水素型陽イオン交換樹脂を用いるリン酸イオンのイオン排除クロマトグラフィー

Ion exclusion chromatography of phosphate ion using cation exchange resin.

田中 一彦

中嶋 邦雄

砂原 広志

分析化学

強酸性陰イオンとリン酸イオンのイオン排除クロマトグラフィーに関して, 陰イナンのキャパシティー比(k')と対応する酸の第一次解離定数(pK1)との間には直線関係であるが, 近接したk'であるため, 両陰イオンを分離するために, カラム温度, 水-有機溶媒系溶離液組成, 及び流量などを検討した.

強酸性陰イオン(塩化物イオン)とリン酸イオンの混合試料において, リン酸イオンのk'はカラム温度の上昇, 水溶離液へのアセトン添加濃度の増大とともにリン酸のpK1が増大するので直線的に増大し, 塩化物イオンとの闘の分離度(Rs)も直線的に増大したことから, リン酸イオンのイオン排除的分離は溶離液の誘電率に依存することが分かった.

カラム温度50℃, 溶離液20%(v/v)アセトン水溶液, 溶離液流量1ml/min, 試料導入容量0,5ml(50μgの両陰イオンを含む)の溶離条件下において, リン酸イオンのk'は0.145, HETPは0.48mm, 電解効率は98%, 両陰イオン間のRsは1.20が得られ, 良好な溶離条件であることを認めた.

In the separation and indirect determination of PO43- by ion exclusion chromatography with a hydrogen type cation exchange resin, a flow coulometric detector was used for the detection of H+ in acid liberated by cation-exchange. The chromatographic conditions, such as column temperature, eluent composition, eluent flow rate and sample volume, were investigated in order to separate PO43- from Cl-. The capacity factor (k') of various anions depended upon the primary dissociation constant (pK1) of the corresponding acids, and the k' of Cl- are similar to that of PO43-. The k' of PO43- increased with lowering dielectric constant (ε) of the eluent due to the rise of column temperature. A linear relationship was obtained between the k' of PO43- and the column temperature in the range of 26 to 80°C. No variation was observed for the k' of Cl-. The k' of PO43- increased with lowering ε of the eluent by addition of acetone. No such effect was observed for the k' of Cl-. A linear relationship was obtained between the k' of PO43- and the concentration of acetone at the range of 0 to 70% (v/v) . The peak resolution (Rs) between Cl- and PO43- increased in proportion to the k' of PO43- due to the lowering of e of eluent. Under the chromatographic conditions of column temperature of 50°C, 20% acetone eluent, eluent flow rate of 1 ml/min and sample volume of 0.5 ml, the Rs between Cl- and PO43- was 1.20 and the electrolytic efficiency of PO43- was 98%. A linear relationship was obtained between chromatogram peak area and concentration of PO43- for the range of 5 to 1000 ppm.

Dielectric constant of eluent

Flow coulometry

Ion exclusion chromatography

Phosphate ion in chloride ion

Water-acetone eluent

化学 [ 430 ]

日本語

日本分析化学会

[ISSN] 0525-1931

[NCID] AN00222633