S. No. Reagent/s used Methodology λmax (nm) Linear range (µgmL-1) LOQ (µg mL-1) Reaction time Remarks Ref. 1. p-Chloroanilic acid Pink coloured C-T complex was measured. 519 10-200 (€=1.28×103 L mol-1cm-1) - Instantaneous Less sensitive 14 2. 0.1 M NaOH LMT in NaOH was measured. 305 2-50 - - 21 3 a) BCG/Dichloromethane Ion-pair extraction 410 1.5-15 1.3 5 min Tedious extraction procedure involved and Less sensitive 22 b) Alcoholic KOH Ion-pair breaking 620 0.5-5.0 0.59 Instantaneous 4 a) BPB/CHCl3 Ion-pair extraction 420 2.5-25 µg mL-1 0.15 5 min Tedious extraction procedure involved   b) Ethanolic H2SO4 Ion-pair breaking 420 50-400 ng mL-1 0.003 Instantaneous 23   c) Ethanolic KOH 600 10-80 ng mL-1 0.0005 5 a) BCP/dichloromethane Ion-pair extraction 410 2.0-20.0 µg mL-1 0.8 5 min 24 b) Ethanol Ion-pair breaking 410 150-1500 ng mL-1 0.06 Instantaneous c) Ethanolic KOH 600 50-600 ng mL-1 0.02 6 a) Bromocresol green/CHCl3 Ion-pair extraction NA 0.15-19.8 µg mL-1 NA NA 25 b) Bromocresol purple/CHCl3 NA 0.15-19.8 µg mL-1 NA NA c) Chlorophenol red/CHCl3 NA 0.05–34.1 µg mL-1 NA NA 7 a) 0.1 M H2SO4 LMT in 0.1 M H2SO4 was measured. 225 0.5-5.0 (€=8.65×104 L mol-1cm-1) 0.02 - Very simple, and wide linear dynamic ranges. Present work. b) Methanol LMT in methanol was measured. 225 1.25-12.5 (€=2.11×104 L mol-1cm-1) 0.09 - NA. Not available

Table 6: Performance characteristic of the existing spectrophotometric methods and the proposed methods.