Revisiting the dependence of retention factor on the content of organic component in the mobile phase in reversed-phase HPLC.

In high-performance liquid chromatography, the dependence of retention factor k on volumetric fraction ϕ of organic phase is expressed by log k = F(ϕ) with F(ϕ) obtained by measuring log k at different ϕ values. From F(ϕ), a value k is calculated by taking ϕ = 0. The equation log k = F(ϕ) is applied for predicting k, and k is a descriptor of hydrophobic character of solutes and stationary phases.

Ternary water-organic solvent mixtures used for insecticide SPE extraction and analysis with acetylcholinesterase biosensor.

Few biosensors are reported for usage in combination with the organic solvent due to their negative impact on the enzymes. The usage of ternary water-organic solvent mixtures in combination with acetylcholinesterase biosensors allows to increase the useable total content of organic solvents with minimum negative effects to a higher content in comparison with a single organic solvent in water. The combination of acetonitrile/ethanol/water has a smaller negative effect on both enzyme activity and inhibition by insecticides in comparison with acetonitrile/methanol/water mixtures.

Sample preparation for large-scale bioanalytical studies based on liquid chromatographic techniques.

Quality of the analytical data obtained for large-scale and long term bioanalytical studies based on liquid chromatography depends on a number of experimental factors including the choice of sample preparation method. This review discusses this tedious part of bioanalytical studies, applied to large-scale samples and using liquid chromatography coupled with different detector types as core analytical technique. The main sample preparation methods included in this paper are protein precipitation, liquid-liquid extraction, solid-phase extraction, derivatization and their versions.

Retention studies for large volume injection of aromatic solvents on phenyl-silica based stationary phase in RP-LC.

The use of a large volume injection of hydrophobic solvents as diluents for less hydrophobic solutes has already been proven for C18 and C8 stationary phases in reversed-phase liquid chromatography. The same possibility is investigated for a phenyl-hexyl stationary phase using aromatic solvents (benzene, toluene, ethylbenzene and propylbenzene) as diluents for several model analytes also containing aromatic rings. Both hydrophobic interaction and π-π stacking account for the competitive interaction of both the diluent and model analytes with the phenyl-hexyl phase.