The Application of Porous Graphitic Carbon as an HPLC Stationary Phase

Bassler, Barbara J.; Hartwick, Richard A.

doi:10.1093/chromsci/27.4.162

Cited by 69 publications

(35 citation statements)

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“…The retention time of each compound in each eluent was determined with three consecutive determinations. The logarithm of the capacity factor, k′ was linearly correlated to the ethanol concentration, V (vol%): log k′=log k′ 0 +bC (1) where log k′ 0 and b are constants to be determined by the least square method. For the determination of the molecular parameters significantly influencing the retention, the intercept and slope values of Eq.…”

Section: Methodsmentioning

confidence: 99%

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Use of Principal Component Analysis for the Study of the Influence of Physicochemical Parameters on the Retention of Barbiturates on Porous Graphitized Carbon Column

Forgács

Cserháti

1998

ANAL. SCI.

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Porous graphitized carbon (PGC) has proved to be an excellent tool for the separation of positional-and stereoisomers of steroids, cephalosporin antibiotics and cresols. 1 The retention mechanism of PGC has been extensively discussed. Under non-polar conditions, PGC acted as an electron-pair acceptor of solutes. 2 Another study indicated the importance of dipoleinduced dipole interactions in the retention mechanism. 3 The influence of physicochemical parameters of some ring-substituted aniline derivatives on their retention on the PGC column has been studied in aqueous eluent systems. It has been established that the retention on the PGC column of ring-substituted aniline derivatives is mainly governed by the sterical parameters of the substituents. 4,5 Multivariate mathematical-statistical methods such as canonical correlation 6 and cluster analysis (CA) 7 , stepwise regression analysis (SRA) 8 , and principal component analysis (PCA) 9 have been frequently used to extract maximum information from retention data matrices of considerable dimensions.The objective of our investigations was to study the retention behavior of some barbituric acid derivatives on a PGC column using ethanol-water mixtures as eluents, to assess the relationship between the physicochemical characteristics and retention parameters of barbituric acid derivatives by means of PCA combined with CA and SRA, and to elucidate the similarities and dissimilarities in the information content of the various calculation methods. The study was motivated by the fact that, to the best of our knowledge the combination of PCA, CA and SRA has not been used so far in the study of molecular structure-retention behavior relationships. ExperimentalThe HPLC system was identical to that described in ref. 5. The flow rate was 1.0 ml min -1 and the detection wavelength was set to 240 nm. Mixtures of ethanolwater were used as eluents; ethanol concentration ranged from 70 to 90%v/v (in steps of 5%v/v). The eluents were not buffered. In agreement with the results of refs. 10 and 11, we found that the column temperature exerts a considerable effect on the retention. The column was thermostated at 22.5±0.5˚C in order to reduce the influence of temperature oscillation. The chemical structure of barbituric acid derivatives is depicted in Table 1. They were dissolved in the eluents in 0.05 mg ml -1 concentration. The retention time of each compound in each eluent was determined with three consecutive determinations. The logarithm of the capacity factor, k′ was linearly correlated to the ethanol concentration, V (vol%): log k′=log k′ 0 +bC (1) where log k′ 0 and b are constants to be determined by the least square method. For the determination of the molecular parameters significantly influencing the retention, the intercept and slope values of Eq. (1) were correlated with the physicochemical characteristics of barbituric acid derivatives, using PCA followed by CA and two-dimensional nonlinear mapping. The physicochemical parameters included in the calculation were: π=Ha...

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Section: Methodsmentioning

confidence: 99%

“…1 The retention mechanism of PGC has been extensively discussed. Under non-polar conditions, PGC acted as an electron-pair acceptor of solutes.…”

mentioning

confidence: 99%

Use of Principal Component Analysis for the Study of the Influence of Physicochemical Parameters on the Retention of Barbiturates on Porous Graphitized Carbon Column

Forgács

Cserháti

1998

ANAL. SCI.

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“…This result can be explained by considering that retention on graphitic columns is controlled by weaker forces than those involved in retention on oxide adsorbents. In fact, retention on PGC is determined by London-dispersion interactions (stronger with those planar molecules which can accommodate themselves better on the flat surface of PGC) and polar, electronic interactions -in particular intramolecular interactions of electron pair donor-acceptor and dipole-induced dipole type with the extended n-electron cloud present on the graphite surface [5,16,[19][20][21][22]. On oxide adsorbents retention is dominated by the possibility of the solute molecule forming hydrogen bonds with -OH groups in the adsorbents, resulting in high enthalpy changes [36].…”

Section: Effect On Retentionmentioning

confidence: 99%

“…Specific effects of PCB molecular structure on AH ~ can be singled out; they are independent of the elution solvent (compare Table II vs. Table III This order corresponds to the retention strength of PCB molecules on PGC stationary phase which is controlled by the planarity of the molecule (i. e., degree of orthosubstitution) and its electronegativity (i. e., number of chlorine atoms present on the biphenyl ring) [16,[19][20][21][22].…”

Section: Solute Effectmentioning

confidence: 99%

Temperature effect on HPLC retention of PCBs on porous graphitic carbon

2000

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KeyWordsColumn liquid chromatography Porous graphitic carbon Temperature effect on retention Polychlorobyphenyls SummaryThe effect of column temperature on solute retention was investigated for 10 PCBs with different degrees of planarity (degree of ortho position substitution). The variation of retention values (ln k) with temperature was measured using two solvents, n-hexane and dichloromethane, as mobile phase: retention decreases as temperature increases. The relationship between Ink values and temperature (l/T) exhibits a good linearity. The AH ~ values calculated are in the -2 to -5 kcal mole-1 range: they are very similar for compounds with the same degree of ortho-substitution and are significantly higher for non-ortho substituted congeners. High temperature significantly improves separation efficiency (plate number significantly increases): this effect is the dominant factor controlling chromatographic resolution, which improves with increasing temperature. Operating at 40 ~ an efficient separation of planar PCBs was obtained with low solvent consumption.

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“…They are prepared by the template replication method [8][9][10][11]129]. They are prepared by the template replication method [8][9][10][11]129].…”

Section: Macroporous Graphitic Carbon Packingsmentioning

confidence: 99%