Ion pair method to determine the CTAB content in gold nanorods samples

Abstract

In this work, we report a fast and accessible method for quantification of cetyltrimethylammonium bromide (CTAB) in solutions of gold nanorods (GNRs) by bromophenol blue (BPB) ion-paring formation and spectrophotometric detection. The ion-par method used to quantify CTAB exhibited adequate figures of merit and was applied to the quantification of CTAB present in solutions of GNRs-CTAB and in GNRs-CLPFFD samples obtained by the seed growth method. This type of methodology could be extensive to others surfactants employed for the synthesis of nanoparticles. In addition, this method allows screening CTAB in GNRs samples and consequently would help to know if CTAB concentration is lower than an acceptable cut-off for cell viability analysis.