A Perkin–Elmer Lambda 12 UV/Vis spectrophotometer was used
for recording absorbance spectra with 5.0 mm quartz cell. An Orion
research model 601 A/digital ionalyzer pH meter was used for
checking the pH of solutions. A water bath with good temperature
control and a centrifuge with 25 mL calibrated centrifuge tubes
(Superior, Germany) were used to accelerate the phase separation
process.