Focussing Review

Chromatography, Vol.22 No.3 (2001)

Focussing Review

Analysis of Carbohydrates by Capillary Electrochromatography
Shigeo Suzuki and Susumu Honda*
Faculty of Pharmaceutical Sciences, Kinki University, 3-4-1, Kowakae, Higashiosaka, Japan
Received for review July４, 200１.

Accepted September 2１, 200１.

Abstract
In this review we summarize the recent advances in capillary electrochromatography of carbohydrates, glycoconjugates, and carbohydraterelated compounds. Intact carbohydrates could be separated on ODS columns with aqueous acetonitrile as eluent. However, detection by UV
absorption in the ordinary wavelengths did not give enough sensitivity for the detection of separated carbohydrates. Absorption at 195 nm allowed much more sensitive detection, but selectivity was rather problematic. Although the use of a light scattering detector was also possible,
it had a similar limitation. Derivatization of carbohydrates enhanced detection sensitivity. Derivatives formed with 1-phenyl-3-methyl-5pyrazolone could be separated on ODS columns with aqueous acetonitrile and sensitively detected by UV absorption. p-Nitrophenyl glycosides of mono- and oligosaccharides were also separated by this system. It was essential that a considerable proportion of silanol groups remained unmodified in the stationary phase in order to induce appropriate velocity of electroosmotic flow for driving the separated solutes inreasonable analysis time. However, the remaining silanol groups caused peak broadening. Tailor-made continuous bed of polyacrylamide columns gave excellent separation, since they were free from this “remaining silanol” problem. Some applications to glycoconjugates are also
overviewed to evaluate CEC in biomedical analysis.
Keywords: capillary electrochromatography, high-performance liquid chromatography, carbohydrates, ODS columns, aminosilica columns,
electroosmotic flow, in-capillary derivatization, PMP sugars, p-nitrophenylgylcosides

other reason to make separation of carbohydrates difficult. Func-

1. Introduction
Carbohydrates are considered to have many key biologicaltional groups, such as the acetamino, O - as well as N -sulfate, andfunctions [1] and have attracted attention of glycobiologists as thephosphate groups, give additional variation and hamper easy sepa-

most important postscriptomes. When conjugated with proteins toration. Thus, the carbohydrate structure is more complex than nu-

form glycoproteins, they can alter the three-dimensional structure

cleic acid and protein structures, and needs separation modes withand thereby the function of proteins. As the components of glyco

higher resolution. Moreover, the inherent lack of chromophoric/

lipids, they can play pivotal roles in cell-cell adhesion and recogni-

fluorescent function requires conversion of carbohydrates to de-tion. The extracellular matrix contains proteoglycans, large glyco-

rivatives amenable to conventional detections. From these reasons,conjugates that take part in many recognition processes and main-

capillary electrochromatography (CEC) of carbohydrates musttenance of homeostasis.

overcome a number of problems and therefore, only limited numbers of papers have hitherto appeared on this subject (included in a

Although numerous carbohydrate structures occur in nature,

few CEC reviews, [2, 3]).

only a little is known about the details on the functions of carbohydrates. This can be attributed mainly to the difficulty in their analy-

2. HPLC as the basis of CEC

sis to effect sufficient information. The chromatographic separationof carbohydrates has often met a difficulty in resolution due to the

In these two decades various separation modes and detection

diversity of homologues, coming from the difference of composi-

methods have been developed for high-performance liquid chroma-tion, sequence as well as branching, and attaching position as welltography (HPLC) of carbohydrates (reviewed for example in Ref

as mode, of the unit monosaccharides. Strong hydrophilicity is an-[4]). Similarly as in other fields, reverse phase partition chromatog-*Corresponding author: Tel, +81-6-6721-2332 ; fax, +81-6-6721-2353 ;e-mail, shonda@phar.kindai.ac.jp―１７１―

Chromatography, Vol.22 No.3 (2001)

Table 1. Separation modes and systems used for HPLC of intact
carbohydrates.

hanced by using non-aqueous media such as a dichloromethanemethanol mixture [7]. Silica gel columns were also used for the
separation of hydrophobic glycoconjugates such as glycolipids [8].
Chemically bonded silica phase, such as aminopropyl silica
could improve the limitation of bare silica. A detailed study by
Niklov and Reilly [9] indicated that the selectivity of aminopropyl
silica is different from that of bare silica, and it also could separate
oligosaccharides of various sizes. For example, maltooligosaccharides were successively resolved up to 30mers by isocratic elution[10]. There have been many applications for the separation of
glycoprotein-derived glycans [11-13]. Though aldoses have a tendency to form glycosylamines in columns of aminopropyl silica,
such phenomenon could be avoided by adding a neutral buffer toan eluent [14], or reduction of aldose samples to alditols. Amideand polyamine-bonded silica gels were similarly used for hydrophilic interaction chromatography of intact carbohydrates [15]. Insite hydrodynamic coating of bare silica columns by adding a small
quantity (<0.1%) of polyamines, such as 1, 4-diaminobutane to theeluent [16] is an alternative to provide polyamine columns. Good
separation of tritium-labeled reduced oligosaccharides from highmannose type glycans of a glycoprotein was reported by Turco[17]. Normal phase columns of diol [18] or polyol-bonded silica[19] were also available, but the separation sometimes required elevation of column temperature [20].
Separation of highly hydrophilic carbohydrates was possible
on ODS columns of low coverage using plain water as eluent [21].
Although this system seems to have limitation for intact carbohydrates, good resolution was obtained for permethylated and peracetylated carbohydrates [22, 23]. Cation-exchange columns of the hydrogen form can also be used as substitute for ODS columns, but
addition of aqueous ethanol is often necessary [24].

raphy nowadays occupies the mainstream for the separation of carbohydrates, though various means are required to conquer the

Use of graphite carbon columns (GCC) is one of the recent

problem of their high hydrophilicity. Since it is important to over-topics of carbohydrate separation. There was a report that cyclo-view HPLC of carbohydrates in order to understand the current

maltooligosaccharides with varying dps were better separated on astates of and the future of CEC of carbohydrate, Table 1 summa-

GCC column than on an ODS column [25]. Separation on GCC

rizes the separation modes and systems reported for HPLC of intact

differs with its batches and the separation mechanism has been

carbohydrates.

considered to be due to charge-transfer. Good separation was also
obtained for glycoprotein-derived neutral high-mannose type glycans [26] as well as sialylated acidic glycans [27]. However,

2.1. Separation

whether the carbon column can generate the electroosmotic flow

At the early stage of HPLC of carbohydrates, normal phase(EOF) in the electric field is not known.

partition mode (hydrophilic interaction) was preferentially used forthe separation of mixtures of mono- and simple oligosaccharides.

Anion-exchange on latex-type anion exchange columns inBare silica packings were used for this purpose, but silica gels havestrong alkaline solutions has been used as a separation mode fora fundamental problem that they are considerably soluble in aque-carbohydrates, combined with pulse amperometric detection [28].

ous solvent, especially in acidic or basic media and at elevated tem-

The hydroxyl groups in carbohydrates are partly dissociated to give

peratures [5]. Therefore, methanol- or acetonitrile-rich (>80%)

alkoxide ions in such alkaline media, and carbohydrates can beaqueous eluent was preferably used for the separation of monosac-

separated by the difference in charge and size. There have beencharides [6]. The durability of bare silica packings could be en-

many reports on this system applied for the separation of

―１
７
２―

Chromatography, Vol.22 No.3 (2001)

Shigeo Suzuki and Susumu Honda

glycoprotein-derived glycans [e.g., 29]. In this system elution oflarger oligosaccharides required stronger alkaline solutions.
Neutral carbohydrates form anionic complexes with borate
ions, which can be separated on anion-exchange columns with borate buffer as eluent. Ligand-exchange chromatography is based on
the complex formation between the hydroxyl groups of carbohydrates and multivalent metal ions such as Pb2+ or Ca2+ trapped on acation exchange resin. Separation of monosaccharides can be attained with plain water as eluent. In open column liquid chromatography oligo- and polysaccharides can be separated by sizeexclusion using cross-linked polysaccharides, but these materials
are so soft that they cannot endure high pressure in HPLC. Cationexchange resins can separate smalloligosaccharides by this mode,
but the separation needs heating the column at 60 - 80℃.
2.2. Detection
Carbohydrates generally have neither chromophore nor
fluorophore. Absorption at low wavelengths (<200 nm) or indirect
detection by fluorescence quenching may be useful in some cases.
Refractive index detector is often used for the detection of carbohydrates. More recently light-scattering detection has been recommended by several authors [30]. Though these detecting methods
are simple, they have the major disadvantages that they are not selective to carbohydrates. Such a drawback may be avoided by converting carbohydrates to fluorescent or UV-absorbing derivatives.
A number of reagents have been reported for pre-column derivatization as shown in Figure 1. These reagents can be classified into
four categories based on the type of derivatization reaction (Figure
Figure 1. Various reagents for pre-column labeling of carbohydrates. ABEE: ethyl p-aminobenzoate, ABHE: hexyl paminobenzoate, TFAN: trifuluoroacetamidoaniline, 4
ABN: 4-aminobenzonitrile, AP: 2-aminopyridine, ACP:
2-amino-6-cyanoethylpyridine, BDP: biotinylated diaminopyridine , 6AQ: 6-aminoquinoline , ABA: 2aminobenzoic acid, 2AB: 2-aminobenzamide, AMAC: 2-aminoacridone, 2ABP: 2-aminobiphenyl, ANTS: 8aminonaphthalene-1,3,6-trisulfonate,
ANDS: 7aminonaphthalene-1,3-disulfonate,
APTS:
8aminopyrene-1,3,6-trisulfonate, AAMC: 3-acetylamino6-aminoacridone , AMC: 7-amino-4-methylcoumarin ,DNS: dansyl- , FMOC-: fluorenylmethoxycarbonyl- ,PITC:phenylisothiocyanate,
TRSE:
4carboxytetramethylrhodamine succinimidyl ester, NBDF: 4-fluoro-7-nitrobenz-2-oxa-1, 3-diazole, CBQCA: 3(4-carboxybenzoyl)-2-quinolinecarboxaldehyde, PMP: 1-phenyl-3-methyl-5-pyrazolone, PMPMP: p-methoxyPMP.

2). The condensation of the reducing end of a reducing carbohydrate with the amino or the substituted amino group in the presenceof a suitable reductant gives a glycamine (Category 1) probably via
a glycosylamine. The labeling method using AP was first reported
by Hase et al. [31] and now widely applied for mapping N -linked
glycans derived from glycoproteins [32]. ABEE [33], AMAC [34],
ANTS [35], and APTS [36] are also frequently used for the same
purpose. The formation of hydrazones (Category 2) is also used forderivatization of reducing carbohydrates, though this category has
a problem of syn/anti isomerism. The glycamines, formed by reductive amination of reducing carbohydrates with a salt of ammonia or methylamine, can be condensed with various reagents togive characteristic derivatives (Category 3). The derivatives formedby condensation with NBD-F [37] and CBQCA [38] are notable,
because they can be sensitively detected by LIF. PMP [39] and its
p-methoxyphenyl analog (PMPMP [40]) are attractive reagents forderivatizing reducing carbohydrates, especially sialylated oligosaccharides, since the derivatization proceeds under mild conditions
and does not cause loss of the sialic acid residues (Category 4). Although a number of tagging reagents have been developed for the

―１
７
３―

Chromatography, Vol.22 No.3 (2001)

Figure 2. Various reaction types for pre-column derivatization of carbohydrates. The arabic numbers on the upper left ofeach structure indicate category numbers.
sensitization of carbohydrates, only PMP has been used in the CEC

mension, 100 µm i.d., 250 mm) and an acetonitrile-4 mM borate

analysis of carbohydrates. Introduction of tags to carbohydrates

buffer (pH 9.2) mixture (25 : 75, v/v), respectively. Separation wascauses change of physico-chemical properties of the original carbo-

good owing to a rather hydrophobic nature of the solute by thehydrates. In most derivatives hydrophobicity increases. This is de-presence of the halogen atoms. Formation of borate complexes

sirable for separation by hydrophobic interaction on ODS, but theshould be taken into account, but it is considered to give only a mi-derivatives formed with the reagents in Categories 1-3 are posi-

nor effect under such a low borate concentration. Detection at 195

tively charged in neutral to weakly acidic media, which giving rise

nm gave satisfactory sensitivity for this process substance analysis.
There was another example for CEC of intact carbohydrates

to an undesirable effect on separation as mentioned in 3.2.
Apart from sensitization by derivatization, pulse amperomet-

by Guo and coworkers [44]. In this case mono- and disaccharides

ric detection on a gold electrode is an attractive method for carbo-

separated on an ODS column was detected by a condensation nu-

hydrate analysis. It has been widely used in combination with ancleation light scattering detector (CNLSD). In this detection theanion-exchange separation with strong alkaline eluent. There haveoutlet end of the separation column was modified to effect vapori-been many reports on HPLC [29] as well as capillary electrophore-zation. Removal of the polyimide coating, followed by spraying thesis [41, 42] using this system, but no papers have appeared yet on

revealed silica surface with gold paint facilitated electrospray at the

CEC of carbohydrates. This is because the use of such strong alka-

outlet. Supplementary pressure was applied to the eluate to stabi-line eluent will require special columns durable to repeated analy-

lize the electrospray process. Good reproducibility was obtained

sis.

and the detection limit reached 6 to 9 pg for galactose, glucose,fructose, and sucrose. Change of applied pressure/voltage ratio
caused alteration of column efficiency and also separation mode.

3. Current status of CEC

The sensitivity in the forgoing two examples of CEC of intact

3.1. Underivatized carbohydrates
HPLC on reverse-phase columns with direct detection is gen-carbohydrates was satisfactory but both methods are not selective

erally not a good strategy for carbohydrate analysis, because sepa-

to carbohydrates, hence the analysis may be interfered by otherration is limited and detection sensitivity in UV absorption is notcompounds in sample.

high. Zhao and Johnson [43] challenged CEC analysis of sucralose
3.2. Derivatized carbohydrates(4, 1’, 6’-trichlorogalactosucrose), a non-nutritional sweetener, andrelated compounds in its manufacturing process. The column and

Derivatization of carbohydrates with various reagents enhanceeluent used were Hypersil ODS (particle size, 3 µm ; column di-

detection sensitivity, but at the same time gives influence on the re-

―１
７
４―

Chromatography, Vol.22 No.3 (2001)

Shigeo Suzuki and Susumu Honda

tention and resolution of carbohydrates, especially on ODS col-anomers of p-nitrophenyl glycosides were readily resolved with anumns. Among various kinds of derivatives substituted glycamines

eluent containing borate buffer.

prepared by reductive amination seem to be strongly adsorbed on

Reports on CEC of derivatized carbohydrates are quite few at

the remaining silanol groups, resulting in peak broadening, and ac-

this point as mentioned above, and they are restricted to PMP de-cordingly poor separation. Such ionic interaction may be sup-rivatives and p-nitrophenyglycosides, which have no amino/iminopressed by using eluent containing higher concentrations of electro-

functions. Column efficiency of ODS columns are generally notlytes (our unpublished results).

high, the height equivalent to a theoretical plate (H) being in a

In contrast to these glycamine derivatives, PMP derivatives

range of 53-60 µm. In addition peaks sometimes show a tailing ten-have rather weakly acidic nature. Therefore, separation can bedency. The low column efficiency is considered to be due to theachieved on chemically bonded silica with low coverage with lowhydrophilic interaction with the silanol group, as generally ob-electrolyte eluents. The authors group reported the CEC of PMP

served on ODS columns in HPLC. Thus, the needs for unprotected

derivatives [45, 46], in which all members of the D-series of al-silanol groups for sufficient velocity of EOF gives negative effectdopentose epimers (Ara, Lys, Rib, and Xyl), and the component

for column efficiency and accordingly separation of derivatives ofmonosaccharides in glycoproteins (Fuc, Gal, Man, GlcNAc, andcarbohydrates.

GalNAc) were well separated from each other on a Hypersil ODS

Organic polymer-based stationary phases will overcome thiscolumn (particle size, 3 µm ; column dimension, 100 µm i.d., 255/

problem of unfavorable hydrophilic interaction on silica-based

300 mm) with a 50 mM HEPES (pH 6.0 to 6.3) -acetonitrile mix-

reverse-phase packings. Palm and Novotny [50] introduced an in-ture (2.2 : 1, v/v) as eluent. The relative standard deviation (RSD)

situ prepared macroporous organic polymer column (continuousof elution time was 0.6% (n = 5) and the RSD value for relativebeds) for CEC of carbohydrates. The inner wall of a capillary col-peak response to 3-O -methyl-D-glucose was less than 5%. Moreumn was treated with a bifunctional silane reagent (Bind silaneR)

recently Gucek and Pihlar [47, 48] similarly succeeded in the reso-

prior to polymer preparation. A mixture of acrylamide andlution of Man, Lac Rib, Glc, and Gal as their PMP derivatives bybisacrylamide (4% T, 60% C) (for preparing strong support), either

using a Hypersil ODS 1 column (particle size, 5 µm ; column di-acrylic or vinylsulfonic acid (for generation of suitable EOF),

mension, 100 µm i.d., 30/50 cm) and 5 mM monosodium phos-

either butyl, hexyls or lauryl acrylate (for obtaining reasonable hy-phate dissolved in acetonitrile water (3 : 1, v/v).

drophobicity), and polyethylene glycol (for preventing turbidity)

Since electroosmotic flow (EOF) is a driving force in CEC,

were co-polymerized inside the capillary. A sample of maltooligo-

the rapidity of analysis in CEC depends on the velocity of EOF,

saccharides was reductively aminated with 2-aminobenzamide inwhich is generated mainly due to the electric double layer between

this case, to prepare derivatives detectable by He-Cd laser (325the particles of supporting materials and eluent. The zeta potentialnm)-induced fluorescence. As shown in Figure 3, good separationon the surface of silica gel particles or modified silica gel particles

was observed by using a capillary column prepared with buty-

becomes higher as the population of the silanol group becomeslacrylate and vinylsufonic acid, and by using an acidic eluent.

more abundant. Therefore, the use of ODS completely modified bySize separation of glucose to maltoheptaose was achieved

endcapping as used for HPLC is not advantageous for CEC. In our

within 12 min with H values of 4.4-5.3 µm. Although this method

experience almost no peaks appeared within 1 h, when we analyzed

requires a tailor-made column and a special device for LIF detec-

the PMP derivatives of some monosaccharides on an endcappedtion, it was proved useful for high-resolution separation.

ODS column (unpublished results). The use of modified silica hav-

Another strategy to conquer the problem of peak broadening

ing reasonable proportions of the unprotected silanol group is bet-

and tailing is the use of hydrophilic interaction of derivatized car-ter for CEC. Yang and El Rassi [49] prepared an ODS stationary

bohydrates as the main separation mode. As already pointed out forphase with low surface coverage by controlling reaction of bare sil-

HPLC of carbohydrates, this mode can be achieved by using either

ica with an octadecyl donor. The introduced amount of the octade-a bare silica column or an aminopropylated silica column with acyl group was estimated to be only 2.1 µmoles/m2, which means

bufferized aqueous acetonitrile as eluent. Figure 4 shows the sepa-that 25% of the silanol group remained unmodified. EOF was de-ration of PMP derivatives of five monosaccharides commonly

pendent on the amount of the packed gels. Thus, the velocity of
EOF generated from a fully packed column was 0.62 mm/s,

found in glycoproteins (Fuc, Gal, Man, GlcNAc and GalNAc) on abare-silica (Develosil silica, 30 A, 3 µm)-packed capillary (100 µm

whereas that from a half packed column was 0.38 mm/s. Several p-i.d., 24.5 cm) [51].

nitrophenyl glycosides of monosaccharides and maltooligosaccha-

Due to fast EOF, separation was achieved in only 8 min.

rides could be separated from each other with an acetonitrile -2.5

It should be noticed that some modified silica gels havingmM phosphate buffer (pH 6.0) mixture (2 : 8, v/v). The α- and β-ionic groups, such as aminopropyl silica gels, generate a bulk flow

―１
７
５―

Chromatography, Vol.22 No.3 (2001)

Figure 3. Isocratic CEC of maltooligosaccharides (dps 1-6) as their
2-aminobenzamide derivatives in a capillary filled witha macroporous polyacrylamie/poly (ethylene glycol) matrix, derivatized with C4 ligand (15%) and containing vinylsulfonic acid (10%). Capillary size, 100 µm i.d., 25
cm; eluent, acetonitrile-10 mM Tris/15 mM boric acid(pH 8.2) mixture (2 : 8, v/v); field strength, 900 V/cm;
sample concentration, 5-10 µM. Reproduced from Ref.
50 with the permission of the publisher.

Figure 4. Analysis of the monosaccharides present in glycoproteins as PMP derivatives. Column, Develosil 30 (particle
size, 3 µm; column dimension, 100 µm i.d., 24.5 cm);
eluent, acetonitrile -50 mM HEPES buffer (pH 6.0) mixture (4 : 1, v/v); applied pressure, 7.5 kg/cm2; applied
voltage, 20 kV; column temperature, 20℃; detection,
245 nm; sample, a mixture of PMP-sugars (10 mMeach); sample injection, 5 kV, 5 s.

from cathode to anode, when packed in an uncoated capillary. On
3.3. Carbohydrate-related compounds

the other hand, the silanol groups on the capillary inner-wall generate a flow toward the opposite direction (anode to cathode). Due to

Carbohydrates exist not only in free state but also in conjuga-

this counter flow analysis time of the solutes increases and columntion with other compounds, such as proteins and sphingonolipids,

efficiency is reduced. We attempted preparation of tailored col-to form glycoproteins and glycosphingolipids, respectively. Conju-

umns of chemically bonded silica by pumping an ethanolic solution

gation with small molecules such as phenolic compounds and trit-of a silylating reagent, such as aminopropyltrimethoxysilane into aerpenes gives various glycosides. From biomedical importance ofcapillary packed with 3 µm-bare silica particles [52]. The silylationthese glycoconjugates, analysis by CEC has been investigated. A

reaction was complete in 1 h by heating the column. Such in-high resolution separation of cardiac glycosides, belonging to tri-

capillary reaction resulted in modification of not only packed silica

terpene glycosides, was reported by Meyer and coworkers [53]. In

gels but also the capillary inner wall. The reproducibility of prepa-

this case a special device was used to obtain high column effi-ration was high; aldopentoses as PMP derivatives were completely

ciency. Frit fabrication is one of the important technical problems

separated in 10 min with an acetonitrile-100 mM HEPES (pH 6.5)

in the preparation of columns for CEC. Frits prepared by hitherto

mixture (3 : 1, v/v) as eluent. The resolution was superior to thedeveloped techniques suffer from physical weakness to handle, low

column prepared by packing a commercial preparation of 3 µm-

reproducibility in preparation, and nucleation stimulating bubble

amino silica gels into an uncoated capillary (analysis time, 20 min).

formation. Meyer and coworkers packed 1.5-µm nonporous ODS

We also attempted preparation of another type of amino silica col-silica gels (NPS ODS II) into a capillary (100 µm i.d., 24.5 cm) ta-

umn, similarly by flowing a dimethyloctadecyltrimethoxysilylam-pered by a laser-based micropipette puller. The tapered end could

monium chloride solution through a bare-silica packed column.

be used as the inlet of CEC column after packing stationary phase.

The resultant column generated faster EOF to the anode, and the

The outlet of the stationary phase did not require fabrication of aresolution of the PMP sugars was slightly better than on the amino-

frit, because the particles were retained in the column by electro-

propylated silica column mentioned above.

static attraction towards the anode under the operating conditionsof CEC. This non-frit technique enabled high-resolution efficiency
of more than 500,000 plates/m. Separation of three cardiac gly-

―１
７
６―

Chromatography, Vol.22 No.3 (2001)

Shigeo Suzuki and Susumu Honda(3 µm). Since this cachetic factor was highly hydrophilic, retention

cosides was attained within 4 min.
It is well known that many drugs and toxic compounds in ani-on the Hypersil ODS column, the more hydrophilic stationary

mal bodies are metabolized to their glucuronides. Hugener and co-phase, was more marked. Thus, the glycoprotein peak appeared atworkers [54] adopted the combination of CEC and MS for theabout 17 min on the Zorbax ODS column and at 32 min on the Hy-

analysis of some aromatic glucuronides. A mixture of phenyl, o-

persil stationary phase. There was no great difference among theseaminophenyl, p-nitrophenyl, and α-naphthyl glucuronides wasthree separation methods, but the cachectic factor could be sepa-

separated into its components by pressurized CEC on a Hamilton

rated from other components by CEC.

RPR-1 (12-20 µm) packed column (220 µm i.d., 20 cm) with an
4. Conclusionacetonitrile-2 mM ammonium acetate (pH 7.0) mixture (5 : 95, v/v)
as eluent. Detection was performed by mass spectrometry via ther-

Although CEC has been accepted as a powerful tool for sepa-

mospray interface by the negative ion mode. Stepwise application

ration of biomedical substances, only a small number of papersof voltages realized reduction of analysis time to ca. 30 min.

have been published for carbohydrate analysis. Since CEC is a kind

Glycosphingolipids are amphiphilic compounds composed ofof chromatography performed in the presence of EOF, the accumu-

a polar moiety of carbohydrates and hydrophobic parts of fatty ac-

lated results of HPLC will be of great help for better separation/de-

ids and sphingosine. The structural diversity of glycosphingolipids

tection systems for CEC.

is mainly due to the carbohydrate chains varying in size from

The major materials for stationary phase are silica gels andmonosaccharide to large branched oligosaccharides. The gly-

modifications. In order to generate EOF rapid enough to drive

cosphingonolipids are known to form stable mixed micelles (C.M.

separated solutes, the surfaces of the stationary phase as well as

C. = 10‐１0~ 10‐８ M) under biological conditions. Therefore, in capil-

capillary inner wall must be electrically charged to a considerable

lary electrophoretic analysis, either organic solvent or a complexa-

extent. This means that a considerable part of the silanol grouption reagent such as cyclodextrins [55] was added to prevent theshould be left unprotected. It is an irony that this reminder plays amicelle formation. Zhang and El Rassi prepared an octadecylsul-

negative role for column efficiency. Therefore, although CEC util-

fonated silica (ODSS) by introducing a hydrophilic sulfonate com-izes EOF as driving force, which is advantageous for high column

pound and a hydrophobic octadecyl compound to the γ-

efficiency by its plug flow nature, the hydrophilic and other inter-glycidoxypropyltrimethoxylsilane-treated silica gels [56], and ana-

actions between the solutes and the silanol group spoil this high ca-

lyzed sialic acid-containing glyconosphingolipids, (gangliosides)

pability of EOF.

on the resultant ODSS [57]. Resolution of gangliosides GM1a, GD1a,

From these reasons development of materials other than silica

GD1b, and GT1b was good, when a column packed with 5-µm ODSShaving a porosity of 120 A was used, eluted with a methanol-gels and modifications will be of keen interest. As already demon-acetonitrile-10 mM borate (pH 9.40) mixture (50 : 30 : 20, v/v).

one of the promising tactics. Continuous bed will be the ultimate

strated by Palm and Novotny [50], use of organic polymers will be

Methanol was essential for the separation of GD1a and GD1b, andstyle of stationary phase. On the other hand detection in CEC willcomplete resolution was achieved by using borate concentrations offollow up the technique in capillary electrophoresis. Thus, UV de-more than 8 mM. A mixture of neutral glycosphingonolipids in-tection will be most suited for routine analysis, and LIF detection

cluding galactosyl-, lactosyl-, globotriosyl- and globotetraosylcera-

can minimize sample scale. Sample reduction will be beneficial for

mide were strongly retained on this column, but fine resolution was

better resolution of solutes.

achieved by using a non-porous ODSS column and a tetrahydrofu-

Since CEC requires packing of stationary phase in narrowran -2 mM ammonium phosphate (pH 7.0) mixture (80 : 20, v/v) as

capillaries, the technique to stabilize the beds in the capillaries iseluent.

important. Preparation of a frit at the outlet of capillary prior to

Cancer patients exhibiting advanced muscle proteolysis se-packing has been the standard procedure for CEC, but the prepara-crete a specific sulfated glycoprotein called the cachectic factor intion of frits by this technique is not easy, and inadequately pre-urine. This glycoprotein consists of a short peptide chain (~4,000

pared frits cause low reproducibility of solute elution. The use of aDa) extensively glycosylated at the Asn and Ser residues. The car-tapered capillary by Guo and coworkers [43] is notable, because it

bohydrate chains are sulfated and these sulfated N - and O -linked

did not need any frit. Such fritless packing will be one of the solu-

glycans have been found to be antigenic determinants [58]. Choud-tions for this problem.

hart and coworkers [59] compared three microanalytical separation

Due to the scarcity of published papers other reviews on CEC

methods including capillary electrophoresis, capillary liquid chro-of carbohydrates seem to have not yet appeared. We are interested

matography, and CEC (with or without pressure) using two types

in the development of this area in the near future.

of columns packed with Zorbax ODS (3.5 µm) and Hypersil ODS

―１
７
７―

Chromatography, Vol.22 No.3 (2001)[27] Kawasaki, N. ; Ohta, M. ; Hyuga, S. ; Hyuga, M. ; Hayak-

References[1]

Varki, A. Glycobiology 1993, 3, 97-130.

[2]

El Rassi, Z. Electrophoresis 1999, 20, 3134-3144.

[3]

Krull, I. S. ; Stevenson, R. L. ; Mistry, K. ; Swartz, M. E. In

awa, T. Anal. Biochem. 2000, 285, 82-91.
[28] Townsend, R. R. ; Hardy, M. R. ; Hindsgaul, O. ; Lee, Y. C.
Anal. Biochem. 1988, 174, 459-470.
[29] Honda, S. ; Suzuki, S. ; Zaiki, S. ; Kakehi, K. J. Chroma-

Capillary Electrochromatography and Pressurized Flow

togr. 1990, 523, 189-200.

Capillary Electrochromatography An Introduction ; HNB[30] Allen, L. B. ; Koropchak, J. A. ; Szostek, B. Anal. Chem.

Publishing : New York, 2000 ; Chapter 6.
[4]

1995, 67, 659-666.

Honda, S. Anal. Biochem. 1984, 140, 1-47.

[5]

Churms, S. C. J. Chromatogr. A 1996, 720, 75-91.

[6]

Iwata, S. ; Narui, T. ; Takahashi, K. ; Shibata, S. Carbohydr.

[7]Herbreteau, B. ; Lafosse, M. ; Morin-Allory, L. ; Dreux, M.

[8]Wells, G. B. ; Turco, S. J. ; Hanson, B. A. ; Lester, R. L.

[31] Hase, S. ; Ikenaka, T. ; Matsushima, Y. Biochem. Biophys.
Res. Commun. 1978, 85, 257-263.
[32] Tomiya, N. ; Awaya, J. ; Kurono, M. ; Endo, S. ; Arata, Y. ;Res. 1984, 133, 157-162.

Takahashi, N. Anal. Biochem. 1988, 171, 73-90.
[33] Wang, W. T. ; LeDonne, Jr. N. C. ; Ackerman, B. ; Sweeley,Anal. Chim. Acta 1992, 267, 147-156.

[9]C. C. Anal. Biochem. 1984, 141, 366-381.

Anal. Biochem. 1981, 110, 397-406.

[34] Jackson, P. Anal. Biochem. 1991, 196, 238-244.

Nikolov, Z. L. ; Reilly, P. J. J. Chromatogr. 1985, 325, 287-

[35] Jackson, P. Biochem. J . 1990, 270, 705-713.

293.

[36] Guttman, A. ; Chen, F. -T. A. ; Evangelista, R. A. ; Cooke,
N. Anal. Biochem. 1996, 233, 234-242.

[10] Koizumi, K. ; Utamura, T. ; Okada, Y. J. Chromatogr.

[37] Suzuki, S. ; Okeda, J. ; Iwanaga, H. ; Kawakami, S. ; Taga,

1985, 321, 145-157.

A. ; Honda, S. ; Imai, K. Anal. Biochem. 2000, 286, 99-111.

[11] Mellis S. J. ; Baenziger, J. U. Anal. Biochem. 1981, 114,

[38] Liu, J. ; Shirota, O. ; Wiesler, D. ; Novotny, M. Proc. Natl.

276-280.

Acad. Sci. USA 1991, 88, 2302-2306.

[12] Bergh, M. L. E. ; Koppen, P. L. ; van den Eijnden, D. H.

[39] Honda, S. ; Akao, E. ; Suzuki, S. ; Okuda, M. ; Kakehi, K. ;Carbohydr. Res. 1983, 117, 275-278.

Nakamura, J. Anal. Biochem. 1989, 180, 351-357.

[13] Parente, J. P. ; Strecker, G. ; Leroy, Y. ; Montreuil, J. ;[40] Kakehi, K. ; Suzuki, S. ; Honda, S. ; Lee, Y. C. Anal. Bio-

Fournet, B. J. Chromatogr. 1982, 249, 199-204.

chem. 1991, 199, 256-268.

[14] Porsch, B. J. Chromatogr. 1982, 253, 49-54.

[41] Colon, L. A. ; Dadoo, R. ; Zare, R. N. Anal. Chem. 1993,[15] Koizumi, K. ; Tanimoto, T. ; Okada, Y. ; Nakanishi, N. ;65, 476-481.

Kato, N. ; Takagi, Y. Hashimoto, H. Carbohydr. Res. 1991,[42] O’Shea, T. J. ; Lunte, S. M. ; LaCourse, W. R. Anal. Chem.

215, 127-136.

1993, 65, 948-951.

[16] Praznik, W. ; Beck, R. H. F. ; Nitsch, E. J. Chromatogr.

[43] Zhao, R. R. ; Johnson, B. P. J. Liq. Chromatogr. Relat.

1984, 303, 417-421.

Technol. 2000, 23, 1851-1857.

[17] Turco, S. J. Anal. Biochem. 1981, 118, 278-283.

[44] Guo, W. ; Koropchak, J. A. ; Yan, C. J. Chromatogr. A[18] Warthesen, J. J. ; Kramer, P. L. J. Food Sci. 1979, 44, 626-

1999, 849, 587-597.

627.

[45] Suzuki, S. ; Yamamoto, M. ; Kuwahara, Y. ; Honda, S.

[19] Verzele, M. ; van Damme, F. J. Chromatogr. 1986, 362, 23-

Chromatography 1997, 18, 316-317.

31.

[46] Suzuki, S. ; Yamamoto, M. ; Kuwahara, Y. ; Makiura, K. ;[20] Brons, C. ; Olieman, C. J. Chromatogr. 1983, 259, 79-86.

Honda, S. Electrophroesis 1998, 19, 2682-2688.

[21] Heyraud, A. ; Rinaudo, M. J. Liq. Chromatogr. 1980, 3, 721[47] Gucek, M. ; Pihlar, B. Acta Chim. Slov. 2000, 47, 165-177.

-739.

[48] Gucek, M. ; Pihlar, B. Chromatographia 2000, 51, S 139-S[22] Wells, G. B. ; Lester, R. L. Anal. Biochem. 1979, 97,184-

142.

190.

[49] Yang, C. ; El Rassi, Z. Electrophoresis 1998, 19, 2061-[23] Valent, B. S. ; Darvill, A. G. ; McNeil, M. ; Robertsen, B.

2067.

K. ; Albersheim, P. Carbohydr. Res. 1980, 79, 165-192.
[24] Honda, S. ; Suzuki, S. Anal. Biochem. 1984, 142, 167-174.

[50] Palm, A. ; Novotny, M. Anal. Chem. 1997, 69, 4499-4507.

[25] Okada, Y. ; Koizumi, K. ; Kitahata, S. Carbohydr. Res.

[51] Suzuki, S. ; Yamamoto, M. ; Kuwahara, Y. ; Honda, S.
Chromatography 1998, 19, 178-179.

1994, 254, 1-13.

[52] Suzuki, S. ; Kuwahara, Y. ; Makiura, K. ; Honda S. J. Chro-[26] Kawasaki, N. ; Ohta, M. ; Hyuga, S. ; Hashimoto, O. ; Hay-

matogr. A 2000, 873, 247-256.

akawa, T. Anal. Biochem. 1999, 269, 297-303.

―１
７
８―

Chromatography, Vol.22 No.3 (2001)

Shigeo Suzuki and Susumu Honda

1994, 13, 715-736.

[53] Mayer, M. ; Rapp, E. ; Marck, C. ; Bruin, G. J. M. Elec-[64] Toomre, D. K. ; Varki, A. Glycobiology 1994, 4, 653-663.

trophroesis 1999, 20, 43-49.

[65] Nashabeh, W. ; El Rassi, Z. J. Chromatogr. 1992, 600, 279-

[54] Hugener, M. ; Tinke, A. P. ; Niessen, W. M. A. ; Tjaden, U.

287.

R. ; van der Greef, J. J. Chromatogr. 1993, 647, 375-385.

[66] Sato, K. ; Sato, K. ; Okubo, A. ; Yamazaki, S. Anal. Bio-[55] Yoo, Y. S. ; Kim, Y. S. ; Jhon, G. -J. ; Park, J. J. Chroma-chem. 1997, 251, 119-121.

togr. A 1993, 652, 431-439.

[67] Bigge, J. C. ; Patel, T. P. ; Bruce, J. A. ; Goulding, P. N. ;[56] Zhang, M. ; El Rassi, Z. Electrophoresis 1998, 19, 2068-

Charles, S. M. ; Parekh, R. B. Anal. Biochem. 1995, 230,

2072.

229-238.

[57] Zhang, M. ; Ostrander, G. K. ; El Rassi, Z. J. Chromatogr. A[68] Nakai, T. ; Ohta, T. ; Takayama, M. Agric. Biol. Chem.

2000, 887, 287-297.

1974, 38, 1209-1212.

[58] Todorov, P. T. ; Deacon, M. ; Tisdale, M. J. J. Biol. Chem.

[69] Lee, K. -B. ; Al-Hakim, A. ; Loganathan, D. ; Linhardt, R. J.

1997, 272, 12279-12288.

Carbohydr. Res. 1991, 214, 155-168.

[59] Choudhary, G. ; Hancock, W. ; Witt, K. ; Rozing, G. ;[70] Charlwood, J. ; Birrell, H. ; Gribble, A. ; Burdes, V. ; Tol-

Torres-Duarte, A. ; Wainer, I. J. Chromatogr. A 1999, 857,

son, D. ; Camilleri, P. Anal. Chem. 2000, 72, 1453-1461.

183-192.

[71] Prakash, C. ; Vijay, I. K. Anal. Biochem. 1983, 128, 41-46.

[60] Poulter, L. ; Karrer, R. ; Burlingame, A. L. Anal. Biochem.

[72] Avigad, G. J. Chromatogr. 1977, 139, 343-347.

1991, 195, 1-13.

[73] Zhang, R. -E. ; Cao, Y. -L. ; Hearn, M. W. Anal. Biochem.

[61] Kallin, E. ; Lönn, H. ; Norberg, T. Glycoconj. J. 1986, 3,

1991, 195, 160-167.

311-319.

[74] Spiro, M. J. ; Spiro, R. G. Anal. Biochem. 1992, 204, 152-[62] Schwaiger, H. ; Oefner, P. J. ; Huber, C. ; Grill, E. ; Bonn,

157.

G. K. Electrophoresis 1994, 15, 941-952.

[75] Zhao, J. Y. ; Diedrich, P. ; Zhang, Y. ; Hindsgaul, O. ; Dovi-[63] Fukase, K. ; Nakayama, H. ; Kurosawa, M. ; Ikegaki, T. ;chi, N. J. J. Chromatogr. B 1994, 657, 307-313.

Kanoh, T. ; Hase, S. ; Kusumoto, S. J. Carbohydr. Chem.

―１７９―