P Nikitas

Summary

Affiliation: Aristotle University of Thessaloniki
Country: Greece

Publications

  1. doi request reprint pH-gradient reversed-phase liquid chromatography of ionogenic analytes revisited
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chem 84:6611-8. 2012
  2. doi request reprint Theory and application of the two-mode gradient elution in liquid chromatography involving simultaneous changes in temperature and mobile-phase composition
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chem 80:5508-14. 2008
  3. ncbi request reprint Expressions of the fundamental equation of gradient elution and a numerical solution of these equations under any gradient profile
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chem 77:5670-7. 2005
  4. doi request reprint A principal component analysis approach for developing retention models in liquid chromatography
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1251:134-40. 2012
  5. doi request reprint Multilinear gradient elution optimization in reversed-phase liquid chromatography based on logarithmic retention models: application to separation of a set of purines, pyrimidines and nucleosides
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1218:5658-63. 2011
  6. ncbi request reprint Simple algorithms for fitting and optimisation for multilinear gradient elution in reversed-phase liquid chromatography
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1157:178-86. 2007
  7. ncbi request reprint Theory of stepwise gradient elution in reversed-phase liquid chromatography coupled with flow rate variations: application to retention prediction and separation optimization of a set of amino acids
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chem 78:5774-82. 2006
  8. ncbi request reprint Multilinear gradient elution optimisation in reversed-phase liquid chromatography using genetic algorithms
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1120:299-307. 2006
  9. ncbi request reprint On the equations describing chromatographic peaks and the problem of the deconvolution of overlapped peaks
    P Nikitas
    Department of Chemistry, Aristotle University of Thessaloniki, Greece
    J Chromatogr A 912:13-29. 2001
  10. ncbi request reprint A study of hominin dispersal out of Africa using computer simulations
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Hum Evol 49:602-17. 2005

Collaborators

  • A Pappa-Louisi
  • A Jouyban
  • S Fasoula
  • Ch Zisi
  • H Gika
  • P Balkatzopoulou
  • A Pappa Louisi
  • G Theodoridis
  • Ch Virgiliou
  • I Sampsonidis
  • A Zitrou

Detail Information

Publications35

  1. doi request reprint pH-gradient reversed-phase liquid chromatography of ionogenic analytes revisited
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chem 84:6611-8. 2012
    ..The extension of these models so that they are not subject to this restriction is also considered...
  2. doi request reprint Theory and application of the two-mode gradient elution in liquid chromatography involving simultaneous changes in temperature and mobile-phase composition
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chem 80:5508-14. 2008
    ..The average percentage error between experimental and predicted retention times is below to 2%...
  3. ncbi request reprint Expressions of the fundamental equation of gradient elution and a numerical solution of these equations under any gradient profile
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chem 77:5670-7. 2005
    ..It was found to be a satisfactory prediction of solute gradient retention behavior even if we used a simple linear description for the isocratic elution of these solutes...
  4. doi request reprint A principal component analysis approach for developing retention models in liquid chromatography
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1251:134-40. 2012
    ....
  5. doi request reprint Multilinear gradient elution optimization in reversed-phase liquid chromatography based on logarithmic retention models: application to separation of a set of purines, pyrimidines and nucleosides
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1218:5658-63. 2011
    ..It was found that the accuracy of the predicted gradient retention times is very satisfactory even if the simple logarithmic expression for the retention behavior of solutes, i.e. the linear dependence of lnk upon lnφ, is used...
  6. ncbi request reprint Simple algorithms for fitting and optimisation for multilinear gradient elution in reversed-phase liquid chromatography
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1157:178-86. 2007
    ....
  7. ncbi request reprint Theory of stepwise gradient elution in reversed-phase liquid chromatography coupled with flow rate variations: application to retention prediction and separation optimization of a set of amino acids
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chem 78:5774-82. 2006
    ....
  8. ncbi request reprint Multilinear gradient elution optimisation in reversed-phase liquid chromatography using genetic algorithms
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1120:299-307. 2006
    ..It was found that the adopted methodology exhibits significant advantages and it can lead to high quality predictions of the gradient retention times and optimisation results...
  9. ncbi request reprint On the equations describing chromatographic peaks and the problem of the deconvolution of overlapped peaks
    P Nikitas
    Department of Chemistry, Aristotle University of Thessaloniki, Greece
    J Chromatogr A 912:13-29. 2001
    ..Finally, it is found that Solver gives much better results than those of modern methods, like the immune and genetic algorithms...
  10. ncbi request reprint A study of hominin dispersal out of Africa using computer simulations
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Hum Evol 49:602-17. 2005
    ..6 Ma, to which our simulation attributes a probability of ca 0.01. Deserts, mountains, and mountain ranges may delay the arrival at a certain location; nevertheless, their effect on the joint probability is very small...
  11. ncbi request reprint New approach to linear gradient elution used for optimisation in reversed-phase liquid chromatography
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1068:279-87. 2005
    ....
  12. ncbi request reprint On the use of genetic algorithms for response surface modeling in high-performance liquid chromatography and their combination with the Microsoft Solver
    P Nikitas
    Department of Chemistry, Aristotle University of Thessaloniki, Greece
    J Chromatogr A 942:93-105. 2002
    ..Finally, the time needed for the optimization of a genetic algorithm and the combination of a genetic algorithm with a non-linear least-squares routine are considered and discussed...
  13. ncbi request reprint Effect of the organic modifier concentration on the retention in reversed-phase liquid chromatography II. Tests using various simplified models
    P Nikitas
    Department of Chemistry, Aristotle University of Thessaloniki, Greece
    J Chromatogr A 946:33-45. 2002
    ..It is also shown that the applicability of a simplified equation does not entail the validity of its model and thus no molecular information can be gained from its use...
  14. ncbi request reprint Effect of the organic modifier concentration on the retention in reversed-phase liquid chromatography I. General semi-thermodynamic treatment for adsorption and partition mechanisms
    P Nikitas
    Department of Chemistry, Aristotle University of Thessaloniki, Greece
    J Chromatogr A 946:9-32. 2002
    ..The next steps needed for the final elucidation of the retention mechanism in reversed-phase chromatographic columns are indicated...
  15. ncbi request reprint New equations describing the combined effect of pH and organic modifier concentration on the retention in reversed-phase liquid chromatography
    P Nikitas
    Department of Chemistry, Aristotle University of Thessaloniki, Greece
    J Chromatogr A 971:47-60. 2002
    ..Finally, the possibility of obtaining reliable pK values of weak acids or bases chromatographically by means of the derived equations is also considered and discussed...
  16. ncbi request reprint Optimisation technique for stepwise gradient elution in reversed-phase liquid chromatography
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1033:283-9. 2004
    ....
  17. ncbi request reprint New insights on the retention mechanism of non-polar solutes in reversed-phase liquid chromatographic columns
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1034:41-54. 2004
    ..2, whereas the case of MeOH is rather obscure, since the various tests did not give a clear picture about the retention mechanism in methanol-water mobile phases...
  18. doi request reprint Retention models for isocratic and gradient elution in reversed-phase liquid chromatography
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1216:1737-55. 2009
    ....
  19. ncbi request reprint Optimisation of multilinear gradient elutions in reversed-phase liquid chromatography using ternary solvent mixtures
    A Pappa-Louisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1166:126-34. 2007
    ....
  20. doi request reprint Modeling the combined effect of temperature and organic modifier content on reversed-phase chromatographic retention. Effectiveness of derived models in isocratic and isothermal mode retention prediction
    A Pappa-Louisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1201:27-34. 2008
    ..We found that a new equation for ln k(T,phi) based on the adsorption model for retention performs better than all the others. The average percentage prediction error ranges from 0.7 to 1.4%...
  21. doi request reprint Multimode gradient elution in reversed-phase liquid chromatography: application to retention prediction and separation optimization of a set of amino acids in gradient runs involving simultaneous variations of mobile-phase composition, flow rate, and temp
    A Pappa-Louisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chem 81:1217-23. 2009
    ....
  22. ncbi request reprint Column equilibration effects in gradient elution in reversed-phase liquid chromatography
    A Pappa-Louisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1127:97-107. 2006
    ..The origin of the discrepancies between theory and experiment as well as their impact on the resolution is also discussed...
  23. doi request reprint Retention prediction and separation optimization of ionizable analytes in reversed-phase liquid chromatography by organic modifier gradients in different eluent pHs
    S Fasoula
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1305:131-8. 2013
    ..Further, this study provides a reliable way for optimizing gradient separations of ionogenic compounds with respect to mobile phase pH. ..
  24. ncbi request reprint Optimization of separation and detection of 6-aminoquinolyl derivatives of amino acids by using reversed-phase liquid chromatography with on line UV, fluorescence and electrochemical detection
    A Pappa-Louisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chim Acta 593:92-7. 2007
    ..The effectiveness of a reliable retention prediction of solutes under any gradient profile using other gradient or isocratic data was also examined...
  25. doi request reprint Simple models for the effect of aliphatic alcohol additives on the retention in reversed-phase liquid chromatography
    P Nikitas
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1218:3616-23. 2011
    ..This feature is also observed in all models described the retention of alkylbenzenes...
  26. ncbi request reprint Retention prediction in ternary solvent reversed-phase liquid chromatography systems based on the variation of retention with binary mobile phase composition
    A Pappa-Louisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1091:21-31. 2005
    ..It was demonstrated the superiority of both new equations derived in this paper to that previously proposed and applied to date in ternary solvent mixtures...
  27. doi request reprint Retention prediction of highly polar ionizable solutes under gradient conditions on a mixed-mode reversed-phase and weak anion-exchange stationary phase
    P Balkatzopoulou
    Department of Chemistry, Aristotle University of Thessaloniki, 54124, Greece
    J Chromatogr A 1396:72-6. 2015
    ..5 or 1.7%, respectively. ..
  28. doi request reprint Retention prediction and separation optimization under multilinear gradient elution in liquid chromatography with Microsoft Excel macros
    S Fasoula
    Department of Chemistry, Aristotle University of Thessaloniki, 54124, Greece
    J Chromatogr A 1395:109-15. 2015
    ..Overall, the best performance is exhibited by the analytical and Nikitas-Pappa's methods, although the former cannot be used under all circumstances. ..
  29. doi request reprint Properties of the retention time of ionizable analytes in reversed-phase liquid chromatography under organic modifier gradients in different eluent pHs
    Ch Zisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1314:138-41. 2013
    ....
  30. doi request reprint Multivariate analysis of chromatographic retention data as a supplementary means for grouping structurally related compounds
    S Fasoula
    Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1387:49-52. 2015
    ..That, in turn, may assist with disambiguation of analyte identification in complex biological extracts. ..
  31. doi request reprint Expressions for multilinear combined pH/organic solvent elution of ionizable analytes in reversed-phase HPLC
    Ch Zisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chem 85:9514-21. 2013
    ..9% and 1.7%, respectively, whereas under simple pH-gradients these errors were 0.9% and 2%, respectively. ..
  32. doi request reprint Retention modeling in combined pH/organic solvent gradient reversed-phase HPLC
    Ch Zisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Analyst 138:3771-7. 2013
    ..The full and the simplified models allowed us to predict the experimental retention data in simultaneous pH/organic solvent double gradient mode very satisfactorily without the solution of the fundamental equation of gradient elution...
  33. ncbi request reprint Fundamental equation of dual-mode gradient elution in liquid chromatography involving simultaneous changes in flow rate and mobile-phase composition
    A Pappa-Louisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chem 79:3888-93. 2007
    ..The average percentage error between experimental and predicted retention times ranged from 0.9 to 2.5%. Two approximations that simplify the calculations considerably without increasing the above error were also proposed...
  34. ncbi request reprint Two- and three-parameter equations for representation of retention data in reversed-phase liquid chromatography
    A Pappa-Louisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    J Chromatogr A 1033:29-41. 2004
    ....
  35. ncbi request reprint Modelling flow rate gradient elution in reversed-phase liquid chromatography
    A Pappa Louisi
    Laboratory of Physical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
    Anal Chim Acta 573:305-10. 2006
    ....