Micellar extraction and spectrophotometric determination of quinoline yellow in drugs

Abstract

A distinctive feature of modern drugs is a complex multicomponent composition, including both medicinal and auxiliary substances. The synthetic food dye Quinoline yellow (QY) is widely used for color correction, however, the determination of QY by the spectrophotometric method is impossible without separating the preparation from the matrix. Micellar extraction with polyoxyethylated alkylphenols Triton X-100 and OP-10 is proposed as an alternative to solid-phase extraction and traditional extraction with organic solvents. The phase separation of aqueous and aqueous-salt solutions of Triton X-100 and OP-10 with a con-centration of 1 to 10% is studied in various modes: polythermal (when heated to cloud point) and isothermal (salting out at 25°C). Sodium and ammonium sulfates and sodium carbonate are used as salting-out agents. Their salting-out ability decreases in the series Na2CO3 > Na2SO4 > (NH4)2SO4. The effect of the acidity of the medium and the nature of the electrolyte on the state of the QY in aqueous and aqueous micellar solutions is also studied. The form of the dye does not change within the pH range 1 – 8 and with the addition of Na2SO4, (NH4)2SO4. At higher pH values and in the presence of Na2CO3, structural changes occur in the molecule. The intensity and position of the maximum in the absorption spectrum change in the presence of surfactant micelles (bathochromic shift, Δλ = 8 nm). The dye distribution between the aqueous and micellar phases is studied in different modes of phase separation. It is shown that the systems with the addition of sodium and ammonium sulfates in the salting-out mode (R > 97%) have the best extraction characteristics. Optimal conditions for the maximum single extraction of the dye in the concentration range of 1 – 10 mg/liter in the aqueous solution C(surfactant) — 10%, solution volume — 10 ml, Na2SO4 — 0.84 g, temperature — 25°C, time — 30 min. A rapid and easy to use method of QY extraction concentration from orodispersible tablets (lozenges) is developed. The error of the method does not exceed 5%. The verification of the correctness of the method, carried out by HPLC, proved the absence of a systematic error.