Reversed-phase Packing Materials Research Articles

Selective effects of mobile and stationary phases in reversed-phase high-performance liquid chromatography of ecdysteroids

Observation of a number of different solvent systems and reversed-phase packing materials used for the chromatography of ecdysteroids has shown that order of elution and degree of separation between compounds of the series can be varied with useful limits by choice of the appropriate stationary and mobile phase. The effect on retention properties of substituent hydroxyl groups varies considerably with their position in the molecule.

Analysis of cysteinyldopas, dopa, dopamine, noradrenaline and adrenaline in serum and urine using high-performance liquid chromatography and electrochemical detection

The catecholic amino acids, dopa, 2-S- and 5-S-cysteinyldopa, and 2,5-S,S-dicysteinyldopa were determined qualitatively in serum from patients with malignant melanoma by reversed-phase high-performance liquid chromatography, using electrochemical detection. In urine the catecholamines dopamine, noradrenaline and adrenaline were also determined qualitatively, as well as the above-mentioned compounds, in a single chromatographic run. The conditions were optimized by changing the pH of the mobile phase and by the addition of methanesulphonic acid. A comparison was made between the performance of four commercial reversed-phase packing materials containing chemically bonded octadecyl groups, using a standard mixture of catecholic amino acids. The influence of ionic strength, pH and amount of methanesulphonic acid on retention was investigated.