Handbook of Ion Chromatography

Heparan Sulfate Separation, Sequencing, and Isomeric Differentiation: Ion Mobility Spectrometry Reveals Specific Iduronic and Glucuronic Acid-Containing Hexasaccharides

“…The resultant product fractions containing hexasaccharides (dp6) were pooled and subjected to strong anion exchange (SAX) chromatography using an IonPac AS7 column. This column type was chosen as it had previously been shown useful in differentiation of polyvalent anions 62, but to our knowledge had not been used in GAG analysis. When running a shallow gradient, the column proved effective in separating both isomeric hexasaccharides as well as those differing in sulfate number (Figure 2).…”

Arsenic Speciation Analysis by Ion Chromatography - A Critical Review of Principles and Applications

“…For a given exchanger material, the ion density is given by the number of exchange sites per material mass (capacity) and the polarizability is similar among columns functionalized by the same ionic groups. So far, R 4 N + , SO 3 -, RCOO -were most often used as ion exchanging groups [127,128]. The analytes charge density and polarizability depends on the molecule size and the charge which is often controlled by a proton association-dissociation equilibrium.…”

“…This can be achieved by a dual mode method, which consists on one hand of an additionally applied CEX procedure (as two columns two procedures [13] or as two columns in series in one procedure [135,136]). On the other hand, a mixed mode ion exchanger (mostly AS7 column,) can be used, containing both, anionic and cationic exchange sites [127]. In many cases, AEX, single or mixed mode, sufficiently separates a restricted number of cationic arsenicals, making a separate CEX-run obsolete.…”

“…This review is intended to better clarify the role of IC in As-speciation and to highlight improved procedures. The different types of IC methods [127], e.g. anion exchange (AEX), cation exchange (CEX), ion exclusion (IEC), ion pair chromatography (IPC) and combinations there of are potentially suitable for As-speciation and are discussed below.…”

Anion exchangers with branched functional ion exchange layers of different hydrophilicity for ion chromatography

“…However, hydroxide as a weak type of mobile phase requires the use of specially designed, rather hydrophilic anion exchangers containing hydroxyethyl substitutes in quaternary ammonium groups (so called, Type II anion exchangers), which provide the increase of the eluent strength [10]. In case of using poly(styrene-divinylbenzene) (PS-DVB) substrates the introduction of hydrophilic anion exchange groups on the hydrophobic surface of the polymer is also beneficial for column efficiency and separation selectivity due to the possible decrease of non-ionic interactions between polarizable anions and substrate surface, as demonstrated in [10][11][12][13][14].…”