Table 6: Comparison of the performance characteristics of the present methods with the published method Spectrophotometry.

Serial number Reagentes used Methodology (nm)Linear range (µg/mL−1)
(L mol−1 cm−1)
RemarksReference

1CAT-methyl orange/indigocarmineUnreacted CAT measured using methyl orange/indigocarmine in acid medium510
610
Employs unstable oxidant [6]

2CAT-metol-Ar. aldehydeMeasurement of unreacted CAT with metol and Ar. aldehyde at pH 2.70 0.15202.5–25
6.24 × 103
Employs unstable oxidant, multiple step reaction, strict pH control[7]

3KBrO3-KBr mixture-MOKinetic measurement of unreacted bromine using methyl orange 510 0.5–4.0
2.89 × 104
Strict control of experimental variables
required
[8]

4KBrO3-KBr mixture in acid mediumMeasurement of residual bromine using methyl orange in acid medium5–25[9]

5NBS-methyl orange/indigo carmineMeasurement of absorbance of acid form of methyl orange or indigocarmine 520
1.5–4.0
3.45 × 104
Employs unstable oxidant
6108–16
1.13 × 104
[10]

6NCS-Fe (II)-SCN Measurement of absorbance of iron (III)-SCN complex4800.62–10.0
4.14 × 104
Employs unstable oxidant, multiple step
reaction and multi reagents
[11]

7NaIO4Measurement of acid form of methyl orange or indigo carmine 5200.5–5.0
2.92 × 104
6102.5–25
5.11 × 103
[12]

8NBS-iron-(II-) thiocyanate or tironMeasurement of absorbance of iron-(III-) thiocyanate or tiron complex0.5–5.0
4.8 × 104
Employs unstable oxidant
1–21
1.1 × 104
[30]

9Folin-Ciocalteu's reagentMeasurement of the absorbance of blue colored chromogen700[32]

10 p-CAMeasurement of absorbance of
charge transfer complex radical anion
5250~280
8.03 × 103
Less sensitive[33]

11(a) DDQMeasurement of absorbance of
charge transfer complex radical anion
5007.50–80
1.83 × 103
Less sensitive
(b) p-CAA45510–85
1.12 × 103
[34]

12 BCG, BTB, BPB, and BPR in acidic mediumMeasurement of absorbance of the ion-pair complex4202–12Involves tedious
extraction step, rigid pH control, and use of large quantity of organic solvent
[35]

13Thymol blue, alizarin (I), alizarin red S (II), alizarin yellow (III), quinalizarin (IV), alizarin fluorine blue (V), and thymol blue (VI)Measurement of
ion-pair complex
6.6–92.8Involves tedious
extraction step, rigid pH control, and use of large quantity of organic solvent, less sensitive
[36]

14 NBS-metol-sulfanilamideCT complex involving metol-sulfanilamide measured520Employs unstable oxidant
NBS-celesteine blueMeasurement of absorbance of CT complex540 [37]

15(a) Bromophenol blueMeasurement of absorbance of yellow coloured ion-pair complex in DCM4451.5–18.0
1.27 × 104
Simple, highly sensitive, extraction free, and wide linear range
(b) Bromothymol blueAbsorbance of yellow coloured ion-pair complex should be measured in DCM4602.0–32.0
7.57 × 103
Simple, sensitive, extraction free, and wide linear range Present
work

BCG: bromo cresol green, BTB: bromo thymol blue, BPB: bromo phenol blue, BPR: bromo phenol red, p-CAA: chloranilic acid.