Liquid chromatographic separation of some PTH-amino acids

Abstract

Liquid chromatographic studies on the separation of ten PTH‐amino acids were carried out using normal phase untreated silica gel plates, C‐18 RP precoated plates and RP‐HPLC. Resolution of a complex mixture of PTH‐amino acids was achieved using all the three types. Certain new successful solvent systems have been worked out in each case. HPLC was carried out with Lichrosphere 100 RP‐18 (5 μm) column. Acetonitrile and sodium acetate buffer of pH 4.0 was used for reversed phase chromatography while for normal phase TLC combinations of chloroform–acetonitrile and chloroform–tetrahydrofuran were applied. Copyright © 1998 John Wiley & Sons, Ltd.

Sustainable solutions for direct TLC enantioseparation with in‐home thought‐out, prepared/modified chiral stationary phases

“…Most often, modern laboratories use commercial pre‐coated TLC plates that are expected to have a better uniformity of the adsorbent, the use of laboratory‐made plates is also quite common for routine applications. Comparison of various enantioseparation using either commercial or laboratory‐made TLC plates from our laboratory did not reveal significant differences in terms of reproducibility and selectivity under the same conditions of mobile phase and temperature (Bhushan & Agarwal, 1998; Bhushan & Batra, 2013; Bhushan & Tanwar, 2010). The CAASP approach plays a fundamental role in enantioselective chromatography with direct separation, sensitive detection, and isolation of enantiomers in pure native forms (for further use) and in assessing and controlling the enantiomeric purity and quantitative determination of chiral APIs (and DL‐AAs and their derivatives) in industry and analytical laboratories (especially associated with regulatory agencies) with the application of planar chromatography.…”

“…These include various β-adrenergic blocking agents, namely, carvedilol, bisoprolol, and salbutamol (Bhushan & Agarwal, 2008b), atenolol, metoprolol, propranolol, and labetalol (Bhushan & Agarwal, 2010a, betaxolol, orciprenaline and atenolol Bhushan & Tanwar, 2008;Nagar et al, 2017;Vashistha & Bhushan, 2020), bisoprolol, atenolol, propranolol, salbutamol, and carvedilol, and a few other APIs, namely, verapamil (Bhushan & Gupta, 2005), ketamine and lisinopril (Bhushan & Agarwal, 2008c), penicillamine (Bhushan & Agarwal, 2008a), bupropion (Bhushan & Batra, 2013), selenomethionine (Nagar & Bhushan, 2014), mexiletine and Ala , ketorolac , and etodolac (Singh & Bhushan, 2016a). An appropriate solvent was selected for different analytes in not reveal significant differences in terms of reproducibility and selectivity under the same conditions of mobile phase and temperature (Bhushan & Agarwal, 1998;Bhushan & Batra, 2013;Bhushan & Tanwar, 2010). The CAASP approach plays a fundamental role in enantioselective chromatography with direct separation, sensitive detection, and isolation of enantiomers in pure native forms (for further use) and in assessing and controlling the enantiomeric purity and quantitative determination of chiral APIs (and DL-AAs and their derivatives) in industry and analytical laboratories (especially associated with regulatory agencies) with the application of planar chromatography.…”

“…The isolation and characterization of native enantiomers is a good enough experimental verification. Of the various factors influencing enantioseparation (via the formation of non‐covalent diastereomeric pairs) the effect of pH (temperature and concentration of the chiral reagent) is very prominent (Bhushan & Martens, 2003, 2010; Bhushan & Thiong'o, 1998; Bhushan & Thiongo, 1999). Separation of diastereomeric ion‐pair occurs using in‐home thought‐out prepared/modified chiral stationary phases prepared (from simple achiral silica gel) via ‘ de novo ’ CAASP (Bhushan & Ali, 1987a, 1987b; Bhushan & Parshad, 1996b; Bhushan et al, 1994), or by ‘pre‐mixing’ approach (Bhushan & Gupta, 2004), introduced from this laboratory because the diastereomers display dissimilar distribution properties in isotropic environments.…”

′Ab Ovo′ Chiral Phases and Chiral Reagents for Liquid Chromatographic Separation and Isolation of Enantiomers

“…Vancomycin was used both as CIR by slurry mode and as CAMP for enantioseparation of ( RS )‐metoprolol atenolol, and propranolol on home made plain plates [58] . Figure 3(B) shows the photograph of actual chromatogram for resolution of ( RS )‐metoprolol.…”

“…Using a variety of CIRs either in the slurry mode or as CAMP native enantiomers of several APIs were isolated and characterized. These include various β‐adrenergic blocking agents, namely, carvedilol, bisoprolol, and salbutamol, [49] atenolol, metoprolol, propranolol, and labetalol, [58] isoxsuprine, [40] betaxolol, orciprenaline and atenolol, [52,66 ] atenolol and propranolol, [121,122,64] bisoprolol, atenolol, propranolol, salbutamol and carvedilol, [60] and a few other APIs, namely, verapamil, [56] ketamine and lisinopril, [123] penicillamine, [124] bupropion, [125] selenomethionine, [126] mexiletine, [127] and ketorolac [128] …”