ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 4, pp. 726!729. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + E.V. Churilina, G.V. Shatalov, Ya.I. Korenman, P.T. Sukhanov, V.M. Bolotov, 2008, published in Zhurnal Prikladnoi Khimii,
2008, Vol. 81, No. 4, pp. 690 ! 692.
Extraction and Preconcentration of Anthocyan Dye
from Aqueous Solutions with Water-Soluble
E. V. Churilina, G. V. Shatalov, Ya. I. Korenman,
P. T. Sukhanov, and V. M. Bolotov
Voronezh State Technological Academy, Voronezh, Russia
Voronezh State University, Voronezh, Russia
Received July 7, 2007
Abstract-Extraction of an anthocyan dye with poly-N-vinylpyrrolidone (PVP) and poly-N-vinylcaprolactam
(PVC) under the conditions of separation of aqueous solutions of this polymer into two phases in the presence
of salting-out agents (sodium chloride and sodium or ammonium sulfate) was studied.
Heterogeneous systems containing water-soluble
polymers poly-N-vinylpyrrolidone (PVP) and poly-N-
vinylcaprolactam (PVC) are used in biotechnology for
separation of proteins, cells, and biologically active
substances, including amino acids and vitamins [1, 2].
The main advantages of application of PVP and PVC
as extractants are their nontoxicity, high hydrophilic-
ity, and ability to form complexes with many low-
and high-molecular-weight organic compounds .
The majority of natural red pigments are derived
from anthocyans, phenolic compounds, whose struc-
ture is similar to that of plant glycosides. These com-
pounds are readily soluble in water and form antho-
cyanides upon hydrolysis . These dyes are used
in food industry .
The common methods for recovery and preconcen-
tration of anthocyan dyes from plant raw materials
and aqueous solutions are based on their repeated ex-
traction with organic solvents . We believe that
liquid extraction of anthocyan dyes can be improved
by using two-phase aqueous systems based on water-
soluble polymers containing no toxic organic solvents.
Such extraction systems based on PVP and PVC have
not been studied previously.
In this study, we examined the extractive precon-
centration of an anthocyan dye from aqueous solutions
with PVP and PVC.
Anthocyan dye was extracted from black-currant
berry with ethanol at 50355oC by the procedure re-
ported in . The PVP polymer of medical grade
with a molecular weight M
Poly-N-vinylcaprolactam was prepared by radical
polymerization of its monomer in isopropanol at 70oC
in the presence of azobis(isobutyronitrile) initiator at
various monomer concentrations. The polymer was
precipitated by adding hexane to the reaction mixture
and then vacuum-dried at 553 60oC. The molecular
weights of the polymers were calculated from the in-
trinsic viscosity [h] of their solutions by the for-
mula [h] = 1.5 0 10
. PVC samples with
the molecular weights of 1 0 10
, and 16 0
, and Na
grade) were used as salting-out agents providing sep-
aration of aqueous solutions of the polymer into two
phases within a wide range of polymer and salt con-
A solution of anthocyan dye (10 ml), contain-
ing a salting-out agent, was placed in a vial with
a ground-glass stopper, and then 1 ml of an aqu-
eous solution of the polymer (concentration 0.0013
2 wt %) was added to obtain a two-phase extraction
system. The extraction was carried out on a vibra-