Huntington' disease--imbalance of amino acid levels in plasma of patients and mutation carriers.

Determination of the plasma amino acid (AA) levels in Huntington's disease (HD) can make it possible to find the metabolic markers used in early diagnosis. The aim of the presented study was to determine the AA profile in plasma samples from HD patients and presymptomatic carriers, compared to healthy subjects. The AA profile was analyzed with HPLC.

Analysis of biologically active peptides using two-dimensional HPLC-CE.

High-performance liquid chromatography (HPLC) is a technique most frequently used for the assessment of biologically active peptides. Owing to the ionic character of these compounds, they may also be separated and assayed using capillary electrophoresis (CE), which offers very high efficiency, short analysis time and low consumption of reagents, and is used increasingly more often. The paper describes the combination of HPLC and CE in order to increase the efficiency of the separation of complex mixture of peptides (active substance and its related impurities).

New approach for amino acid profiling in human plasma by selective fluorescence derivatization.

A new approach for the separation of 6-aminoquinolyl-carbamyl (AQC)-derivatized amino acids has been proposed. The chromatography used ion-pairing mechanism to increase the method selectivity. Mobile phase was based on triethylamine buffer containing N,N-dimethyloctylamine as a modifier.

Determination of impurities in medical products containing metformin hydrochloride.

The object of this study was to present a high-performance liquid chromatography (HPLC) method allowing to identify and quantify the impurities in medical products in which the only active substance is metformin hydrochloride. Metformin (dimethylbiguanide) is a biguanide derivative active after oral administration. It reduces the basic and postprandial blood glucose levels in patients with type II diabetes (insulin-independent), with partially maintained insulin secretion.

Determination of the stereoisomers of racemic alpha-tocopherol in pharmaceutical preparations by high-performance liquid chromatography and gas chromatography.

In the present study we used chiral high performance liquid chromatography and gas chromatography to determine the stereoisomers of racemic alpha-tocopherol. The Chiralcel OD-H and Silar-100 AT columns were used. Statistical evaluation of the results established the precision of these methods.

Determination of impurities in pharmaceutical preparations containing folic acid.

In the presented study, the HPLC method was used for the determination of impurities (p-aminobenzoic acid and p-aminobenzoyl-L-glutamic acid) in single-component pharmaceutical products containing folic acid. The determination was performed using a spectrophotometric detector at lambda = 269 nm wavelength.

Determination of d-alpha-tocopherol and its impurity by chiral high performance liquid chromatography in pharmaceutical preparations.

In the present study we used chiral high performance liquid chromatography to determine d-alpha-tocopherol and its impurity in vitamin preparations. A chiralcel OD-H column was used for the chiral separation. Statistical evaluation of the results established a high accuracy and precision of this method.

Determination of the content of vitamin K, in complex vitamin preparations by the HPLC method.

In the present study we tried to use HPLC method to determine the vitamin K1 content in complex vitamin preparations. The reverse phases technique was applied and measurements were made at the wavelength 248 nm. On the base of statistical analysis we can note that conditions for HPLC method used in our work gave us precise and accurate results.