Determination and Pharmacokinetics of Omeprazole Enantiomers in Human Plasma and Oral Fluid Utilizing Microextraction by Packed Sorbent and Liquid Chromatography-Tandem Mass Spectrometry.

In the present work, the determination of omeprazole (OME) enantiomers in oral fluid and plasma samples was carried out utilizing microextraction by packed sorbent (MEPS) and liquid chromatography-tandem mass spectrometry. A chiral column with cellulose-SB phase was used for the first time for enantiomeric separation of OME with an isocratic elution system using 0.2% ammonium hydroxide in hexane-ethanol mixture (70 : 30, v/v) as the mobile phase.

Determination of metoprolol enantiomers in human plasma and saliva samples utilizing microextraction by packed sorbent and liquid chromatography-tandem mass spectrometry.

A sensitive, accurate and reliable bioanalytical method for the enantioselective determination of metoprolol in plasma and saliva samples utilizing liquid chromatography-electrospray ionization tandem mass spectrometry was developed and validated. Human plasma and saliva samples were pretreated by microextraction by packed sorbent (MEPS) prior to analysis. A new MEPS syringe form with two inputs was used.

Online post-column solvent assisted and direct solvent-assisted electrospray ionization for chiral analysis of propranolol enantiomers in plasma samples.

An Online post-column solvent-assisted ionization (OPSAI) method was developed for enhancing the ionization of the beta-blocker propranolol utilizing normal phase LC-MS/MS. Solvent-assisted electrospray ionization (SAESI) was studied by the introduction of the assistant solvents A: 0.5% Formic acid in Isopropanolol, B: 0.

Simultaneous spectrophotometric determination of the three structural isomers of cresol using multivariate regression methods.

The simultaneous determination of the structural isomers of cresol was carried out using UV spectrophotometry by applying the principle component regression (PCR) and partial least squares (PLS) regression methods. Different concentration levels of cresol isomers were determined in their mixtures by construction of a partial factorial calibration design at four levels. Both multivariate calibration models were constructed using the correlation between the concentration and absorbance data matrices in the spectral region 283-305 nm.

Enantioselective HPLC-DAD method for the determination of etodolac enantiomers in tablets, human plasma and application to comparative pharmacokinetic study of both enantiomers after a single oral dose to twelve healthy volunteers.

An enantioselective high performance liquid chromatographic method with diode array detection (HPLC-DAD) was developed and validated for the determination of etodolac enantiomers in tablets and human plasma. Enantiomeric separation was achieved on a Kromasil Cellucoat chiral column (250 mm × 4.6mm i.

Simultaneous determination of the two non-steroidal anti-inflammatory drugs ; diflunisal and naproxen in their tablets by chemometric spectrophotometry and HPLC.

Chemometric spectrophotometry and HPLC were applied to the simultaneous determination of the two non-steroidal anti-inflammatory drugs; diflunisal (I) and naproxen (II). The applied chemometric techniques are multivariate methods including classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS); and the second derivative of the ratio spectra ((2)D(r)) method. To develop the multivariate methods, the UV absorption spectra of the standard solutions of the training and validation sets in methanol were recorded in the range of 242-274 nm at 2 nm intervals.

Application of multivariate methods to the simultaneous Fourier Transform Infrared (FT-IR) spectrometric determination of stereo-isomers; quinine and quinidine.

The two stereo-isomers; quinine and quinidine have been determined in their mixtures in the IR region using chemometric multivariate methods, principal component regression (PCR) and partial least squares (PLS). A training set of thirty synthetic binary mixture solutions in the possible combinations containing 0.0 - 4.

Derivative spectrophotometry in the visible region using absorbance versus log wavelength or wavenumber determination of cyanocobalamin in injection solutions.

Two approaches have been adopted to increase the steepness of the slopes and the sharpness of the curvature of an absorption curve in the visible region. These are recording (i) A (1cm) versus log wavelength or (ii) A (1cm) versus wavenumber. The computer program was tested by calculating the ratios of the first derivative optima for a Gaussian band, and proved that changing wavelength into log wavelength or wavenumber is effective to squeeze an absorption curve non-linearly.

Spectrophotometric methods for the determination of Ibuprofen in tablets.

Ibuprofen in film coated tablets of different strengths has been determined using different spectrophotometric methods. These are: (i) the compensation method, (ii) a two wavelengths method, (iii) second-order and (iv) fourth-order derivative methods, and (v) a curve fitting method based upon computing the quadratic coefficient of the orthogonal polynomials expansion of its benzenoid absorption characteristics. All results were compared with the HPLC method of the B.