Comparative study of test methods for reversed-phase columns for high-performance liquid chromatography

Characterization of HPLC columns for two‐dimensional LC × LC separations of phenolic acids and flavonoids

“…Equation (2) and experimental log k * of these calibration standards determined in the isocratic experiments provided parameters A 0 and B 0 by linear regression of the experimental plots for a given mobile phase. Subsequently, the best-fit regression parameters A 0 and B 0 of Eq.…”

“…Characterization of column quality is not a simple task, as a number of factors should be taken into account, affecting the intermolecular interactions between the analytes, the stationary phase and the mobile phases controlling the retention [2,3]. The type of the support material, the chemistry, arrangement and density of the stationary phase bonded on the adsorbent surface, the homogeneity of the chromatographic bed, particle size and porosity and other factors control the selectivity, efficiency and resolution of separation and reproducibility of chromatographic data.…”

“…In addition to simple measurements of the retention factors of test compounds in selected mobile phases, tests performed over a more or less broad range of mobile phase composition provide more complete information on the properties of stationary phases. Non-polar alkylbenzenes, various polar, weakly acidic or basic compounds, naphthalene sulphonic acids, oligomers and macromolecular test compounds are available for mapping various aspects of the retention properties of the chromatographic system [2][3][4].…”

O desafio de analisar solutos básicos por cromatografia líquida em modo reverso: algumas alternativas para melhorar as separações

“…A hidrofobicidade é avaliada pelo fator de retenção de um soluto apolar, enquanto que a atividade silanofílica é estudada através do fator de assimetria de um soluto básico ou do fator de separação entre um soluto básico e um neutro. [18][19][20][21][22][23]58,[84][85][86] Neste ponto, cabe ressaltar que o termo atividade silanofílica não é bem definido na literatura, por exemplo, a atividade silanofílica pode ser definida como "se fase estacionária é adequada para analisar solutos básicos", neste caso a atividade silanofílica é avaliada pelo fator de assimetria de um soluto básico, como no teste SRM 870 24,25 e na Figura 2, ou ser definida como a participação dos silanóis residuais na retenção de solutos básicos, sendo avaliada pelo fator de separação entre um soluto básico e um neutro, como no teste de Tanaka 26,79-81 e na Figura 16S (material suplementar).…”

Tris(2-methyl-8-quinolinolato)gallium(III) as a Fluorescent Probe for Sensitive Silanol-Testing

“…5,7,[10][11][12][13][14][15][16] Most of the probe compounds are small molecules containing nitrogen atoms, because much interest has been focused on the interaction through the ion-exchange or hydrogen-bonding function to which nitrogen-containing compounds are considered to respond. 10,[17][18][19][20][21][22][23] Claessens et al 16,24,25 examined the relations between various silanol-detecting molecules containing nitrogen atoms, and found a correlation among the results of the tests. They concluded that the silanol activity was influenced by individual factors on the surface of silica-base packing materials, such as deprotonation of the silanol groups, the existence of highly acidic silanol and metal impurities, and that each silanol test evaluated the degree of silanol activity differently.…”