Determination of trace carvedilol by solid substrate-room temperature phosphorimetry, based on its activating effect on hypochlorite-oxidizing amaranth using sodium dodecyl benzene sulphonate as sensitizer.

This work proposes a simple and sensitive solid substrate-room temperature phosphorimetry (SS-RTP) for the selective determination of carvedilol (CV). The method is based on the sensitizing effect of sodium dodecyl benzene sulphonate (SDBS) on CV to activate the oxidation between NaClO and amaranth, resulting in the intense quenching of room temperature phosphorescence (RTP) of the system. Compared with non-SDBS system, the reduction of phosphorescence intensity (ΔI(p)) with SDBS is 16.5 times higher and is directly proportional to the content of CV, covering a wide range 0.080-16.00 fg/spot. The regression equation of the working curve can be expressed as ΔI(p) = 0.7780 + 7.057 m(CV) (fg/spot) (correlation coefficient (r) = 0.9976, n = 8), with a detection limit (LD) of 0.020 fg/spot (corresponding concentration is 5.1 × 10(-14) g/mL, sample volume is 0.40 μL/spot). This sensitive method has also been applied to determine trace CV in human plasma and the results agreed with synchronous fluorimetry (SF). The activation energy (E) and rate constant (k) of this activating reaction were 69.04 kJ/mol and 3.580 × 10(-4) s(-1), respectively. The reaction mechanism is also discussed.