Enantioselective determination of selfotel in human urine by high-performance liquid chromatography on a chiral stationary phase after derivatization with 9-fluorenylmethyl chloroformate

Comparison of several polysaccharide-derived chiral stationary phases for the enantiomer separation ofN-fluorenylmethoxy-carbonyl α-amino acids by hplc

The liquid chromatographic enantiomer separation of N-fluorenylmethoxycarbonyl (FMOC) protected alpha-amino acids was performed on nine polysaccharide-derived chiral stationary phases (CSPs). The cellulose derived coated CSPs, Chiralcel OD-H (separation factor = 1.09-2.70) and Chiralcel OD (separation factor = 1.08-2.55), had the best performance of all the CSPs for resolution of N-FMOC alpha-amino acids and therefore, all analyte enantiomers were base-line separated on Chiralcel OD-H and/or Chiralcel OD. Enantioseparation on cellulose tris(3,5-dimethylphenylcarbamate) derived CSPs (Chiralcel OD-H, Chiralcel OD and Chiralpak IB) is generally greater than that on amylose tris(3,5-dimethylphenylcarbamate) derived CSPs (Chiralpak AD-RH, Chiralpak AD and Chiralpak IA). Additionally, coated type CSPs (Chiralcel OD-H or Chiralcel OD, and Chiralpak AD) generally provided better enantioseparation for these analytes than the covalently bonded type CSPs (Chiralpak IB and Chiralpak IA) with the same chiral selector of cellulose tris(3,5-dimethylphenylcarbamate) and amylose tris(3,5-dimethylphenylcarbamate), respectively. However, Chiralpak IB and Chiralpak IA had an advantage over the coated type CSPs in that a broader range of solvents could be used due to its covalently bonded nature.

Liquid chromatographic enantiomer resolution ofN-fluorenylmethoxycarbonyl α-amino acids and their ester derivatives on polysaccharide-derived chiral stationary phases

The liquid chromatographic enantiomer separation of N-fluorenylmethoxycarbonyl (FMOC) protected alpha-amino acids and their ethyl ester derivatives was performed on polysaccharide-derived chiral stationary phases, Chiralcel OD, Chiralpak AD, and Chiralpak AS. In general, Chiralcel OD and Chiralpak AD showed good performance for resolution of N-FMOC alpha-amino acids and their ethyl esters, respectively. All investigated N-FMOC alpha-amino acid enantiomers were baseline separated on Chiralcel OD or Chiralpak AD, whereas N-FMOC alpha-amino acid ethyl ester enantiomers were baseline resolved (alpha = 1.15-3.03) on Chiralpak AD, except for two analytes. The L-enantiomers of all examined FMOC alpha-amino acid ethyl ester derivatives are preferentially retained on Chiralpak AD, while the elution orders of the other enantiomer separations are not consistent.

Determination of 1-deoxynojirimycin in Morus alba L. leaves by derivatization with 9-fluorenylmethyl chloroformate followed by reversed-phase high-performance liquid chromatography

A rapid and reliable method suitable for assays of a large number of Morus alba leaves for 1-deoxynojirimycin (DNJ) has been developed. DNJ in 0.1 g of freeze-dried leaves was double-extracted in 10 mL of aqueous 0.05 M HCl by vortexing for 15 s at room temperature, derivatized with 9-fluorenylmethyl chloroformate (FMOC-Cl), and analyzed by reversed-phase high-performance liquid chromatography (RP-HPLC) equipped with a fluorescence detector. The double extraction recovered > 99% of extractable DNJ from the leaves. Stabilization of FMOC-derivatized DNJ (DNJ-FMOC) was achieved by diluting the reactant with aqueous acetic acid after derivatization. DNJ-FMOC was stable for at least 16 days under acidic conditions at room temperature (24 degrees C). Linearity ranged between 0.3 and 30 microg mL(-1). The intra- and inter-day precision for DNJ-spiked biological samples was between 0.6 and 1.8% and between 3.7 and 4.5%, respectively.

Stereoselective determination of pyridoglutethimide enantiomers in serum with a chiral cellulose-based high-performance liquid chromatographic column using solid phase extraction and UV detection

A sensitive method for the separation and determination of R(+)- and S(-) enantiomers of pyridoglutehimide in serum by high performance liquid chromatography (HPLC) with UV detection was developed. The assay involves the use of a solid-phase extraction for serum sample clean-up prior to HPLC analysis using a C18 Bond-Elute column. Chromatographic resolution of the enantiomers was performed on a reversed-phase cellulose-based chiral column (Chiralcel OD-R, 250 x 4.6 mm I.D.) under isocratic conditions using a mobile phase of 25:75 v/v acetonitrile-0.3 M aqueous sodium perchlorate (pH 6.2 adjusted with perchloric acid) at a flow rate of 0.8 ml/min. Recoveries for R(+)- and S(-)-pyridoglutethimide enantiomers were in the range 86-91% at 300-900 ng/ml level. Intra-day and inter-day precision calculated as %R.S.D. were in the ranges of 2.9-3.9 and 1.5-4.7% for both enantiomers, respectively. Intra-day and inter-day accuracies calculated as percentage error were in the ranges of 1.9-3.3 and 1.5-3.9% for both enantiomers, respectively. Linear calibration curves in the concentration ranges of 100-1500 ng/ml for each enantiomer show correlation coefficient (r) of more than 0.9995. The limit of quantification (LOQ) of each enantiomer was 100 ng/ml using 1 ml of serum. The detection limit (LOD) for each enantiomer in serum using a UV detection set at 257 nm was 50 ng/ml (S/N = 2).

Recent applications of stereoselective chromatography

Some recent applications of stereoselective chromatography in the fields of clinical pharmacy, drug analysis, food, and natural products are reviewed. The review is documented with up-to-date literature, which will assist further expansion of research in these areas.

Pharmaceutical and biomedical applications of enantioseparations using liquid chromatographic techniques

The chiral separation methods using liquid chromatographic techniques can be divided into two categories: one is a direct method, which is based on a diastereomer formation on stationary phase or in mobile phase. The other is an indirect method, which is based on a diasteromer formation by reaction with a homochiral reagent. The enantiomer separation on a chiral stationary phases followed by derivatization with an achiral reagent is also dealt with this review article as the indirect method. The pharmaceutical and biomedical applications of enantioseparations using the direct and indirect methods have been considered in this review.