Redox-Reaction Based Spectrophotometric Assay of Isoniazid in Pharmaceuticals

Table 6

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

Sl. No.	Reagent/s used	Methodology	𝜆max; (nm)	Linear range; (µg mL^−1); (𝜀 = L/mol/cm)	Remarks	References
1	Epichlorohydrin	Measurement of purple colored coupled complex	405	2–22; (0.51 × 10^4)	Longer reaction time and heating	[45]
	hydroxyphenacylchloride		402	20–120; (0.10 × 10^4)
2	Ethyl vanillin	Measurement of yellow colored hydrazone complex	410	2–16; (7.1 × 10^3)	—	[46]
3	Vanillin	Measurement of yellow colored hydrazone complex	405	1–12	—	[47]
4	Isatin	Measurement of yellow colored hydrazone complex	340	0–32; (1.2 × 10^4)	Requires close pH control and 40 min standing time, measurement at a shorter wavelength	[48]
5	Sodium 1,2-naphthoquinone-4-sulfonate and cetyltrimethyl ammonium bromide	Absorbance of condensation product measured	500	2.0–5.6	Employs a costly reagent	[49]
6	Chloranilic acid	Measurement of charge-transfer complex	500	1.37–8.2	Use of organic solvent, requires heating step	[50]
	Tetracyanoethylene		480	6.85–34.27
	2,3-dichloro-5,6-dicyano-1,4-benzoquinone		580	10.96–21.93
	Thymol blue	Measurement of ion-associate complex	390	6.85–41.13	Require close pH control, liquid-liquid extraction step
	Bromophenol blue		410	1.37–6.85
	Bromocresol green		320	1.37–8.22
7	2-Hydroxy-1,4-napthoquinone	Measurement of derivatized product	365	5–25	Requires close pH control, use of nonaqueous medium, measurement at a shorter wavelength	[51]
8	1, 2-Naphthoquinone-4-sulfonate	Measurement of pink colored condensed product	495	0.5–3.0; (1.18 × 10^4)	Requires close pH control	[52]
9	6-Methyl-2-pyridinecarboxaldehyde	Measurement of hydrazone derivative	328	2–16	Measurement at lower analytical wavelength	[53]
10	9-Chloroacridine	Measurement of absorbance of derivatized complex	500	—	Requires heating step, time consuming	[54]
11	4,4′-Methylene-bis-m-nitroaniline	Measurement of purple colored diazo-coupled complex	495	0.1–15; (5.63 × 10^4)	Requires low temperature	[55]
12	4,4′-Sulphonyldianiline	Measurement of purple colored diazo-coupled complex	440; 335	0.5–20; (5.72 × 10^4)	Requires low temperature	[56]
13	Tiron-NaIO4	Measurement of red-colored oxidative-coupled product	507	1.0–15; (1.84 × 10^4)	Use of multireaction system step	[57]
14	Tiron-KIO4	Measurement of red-colored oxidative-coupled product	505	1.5–18; (1.77 × 10^4)	Use of multistep reaction system	[58]
15	Uranyl acetate	Measurement of yellow-colored uranyl isonicotinoyl dithiocarbazate complex	410	—	Multistep reaction, time consuming	[59]
16	Neocuproine	Measurement of redox complex	454	0.3–3.5	Requires close pH control, a multistep reaction	[60]
17	Rose bengal	Measurement of acetone-chloroform extractable ion-pair complex	555	2.8–5.6	Requires time consuming and tedious extraction step, use of organic solvent	[61]
18	*NBS	Measurement of starch-iodine Complex	572	0.1–3.4	Multistep reaction, employs an unstable oxidant	[62]
19	*NBS	Absorbance of starch-iodine complex measured	572	0.1–3.4	Multistep reaction, employs an unstable oxidant	[63]
20	Potassium ferricyanide	Measurement of Prussian blue	735	0.04–8; (3.92 × 10^4)	—	[64]
21	3-(2-Pyridyl)-5,6-diphenyl-1,2,4-triazine	Measurement of redox complex	558	0.62–6.15	Multistep reaction, requires an expensive reagent	[65]
22	(a) * FC reagent	Measurement of molybdenum-tungsten mixed acid blue absorbance in sodium carbonate medium	760	0.5–10; (1.12 × 10 ^4)	Simple, rapid, sensitive, uses aqueous medium and extraction free, no use of organic solvent, based on a single step reaction	Present work
	(b) Ferric chloride and potassium ferricyanide	Measurement of absorbance of Prussian blue in acid medium	760	0.2–3.0; (4.55 × 10 ^4)

∗NBS-N-bromosuccinimide, KMnO₄-potassium permanganate, FC reagent-Folin-Ciocalteu reagent.