Kazue Tani

Retention behavior of monosaccharides and disaccharides on titania

SummaryThe ability of titania to recognize the position of hydroxyl groups was previously found to result from the formation of a chelate ring between a titanium ion and the two oxygen atoms of the hydroxyl group and carboxylate anion of 2-hydroxycarboxylic acids. We investigated how titania could recognize the position of hydroxyl group of monosaccharides and disaccharides. The retention behavior of monosaccharides and disaccharides on titania was found to be characteristic. Thus, sucrose was eluted much faster than the other sugars, whereas D-ribose, D-fructose and L-sorbose were most strongly retained on titania of all of the sugars tested. It is apparent that the sugars strongly retained on titania have an axial hydroxyl group or neighboring hydroxyl groups of the same conformation.

Poly(allylamine) beads as selective sorbent for preconcentration of formaldehyde and acetaldehyde in high-performance liquid chromatographic analysis

Formaldehyde and acetaldehyde in water were determined by preconcentration with poly(allylamine) beads, derivatization with 2,4-dinitrophenylhydrazine (DPH) and analysis by HPLC. Poly(allylamine) beads (0.5 g) were used to adsorb formaldehyde and acetaldehyde at 1.2-150 microg l(-1) and 3.5-220 microg l(-1) from water (1 l). The concentration factor is 50 fold. The aldehydes were eluted and derivatized with 2 mM DPH in 0.5 M H2SO4 (10 ml). The time of analysis was 1 h. The detection limits (S/N=3) for formaldehyde and acetaldehyde were 0.6 and 2 microg l(-1), respectively.

Evaluation of hydrous zirconium oxide loaded porous polymer resin for ion chromatographic separation of carboxylic acids

SummaryA porous polymer resin loaded with hydrous zirconium oxide (Zr-gel) was evaluated as a selective stationary phase for the ion chromatographic separation of carboxylic acids. We have found that Zr-gel has a specificity to the α-hydroxyl groups on carboxylic acids. Using 3×10−3 mol l−1 of sodium carbonate as a mobile phase, monocarboxylic acids such as formate, acetate, propionate and butyrate, were immediately eluted at the void volume of the Zr-gel column, whereas α-hydroxy-monocarboxylic acids such as glycolate and lactate were clearly retained. Dicarboxylic acids with an α-hydroxyl group, viz., malate and tartarate, were also strongly retained and not eluted from the Zr-gel column.

Determination of the specific interaction of disubstituted aromatic compounds on hydrous zirconium oxide-loaded porous polymer resin

SummaryA porous polymer resin loaded with hydrous zirconium oxide (Zr-gel) was evaluated as a stationary phase for the liquid chromatographic separation of disubstituted aromatic compounds. The prepared Zr-gel was used to separate disubstituted phenols andortho-substituted benzoic acid derivatives in reversed-phase mode. The retention time of catechol was greater than those of other disubstituted phenols; this implies that the Zr-gel has specificity for the phenolic hydroxyl group. The retention behavior ofortho-substituted benzoic acid derivatives on the Zr-gel was also evaluated in reversedphase mode using buffer. Phthalic acid was specifically retained in the vicinity of pH 6.0, which has been regarded as the equal adsorbic point. Similar behavior was also observed for salicylic acid, although the retention time of salicylic acid was less than that of phthalic acid. It seems that the specific retention behavior of hydrous zirconium oxide is a result of complexation with ligands such as hydroxyl and carboxyl groups. The results of this study have revealed that the retention mechanism of hydrous zirconium oxide is a combination of ion exchange and interaction based on complexation with ligands.

Measurements of Room-Temperature Phosphorescence Spectra of Polycyclic Aromatic Compounds Using Pullulan Films Containing β-Cyclodextrin and 2-Bromoethanol

A clear film was easily prepared by air-drying anaqueous solution of pullulan (6%w/w) containing β-cyclodextrin(CD, 1%w/w) and 2-bromoethanol (1%v/w). The resultingpullulan film was used as a substrate for simple measurements ofroom-temperature phosphorescence (RTP) spectra of polycyclicaromatic compounds (PACs). Only a drop (ca. 10 μL) of a 100 μgmL-1 sample solution in 95% ethanol was spotted onto the surfaceof the disk film (7–8 mm diameter) and the solvent wasallowed to evaporate at room temperature. The sample-spottedfilm was pasted on a glass plate (75 × 20 × 1 mm) with smallamounts of a starch glue. The plate was mounted into a solidsample holder, or alternatively inserted diagonally into a 1-cm cell holder.Without a dry gas flush during the measurements, RTPspectra based on the CD inclusion complexes of PACs wereobtained from six typical two- and three-ring compounds,including naphthalene, acenaphthene, fluorene, phenanthrene,carbazole, and dibenzofuran. Only anthracene did notproduce a discernable phosphorescence signal by the presenttechnique. This technique was directly applied to the spectralidentification of acenaphthene in commercially available kerosene.

Evaluation of the influence of the base material loaded with hydrous zirconium oxide gel on the retention behavior of disubstituted benzoic acids

SummarySilica gel loaded with hydrous zirconium oxide (Zr-gel-S) has been prepared and the influence of the base material on the retention behavior ofo-phthalic acid on the hydrous zirconium oxide was evaluated. The retention behavior of the acid on the Zr-gel-S was compared with that on Zr-gel-5, the polymer-based Zr-gel. Comparable retention behavior,i.e. maximum retention in the vicinity of pH 6, which has been regarded as the equal adsorbic point, was observed for both types of Zr-gel, although there was a large difference in the retention times. The difference in retention on the two types of Zr-gel could be ascribed to nature of the base material. The results in this experiments showed, however, that the specific behavior at pH 6 was an essential characteristic of hydrous zirconium oxide and was not related to the influence of the base materials.

Effect of suppressed system on detection of ion chromatographic peaks using organic acid eluents.

イオンクロマトグラフィーにおいて,有機酸溶離液を用いてサプレッサーを使用しない場合と使用した場合に電気伝導度検出を行ったときの有機酸ピークの応答について検討した.2.5mMフタル酸水素カリウム(pH4.15)溶離液ではサプレッサーを使用しないとき,有機酸は正のピークを示した.サプレッサー(除去液15mM硫酸)を使用すると,酢酸,乳酸,コハク酸,リンゴ酸,酒石酸のピークは負のピークとして現れ,クエン酸のピークは検出されなかった.一方,2.5mMフタル酸(pH2.90)溶離液では酢酸,乳酸,コハク酸,リンゴ酸は正のピークとして検出された.検出器内では溶離液の電気伝導度がバックグラウンドとなり,有機酸はそれに対する電気伝導度の変化分として応答を示す.しかし,pHの高い溶離液ではカラム中の有機酸は十分解離しているが,サプレッサーを通過させると解離が抑制される.フタル酸溶離液では有機酸の解離は既に抑制されているため,サプレッサーの使用の有無による解離に変化はない.この違いが検出器での応答の差となり,フタル酸水素カリウム溶離液でサプレッサーを用いたときに,電気伝導度(極限当量伝導度とイオン化率の積)の低い有機酸が負のピークを示したと考えられた.又,負のピークの大きさは注入された試料濃度に比例していた.

Ion exchange chromatography of organic acids using a chemically bonded hydrophilic anion-exchange column with potassium biphthalate eluent.

化学結合型イオン交換樹脂(SAM)の充てんカラムは陰イオンクロマトグラフィー用として開発された.溶離液として炭酸系を用いて分離後,除去システムと電導度検出器を組み合わせた検出方法により,各種の陰イオンや有機酸が分析されている.しかし,このカラムでは炭酸系以外の溶離液についての保持挙動はほとんど研究されていない.本報では異なる装置間でのカラムの互換性を図る目的でフタル酸水素カリウム溶離液での有機酸の保持挙動を明らかにした.又フタル酸系溶離液を使用する場合の最適条件を検討した結果,2.5mMフタル酸水素カリウム,流量1.6ml/min,カラム温度40℃で10種類の有機酸の一斉分離が30分以内で達成できた.各種食品中の有機酸の相互分離及び定量分析に本法を適用した.