Journal of Chromatography A, 1195 (2008) 146–149
Contents lists available at ScienceDirect
Journal of Chromatography A
journal homepage: www.elsevier.com/locate/chroma
New procedure for the determination of Hansen solubility parameters by means
of inverse gas chromatography
K. Adamska
a,∗
, R. Bellinghausen
b
, A. Voelkel
a
a
Pozna´ n University of Technology, Institute of Chemical Technology and Engineering, pl. M. Sklodowskiej-Curie 2, 60-965 Pozna´ n, Poland
b
Bayer Technology Services GmbH, BTS-PT-PT – Product Design & Solid Processing, D-51368 Leverkusen, Germany
article info
Article history:
Received 6 February 2008
Received in revised form 30 April 2008
Accepted 8 May 2008
Available online 14 May 2008
Keywords:
Hansen solubility parameters
Inverse gas chromatography
Interaction coefficient
Pharmaceutical excipients
abstract
The Hansen solubility parameter (HSP) seems to be a useful tool for the thermodynamic characteriza-
tion of different materials. Unfortunately, estimation of the HSP values can cause some problems. In this
work different procedures by using inverse gas chromatography have been presented for calculation of
pharmaceutical excipients’ solubility parameter. The new procedure proposed, based on the Lindvig et al.
methodology, where experimental data of Flory–Huggins interaction parameter are used, can be a rea-
sonable alternative for the estimation of HSP values. The advantage of this method is that the values of
Flory–Huggins interaction parameter for all test solutes are used for further calculation, thus diverse
interactions between test solute and material are taken into consideration.
© 2008 Elsevier B.V. All rights reserved.
1. Introduction
Solubility parameter determined for different materials can
be used for estimating various physicochemical parameters, e.g.
surface free energy, surface tension [1]. The solubility parameter
concept has also been used to estimate the miscibility of different
species [2]. Two materials having close values of solubility parame-
ter are likely to be compatible and should be miscible when mixed
together. Thus, solubility parameter has been used in coating indus-
try for selection of solvents in paint formulation [3,4] or matching a
binder to pigment [5], in printing industry for selection of the best
cleaning agent for binder(s) [6] as well as for characterization of
different additives (plasticizers, antistatic agents) used in polymers
[7].
The concept of the solubility parameter was proposed by
Scatchard et al. and initially applied to systems whose cohesion
arises only from dispersion forces. This solubility parameter is the
square root of cohesive energy density (CED) [8].
ı = (CED)
1/2
=
H - RT
V
m
1/2
=
E
V
m
1/2
(1)
where ı = solubility parameter, R = gas constant, T = temperature,
H = enthalpy of vaporization, V
m
= molar volume and E = energy
of vaporization.
∗
Corresponding author. Tel.: +48 608 55 17 99; fax: +48 61 665 36 49.
E-mail address: kaska.adamska@wp.pl (K. Adamska).
For low- or non-volatile compounds it is impossible. There-
fore, different methods were elaborated to facilitate the estimation
of solubility parameter for this group of materials. These were:
swelling measurements [9], group additive methods [10–12],
where knowledge of the molecular structure of a material is
required; viscosity measurements [13,14] and inverse gas chro-
matography (IGC) [15–20].
Hansen introduced three dimensional solubility parameter or
the Hansen solubility parameters (HSP) [21]. According to the
Hansen theory, the cohesive energy can be considered as a sum of
contributions from dispersive (E
d
), polar (E
p
) and hydrogen bond-
ing (E
h
) interactions:
-E
coh
=-E
d
- E
p
- E
h
(2)
and the total solubility parameter (ı
T
) is expressed as
ı
2
T
= ı
2
d
+ ı
2
p
+ ı
2
h
(3)
where ı
p
, ı
p
, ı
h
denote dispersive, polar and hydrogen bonding
contribution, respectively.
Hansen solubility parameters could be determined by, e.g. solu-
bility measurement and fit of data. A number of solvents are chosen
in which the new substance with unknown Hansen parameters
is solved and the solubility is measured. Depending on the sub-
stances the fraction of the dissolved substance is determined by
HPLC (actives, solids), GC (surfactants, solvents) or by balance mea-
surements (solids/high boiling substances in volatile solvents) [21].
The solubility data are used to calculate the stability radius which
define a sphere around the solvents in the Hansen “room”. The
0021-9673/$ – see front matter © 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.chroma.2008.05.020