M. Balcan et al., Hydrophile-lipophile properties of ethoxylated nonionic surfactants as revealed by reversed-phase high-performance liquid chromatography (RP-HPLC), REV RO CHIM, 44(4), 1999, pp. 369-375
The chromatographic behavior of nonionic surfactants was studied by RP-HPLC
using an octylsilica column (RP-8, 10 m, 4.6 x 200 mm). The eluents were t
he methanol-water mixtures and the detection was done at 280 nm. The surfac
tants taken into consideration were polydisperse ethoxylated fatty alcohols
and nonylphenols. The former were compared with their homogeneously ethoxy
lated counterparts. The relationship between the capacity factor and the el
uent composition was used to obtain the hydrophobicity parameters k(w) (the
capacity factor with pure water as the eluent) and phi(0) (the organic mod
ifier content of the mobile phase required for fog k' = 0). A linear relati
onship was observed between them and the HLB values of surfactants. The ano
malous comportment of k(w) for ethoxylated nonylphenols was explained by co
nformational changes of the PEO chain. The RP-HPLC proved to be a reliable
and useful tool to investigate the hydrophilic-lipophilic properties of eth
oxylated surfactants.