Spectrophotometric determination of phenylephrine hydrochloride by coupling with diazotized 2-aminobenzothiazole

Abstract EN

A spectrophotometric method for determination of microgram amounts of phenylephrine-HCl (PE) has been proposed.

The method is based on coupling of phenylephrine-HCl with diazotized 2-aminobenzothiazole in alkaline medium.

The molar absorptivity of the formed dye is 6.620 × 103 l.mol-1.

cm-1 at λ max 510 nm and Beer's law obeyed within in the range of 10-250 μg of phenylephrine-HCl / 25 ml (0.4-10 ppm).

The color reaction was highly stable and did not show a significant change in absorbance (within acceptable analytical error) up to 48 h with a relative error + 0.31 to + 1.07 % and a relative standard deviation of ± 0.95 to ± 3.09 %, depending on concentration level.

The method has been applied successfully to the determination of phenylephrine-HCl in pharmaceutical preparation (nose drop).