A Rapid Extractive Spectrophotometric Method for the Determination of Tin with 6-Chloro-3-hydroxy-2-(2′-thienyl)-4-oxo-4H-1-benzopyran

Table 2

Effect of various parameters on the absorbance of Sn(II)-CHTB complex.

HCl^a (M)	0.043	0.044	0.045	0.046–0.060	0.065
Absorbance	0.370	0.420	0.460	0.490	0.450
CHTB^b (mL)	0.2	0.3	0.4	0.5–2.2	2.5
Absorbance	0.310	0.375	0.440	0.490	0.430
Equilibration time^c (sec)	0.0	2	4	5–300	—
Absorbance	0.100	0.320	0.480	0.490	—

Conditions: (a) Sn(II) = 10 g; HCl = variable; CHTB (0.1% (m/v) in acetone) = 1 mL; aqueous volume = solvent volume = 10 mL; solvent = dichloromethane; equilibration time = 20 s; = 435 nm, (b) HCl = 0.046–0.060 mol L⁻¹; other conditions being the same as in (a) except for the variation in CHTB concentration; also b = 6-chloro-3-hydroxy-2-(2′-thienyl)-4-oxo-4H-1-benzopyran (CHTB), and (c) 0.1% CHTB in acetone = 1 mL; other conditions being the same as in (b) except for the variation in equilibration time.