101
|
Chiaochan C, Koesukwiwat U, Yudthavorasit S, Leepipatpiboon N. Efficient hydrophilic interaction liquid chromatography–tandem mass spectrometry for the multiclass analysis of veterinary drugs in chicken muscle. Anal Chim Acta 2010; 682:117-29. [DOI: 10.1016/j.aca.2010.09.048] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Accepted: 09/29/2010] [Indexed: 10/19/2022]
|
102
|
Huang G, Zeng W, Lin X, Xie Z. Silica-based zwitterionic monolithic stationary phase for separation of neutral and ionized solutes using pressurized CEC. J Sep Sci 2010; 33:1625-32. [PMID: 20437413 DOI: 10.1002/jssc.200900764] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A porous zwitterionic monolith was prepared by in situ covalent attachment of lysine to a gamma-glycidoxypropyltrimethosysilane-modified silica monolith. The prepared column was used to perform neutral and ionized solutes separations by pressurized (pCEC). Due to the zwitterionic nature of the resulting stationary phase, the monolithic column provided both electrostatic attraction and repulsion sites for electrochromatographic retention for ionized solutes. Separation of several nucleotides was investigated on the monolithic column. It was shown that the nucleotides could be separated based on hydrophilic and electrostatic interactions between the stationary phase and analyte. Besides, the separation property of the zwitterionic silica monolith was compared with the use of diamine-bonded silica monolith as stationary phase. As expected, the lysine monolith exhibited a lower retention for the five nucleotides, which was due to the dissociation of the external carboxylic acid groups, leading to electrostatic repulsion with negatively charged solutes. Under the same experimental conditions, separation of the five nucleotides on the zwitterionic column was in less than 8 min, while that on the diamine column was in approximately 60 min.
Collapse
Affiliation(s)
- Guihua Huang
- Department of Pharmaceutics, Fujian University of Traditional Chinese Medicine, Fuzhou, P. R. China
| | | | | | | |
Collapse
|
103
|
He L, Zhang J, Sun Y, Liu J, Jiang X, Qu L. A multiple-function stationary phase based on perhydro-26-membered hexaazamacrocycle for high-performance liquid chromatography. J Chromatogr A 2010; 1217:5971-7. [DOI: 10.1016/j.chroma.2010.07.064] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 07/15/2010] [Accepted: 07/23/2010] [Indexed: 10/19/2022]
|
104
|
Xie D, Mattusch J, Wennrich R. Retention of arsenic species on zwitterionic stationary phase in hydrophilic interaction chromatography. J Sep Sci 2010; 33:817-25. [DOI: 10.1002/jssc.200900738] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
105
|
Nkem Ihunegbo F, Tesfalidet S, Jiang W. Determination of melamine in milk powder using zwitterionic HILIC stationary phase with UV detection. J Sep Sci 2010; 33:988-95. [DOI: 10.1002/jssc.200900815] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
106
|
Van Dorpe S, Vergote V, Pezeshki A, Burvenich C, Peremans K, De Spiegeleer B. Hydrophilic interaction LC of peptides: Columns comparison and clustering. J Sep Sci 2010; 33:728-39. [DOI: 10.1002/jssc.200900476] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
107
|
|
108
|
Watanabe Y, Abolhassani M, Tojo Y, Suda Y, Miyazawa K, Igarashi Y, Sakuma K, Ogawa T, Muramoto K. Evaluation of silica gel-immobilized phosphorylcholine columns for size exclusion chromatography and their application in the analysis of the subunit structures of fish-egg lectins. J Chromatogr A 2009; 1216:8563-6. [PMID: 19857867 DOI: 10.1016/j.chroma.2009.10.046] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 10/09/2009] [Accepted: 10/12/2009] [Indexed: 01/29/2023]
Abstract
Columns of phosphorylcholine (PC) immobilized on silica gel were shown to be useful for size exclusion chromatography (SEC) of proteins. The columns provided good separation of proteins in 50mM sodium phosphate buffer (pH 6.9) containing 0.25 M NaCl, and there was a linear relationship between the retention times and the logarithmic values of the molecular weights with a correlation coefficient (R(2)) of 0.978-0.992. The columns were used in analyzing the subunit structures of the rhamnose-binding lectins CSL1, CSL2, and CSL3, isolated from chum salmon (Oncorhynchus keta) eggs. Although the lectins, which are a group of carbohydrate-binding and hydrophobic proteins, behaved anomalously in SEC with conventional matrices, they could be eluted from the immobilized PC columns without non-size-related retention, thereby allowing their molecular weights to be reliably estimated.
Collapse
Affiliation(s)
- Y Watanabe
- Department of Biomolecular Science, Graduate School of Life Sciences, Tohoku University, Aoba-ku, Tsutsumidori, Sendai 981-8555, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
109
|
Nesterenko EP, Nesterenko PN, Paull B. Zwitterionic ion-exchangers in ion chromatography: A review of recent developments. Anal Chim Acta 2009; 652:3-21. [DOI: 10.1016/j.aca.2009.06.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2009] [Revised: 06/02/2009] [Accepted: 06/03/2009] [Indexed: 10/20/2022]
|
110
|
Chen M, Ma Q, Feng YQ. A Bidentate Amino Stationary Phase for Hydrophilic Interaction Chromatography. J LIQ CHROMATOGR R T 2009. [DOI: 10.1080/10826070903163149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Ming Chen
- a Department of Chemistry , Wuhan University , Wuhan, P.R. China
| | - Qiao Ma
- a Department of Chemistry , Wuhan University , Wuhan, P.R. China
| | - Yu-Qi Feng
- a Department of Chemistry , Wuhan University , Wuhan, P.R. China
| |
Collapse
|
111
|
Jiang Z, Smith NW, Ferguson PD, Taylor MR. Novel highly hydrophilic zwitterionic monolithic column for hydrophilic interaction chromatography. J Sep Sci 2009; 32:2544-55. [DOI: 10.1002/jssc.200900130] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
112
|
Wikberg E, Verhage JJ, Viklund C, Irgum K. Grafting of silica with sulfobetaine polymersviaaqueous reversible addition fragmentation chain transfer polymerization and its use as a stationary phase in HILIC. J Sep Sci 2009; 32:2008-16. [DOI: 10.1002/jssc.200800554] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
113
|
Matsuno R, Ishihara K. Molecular-Integrated Phospholipid Polymer Nanoparticles with Highly Biofunctionality. ACTA ACUST UNITED AC 2009. [DOI: 10.1002/masy.200950519] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
114
|
Novel zwitterionic polyphosphorylcholine monolithic column for hydrophilic interaction chromatography. J Chromatogr A 2009; 1216:2439-48. [DOI: 10.1016/j.chroma.2009.01.028] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Revised: 01/06/2009] [Accepted: 01/12/2009] [Indexed: 11/13/2022]
|
115
|
Hydrophilic interaction liquid chromatography with alcohol as a weak eluent. J Chromatogr A 2009; 1216:2362-70. [DOI: 10.1016/j.chroma.2009.01.012] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 12/11/2008] [Accepted: 01/05/2009] [Indexed: 11/21/2022]
|
116
|
Hoffmann CV, Reischl R, Maier NM, Lämmerhofer M, Lindner W. Investigations of mobile phase contributions to enantioselective anion- and zwitterion-exchange modes on quinine-based zwitterionic chiral stationary phases. J Chromatogr A 2009; 1216:1157-66. [DOI: 10.1016/j.chroma.2008.12.044] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 12/12/2008] [Accepted: 12/18/2008] [Indexed: 10/21/2022]
|
117
|
Nakurte I, Mekss P, Klavins K, Zicmanis A, Vavilina G, Dubrovina S. Collision-induced dissociation of imidazolium-based zwitterionic liquids. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2009; 15:471-478. [PMID: 19661555 DOI: 10.1255/ejms.997] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Fragmentation pathways of some imidazolium based zwitterionic liquids-3-(3-alkyl-1-imidazolio)- propane sulfonates and 3-(2-methyl-3-alkyl-1-imidazolio)-propane sulfonates -- have been studied by tandem electrospray mass spectrometry and collision-induced dissociation. The relative abundances of the lowest energy fragment ions depend on the length of the alkyl chain at the (II)N of the imidazolium ring and the cone voltage. The first fragment ions originate from the scission of C(non aromatic)-N bond of compounds investigated, but with increasing collision energy, scission of C-C bonds occurs. Aggregates of the general formula [(M + H)(x) + (M)(y)](+) (x;y = 1-2) formed. Methyl substituted zwitterionic liquids show higher molecular stability than 3-(3-alkyl-1-imidazolio)-propane sulfonates.
Collapse
Affiliation(s)
- Ilva Nakurte
- Faculty of Chemistry, University of Latvia, Riga, Latvia.
| | | | | | | | | | | |
Collapse
|
118
|
Jandera P. Stationary phases for hydrophilic interaction chromatography, their characterization and implementation into multidimensional chromatography concepts. J Sep Sci 2008; 31:1421-37. [PMID: 18428181 DOI: 10.1002/jssc.200800051] [Citation(s) in RCA: 185] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Hydrophilic interaction chromatography (HILIC) is becoming increasingly popular for separation of polar samples on polar columns in aqueous-organic mobile phases rich in organic solvents (usually ACN). Silica gel with decreased surface concentration of silanol groups, or with chemically bonded amino-, amido-, cyano-, carbamate-, diol-, polyol-, or zwitterionic sulfobetaine ligands are used as the stationary phases for HILIC separations, in addition to the original poly(2-sulphoethyl aspartamide) strong cation-exchange HILIC material. The type of the stationary and the composition of the mobile phase play important roles in the mixed-mode HILIC retention mechanism and can be flexibly tuned to suit specific separation problems. Because of excellent mobile phase compatibility and complementary selectivity to RP chromatography, HILIC is ideally suited for highly orthogonal 2-D LC-LC separations of complex samples containing polar compounds, such as peptides, proteins, oligosaccharides, drugs, metabolites and natural compounds. This review attempts to present an overview of the HILIC separation systems, possibilities for their characterization and emerging HILIC applications in 2-D off-line and on-line LC-LC separations of various samples, in combination with RP and other separation modes.
Collapse
Affiliation(s)
- Pavel Jandera
- Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czech Republic.
| |
Collapse
|
119
|
Weber G, von Wirén N, Hayen H. Hydrophilic interaction chromatography of small metal species in plants using sulfobetaine- and phosphorylcholine-type zwitterionic stationary phases. J Sep Sci 2008; 31:1615-22. [PMID: 18428183 DOI: 10.1002/jssc.200800060] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hydrophilic interaction chromatography (HILIC) was applied for the separation of small, noncovalent metal species, and free ligands in plants, using two different zwitterionic stationary phases at pH 7.3. Ligands ranged from amino acids and phytosiderophores to organic acids and synthetic chelators like EDTA. Our results confirmed the suitability of zwitterionic stationary phases for the separation of such ligands and their metal complexes. In particular, the chromatographic behavior of phytosiderophore complexes of copper, nickel, and zinc on a sulfobetaine-type material was compared to that on a phosphorylcholine-type material under otherwise identical conditions. A compression of the usable retention range for phytosiderophore species on the latter phase was found, which can be traced back to the reversed charge orientation of the zwitterionic functionalities. Differences were also found for the integrity of more labile metal chelates during separation on the two columns. In particular, Ni-malate could only be analyzed on the sulfobetaine phase, and Cu-glutathione, Ni-aspartate, and Ni-citrate complexes were only stable on the phosphorylcholine stationary phase at pH 7.3. Ni-histidine species were only found after lowering the pH to 4-5. The identification of separated species is possible by online ESI-MS in the negative ionization mode.
Collapse
Affiliation(s)
- Günther Weber
- Institute of Plant Nutrition, University of Hohenheim, Stuttgart, Germany
| | | | | |
Collapse
|
120
|
Wang Y, Lu X, Xu G. Simultaneous separation of hydrophilic and hydrophobic compounds by using an online HILIC-RPLC system with two detectors. J Sep Sci 2008; 31:1564-72. [DOI: 10.1002/jssc.200700663] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
121
|
|
122
|
Nováková L, Solichová D, Pavlovičová S, Solich P. Hydrophilic interaction liquid chromatography method for the determination of ascorbic acid. J Sep Sci 2008; 31:1634-44. [DOI: 10.1002/jssc.200700570] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
123
|
Liu X, Pohl C. New hydrophilic interaction/reversed-phase mixed-mode stationary phase and its application for analysis of nonionic ethoxylated surfactants. J Chromatogr A 2008; 1191:83-9. [DOI: 10.1016/j.chroma.2007.12.012] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 12/03/2007] [Accepted: 12/06/2007] [Indexed: 11/24/2022]
|
124
|
Matsuda Y, Kobayashi M, Annaka M, Ishihara K, Takahara A. UCST-Type Cononsolvency Behavior of Poly(2-methacryloxyethyl phosphorylcholine) in the Mixture of Water and Ethanol. Polym J 2008. [DOI: 10.1295/polymj.pj2008009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
125
|
Ikegami T, Tomomatsu K, Takubo H, Horie K, Tanaka N. Separation efficiencies in hydrophilic interaction chromatography. J Chromatogr A 2008; 1184:474-503. [PMID: 18294645 DOI: 10.1016/j.chroma.2008.01.075] [Citation(s) in RCA: 331] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 01/30/2008] [Accepted: 01/30/2008] [Indexed: 11/19/2022]
Abstract
Hydrophilic interaction chromatography (HILIC) is important for the separation of highly polar substances including biologically active compounds, such as pharmaceutical drugs, neurotransmitters, nucleosides, nucleotides, amino acids, peptides, proteins, oligosaccharides, carbohydrates, etc. In the HILIC mode separation, aqueous organic solvents are used as mobile phases on more polar stationary phases that consist of bare silica, and silica phases modified with amino, amide, zwitterionic functional group, polyols including saccharides and other polar groups. This review discusses the column efficiency of HILIC materials in relation to solute and stationary phase structures, as well as comparisons between particle-packed and monolithic columns. In addition, a literature review consisting of 2006-2007 data is included, as a follow up to the excellent review by Hemström and Irgum.
Collapse
Affiliation(s)
- Tohru Ikegami
- Department of Biomolecular Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
| | | | | | | | | |
Collapse
|
126
|
Pragst F. Chapter 13 High performance liquid chromatography in forensic toxicological analysis. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/s1567-7192(06)06013-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023]
|
127
|
Alpert AJ. Electrostatic repulsion hydrophilic interaction chromatography for isocratic separation of charged solutes and selective isolation of phosphopeptides. Anal Chem 2007; 80:62-76. [PMID: 18027909 DOI: 10.1021/ac070997p] [Citation(s) in RCA: 396] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
If an ion-exchange column is eluted with a predominantly organic mobile phase, then solutes can be retained through hydrophilic interaction even if they have the same charge as the stationary phase. This combination is termed electrostatic repulsion-hydrophilic interaction chromatography (ERLIC). With mixtures of solutes that differ greatly in charge, repulsion effects can be exploited to selectively antagonize the retention of the solutes that normally would be the best retained. This permits the isocratic resolution of mixtures that normally require gradients, including peptides, amino acids, and nucleotides. ERLIC affords convenient separations of highly charged peptides that cannot readily be resolved by other means. In addition, phosphopeptides can be isolated selectively from a tryptic digest.
Collapse
Affiliation(s)
- Andrew J Alpert
- PolyLC Inc./ 9151 Rumsey Road, ste. 180, Columbia, Maryland 21045, USA.
| |
Collapse
|
128
|
Yu Q, Lin B, Feng Y, Zou F. Application of Humic Acid Bonded‐Silica as a Hydrophilic‐interaction Chromatographic Stationary Phase in Separation of Polar Compounds. J LIQ CHROMATOGR R T 2007. [DOI: 10.1080/10826070701665618] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Qiong‐Wei Yu
- a Department of Chemistry , Wuhan University , Wuhan, P. R. China
| | - Bo Lin
- a Department of Chemistry , Wuhan University , Wuhan, P. R. China
| | - Yu‐Qi Feng
- a Department of Chemistry , Wuhan University , Wuhan, P. R. China
| | - Feng‐Ping Zou
- b Faculty of Material Science and Chemical Engineering , China University of Geosciences , Wuhan, P. R. China
| |
Collapse
|
129
|
Qiu H, Jiang Q, Wei Z, Wang X, Liu X, Jiang S. Preparation and evaluation of a silica-based 1-alkyl-3-(propyl-3-sulfonate) imidazolium zwitterionic stationary phase for high-performance liquid chromatography. J Chromatogr A 2007; 1163:63-9. [PMID: 17582425 DOI: 10.1016/j.chroma.2007.06.001] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Revised: 05/29/2007] [Accepted: 06/01/2007] [Indexed: 11/28/2022]
Abstract
A new zwitterionic stationary phase based on silica bonded with 1-alkyl-3-(propyl-3-sulfonate) imidazolium was synthesized and characterized in this paper. The materials have been confirmed and evaluated by elemental analysis, thermogravimetric analysis and X-ray photoelectron spectroscopy. Potassium and calcium were separated simultaneously with several common inorganic anions including an iodate, chloride, bromide, nitrate and iodide on the phase. The effects of the concentration, organic solvent and pH of the eluent on the separation of anions were studied. Operated in the anion-exchange mode, this new stationary phase shows considerable promise for the separation of anions. Bases, vitamins and three imidazolium ionic liquids with different alkyl chains are also separated successfully on this column. The stationary phase has multiple retention mechanisms, such as anion-exchange, electrostatic attraction and repulsion interactions, and hydrophobic interaction between the zwitterionic stationary phase and specimens.
Collapse
Affiliation(s)
- Hongdeng Qiu
- Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | | | | | | | | | | |
Collapse
|
130
|
Nezirević D, Arstrand K, Kågedal B. Hydrophilic interaction liquid chromatographic analysis of aminohydroxyphenylalanines from melanin pigments. J Chromatogr A 2007; 1163:70-9. [PMID: 17588592 DOI: 10.1016/j.chroma.2007.06.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Revised: 05/30/2007] [Accepted: 06/04/2007] [Indexed: 10/23/2022]
Abstract
Malignant melanomas are more often seen in subjects with light colored skin who tan poorly than in persons who tan more rapidly. This has been attributed to the structure of their pigment, pheomelanin, which differs markedly from the eumelanin of persons with darker skin. To study the hydrolysis products of pheomelanin pigments a new method was developed for analysis of 4-amino-3-hydroxyphenylalanine (4-AHP) and 3-amino-4-hydroxyphenylalanine (3-AHP). Pheomelanin samples were hydrolyzed and extracted with solid-phase extraction columns using strong cation-exchange (SCX) cartridges. Separation of 4-AHP and 3-AHP was achieved on a ZIC-HILIC column (150 mm x 2.1mm I.D.) with a mobile phase consisting of acetonitrile: 0.1 M ammonium acetate buffer, pH 4.5 (82:18, v/v). Detection was performed with an electrochemical detector at +400 mV. Run time was 30 min. The limits of detection were 73 pg and 51 pg for 4-AHP and 3-AHP respectively, using 2 microl injections. Good linearity was found within the range 0.05-5.0 microg/ml. Absolute recovery was 70% and relative recovery was 100%. The AHPs were stable for 1 year in the hydrolyzed samples, for 4 days in the eluates from solid-phase sorbents stored in the refrigerator, and for 2 days diluted with mobile phase and stored in the autosampler at 10 degrees C. The within-day imprecision was <5% and the between-day imprecision was <7% for the two analytes. The method, applied to the analysis of pheomelanin in urine from human melanoma patients, allows the analysis of 30 samples in one set and is suitable for routine work with human hair and melanoma cells. By using the ZIC-HILIC stationary phase, ion-pairing reagents could be avoided, which makes the method suitable to further analysis of degradation products from pheomelanins using mass spectrometric detection.
Collapse
Affiliation(s)
- Dzeneta Nezirević
- Division of Clinical Chemistry, Department of Biomedicine and Surgery, Linköping University, Linköping, Sweden.
| | | | | |
Collapse
|