Micelle-mediated cloud point extraction and spectrophotometric determination of rhodamine B using Triton X-100

A new micelle-mediated cloud point extraction method is described for sensitive and selective determination of trace amounts of rhodamine B by spectrophotometry. The method is based on the cloud point extraction of rhodamine B from aqueous solution using Triton X-100 in acidic media. The extracted surfactant rich phase is diluted with water and its absorbance is measured at 563 nm by a spectrophotometer. The effects of different operating parameters such as concentration of surfactant and salt, temperature and pH on the cloud point extraction of rhodamine B were studied in details and a set of optimum conditions were obtained. Under optimum conditions a linear calibration graph in the range of 5-550 ng mL(-1) of rhodamine B in the initial solution with r=0.9991 (n=15) was obtained. Detection limit based on three times the standard deviation of the blank (3S(b)) was 1.3 ng mL(-1) (n = 10) and the relative standard deviation (R.S.D.) for 50 and 350 ng mL-1 of rhodamine B was 2.40 and 0.87% (n = 10), respectively. The method was applied for the determination of rhodamine B in soft pastel, hand washing liquid soap, mathces tip and textile dyes mixture samples. (C) 2008 Elsevier B.V. All rights reserved.