Synthesis and Application of a New Thiazolylazo Reagent for Cloud Point Extraction and Determination of Cobalt in Pharmaceutical Preparations

Abstract

The synthesis and characterization of the reagent 2-(5-bromothiazolylazo)-4-chlorophenol and its application in the development of a preconcentration procedure for cobalt determination using flame atomic absorption spectrometry after cloud point extraction is presented. This procedure is based on cobalt complexing and entrapment of the metal chelates into micelles of a surfactant-rich phase of Triton X-114. The preconcentration procedure was optimized by using a response surface methodology through the application of the Box-Behnken matrix. Under optimum conditions, the procedure determined the presence of cobalt with an LOD of 2.8 μg/L and LOQ of 9.3 μg/L. The enrichment factor obtained was 25. The precision was evaluated as the RSD, which was 5.5% for 10 μg/L cobalt and 6.9% for 30 μg/L. The accuracy of the procedure was assessed by comparing the results with those found using inductively coupled plasma-optical emission spectrometry. After validation, the procedure was applied to the determination of cobalt in pharmaceutical preparation samples containing cobalamin (vitamin B12).

Use of a Hydrophobic Azo Dye for the Centrifuge-Less Cloud Point Extraction–Spectrophotometric Determination of Cobalt

“…The reported heating temperatures for CPE systems based on the same surfactant, TX-114, are commonly between 40 °C and 65 °C [ 23 , 31 , 32 , 35 , 36 , 38 , 39 , 59 , 60 , 61 ]. The results of our experiments at 50 °C are represented in Figure 6 .…”