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ID 14843
Eprint ID
14843
FullText URL
Title Alternative
Development of a micro-flow titration method and application to acid-base titration
Author
Konishi, Hironobu
Oshima, Mitsuko
Motomizu, Shoji
Abstract
容量分析法の簡便化,迅速化,自動化及び省力化を含む高機能化を目的として,送液ポンプの流量比に基づくフロー滴定システムの構築と応用について検討した.フロー滴定分析法は,連続して流れる試料液,滴定剤溶液の正確な流量制御を基本原理としている.2台の送液ポンプを用いてそれらの流量を変化させながら試料液(被滴定液)と滴定剤(滴定液)を送液し,流れ内において混合・反応させ,指示薬の変色を用いて試料液中の分析対象物質濃度を流量比から定量する容量分析法である.各種酸塩基滴定を通して本法の性能評価を行い,従来法との比較を行った.酸塩基指示薬としてフェノールフタレイン,あるいはクレゾールレッドを試料液又は滴定剤へ添加したところ,強酸,弱酸を問わず検討したすべての系において直線性の高い検量線が得られた.また,終点検出の相対標準偏差は0.3%未満であった.更に,滴定剤に2種類の指示薬を用いる多塩基酸・多酸塩基の連続滴定法について検討した.炭酸塩の分析ではブロモクレゾールグリーンとフェノールフタレインを指示薬として用い,炭酸イオン,重炭酸イオンに由来する二つの当量点を一試料測定で検出できた. 本法を市販されている食酢の分析に適用したところ,従来法により決定した酢酸濃度と良好な一致を得た.1試料測定当たりの廃液量は50 ml程度から100 μl程度まで大幅に低減化することができ,フロー滴定分析法により全操作の自動化,試料・廃液量の大幅な低減化,滴定時間の短縮等の高機能化を達成した.
Abstract Alternative
A flow titration analysis method based on flow ratiometry was developed in this study from the viewpoint of simplicity, rapidity, automation, and cost efficiency. Sample and titrant solutions react while the solutions are continuously propelled by individual pumps at different flow rates. The flow rates are accurately controlled and changed independently, and the color change of an indicator gives an equivalent point. The concentration of analyte was determined by using the ratio of the flow rate and the equivalent point. The fundamental properties of the flow titration method were evaluated through acid-base titration, and compared with the conventional manual titration. When Phenolphthalein or Cresol Red was used as an indicator added in either the sample solution or the titrant solution, linear calibration graphs were obtained for all titrations examined, including strong and weak acids. The proposed method was applied to the titration of carbonate salt using Bromocresol Green and Phenolphthalein. Two isolated end-points were obtained in one sequential measurement corresponding to carbonate and bicarbonate ions. The proposed titration method was applied to the analysis of commercial vinegar samples. The results agreed well with the ones obtained by the conventional titration method; the relative standard deviations for the end point were within 0.3%. The volume of wastewater per one measurement can be reduced down to about 100 μl by the proposed method, while a practical method requires about 50 ml.
Keywords
flow titration analysis
flow ratiometry
acid-base titration
Published Date
2004
Publication Title
分析化学
Publication Title Alternative
Bunseki Kagaku
Volume
volume53
Issue
issue1
Publisher
日本分析化学会
Publisher Alternative
The Japan Society for Analytical Chemistry
Start Page
1
End Page
6
ISSN
0525-1931
NCID
AN00222633
Content Type
Journal Article
language
日本語
Copyright Holders
The Japan Society for Analytical Chemistry
File Version
publisher
Refereed
True
DOI