Titrimetric and Spectrophotometric Methods for the Assay of Ketotifen Using Cerium(IV) and Two Reagents

Table 1

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

Serial; number	Reagent(s) used	Methodology	𝜆max (nm)	Linear range (µg/mL); (𝜀 = L/mol/cm)	Remarks	Reference
1	(a) Molybdenum thiocyanate; (b) DDQ	Methylene chloride extractable ion-pair complex measured	469.5; 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 measured	—	0	Required close pH control and narrow linear range and involved tedious time consuming extraction steps	[26]
4	Bromocresol green	Chloroform extractable 1 : 1 ion-pair complex was measured	423	5.15–61.91	Required close pH control and narrow linear range and involved tedious time consuming extraction steps	[27]
5	Ce(IV)-𝑝-DMAB	Oxidation form of 𝑝-DMAB measured	460	0.4–8.0; (4.0 × 10^4)	Simple, highly sensitive, extraction free, and use of stable cerium(IV) solution	This work
	Ce(IV)-𝑜-dianisidine	Oxidation form of 𝑜-dianisidine measured	470	0.4–10; (3.7 × 10^4)