Liquid-Liquid extraction of phenolic compounds in systems based on acetonitrile + water + polyvinylpyrrolidone at 298.15 K

This paper contains data related to the research paper entitled “Organic two-phase system based on acetonitrile + water + polyvinylpyrrolidone, a novel concept of liquid–liquid equilibrium: phase diagrams and phenolic compounds partitioning”. Data of phase equilibrium were obtained using the cloud point method. After this step, some blending points were chosen to perform the phenolic compounds partitioning (gallic acid, quercetin dihydrate and cyanidin 3-O-glucoside chloride)


Data format
Raw (Tables DB1-DB6) and analyzed ( With this article.

Related research article
Organic two-phase system based on acetonitrile þ water þ polyvinylpyrrolidone, a novel concept of liquid-liquid equilibrium: phase diagrams and phenolic compounds partitioning

Value of the data
The liquid-liquid equilibrium data for the proposed systems are not yet presented in the literature. The phase equilibrium data shows that the phases are rich in acetonitrile, so the systems are called biphasic organic The data can help in the choice of mixing points for the partitioning of phenolic compounds. The data of partition coefficients allow the application of the proposed systems in the purification and/or the concentration of phenolic compounds.

Phase diagrams
Aqueous solution of PVP (20-39 wt%) and ACN (80 wt%) were prepared and used for the binodal curve determination at 298.15 7 1.00 K and 0.10 7 0.01 MPa by cloud point method [2]. The experimental data were determined gravimetrically, within an uncertainty of 7 10 À 5 g (Shimadzu AUW220D, Philippines). PVP or ACN aqueous solutions were added drop-wise to each other until the visual detection of a cloudy solution (biphasic region). At this point water was drop-wised until the detection of a clear and limpid solution (monophasic region). This protocol was performed under constant magnetic stirring (Tecnal TE-085, Piracicaba-SP, Brazil) and was repeated several times in order to obtain enough points for the construction of a liquid-liquid equilibrium binodal curve. The experimental data of binodal curves were correlated using Merchuck et al. [2] (Eq. (1)).

½ACN ¼
Where [ACN] and [PVP] are respectively the percentages by weight of acetonitrile and polyvinylpyrrolidone, and A, B and C are constants obtained by regression.
A mixture point at the biphasic region of each ternary system was prepared, vigorously stirred, and allowed to reach equilibrium and phase separation, for a minimum of 12 h at 298.15 7 1.00 K and 0.10 7 0.01 MPa and used to build the tie-lines (TLs). After the equilibration step, the top and bottom phases were carefully separated and weighted within 7 10 À 5 g. Each individual TL was determined by the application of the lever-arm rule, which describes the relationship between the weight of the top phase and the overall system weight and composition. The determination of the TLs was then accomplished by solving the following system of four equations (Eqs. (2) Where the subscripts M, T and B correspond to the initial mixture, top and bottom phases, respectively. The value of α is the ratio between the mass of the top phase and the total weight of the mixture. The system solution results in the ACN and PVP concentration in the top and bottom phases, and thus, TLs can be simply represented.
After the complete mixing of all components for a given mixture composition, each system was centrifuged at 2000 Â g for 10 min at 298.15 7 1.00 K (Hettich Universal 320R, Germany) to favor the phase separation, and then each tube was placed in a thermostatic bath (Marconi MA-127) at 298.15 7 1.00 K for at least 12 h, to reach the equilibrium. The tubes were sealed to avoid the ACN vaporisation. The volume and weight of each phase was measured and both phases were further separated for the quantification of each phenolic compound and for the determination of their pH values (phmeter DM-22 Digimed). At least three independent replicates were made and the average partition coefficients and associated standard deviations were therefore determined.
The concentrations of each phenolic compounds at top and bottom phase were quantified through UV-spectroscopy, using a Varian Cary 50 Bio UV-vis spectrophotometer, and at a wavelength of 435 nm (gallic acid), 690 nm (quercetin) and 525 nm (cyanidin 3-O-glucoside chloride) using a calibration curve previously established.
The extraction efficiency in the top (EE) was evaluated using Eq. (7): where R V is the ratio between the volumes of the top (V T ) and bottom (V B ) phase.  a Standard uncertainties u are u(ρ) ¼ 5 Â 10 À 4 g cm À 3 , u(η) ¼ 0.35%, u(T) ¼ 0.02 K, and u(p) ¼ 10 kPa.