IV)- -DMABOxidation form of -DMAB measured460
0.4–8.0
(4.0 × 104)
Simple, highly sensitive, extraction free, and use of stable cerium(IV) solutionThis work
Ce(IV)- -dianisidineOxidation form of -dianisidine measured4700.4–10
(3.7 × 104)