Enantiomeric analysis

In any form of analysis it is important to determine the integrity of the system and confirm that artefacts are not produced as a by-product of the analytical procedure. This is particularly important in enantiomeric analysis, where problems such as the degradation of lactone and furanon species in transfer lines has been reported (40). As chromatography unions, injectors, splitters, etc. become more stable and greater degrees of deactivation are possible, problems of this kind will hopefully be reduced. Some species, however, such as methyl butenol generated from natural emissions, still remain a problem, undergoing dehydration to yield isoprene on some GC columns. 

Perez-Femandez V, Garcia MA, Marina ML (2010) Characteristics and enantiomeric analysis of chiral pyrethroids. J Chromatogr A 1217 968-989... 

S Weinstein, MH Engel, PE Hare. The enantiomeric analysis of a mixture of all common protein amino acids by high-performance liquid chromatography using a new chiral mobile phase. Anal Biochem 121, 370, 1982. 

Figure 33. HPLC enantiomeric analysis of gly-leu occluded in crystals of gly-gly. Material taken from (a) tip of the crystal at the + b end, (b) tip of the same crystal at the -b end, (c) whole crystal.

Chapman, J., and Chen, R-T. A. (2001). Implementing generic methods development strategy for enantiomeric analysis. LC-GC Europe (Jan), 33—37. 

Although (Z)-hinokiresinol is stable during silica gel TLC separation, it was isomerized into the (ii)-form after storage for 3 years in a freezer at -20°C (Yamamura, Suzuki, Hattori, Umezawa, unpublished). In addition, the ( )-isomer is rather unstable under slightly acidic conditions (such as old deutrochloroform for NMR measurements) (Umezawa, unpublished). Hence, we established a system for enantiomeric analysis of hinokiresinols by converting them into the corresponding... 

Capillary gas chromatography on optically active modified cyclodextrin phases is a simple, fast, accurate and highly sensitive method for the enantiomeric analysis of chiral volatile compounds. 

The submitters used HPLC analysis to determine the enantiomeric purity (Daicel Co. CHIRALCEL OB column 99.5/0.5 hexane/2-propanol mixture, 1.0 mL/min flow rate detection at 254-nmS-isomer tp, 19.2 min, R-isomer tp 24.6 min)). Under these conditions, however, the propiophenone contaminant Is coincident with the S-enantiomer thus affording unreliable enantiomeric analysis. 

The reversal of the order of peak elution (peak inversion) for enantiomerically enriched samples by inverting the chirality of the stationary phase represents not only a diagnostic tool for verification of an enantiomer separation147, but also has important merits in enantiomeric analysis. Thus, this technique should be employed for the evaluation of trace amounts of... 

YP Belov, AY Aksinenko, B Blessington, AH Newman. Chiral aminophosphonate eluent for enantiomeric analysis of amino acids. Chirality 8 122-125, 1996. 

O Hagan D, Goss RJM, Meddour A, Courtieu J (2003) Assay for the Enantiomeric Analysis of I HJ-Fluoroacetic Acid Insight in the Stereochemical Course of Fluorination During Fluorometabolite Biosynthesis in Streptomyces cattleya. J Am Chem Soc 125 379... 

F. X. Zhou and I. S. Krull, Direct enantiomeric analysis of amphetamine in plasma by simultaneous solid phase extraction and chiral derivatization, Chromatographia, 55 153 (1993). 

An HPLC method to determine etodolac enantiomers and their major metabolites in urine, using a bovine serum albumin stationary phase, has been developed [13]. After extraction of etodolac from acidified urine with cyclohexane / ethyl acetate (95 5, v/v), the organic layer was separated, evaporated, and reconstituted in 2-propanol. The samples were injected onto a 125 x 4 mm i.d. (10 pm particles) column. The mobile phase used was 0.05 M pH 4 phosphate buffer / 2-propanol (98 2, v/v) at a flow rate of 1.2 mL/min. Detection was effected at 230 nm using a UV detector. The (5)-(+)-etodolac enantiomer eluted before the (/ )-(-)-enantiomer. The enantiomeric analysis of various metabolites of etodolac was also described. 

W.A. Tao et al., Copper(II)-assisted enantiomeric analysis of D, L-amino acids using the kinetic method Chiral recognition and quantification in the gas phase. J. Am. Chem. Soc. 122, 10598-10609 (2000)... 

C. Devos, K. Sandra, P. Sandra, Capillary gas chromatography inductively coupled plasma mass spectrometry (CGC-ICPMS) for the enantiomeric analysis of d,l-selenomethionine in food supplements and urine, J. Pharm. Biomed. Anal, 27 (2002), 507D514. 

F NMR is also extremely useful in the analysis of MTPA esters, and is often used in combination with H NMR. The CF3 peak(s) is easy to observe, being unencumbered by unrelated peaks. Enantiomeric analysis of primary alcohols, e.g. (7), as well as secondary alcohols (8) and (9) has been performed utilizing this method. F NMR analysis of MTPA esters in the presence of shift reagents has also been utilized to increase the separation between diastereomeric F peaks. ... 

Enantiomeric analysis of a new antiinflammatory agent in rat plasma using a chiral p-cyclodextrin stationary phase" (71). The R,R S,S enantiomers of the investigational antiinflammatory agent trans-6,6a,7,10, 10a,ll-hexahydro-8,9-dimethyl-U-oxodibenz[b,e]-oxepin-3-acetic add (HOA) were resolved on the p-CD CSP after extraction from rat plasma. The mobUe phase was a mixture of 0.05 M potassium dihydrogenphosphate (pH 5.3) and methanol (35 65, v/v) the flow rate was 1.0 mL/min and the temperature was 22 1 C. The results of the study indicated that the inactive (—) enantiomer was cleared from the plasma more rapidly than the active (+) isomer. 

Schiigerl, K. Ulber, R. Scheper, T., Developments of biosensors for enantiomeric analysis, Trends Anal. Chem. 1996, 15, 56-62... 

In the pharmaceutical industry, the production of enantiomerically pure substances is of tremendous importance because the same compounds but of opposite chirality often have extremly different therapeutic effects. Thus, enantiomeric analysis is of special importance. Nowadays, enantioselective syntheses are monitored via time-consuming, expensive and complicated procedures (e.g., chiral GC and HPLC). Biosensors might be an interesting alternative or a supplement to existing techniques. Here, immobilized enzymes with different enan-... 

MR Hadley, P Camilleri, AJ Hutt. Enantiomeric analysis by capillary electrophoresis Applications in drug metabolism and pharmacokinetics. Electrophoresis 21 ... 

Doyle, T.D. Brunner, C.A. Vick, J.A. Enantiomeric analysis of phenylpropanolamine in plasma via resolution of dinitrophenylurea derivatives on a high performance liquid chromatographic chiral stationary phase. Biomed.Chromatogr., 1991, 5, 43—46... 

These results suggest that, in addition to an enantiomeric analysis, (16,17) this analytical method can be applied to evaluate the genuineness of essential oils. Furthermore, it is expected that this technique of isotope ratio analysis will be applicable to evaluate the origin of citrus essential oils and their products, and also to specify organic compounds from natural resources. 

Rutten AJ, Mather LE, McLean CF. Cardiovascular effects and regional clearances of IV bupivacaine in sheep enantiomeric analysis. Br J Anaesth 1991 67 247-256. 

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