電量検出器を用いるイオン排除クロマトグラフ法による生物学的硝化工程水中の炭酸水素イオンの定量

Determination of bicarbonate ion in biological nitrification process water by ion-exclusion chromatography with coulometric detection.

Tanaka Kazuhiko

分析化学

溶離液として水を用いるH+型陽イオン交換樹脂におけるイオン排除クロマトグラフ法により, 生物学的硝化工程水申のHCO3-が定量された. 分離カラムから溶出したHCO3-は炭酸として導電率検出器及びH+を検出するための電量検出器によってモニターされた. 種々の共存陰イオン(Cl-, SO42-, NO3-, NO2-及びPO43-)からのHCO3-の良好な分離は内径9mm×200mmの分離カラムを用いることによって達成できた. 炭酸は極めて弱い酸であるため導電率検出器による検量線は非直線性を示したが, 電量検出器によるそれは少なくとも200ppmまで良好な直線性を示した. 電量検出器によるHCO3-のクロマトグラムのピーク面積再現性は1,9%の変動係数(n=10)であった. 種々のpH条件下での硝化工程水中のHCO3-を定量したところ, NH4+のNO3-への硝化反応における効率が100%以下になるpH領域ではHCO3-が5ppm以下となることが分かった.

The ion-exclusion chromatography with a cation exchange resin (H+ form) using water as an eluent was investigated for the determination of HCO3- in biological nitrification process water. Bicarbonate ion in the effluent from the column was monitored by a conductometric detector (COND) and a flow coulometric detector (FCD) based on the electrochemical reaction of hydrogen ion from H2CO3 with p-benzoquinone at a constant applied potential (+0.45 V vs. Ag-AgI). A good separation of HCO3- from the diverse anions such as Cl-, SO42-, NO3-, PO43-, and NO2- was accomplished by elution with water alone. The calibration graph for HCO3- obtained by the COND was nonlinear, probably because of the low dissociation of H2CO3 at higher concentrations. However, the linear relationship was obtained over the range (10~200) ppm of HCO3- by the FCD. Therefore, it is recommended to use the FCD in this method. The reproducibility of the peak area of chromatogram of HCO3- obtained by the FCD was satisfactory with a coefficient of variation of 1.9 % for ten determinations of 10 ppm of HCO3-. The present method was applied to the determination of HCO3 in the process water under the aerobic conditions over the pH range 510 with satisfactory results.

ion-exclusion chromatography with cation exchange resin

determination of HCO3- in biological nitrification process water

flow coulometric detection

Chemistry [ 430 ]

jpn

日本分析化学会

[ISSN] 0525-1931

[NCID] AN00222633