Chiral separation of polychlorinated biphenyls using a combination of hydroxypropyl-γ-cyclodextrin and a polymeric chiral surfactant

Abstract

Chiral separation of moderately to highly hydrophobic polychlorinated biphenyls (PCBs) using a conventional chiral micelle or a polymeric chiral surfactant, as the single chiral selector is very difficult since the hydrophobic interactions between the chiral PCB and the monomeric or polymeric surfactant is very strong. Combined use of a polymeric chiral surfactant, polysodium N-undecanoyl-D-valinate (poly-D-SUV) with hydroxypropyl-gamma-cyclodextrin (HP-gamma-CD) was successful in cyclodextrin modified electrokinetic chromatography (CD-EKC) enantioseparation of PCB congeners. Addition of HP-gamma-CD to the background electrolyte containing poly-D-SUV functioned to improved chiral resolution for the PCBs and reduce the analysis time for these congeners. In addition, concentration of methanol, concentration of 2-(N-cyclohexylamino) ethanesulfonic acid (CHES) buffer and separation voltage was also varied to optimize multicomponent separation of five chiral PCBs. Simultaneous separation and enantioseparation of all five PCBs was possible in less than 50 min under optimized conditions that requires a 5 mM CHES solution buffered at about pH 10 with 1.5% w/v (ca. 60 mM) poly-D-SUV and 16 mM HP-gamma-CD. In addition, 1 M urea and 20% v/v methanol should be added as organic modifier and the capillary temperature maintained at 45 degrees C. As expected the polymeric surfactant showed improved chiral resolution of PCBs over conventional micelles of SUV. Under optimized conditions, when CD-EKC of chiral PCBs using poly-D-SUV was compared to sodium dodecyl sulfate (SDS), better resolution, higher efficiency and shorter analysis time was achieved with poly-D-SUV.

Developments in the use of soluble ionic polymers as pseudo-stationary phases for electrokinetic chromatography and stationary phases for electrochromatography

“…Poly(sodium undecenyll-valinate) provided better separations at low pH, while poly(sodium undecenyl-l-norvalinate) provided better separations at high pH, where a more open polymer structure is proposed to enhance selectivity. Using a combination of poly(sodium undecenyl-d-valinate) and hydroxypropyl cyclodextrin, 5 PCB pairs were resolved in less than 40 min [67].…”

Packed‐column capillary electrochromatography and capillary electrochromatography‐mass spectrometry using a lithocholic acid stationary phase

“…This trend follows an increase in hydrophobic nature of the analyte, which is a similar trend observed for PAHs (Fig. 5) and as shown in our previous work using MEKC [27,28].…”

Chiral separation of econazole using micellar electrokinetic chromatography with hydroxypropyl-γ-cyclodextrin

“…The addition of HP-␥-CD to the buffer displace the distribution of the enantiomers from the micellar to the water phase as a function of the possible interaction between the water soluble HP-␥-CD and the enantiomers. The results obtained in this work are similar with those obtained by other authors on the chiral separation of polychlorinated biphenyls [10] and pemoline enantiomers [11] by CD-MEKC methods.…”

“…It has no need for expensive chiral stationary phases, since the chiral selector is simply added to the buffer. Cyclodextrinmodified micellar electrokinetic chromatography (CD-MEKC) has been established as a versatile and robust capillary electrophoresis (CE) method for the separation of enantiomers [5][6][7][8][9][10][11]. The advantages of CD-MEKC for enantiomer separations are rapid method development, low consumption of analyte and minimal use of expensive chiral reagents.…”

“…The HP-␥-CD is a nonionic cyclic oligosaccharides consisting of eight glucose units and has numerous chiral recognition centers. It has been used as chiral selector in the CD-MEKC methods [5][6][7][8][9][10]. The choice of HP-␥-CD as chiral selector is based on our previous successful triazole fungicides separation [5][6][7][8].…”