Enantiomeric separation of acidic compounds by nano‐liquid chromatography with methylated‐β‐cyclodextrin as a mobile phase additive

Abstract

Some racemic nonsteroidal anti-inflammatory drugs, namely naproxen, indoprofen, ketoprofen, flurbiprofen, carprofen, cicloprofen, flunoxaprofen and suprofen were separated into their enantiomers by nano-LC. Chiral recognition was achieved adding to the mobile phase heptakis (2,3,6-tri-O-methyl)-beta-cyclodextrin (TM-beta-CD). Capillary columns of 100 microm id, packed with different RP particles were used for experiments. Effect of experimental parameters such as mobile phase composition, stationary phase type and length of packed capillary column on retention factor and chiral resolution of analytes were studied. The stationary phase type played a very important role in the enantiorecognition process. Best results in terms of highest enantioresolution factor and largest number of separated enantiomers were obtained reducing the particles size to 3 microm with RP(18) stationary phase. Most favourable mobile phase for enantiodiscrimination was obtained using relatively low concentrations of ACN (30%, v/v), 30 mM of TM-beta-CD and pH value of 3.0. The retention time of all studied enantiomers decreased by increasing the CD derivative concentration. The retention factors of selected studied compounds, specifically flurbiprofen, naproxen and suprofen, were measured employing TM-beta-CD concentrations in the range 0-40 mM. Assuming a 1:1 enantiomer/CD ratio, the apparent association constants of the studied enantiomers were calculated.

Enantiomeric Separation of Ofloxacin by Nano-Liquid Chromatography Using a Sulfated-β-Cyclodextrin as a Chiral Selector in the Mobile Phase

“…By this way, dimethyl (DM), trimethyl (TM), carboxymethyl (CM), sulfobutyl ether (SBE) and heptakis diacetyl sulfo (HDAS) -CDs were tested. The CD concentration was fixed at 30 mM, considering the good resolutions obtained for other racemic drugs in previous reports based on nano-LC with DM [22] or TM--CD as mobile phase additive [23]. The retention times observed for the racemic ofloxacin were between 3.5 and 6.0 min for the CM and the TM--CD respectively.…”

“…The estimated flow rate was about 620 nL/min and the wavelength for UV detection was fixed at 290 nm. Injection was performed by introducing standard solution into the injection valve during 10 s and afterwards filling the loop (30 μL) with mobile phase [23]. Chromatographic experiments were done using acetonitrile-50 mM sodium acetate buffer at pH 3.0 (30:70 v/v) and eventually 5 mM HDAS--CD as mobile phase.…”

“…The packing procedure was similar to that previously described elsewhere [23][24][25][26]. Briefly, stationary phase particles were suspended in acetone and packed into the capillary for about 30 or 20 cm.…”

“…Specifically, several methods have been published for the chiral separation of dansyl phenylalanine analogs [19], substituted binaphtyl compounds [20,21], racemic naproxen [22] and other non-steroidal anti-inflammatory drugs [23], while none is reported for antibiotics of the quinolones group.…”

Nano and rapid resolution liquid chromatography–electrospray ionization–time of flight mass spectrometry to identify and quantify phenolic compounds in olive oil

“…Among these, nanoLC, first introduced by Karlsson and Novotny in 1988 [1], has emerged as a new powerful analytical tool, complementary and/or competitive to conventional HPLC, providing a wide number of important applications, especially in proteomics and related fields [2][3][4][5], mainly due to the very low sample requirements. Other applications of nanoLC can be also found in fields such as pharmaceutical [6], environmental [7,8] and enantiomeric analysis [9,10]. The use of nanoLC for food analysis has not been so widely extended so far, although in the last years some interesting works have demonstrated its potential in this field [11][12][13][14][15].…”