Spectrophotometric Determination of Mycophenolate Mofetil as Its Charge-Transfer Complexes with Two π-Acceptors

Abstract

Two simple, selective, and rapid spectrophotometric methods are described for the determination of mycophenolate mofetil (MPM) in pure form and in tablets. Both methods are based on charge-transfer complexation reaction of MPM with p-chloranilic acid (p-CA) or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in dioxane-acetonitrile medium resulting in coloured product measurable at 520 nm (p-CA) or 580 nm (DDQ). Beer's law is obeyed over the concentration ranges of 40-400 and 12-120 μg mL(-1) MPM for p-CA and DDQ, respectively, with correlation coefficients (r) of 0.9995 and 0.9947. The apparent molar absorptivity values are calculated to be 1.06 × 10(3) and 3.87 × 10(3) L mol(-1) cm(-1), respectively, and the corresponding Sandell's sensitivities are 0.4106 and 0.1119 μg cm(-1). The limits of detection (LOD) and quantification (LOQ) are also reported for both methods. The described methods were successfully applied to the determination of MPM in tablets. Statistical comparison of the results with those of the reference method showed excellent agreement. No interference was observed from the common excipients present in tablets. Both methods were validated statistically for accuracy and precision. The accuracy and reliability of the methods were further ascertained by recovery studies via standard addition procedure.

Figure 1

Absorption spectra of (a) MPM-p-CA C-T complex and its blank and (b) MPM-DDQ C-T complex and its blank.

Figure 2

Effect of reagents concentration on color development: (1) p-CA (0.5%) using 200 μg mL⁻¹ MPM, and (2) DDQ (0.25%) using 40 μg mL⁻¹ MPM.

Figure 3

Effect of reaction time.

Figure 4

Job's plots obtained for (a) 4.61 × 10^-4M MPM and p-CA C-T complex and (b) 2.31 × 10⁻⁴ M MPM and DDQ C-T complex.

Scheme 1

Proposed reaction path way for the formation of C-T complex between MPM and p-CA/DDQ.