Biomedical Chromatography

Malinowska, Irena; Rózylo, Jan K.

doi: 10.1002/(SICI)1099-0801(199709)11:5<272::AID-BMC695>3.0.CO;2-Vpmid: 9376707

The possibilities of separation of seven d,l‐mixtures of amino acids on chitin, chitosan beds and their modifications are tested, using TLC methods. From investigated stationary phases chitin modified by Cu2+ ions may be used for separation of optical isomers of amino acids. The best results have been obtained in chromatographic systems with ternary mobile phases. © 1997 John Wiley & Sons, Ltd.

Yuasa, S.; Fukuhara, T.; Isoyama, M.; Tanaka, M.; Shimada, A.

doi: 10.1002/(SICI)1099-0801(199709)11:5<276::AID-BMC696>3.0.CO;2-Gpmid: 9376708

We have studied the resolution of dl‐amino acids on a native cellulose column. All the dl‐amino acids related to protein and their 16 DNP‐dl‐amino acids were separated. The resolution capability depends mainly upon the bulkiness of the side group attached to the α‐carbon, but also on structural and functional interaction of amino acid with cellulose. We propose a plausible resolution mechanism that is thought to be governed by a so‐called key and lock relation between an amino acid and cellulose. Then, the affinity of each enantiomer for cellulose was calculated based on the resolution factor, which was known to be some 10−2–10−3 eV. © 1997 John Wiley & Sons, Ltd.

Bhushan, R.; Martens, J.

doi: 10.1002/(SICI)1099-0801(199709)11:5<280::AID-BMC697>3.0.CO;2-Upmid: 9376709

Direct resolution of enantiomers has acquired greater analytical importance. Of various chromatographic techniques, TLC continues to enjoy considerable reputation for the purpose. The present paper deals with an important and yet less explored aspect of TLC i.e. impregnation. Methods of impregnation of thin layer material with a variety of reagents and the role of impregnating reagents in resolving compounds on these layers, with special reference to main/basic approaches of impregnation as applied to direct enantiomeric resolution, are discussed. © 1997 John Wiley & Sons, Ltd.

Bhushan, R.; Martens, J.; Wallbaum, Sabine; Joshi, Shalini; Parshad, Vineeta

doi: 10.1002/(SICI)1099-0801(199709)11:5<286::AID-BMC698>3.0.CO;2-9pmid: 9376710

The enantiomeric resolution of certain amino acids and some of their dansyl derivatives was achieved on thin silica gel plates impregnated with (1R, 3R, 5R)‐2‐azabicyclo(3,3,0)octan‐3‐carboxylic acid, which is an industrial waste material, and a proline analogue non proteinogenic α‐amino acid. Different combinations of 0.5 m NaCl–MeCN were found to be successful in resolving dansyl‐dl‐amino acids; addition of methanol was required in some cases. Spots were visualised using a fixed wavelength (254 nm) ultraviolet chamber. Resolution of dl‐amino acids was successful in different combinations of MeCN–MeOH–H2O and detection was made with ninhydrin (0.2% in acetone). © 1997 John Wiley & Sons, Ltd.

Löwendahl, Christina; Allenmark, Stig

doi: 10.1002/(SICI)1099-0801(199709)11:5<289::AID-BMC699>3.0.CO;2-Ypmid: 9376711

As part of our investigation of structure–activity relationships in a Candida rugosa lipase‐catalyzed ester hydrolysis reaction, methyl 2‐(octylsulfinyl)benzoate has been studied, with respect to rate and enantioselectivity behaviour, using two different lipase preparations. A chiral normal‐phase liquid chromatography method has been developed for determination of the experimental data, degree of conversion (c) and enantiomeric excess of the substrate (ees) or the product (eep), needed for calculation of the enantioselectivity in a kinetic resolution of this kind. A recently developed new class of network‐polymeric chiral stationary phases, giving baseline‐resolution with high selectivities for the ester substrates as well as their corresponding carboxylic acid products, permits, without any derivatization, an accurate and direct determination of the rate of the hydrolysis reaction and of the enantioselectivity from one and the same chromatogram. © 1997 John Wiley & Sons, Ltd.

Oi, Naobumi; Hashimoto, Shigeru; Ishizuka, Norio; Ohtake, Jun

doi: 10.1002/(SICI)1099-0801(199709)11:5<296::AID-BMC700>3.0.CO;2-1pmid: 9376712

Lin, Jin‐Ming; Nakagama, Tatsuro; Uchiyama, Katsumi; Hobo, Toshiyuki

doi: 10.1002/(SICI)1099-0801(199709)11:5<298::AID-BMC702>3.0.CO;2-Qpmid: 9376713

l‐Aromatic amino acid imprinted polymers were prepared using azobisnitriles as either photoinitiators or thermal initiators at temperature ranging from 4 to 60°C. Methacrylic acid (MAA) was used as functional monomer and ethylene glycol dimethacrylate (EDMA) was used as cross‐linker. The result polymers were ground and sieved to particles <10 μm, filled into the capillary columns and used for enantiomeric separations in capillary electrochromatographic (CEC) mode. The polymer particles <25 were packed into high performance liquid chromatographic (HPLC) columns and used for enantioseparations in the HPLC mode. The mobility and chiral separation of some amino acids were studied on CEC and HPLC columns at different temperature. The relationships of separation factor and column temperatures are demonstrated in linear between logarithm of the separation factor (ln α) and the inverse of absolute temperature (1/T). Some thermodynamic parameters, such as the apparent change of enthalpy (δHo) and the apparent change of entropy (δo), were obtained using van't Hoff plots. The information obtained from the thermodynamic study is discussed in developing strategies for chiral recognitions of amino acids by molecular imprinting technique. © 1997 John Wiley & Sons, Ltd.

Aboul‐Enein, Hassan Y.; Serignese, Vince; Minguillon, Cristina; Oliveros, Laureano

doi: 10.1002/(SICI)1099-0801(199709)11:5<303::AID-BMC703>3.0.CO;2-7pmid: 9376714

A series of piperidine‐2, 6‐dione drugs were enantiomerically resolved on a covalently bonded cellulose 3,5‐dimethylphenyl carbamate/10‐undecenoate chiral stationary phase (CSP), under normal‐ or reversed‐phase conditions. A single column that can be applied in both modes may be advantageous when considering the shorter setup time required and the solubility of the compound to be analysed since many samples possess different solubilities. The covalently bonded CSP was compared to a commercially available chiral adsorbent, Chiralcel OD, which was previously used in our laboratory for the enantiomeric resolution of the above‐mentioned drug series. Chiralcel OD is used in the normal‐phase mode and is more fragile than the column used in this study. The user is restricted to the range of solvents available as eluents. Hence, it was of interest to look at the possible advantages of using a chemically bonded phase that can be applied in dual mode. © 1997 John Wiley & Sons, Ltd.