陽イオン交換カラム分離/溶媒抽出法を用いるナトリウム及びカリウムイオンのフローインジェクション吸光光度法

Na(+), K(+)の溶媒抽出/吸光光度定量をFIAにより行った.両イオンの分離は低交換容量の陽イオン交換樹脂カラムにより行った.イオン交換樹脂は内径2.5mm,長さ12mmの樹脂製カラムに充てんして用いた.流れ系はキャリヤー,溶離液,抽出液の3流路を用い,試料はキャリヤーに注入した.キャリヤーは溶離液と合流し,カラムでNa(+)とK(+)は分離された.溶離液には4×10(-4)M EDTA・3Liを使用した.分析イオンを含む溶出液は,陰イオン交換膜チューブでアルカリ性となり,T字型セグメンターで有機相と合流し,抽出コイル内でNa(+), K(+)の抽出が行われた.有機相はイオン会合体形成用の染料陰イオンTBPE(テトラブロモフェノールフタレインエチルエステル)とクラウン化合物を含むベンゼン,クロロベンゼン(1+1)の混合溶媒である.ポリテトラフルオロエチレン膜を備えた相分離器により分離された有機相の吸光度は615nmで測定された. 5×10(-4)M以下のNa(+), 8×10(-5)M以下のK(+)に対して検量線は直線関係を示した.又本法による分析速度は毎時12試料であった.

Sodium and potassium ions were spectrophotometrically determined by a solvent extraction/flow injection method incorporated with a cation exchanger column. The ion association complexes which formed between alkali metal-crown ether complexes and anionic dye were extracted into an organic phase, and the absorbance of the organic phase was measured after the phase separation by a phase separator with poly (tetrafluoroethylene) porous membrane. The manifold was composed of three streams: 1. a carrier stream, 2. an eluent stream, and 3. an extraction solvent stream. The eluent contained 4×10(-3)M EDTA·3Li. The extraction solvent (1+1 mixture of benzene and chlorobenzene) contained 3×10(-3)M tetrabromophenolphthalein ethyl ester and 2×10(-3)M dicyclohexano-18-crown-6. Sodium and potassium ions were separated on a cation exchanger column (2.5mm i.d.×12mm). The eluent was made alkaline (pH 10) by passing through the anion exchanger membrane tubing which was kept in a 0.1M LiOH solution. The absorbance of the organic phase was measured at 615nm. Calibration graphs were linear up to 5×10(-4)M for Na(+) and 8×10(-5)M for K(+), respectively. The sample throughput was 12h(-1). The procedure was applicable to river and tap water samples.