Validation of oxybutynin

In this study, we have developed two facile spectroscopic methods for
quantifying oxybutynin hydrochloride in its pure form and tablets using
design of experiments (DOE). The spectroscopic methods depended on the
ion-pair complex formation between the tertiary amino group in the drug
and in the 0.2-M acetate buffer of pH 4. Method I involves
spectrophotometric measurement of the absorbance of the developed complex
at 550 nm and showed linearity through 1.0–10.0 μg/mL. Method II involves
spectrofluorometric measurement of the quenching influence of oxybutynin
on the native fluorescence of eosin (λexcitation/λemission of
304/548 and showed linearity through 1.0–6.0 μg/mL. Critical
parameters were identified through preliminary trials and optimized using
the DOE. Additionally, the quenching mechanism was investigated, and the
pathway of the reaction was postulated. The fluorescence-quenching
constant and thermodynamic parameters were explored using the
Stern– Volmer plot and Van't Hoff graph, respectively.
Assessments conducted via Analytical ecoscale revealed the
"excellent-greenness" of the methodology. The two methods can be
greener and faster than other reported methods.