Supramolecular Study on the Interaction Between Ofloxacin and Methyl β-Cyclodextrin by Fluorescence Spectroscopy and its Analytical Application

The supramolecular interaction of ofloxacin (Oflo) and methyl β-cyclodextrin (Mβ-CD) has been examined by UV–vis, IR and fluorescence spectroscopy. The formation of inclusion complex has been confirmed based on the changes of the spectral properties. The results showed that Mβ-CD reacted with Oflo to form an inclusion complex. The Oflo and Mβ-CD complex formed a host-guest complex in 1:1 stoichiometry and inclusion constant (K?=?7.8?×?10^?3 L mol^?1) was ascertained by the typical double reciprocal plots. Furthermore, the thermodynamic parameters (?H°, ?S° and ?G°) associated with the inclusion process were also determined. In addition, solid inclusion complex was synthesized. Based on the significant enhancement of the fluorescence intensity of Oflo produced through complex formation, a simple, accurate, rapid and highly sensitive spectrofluorometric method for the determination of Oflo in pharmaceutical formulation was developed. The measurement of relative fluorescence intensity was carried out at 497 nm with excitation at 296 nm. The factors affecting the inclusion complex formation were studied and optimized. Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.9995) were in the concentration range of 50–350 ng/mL for spectrofluorimetry. The limit of detection (LOD) was 11.5 ng/mL. The proposed method was successfully applied to the analysis of Oflo in pharmaceutical preparation.     

Facilitated transport of 5-aminosalicylic acid through bulk liquid membrane

This paper describes the experimental results obtained at the transport of 5-aminosalicylic acid (5ASA) through agitated bulk liquid membrane, using Aliquat 336, as carrier, dissolved in a chloroform membrane. The influence of 5-aminosalicylic acid concentration in the feed source, HCl concentration in the stripping phase and carrier (Aliquat 336) concentration in the membrane were investigated. The optimal pH condition of feed source was established based on the speciation diagram of 5-aminosalicylic acid. The assessment of the transport process was performed by determining the kinetic parameters—mass transfer coefficient and entrance and exist flow in and out of the chloroform membrane.     

Chiral Separation of 4-Iminoflavan Derivatives on Several Polysaccharide-Based Chiral Stationary Phases by HPLC

The HPLC enantiomeric separation of seven 4-iminoflavans was successfully accomplished in the normal phase mode using six polysaccharide-based chiral stationary phases namely, Chiralcel^®OD-H, Chiralcel^®OD, Chiralcel^®OJ, Chiralpak^®AD, Chiralpak^®IA and Chiralpak^®IB under normal and polar organic phase modes. The resolution depended on nature and concentration of alcoholic modifier. The results demonstrate clearly that the chromatographic system based on the coated and immobilized type Chiralpak^®IB and Chiralcel^®OD-H CSPs provide a powerful analytical tool for enantiomeric separation of all the 4-iminoflavans used in this study.     

Validation criteria for developing ion-selective membrane electrodes for analysis of pharmaceuticals

 The problem of validation criteria for developing ion-selective membrane electrodes for the analysis of pharmaceuticals arises from the connection between the reliability of ion-selective membrane electrodes construction and the reliability of the analytical information. Liquid membrane selective electrodes are more suitable for validation than the solid variety. The influence of the stability of ion pair complexes from the membrane on various parameters (e.g. response, limit of detection, and selectivity) is discussed. Validation criteria are proposed. Received: 18 September 1997 · Accepted: 17 November 1997     

Hyphenation in sample preparation: advancement from the micro to the nano world

Analysis at trace levels, an ideal area of application for hyphenated techniques, is steadily gaining importance. Many sample pre-concentration and clean-up methods have been hyphenated with core analytical techniques to accomplish the task of low level detection. The present article describes the state of the art of hyphenation of various techniques such as solid phase extraction, micro-solid phase extraction, dialysis, and chromatographic modalities etc. with liquid chromatography, gas chromatography, capillary electrophoresis, and spectroscopic methods. Besides, attempts have been made to address the hyphenation approach in microfluidic devices.     

Enantioseparation of (R,S)-ketoprofen using Candida antarctica lipase B in an enzymatic membrane reactor

An enzymatic membrane reactor (EMR) for enantioseparation of (R,S)-ketoprofen via Candida antarctica lipase B (CALB) as biocatalyst was investigated. A comparative study of free and immobilized CALB was further conducted. The catalytic behaviour of CALB in an EMR was affected by the process parameters of enzyme load, substrate concentration, substrate molar ratio, lipase solution pH, reaction temperature, and substrate flow rate. Immobilization of CALB in the EMR was able to reduce the amount of enzyme required for the enantioseparation of (R,S)-ketoprofen. Immobilized CALB in the EMR assured higher reaction capacity, better thermal stability, and reusability. It was also found to be more cost effective and practical than free CALB in a batch reactor.     

Recent Trends in Chiral Separations by 2D-HPLC

Chromatographia - 2D-HPLC is an important development in chiral separations due to its excellent capability to resolve the enantiomers. This article describes the latest update in the chiral...     

Reverse elution order of β-blockers in chiral separation

In the field of chiral separation, the elution order of the enantiomers is one of the most important phenomena. Although the reversal of enantiomeric elution order is rare, it has certain significance. In the determination of the optical purities, the study of this phenomenon is helpful because it is favorable to elute the minor enantiomeric impurity before the major component. This mini review reports the reversal order of elution of the most important class of the drugs of β-blockers. This mini review describes the effects of the composition of the mobile phase, pH, and temperature on the reversal order of elution of β-blockers. The efforts are also made to discuss the possible future perspectives of reversal order of elution.     

Validated HPLC-Fl Method for the Analysis of S-Adenosylmethionine and S-Adenosylhomocysteine Biomarkers in Human Blood

The natural methyl donor group, S-adenosylmethionine and its product, S-adenosylhomocysteine play an important role in many biochemical reactions involving transmethylation reactions. These compounds can be used as biomarkers in incipient diagnosis of various pathological disorders therefore the validation of a suitable method to routinely analysis of these compounds is very important. In this paper, a high performance liquid chromatrography method for S-adenosylmethionine and S-adenosylhomocysteine measurement as fluorescent 1,N ⁶-ethanoderivatives from biological samples was validated in terms of selectivity, linearity range of the response (R?>?0.9993), detection limit (9?×?10^?9 and 4.4?×?10^?9 molL^?1), the limit of quantitation (9.7?×?10^?9 and 5.7?×?10^?9?mol?L^?1), precision, trueness and robustness. The method for quantification simultaneous of these compounds is rapid, sensitive and precise and appropriate for clinical analysis.