Determination of Fluoroquinolones in Pharmaceutical Formulations by Extractive Spectrophotometric Methods Using Ion-Pair Complex Formation with Bromothymol Blue

Table 6

The comparison of present study with other spectrophotometric methods.

Drug	Reagent	λmax (nm)	Range of determination (μg/mL)	Molar absorptivity (L/mol⋅cm)	Remarks	Reference
Ciprofloxacin	Co (II) tetrathiocyanate	623	20–240	8.38 × 10^2	Less sensitive	[34]
	Supracene violet 3	575	2.5–30	8.62 × 10^3	Less sensitive	[35]
	Eosin Y	547	2–8	3.56 × 10^4	Less stable colour	[36]
	Merbromin	545	2–15	1.23 × 10^4	Addition of CN^–to inhibit Hg^+2 ions
	Ce(IV)- MBTH	630	10–50	—	Involves shaking time	[17]
	Tris(o-phenanthroline) iron(II)	510	0.04–7.2	3.4 × 10^4	Involves shaking time and heating	[18]
	Tris (bipyridyl) iron(II)	522	0.05–9	2.95 × 10^4	Involves shaking time and heating
	CL	520	16–96	—	Involves shaking time and heating	[16]
	TCNE	335	0.25–15	—	Involves shaking time and heating
	Sudan II	550	0.8–7.1	5.3 × 10^4	Narrow linear range	[8]
	Congo red	517	0.5–6.0	2.83 × 10^4
	Gentian violet	585	0.5–10	2.21 × 10^4
	Brilliant blue G	610	0.5–6.0	2.86 × 10^4	Narrow linear range and required pH adjustment	[37]
	Bromocresol green	412	1–20	2.28 × 10^4	Required pH adjustment	[14]
	BTB	420	0.5–25	2.09 × 10^4	Highly sensitive with wide linear dynamic ranges, no heating, and no pH adjustment	This study
Levofloxacin	Chloranilic acid	521	15–250	1.2 × 10^3	Less sensitive	[14]
	Bromocresol green	411	1–20	2.16 × 10^4	Required pH adjustment
	Eosin Y	547	2–8	4.83 × 10^4	Less stable colour	[36]
	Merbromin	545	2–15	1.58 × 10^4	Addition of CN^–to inhibit Hg^+2 ions
	Cobalt (II) tetrathiocyanate	623	20–240	—	Less sensitive	[34]
	Bromophenol blue	424	1.85–31.5	1.98 × 10^4	Required pH adjustment	[19]
	Bromocresol green	428	1.85–25	1.82 × 10^4
	BTB	415	0.5–25	2.07 × 10^4	Highly sensitive with wide linear dynamic ranges, no heating, and no pH-adjustment	This study
Ofloxacin	Supracene violet 3	575	2.5–25	1.09 × 10^4	Less sensitive	[35]
	Tropaeolin 000	485	2.5–30	8.23 × 10^2	Less sensitive
	Sudan II	560	0.8–8.4	2.97 × 10^4	Narrow linear range	[8]
	Congo red	530	0.5–5.5	3.29 × 10^4
	Gentian violet	575	0.8–11	2.51 × 10^4
	Bromocresol purple	400	1.0–16.0	2. 4 × 10^4	Required pH adjustment	[38]
	Bromocresol green	410	1.0–16.0	1.96 × 10^4	Required pH adjustment
	Bromophenol blue	410	5–25	1.03 × 10^4	Required close pH control and involved extraction steps	[20]
	Bromothymol blue	415	2–15	2.01 × 10^4
	Bromocresol purple	410	2–20	1.64 × 10^4
	Bromothymol blue	415	1–35	1.44 × 10^4	Highly sensitive with wide linear dynamic ranges, no heating, and no pH-adjustment	This study