カラム分離/溶媒抽出フローインジェクション分析法によるナトリウムとカリウムの吸光光度法

シリカゲルカラムによるNa(+)とK(+)の分離及びクラウン錯体の陰イオン染料とのイオン会合体の溶媒抽出を組み込んだFIAによる吸光光度法を検討した.内経1mm,長さ20cmのPTFEチューブに100～200メッシュのシリカゲルを詰めたカラムを用いた.溶離液として,5×10(-3)Mベンゾ-18-クラウン-6及び,10(-2)M酢酸リチウムを含む水溶液を用いた.分析イオンを含む溶出液は試薬溶液(5×10(-4)Mの4'-ジエチルアミノ-2,5-ジクロロアゾベンゼン-4-スルホン酸イオン,5×10(-3)Mのベンゾ-18-クラウン-6,10(-3)MのEDTA及び3×10(-3)Mの水酸化リチウムを含む)と混合され,T字型セグメンターで抽出溶媒(ベンゼン+クロロベンゼン=1+1)と合流し,抽出コイル中で抽出が行われた.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,有機相は分離され,8μlのフローセルで450nmの吸光度が測定された.1×10(-4)M～2×10(-3)MのNa(+),5×10(-6)M～1×10(-4)MのK(+)に対して,検量線は直線となった.

Sodium and potassium ions were spectrophotometrically determined by solvent extraction flow injection incorporated with a silica gel column. The ion association complexes which formed between alkali metal-crown ether complexes and an 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 a poly(tetrafluoroethylene) porous membrane (pore size: 0.8 μm). Sodium and potassium were separated on a silica gel column (1 mm i.d.×20 cm; 100200 mesh silica gel). Four streams, a carrier, an eluent, a reagent solution and an extraction solvent, were propelled at the flow rate of 0.8 ml min(-1) The carrier was distilled water. The eluent contained 10(-2) M lithium acetate and 5×10(-3) M benzo-18-crown-6 (B18C6), and the reagent solution consisted of 5×10(-4) M 4-diethylamino-2, 5-dichloroazobenzene-4-sulfonate, 5×10(-3) M B18C6, 10(-3)M EDTA (dilithium salt) and 3×10(-3) M lithium hydroxide. The extraction solvent was a mixture of benzene and chlorobenzene (1+1). The absorbance was continuously measured at 450 nm with a 8 μl flow cell (path length: 10 mm). Calibration curves for sodium and potassium were linear in the range from 1×10(-4) M to 2×10(-3) M and from 5×10(-6) M to 1×10(-4) M, respectively. The sampling rate was about 20 samples per hour.