ADVANCES IN HYDROPHILIC INTERACTION LIQUID
5. SUMMARY AND PERSPECTIVES FOR FURTHER DEVELOPMENT
The BIGDMA-MEDSA column in the first dimension coupled online with a short monolithic or coreeshell C18column was used for combined alternating HILICRP and RPRP comprehensive 2D separations of polyphenolic compounds. During the HILICRP period, a gradient of decreasing acetonitrile gradient was used for the separation in the first dimension. At the end of the gradient, the polymeric monolithic microcolumn was equilibrated with a highly aqueous mobile phase and was ready for the second sample injection in the RPRP period. This time a gradient of increasing concentration of acetonitrile was used in the first dimension.Fig. 2.10presents 2D chromatograms of flavones and related polyphenolic compounds, acquired with a single first-dimension BIGDMA- MEDSA capillary column in two experiments with consecutive injections of the sample, the first one into a decreasing and the second into an increasing acetonitrile gradient (Ha´jek et al., 2016). The automated dual LCLC approach allows obtaining three-dimensional data in a relatively short time.
compounds. Large differences in retention and separation selectivity, depending on the chemistry of stationary phases, indicate that the retention mechanism is more complex than the originally suggested partition between the water layer adsorbed on a solid support and the bulk mobile phase. Probably, a sample-dependent mix of nonpolar and selective polar [hydrogen bonding, dipoleedipole, ion- exchange, and ion-repulsion (ERLIC)] interactions participates in separation.
The column types used in HILIC strongly differ in the adsorption capacity for water. The columns based on hydrosilated silica show less than a monomolecular water layer capacity, which suggests that the adsorption process (i.e., NP-LC) characterizes the retention more appropriately than the partition process.
We can expect future development of tailor-made HILIC stationary phases intended for specific types of samples. Another almost unexplored promising field is better utilization of mobile phases for adjusting the retention mechanism (HILIC-RP) on a single column to extend separation selectivity by alternating use of different separation conditions. These possibilities can probably be used in future 2D combinations implementing the HILIC mode in off-line, serial, stop-and-go, and comprehensive setups, and their combinations, to improve peak capacities for complex samples containing hundreds of compounds.
REFERENCES
Abraham, M.H., Ibrahim, A., Zissimos, A.M., 2004. Determination of sets of solute descriptors from chro- matographic measurements. J. Chromatogr. A 1037, 29e47.
Ahn, J., Bones, J., Yu, Y.Q., Rudd, P.M., Gilar, M., 2010. Separation of 2-aminobenzamide labeled glycans using hydrophilic interaction chromatography columns packed with 1.7mm sorbent. J. Chromatogr. B 2010 (878), 403e408.
Alpert, A.J., 1983. Cation-exchange high-performance liquid chromatography of proteins on poly(aspartic acid)- silica. J. Chromatogr. A 266, 23e37.
Alpert, A.J., 1990. Hydrophilic-interaction chromatography for the separation of peptides, nucleic acids and other polar compounds. J. Chromatogr. 449, 177e196.
Alpert, A.J., 2008. Electrostatic repulsion hydrophilic interaction chromatography for isocratic separation of charged solutes and selective isolation of phosphopeptides. Anal. Chem. 80, 62e76.
Alpert, A.J., Andrews, P.C., 1988. Cation-exchange chromatography of peptides on poly(2-sulfoethyl asparta- mide)-silica. J. Chromatogr. 443, 85e96.
Alpert, A.J., Shukla, M., Shukla, A.K., Zieske, L.R., Yuen, S.W., Ferguson, M.A.J., Mehlert, A., Pauly, M., Orlando, R., 1994. Hydrophilic-interaction chromatography of complex carbohydrates. J. Chromatogr. A 676, 191e202.
Alpert, A.J., Hudecz, O., Mechtler, K., 2015. Anion-exchange chromatography of phosphopeptides: weak anion exchange versus strong anion exchange and anion-exchange chromatography versus electrostatic repulsion- hydrophilic interaction chromatography. Anal. Chem. 87, 4704e4711.
Alvarez-Segura, T., Torres-Lapasio, J.R., Ortiz-Bolsico, C., Garcia-Alvarez-Coque, M.C., 2016. Stationary phase modulation in liquid chromatography through the serial coupling of columns: a review. Anal. Chim. Acta 923, 1e23.
Appelblad, P., Abrahamsson, P., September, 2005. MS detection of homocysteine, methyl-malonic acid, and succinic acid using HILIC separation on a covalently bonded zwitterionic stationary phase. LCGC N. Am.
(Suppl.), 24e25.
Aral, T., Aral, H., Zizadanogullari, B., Zizadanogullari, R., 2015. Synthesis of a mixed-model stationary phase derived from glutamine for HPLC separation of structurally different biologically active compounds: HILIC and reversed-phase applications. Talanta 131, 64e73.
Armstrong, D.W., Jin, H.L., 1989. Evaluation of the liquid chromatographic separation of monosaccharides, di- saccharides, trisaccharides, tetrasaccharides, deoxysaccharides and sugar alcohols with stable cyclodextrin bonded phase columns. J. Chromatogr. 462, 219e232.
Arrua, R.D., Causon, T.J., Hilder, E.F., 2012. Recent developments and future possibilities for polymer monoliths in separation science. Analyst 137, 5179e5189.
Aturki, Z., D’Orazio, G., Rocco, A., Si-Ahmed, K., Fanali, S., 2011. Investigation of polar stationary phases for the separation of sympathomimetic drugs with nano-liquid chromatography in hydrophilic interaction liquid chromatography mode. Anal. Chim. Acta 685, 103e110.
Beelders, T., Kalili, K.M., Joubert, E., de Beer, E., de Villiers, A., 2012. Comprehensive two-dimensional liquid chromatographic analysis of rooibos (Aspalathus linearis) phenolics. J. Sep. Sci. 35, 1808e1829.
Berthod, A., Chang, S.S.C., Kullman, J.P.S., Armstrong, D.W., 1998. Practice and mechanism of HPLC oligo- saccharide separation with a cyclodextrin bonded phase. Talanta 47, 1001e1012.
Bicker, W., Wu, J.Y., Lammerhofer, M., Lindner, W., 2008. Hydrophilic interaction chromatography in nonaqueous elution mode for separation of hydrophilic analytes on silica-based packings with noncharged polar bondings. J. Sep. Sci. 31, 2971e2987.
Blahova´, E., Jandera, P., Cacciola, F., Mondello, L., 2006. Two-dimensional and serial column reversed-phase separation of phenolic antioxidants on octadecyl-, polyethyleneglycol-, and pentafluorophenylpropyl-silica columns. J. Sep. Sci. 29, 555e566.
Boersema, P.J., Divecha, N., Heck, A.J.R., Mohammed, S., 2007. Evaluation and optimization of ZIC-HILIC-RP as an alternative MudPIT strategy. J. Proteome Res. 6, 937e946.
Booth, T.J., Blake, P., Nair, R.R., Jiang, D., Hill, E.W., Bangert, U., Bleloch, A., Gass, M., Novoselov, K.S., Katsnelson, M.I., 2008. Macroscopic graphene membranes and their extraordinary stiffness. Nano Lett. 8, 2442e2446.
Boysen, R.A., Yang, Y., Chowdhury, J., Matyska, M.T., Pesek, J.J., Hearn, M.T.W., 2011. Simultaneous separation of hydrophobic and hydrophilic peptides with a silica hydride stationary phase using aqueous normal phase conditions. J. Chromatogr. A 1218, 8021e8026.
Buszewski, B., Noga, S., 2012. Hydrophilic interaction liquid chromatography (HILIC)da powerful separation technique. Anal. Bioanal. Chem. 402, 231e247.
Cabooter, D., Choikhet, K., Lestreau, F., Dittman, M., Desmet, G., 2014. Towards a generic variable column length method development strategy for samples with a large variety in polarity. J. Chromatogr. A 1372, 174e186.
Cacciola, F., Jandera, P., Hajdu´, Z.,Cesla, P., Mondello, L., 2007. Comprehensive two-dimensional LC LC with parallel gradients for separation of phenolic and flavone antioxidants. J. Chromatogr. A 1149, 73e87.
Cacciola, F., Delmonte, P., Jaworska, K., Dugo, P., Mondello, L., Rader, J.I., 2011. Employing ultra high pressure liquid chromatography as the second dimension in a comprehensive two-dimensional system for analysis of Stevia rebaudianaextracts. J. Chromatogr. A 1218, 2012e2018.
Chalcraft, K.R., McCarry, B.E., 2013. Tandem LC columns for the simultaneous retention of polar and nonpolar molecules in comprehensive metabolomics analysis. J. Sep. Sci.
Chauve, B., Guillarme, D., Cle´on, P., Veuthey, J.-L., 2010. Evaluation of various HILIC materials for the fast separation of polar compounds. J. Sep. Sci. 33, 752e764.
Cheng, X.D., Peng, X.T., Yu, Q.W., Yuan, B.F., Feng, Y.Q., 2013. Preparation of a novel amino-phosphate zwitterionic stationary phase for hydrophilic interaction chromatography. Chromatographia 76, 1569e1576.
Chirita, R.-I., West, C., Zubrzycki, S., Finaru, A.L., Elfakir, C., 2011. Investigations on the chromatographic behaviour of zwitterionic stationary phases used in hydrophilic interaction chromatography. J. Chromatogr. A 1218, 5939e5963.
Churms, S.C., 1996. Recent progress in carbohydrate separation by high-performance liquid chromatography based on hydrophilic interaction. J. Chromatogr. A 720, 75e91.
Cı´fkova´, E., Ha´jek, R., Lı´sa, M., Holcapek, M., 2016. Hydrophilic interaction liquid chromatography-mass spectrometry of (lyso)phosphatidyl acids, (lyso)phosphatidylserines and other lipid classes. J. Chromatogr.
A 1439, 65e73.
Currivan, S., Jandera, P., 2014. Modification reactions applicable to polymeric monolithic columns. A review.
Chromatography 1, 24e53.
Currivan, S., Maca´k, J.M., Jandera, P., 2015. Polymethacrylate monolithic columns for hydrophilic interaction liquid chromatography prepared using a secondary surface polymerization. J. Chromatogr. A 1402, 82e93.
da Silva, C.G.A., Collins, C.H., Bottoli, C.B.G., 2014. Monolithic capillary columns based on silica and zirconium oxides for use in hydrophilic interaction liquid chromatography. Microchem. J. 116, 249e254.
Dejaegher, B., Vander Heyden, Y., 2010. HILIC methods in pharmaceutical analysis. J. Sep. Sci. 33, 698e715.
Dejaegher, B., Mangelins, D., Vander Heyden, Y., 2008. Method development for HILIC assays. J. Sep. Sci. 31, 1438e1448.
Dinh, N.P., Jonsson, T., Irgum, K., 2011. Probing the interaction mode in hydrophilic interaction chromatography.
J. Chromatogr. A 1218, 5880e5891.
Dinh, N.P., Jonsson, T., Irgum, K., 2013. Water uptake on polar stationary phases under conditions for hydrophilic interaction chromatography and its relation to solute retention. J. Chromatogr. A 1320, 33e47.
Dolzan, M.D., Spudeit, D.A., Breitbach, Z.S., Barber, W.E., Micke, G.A., Armstrong, D.W., 2014. Comparison of superficially porous and fully porous silica supports used for a cyclofructan 6 hydrophilic interaction liquid chromatographic stationary phase. J. Chromatogr. A 1365, 124e130.
Dreyer, D.R., Park, S., Bielawski, C.W., Ruoff, R.S., 2010. The chemistry of graphene oxide. Chem. Soc. Rev. 39, 228e240.
Dun, H., Zhang, W., Wei, Y., Song, X., Li, Y., Chen, L., 2004. Layer-by-layer self-assembly of multilayer zirconia nanoparticles on silica spheres for HPLC packings. Anal. Chem. 76, 5016e5023.
Fairchild, J.N., Horva´th, K., Guiochon, G., 2009. Approaches to comprehensive multidimensional liquid chro- matography systems. J. Chromatogr. A 1216, 1363e1371.
Falasca, S., Petruzziello, F., Kretz, R., Rainer, G., Zhang, X.Z., 2012. Analysis of multiple quaternary ammonium compounds in the brain using tandem capillary column separation and high resolution mass spectrometric detection. J. Chromatogr. A 1241, 46e51.
Feste, A.S., Khan, I., 1992. Separation of glucooligosaccharides and polysaccharide hydrolysates by gradient elution hydrophilic interaction chromatography with pulsed amperometric detection. J. Chromatogr. 630, 129e139.
Foo, H.C., Heaton, J., Smith, N.W., Stanley, S., 2012. Monolithic poly (SPE-co-BVPE) capillary columns as a novel hydrophilic interaction liquid chromatography stationary phase for the separation of polar analytes.
Talanta 100, 344e348.
Fountain, K.J., Xu, J., Diehl, D.M., Morrison, D., 2010. Influence of stationary phase chemistry and mobile-phase composition on retention, selectivity, and MS response in hydrophilic interaction chromatography. J. Sep. Sci.
33, 740e751.
Garbis, S.D., Melse-Boonstra, A., West, C.E., van Breemen, R.B., 2001. Determination of folates in human plasma using hydrophilic interaction chromatography e tandem mass spectrometry. Anal. Chem. 73, 5358e5364.
Gilar, M., Olivova, P., Daly, A.E., Gebler, J.C., 2005. Orthogonality of separation in two-dimensional liquid chromatography. Anal. Chem. 77, 6426e6434.
Greco, G., Grosse, S., Letzel, T., 2013. Serial coupling of reversed-phase and zwitterionic hydrophilic interaction LC/MS for the analysis of polar and nonpolar phenols in wine. J. Sep. Sci. 36, 1379e1388.
Greiderer, A., Trojer, L., Huck, C.W., Bonn, G.K., 2009. Influence of the polymerisation time on the porous and chromatographic properties of monolithic poly(1,2-bis(p-vinylphenyl))ethane capillary columns.
J. Chromatogr. A 1216, 7747e7754.
Gritti, F., dos Santos Pereira, A., Sandra, P., Guiochon, G., 2010. Efficiency of the same neat silica column in hydrophilic interaction chromatography and per aqueous liquid chromatography. J. Chromatogr. A 1217, 683e688.
Grosskreutz, S.R., Secor, M.H., Stoll, D.R., 2012. Selective comprehensive multidimensional separation for resolution enhancement in HPLC. Part I: principles and instrumentation. J. Chromatogr. A 1228, 31e40.
Grumbach, E.S., Diehl, D.M., Neue, U.D., 2008. The application of novel 1.7mm ethylene bridged hybrid par- ticles for hydrophilic interaction chromatography. J. Sep. Sci. 31, 1511e1518.
Guiochon, G., Marchetti, N., Mriziq, K., Shaliker, R.A., 2008. Implementation of two-dimensional liquid chromatography. J. Chromatogr. A 1189, 109e168.
Guo, Y., Gaiki, S., 2005. Retention behavior of small polar compounds on polar stationary phases in hydrophilic interaction chromatography. J. Chromatogr. A 1074, 71e90.
Guo, Y., Srinivasan, S., Gaiki, S., 2007. Investigating the effect of chromatographic conditions on retention of organic acids in hydrophilic interaction chromatography using a design of experiment. Chromatographia 66, 223e229.
Ha´jek, T., Jandera, P., Stankova´, M.,Cesla, P., 2016. Automated dual two-dimensional liquid chromatography approach for fast acquisition of three-dimensional data using combinations of zwitterionic polymethacrylate and silica-based monolithic columns. J. Chromatogr. A 1446, 91e102.
Hao, Z., Xiao, B., Weng, N., 2008. Impact of column temperature and mobile phase composition on selectivity of hydrophilic interaction chromatography (HILIC). J. Sep. Sci. 31, 1449e1464.
Hartmann, E., Chen, Y., Mant, C.T., Jungbauer, A., Hodges, R.S., 2003. Comparison of reversed-phase liquid chromatography and hydrophilic interaction/cation-exchange chromatography for the separation of amphi- pathica-helical peptides with L- and D-amino acid substitutions in the hydrophilic face. J. Chromatogr. A 1009, 61e71.
Heaton, J.C., McCalley, D.V., 2014. Comparison of the kinetic performance and retentivity of sub-2mm core-shell, hybrid and conventional bare silica phases in hydrophilic interaction chromatography. J. Chromatogr. A 1371, 106e116.
Heaton, J.C., Russell, J.J., Underwood, T., Boughtflower, R., McCalley, D.V., 2014. Comparison of peak shape in hydrophilic interaction chromatography using acidic salt buffers and simple acid solutions. J. Chromatogr. A 1347, 39e48.
Hemstro¨m, P., Irgum, K., 2006. Hydrophilic interaction chromatography. J. Sep. Sci. 29, 1784e1821.
Horie, K., Ikegami, T., Hosoya, K., Saad, N., Fiehn, O., Tanaka, N., 2007. Highly efficient monolithic silica capillary columns modified with poly(acrylic acid) for hydrophilic interaction chromatography.
J. Chromatogr. A 1164, 198e205.
Hou, Y., Zhang, F., Liang, X., Yang, B., Liu, X., Dasgupta, P.K., 2016. Poly (vinyl) alcohol modified porous graphitic carbon stationary phase for hydrophilic interaction chromatography. Anal. Chem. 88, 4676e4681.
Hsieh, Y., 2008. Potential of HILIC-MS in quantitative bioanalysis of drugs and drug metabolites. J. Sep. Sci. 31, 1481e1491.
Huber, J.F.K., Pawlowska, M., Markl, P., 1984. Solvent-generated liquid-liquid chromatography with aqueous ternary systems. Chromatographia 19, 19e28.
Ibrahim, M.E.A., Lucy, C.A., 2012. Mixed mode HILIC/anion exchange separations on latex coated silica monolith. Talanta 100, 313e339.
Ibrahim, M.E.A., Zhou, T., Lucy, C.A., 2010. Agglomerated silica monolithic column for hydrophilic interaction LC. J. Sep. Sci. 33, 773e778.
Idborg, H., Zamani, L., Edlund, P.-O., Schuppe-Koistinen, I., Jacobsson, S.P., 2005a. Metabolic fingerprinting of rat urine by LC/MS: part 1. Analysis by hydrophilic interaction liquid chromatography-electrospray ionization mass spectrometry. J. Chromatogr. B 828, 9e13.
Idborg, H., Zamani, L., Edlund, P.-O., Schuppe-Koistinen, I., Jacobsson, S.P., 2005b. Metabolic fingerprinting of rat urine by LC/MS: part 2. Data pretreatment methods for handling of complex data. J. Chromatogr. B 828, 14e20.
Ikegami, T., Tomomatsu, K., Takubo, H., Horie, K., Tanaka, N., 2008. Separation efficiencies in hydrophilic interaction chromatography. J. Chromatogr. A 1184, 474e503.
Iwasaki, Y., Ishii, Y., Ito, R., Saito, K., Nakazawa, H., 2007. New approaches for analysis of metabolism com- pounds in hydrophilic interaction chromatography. J. Liq. Chromatogr. Rel. Technol. 30, 2117e2126.
Jandera, P., 2008. Stationary phases for hydrophilic interaction chromatography, their characterization and implementation into multidimensional chromatography concepts. J. Sep. Sci. 31, 1421e1437.
Jandera, P., 2011. Stationary and mobile phases in hydrophilic interaction chromatography. Anal. Chim. Acta 692, 1e25.
Jandera, P., 2012a. Programmed elution in comprehensive two-dimensional liquid chromatographyea review.
J. Chromatogr. A 1255, 112e129.
Jandera, P., 2012b. Comprehensive two-dimensional liquid chromatography e theoretical considerations, a review. Cent. Eur. J. Chem. 10, 844e875.
Jandera, P., Chura´cek, J., 1974. Gradient elution in liquid chromatography. I. The influence of the composition of the mobile phase on the capacity ratio (retention volume, band width, and resolution) in isocratic elutione theoretical considerations. J. Chromatogr. 91, 207e221.
Jandera, P., Ha´jek, T., 2009. Utilization of dual retention mechanism on columns with bonded PEG and diol stationary phases for adjusting the separation selectivity of phenolic and flavone natural antioxidants. J. Sep.
Sci. 32, 3603e3619.
Jandera, P., Stankova´, M., 2015. The effects of the column length on the efficiency of capillary zwitterionic organic polymer monolithic columns in HILIC chromatography. Chromatographia 79, 853e859.
Jandera, P., Novotna´, K., Beldean-Galea, M.S., Jı´sa, K., 2006. Retention and selectivity tests of silica-based and metal-oxide bonded stationary phases for RP-HPLC. J. Sep. Sci. 29, 856e871.
Jandera, P., Vynuchalova´, K., Ha´jek, T.,Cesla, P., Vohralı´k, G., 2008. Characterization of HPLC columns for two- dimensional LCLC separations of phenolic acids and flavonoids. J. Chemom. 22, 203e217.
Jandera, P., Ha´jek, T.,Skerı´kova´, V., Soukup, J., 2010a. Dual hydrophilic interaction-reversed phase retention mechanism on polar columns: structural correlations and implementation for 2D separations on a single column. J. Sep. Sci. 33, 841e852.
Jandera, P., Urban, J.,Ske rı´kova´, V., Langmaier, P., Kubı´ckova´, R., Planeta, J., 2010b. Polymethacrylate mono- lithic and hybrid particle-monolithic columns for reversed-phase and hydrophilic interaction capillary liquid chromatography. J. Chromatogr. A 1217, 22e33.
Jandera, P., Ha´jek, T.,Cesla, P., 2011. Effects of the gradient profile, sample volume and solvent on the separation in very fast gradients, with special attention to the second-dimension gradient in comprehensive two- dimensional liquid chromatography. J. Chromatogr. A 1218, 1995e2006.
Jandera, P., Ha´jek, T., Stankova´, M., Vynuchalova´, K.,Cesla, P., 2012. Optimization of comprehensive two- dimensional gradient chromatography coupling in-line hydrophilic interaction and reversed phase liquid chromatography. J. Chromatogr. A 1268, 91e101.
Jandera, P., Stankova´, M., Ha´jek, T., 2013. New zwitterionic polymethacrylate monolithic columns for uni- dimensional and two-dimensional micro liquid chromatography. J. Sep. Sci. 36, 2430e2440.
Jandera, P., Ha´jek, T., Stankova´, M., 2015. Monolithic and core-shell columns in comprehensive two-dimensional liquid chromatographyereview. Anal. Bioanal. Chem. 407, 139e151.
Janeckova´, L., Kalı´kova´, K., Bosa´kova´, Z., Tesarova´, E., 2010. Study of interaction mechanisms on zirconia-based polystyrene HPLC column. J. Sep. Sci. 33, 3043e3051.
Ji, S.L., Zhang, F.F., Wu, S.J., Yang, B.C., Liang, X.M., 2014. Facile preparation of polyvinyl alcohol coated SiO2
stationary phases for high performance liquid chromatography. Analyst 139, 5594e5599.
Jian, W., Edom, R.W., Xu, Y., Weng, N., 2010. Recent advances in application of hydrophilic interaction chro- matography for quantitative bioanalysis. J. Sep. Sci. 33, 681e697.
Jiang, W., Irgum, K., 1999. Covalently bonded polymeric zwitterionic stationary phase for simultaneous sepa- ration of inorganic cations and anions. Anal. Chem. 71, 333e344.
Jiang, W., Fischer, G., Girmay, Y., Irgum, K., 2006. Zwitterionic stationary phase with covalently bonded phosphorylcholine type polymer grafts and its applicability to separation of peptides in the hydrophilic interaction liquid chromatography mode. J. Chromatogr. A 1127, 82e91.
Jiang, Z., Smith, N.W., Ferguson, P.D., Taylor, M.R., 2007. Hydrophilic interaction chromatography using methacrylate-based monolithic capillary column for the separation of polar analytes. Anal. Chem. 79, 1243e1250.
Jin, G., Guo, Z., Zhang, F., Xue, X., Jin, Y., Liang, X., 2008. Study on the retention equation in hydrophilic interaction liquid chromatography. Talanta 76, 522e527.
Kalili, K.M., de Villiers, A., 2013. Systematic optimisation and evaluation of on-line, off-line and stop-flow comprehensive hydrophilic interaction chromatographyreversed phase liquid chromatographic analysis of procyanidins, Part I: theoretical considerations. J. Chromatogr. A 1289, 58e68.
Kallili, K.M., de Villiers, A., 2010. Off-line comprehensive two-dimensional hydrophilic interactionreversed phase liquid chromatographic analysis of green tea phenolics. J. Sep. Sci. 33, 853e863.
Karatapanis, A.E., Fiamegos, Y.C., Stalikas, C.D., 2011. A revisit to the retention mechanism of hydrophilic interaction liquid chromatography using model organic compounds. J. Chromatogr. A 1218, 2871e2879.
Karlsson, G., Winge, S., Sandberg, H., 2005. Separation of monosaccharides by hydrophilic interaction chro- matography with evaporative light scattering detection. J. Chromatogr. A 1092, 246e249.
Kawachi, Y., Ikegami, T., Takubo, H., Ikegami, Y., Miyamoto, M., Tanaka, N., 2011. Chromatographic charac- terization of hydrophilic interaction liquid chromatography stationary phases: hydrophilicity, charge effects, structural selectivity, and separation efficiency. J. Chromatogr. A 1218, 5903e5919.
Kikta, E.J., Grushka, E., 1977. Bonded peptide stationary phases for separation of amino-acids and peptides using liquid-chromatography. J. Chromatogr. 135, 367e376.
Kulsing, C., Yang, Y., Munerab, C., Tseb, C., Matyska, M.T., Pesek, J.J., Boysen, R.L., Hearn, M.T.W., 2014.
Correlations between the zeta potentials of silica hydride-based stationary phases, analyte retention behaviour and their ionic interaction descriptors. Anal. Chim. Acta 817, 48e60.
Kulsing, C., Nolvachai, Y., Marriott, P.J., Boysen, R.L., Matyska, M.T., Pesek, J.J., Hearn, M.T.W., 2015. In- sights into the origin of the separation selectivity with silica hydride adsorbents. J. Phys. Chem. B 119, 3063e3069.
Kumar, A., Heaton, J.C., McCalley, D.V., 2013. Practical investigation of the factors that affect the selectivity in hydrophilic interaction chromatography. J. Chromatogr. A 1276, 33e46.
Lammerhofer, M., Richter, M., Wu, J., Nogueira, R., Bicker, W., Lindner, W., 2008. Mixed-mode ion-exchangers and their comparative chromatographic characterization in reversed-phase and hydrophilic interaction chro- matography elution modes. J. Sep. Sci. 31, 2572e2588.
Langmuir, I., 1916. The constitution and fundamental properties of solids and liquids. Part I. Solids. J. Am. Chem.
Soc. 38, 2221e2295.
Li, J., Li, Y., Chen, T., Xu, L., Liu, X., Zhang, X., Zhang, H., 2013. Preparation, chromatographic evaluation and comparison between linear peptide- and cyclopeptide-bonded stationary phases. Talanta 109, 152e159.
Li, H., Liu, C., Wang, Q., Zhou, H., Jiang, Z., 2016. The effect of charged groups on hydrophilic monolithic stationary phases on their chromatographic properties. J. Chromatogr. A 1469, 77e87.
Liang, Z., Li, K., Wang, X., Ke, Y., Liang, X., 2012. Combination of off-line two-dimensional hydrophilic interaction liquid chromatography for polar fraction and two-dimensional hydrophilic interaction liquid chromatographyereversed-phase liquid chromatography for medium-polar fraction in a traditional Chinese medicine. J. Chromatogr. A 1224, 61e69.
Liang, T., Fu, Q., Shen, A.J., Wang, H., Jin, Y., Xin, H.X., Ke, Y.X., Guo, Z.M., Liang, X.M., 2015. Preparation and chromatographic evaluation of a newly designed steviol glycoside modified-silica stationary phase in hydrophilic interaction liquid chromatography and reversed phase liquid chromatography. J. Chromatogr. A 1388, 110e118.
Lin, S.C., Lee, W.C., 1998. Separation of a fructo-oligosaccharide mixture by hydrophilic interaction chroma- tography using silica-based micropellicular sorbents. J. Chromatogr. A 803, 302e306.
Lin, H., Ou, J., Zhang, Z., Dong, J., Wu, M., Zou, H., 2012. Facile preparation of zwitterionic organic-silica hybrid monolithic capillary column with an improved “one-pot” approach for hydrophilic-interaction liquid chro- matography (HILIC). Anal. Chem. 84, 2721e2728.
Linden, J.C., Lawhead, C.L., 1975. Liquid chromatography of saccharides. J. Chromatogr. 105, 125e133.
Liu, X., Pohl, C.A., 2010. HILIC behavior of a reversed-phase/cationexchange/anion-exchange trimode column.
J. Sep. Sci. 33, 779e786.
Liu, Y., Xue, X., Guo, Z., Xu, Q., Zhang, F., Liang, X., 2008. Novel two-dimensional reversed-phase liquid chromatography/hydrophilic interaction chromatography, an excellent orthogonal system for practical analysis. J. Chromatogr. A 1208, 133e140.
Liu, C., Chen, W., Yuan, G., Xiao, Y., Crommen, J., Xu, S., Jiang, Z., 2014. Influence of the cross-linker type on the chromatographic properties of hydrophilic sulfoalkylbetaine-type monolithic columns. J. Chromatogr. A 1373, 73e80.
Louw, S., Pereira, A.S., Lynen, F., Hanna-Brown, M., Sandra, P., 2008. Serial coupling of reversed-phase and hydrophilic interaction liquid chromatography to broaden the elution window for the analysis of pharma- ceutical compounds. J. Chromatogr. A 1208, 90e94.
Lowe, A.B., 2010. Thiol-ene “click” reactions and recent applications in polymer and materials synthesis. Polym.
Chem. 1, 17e36.
Lurie, I.S., Li, L., Toske, S.G., 2011. Hydrophilic interaction chromatography of seized drugs and related com- pounds with sub 2mm particle columns. J. Chromatogr. A 1218, 9336e9344.
Mant, C.T., Hodges, R.S., 2008. Mixed-mode hydrophilic interaction/cation-exchange chromatography: separa- tion of complex mixtures of peptides of varying charge and hydrophobicity. J. Sep. Sci. 31, 1573e1584.
Marclay, F., Saugy, M., 2010. Determination of nicotine and nicotine metabolites in urine by hydrophilic inter- action chromatography-tandem mass spectrometry: potential use of smokeless tobacco products by ice hockey players. J. Chromatogr. A 1217, 7528e7538.
Marrubini, G., Castillo-Mendoza, B.E., Massolini, G., 2010. Separation of purine and pyrimidine bases and nucleosides by hydrophilic interaction chromatography. J. Sep. Sci. 33, 803e816.
Matyska, M.T., Pesek, J.J., Duley, J., Zamzami, M., Fischer, S.M., 2010. Aqueous normal phase retention of nucleotides on silica hydride-based columns: method development strategies for analytes relevant in clinical analysis. J. Sep. Sci. 33, 930e938.
McCalley, D.V., 2007. Is hydrophilic interaction chromatography with silica columns a viable alternative to reversed-phase liquid chromatography for the analysis of ionisable compounds? J. Chromatogr. A 1171, 46e55.
McCalley, D.V., 2008. Evaluation of the properties of a superficially porous silica stationary phase in hydrophilic interaction chromatography. J. Chromatogr. A 1193, 85e91.
McCalley, D.V., 2010. Study of the selectivity, retention mechanisms and performance of alternative silica-based stationary phases for separation of ionised solutes in hydrophilic interaction chromatography. J. Chromatogr.
A 1217, 3408e3417.
McCalley, D.V., 2015. Study of retention and peak shape in hydrophilic interaction chromatography over a wide pH range. J. Chromatogr. A 1411, 41e49.
McCalley, D.V., Neue, U.D., 2008. Estimation of the extent of the water-rich layer associated with the silica surface in hydrophilic interaction chromatography. J. Chromatogr. A 1192, 225e229.
Melander, W., Horvath, C., 1980. Reversed-phase chromatography. In: Horvath, C. (Ed.), High-performance Liquid Chromatography, vol. 2. Academic Press, New York, pp. 114e320.
Melnikov, S.M., Hoeltzel, A., Seidel-Morgenstern, A., Tallarek, U., 2011. Composition, structure and mobility of water-acetonitrile mixtures in a silica nanopore studied by molecular dynamics simulations. Anal. Chem. 83, 2569e2577.
Moni, L., Ciogli, A., Acquarica, I.D., Dondoni, A., Gasparrini, F., Marra, A., 2010. Synthesis of sugar-based silica gels by copper-catalysed azide-alkyne cycloaddition via a single-step azido-activated silica intermediate and the use of the gels in hydrophilic interaction chromatography. Chem. Eur. J. 16, 5712e5722.
Moravcova´, D., Haapala, M., Planeta, J., Hyotylainen, T., Kostiainen, R., Wiedmer, S.K., 2014. Separation of nucleobases, nucleosides, and nucleotides using two zwitterionic silica-based monolithic capillary columns coupled with tandem mass spectrometry. J. Chromatogr. A 1373, 90e96.