Closed-loop flow-injection analysis for the determination of a strong acid and base using an acetate buffer solution and Methyl Orange.

ZENKI Michio, NAKAKITA Yoshihiko, KOMATSU Aika, YOKOYAMA Takashi

doi:10.2116/bunsekikagaku.49.121

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Other Title

酢酸‐酢酸ナトリウム緩衝液とメチルオレンジを用いる循環式フローインジェクション法による強酸・強塩基の定量
酢酸-酢酸ナトリウム緩衝液とメチルオレンジを用いる循環式フローインジェクション法による強酸・強塩基の定量
サクサンサクサンナトリウムカンショウエキトメチルオレンジオモチイルジュンカンシキフローインジェクションホウニヨルキョウサンキョウエンキノテイリョウ

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Description

The use of a closed-loop system in flow-injection analysis(FIA) allows for the recycling of reagents which are present in excess. Strong acids and bases are determined by injection into a continually circulated buffer solution containing an acid-base indicator. Neutralization occurs in the sample zone and discoloration of an indicator is monitored by spectrophotometry. Passing though the flow cell, the resulting solution is then buffered and returns to the reservoir. A typical aqueous reservoir solution contained 0.1M acetate buffer and 1.5×10^-4M Methyl Orange. This solution was circulated at a flow rate of 2.5ml/min. Sample(acid or base) aliquots of 2μl were introduced into the stream and the differential absorbances were monitored at 530nm. The calibration curve of samples by this method showed good linearity over a range of 0.1-5M. Acids(HCl, HNO₃, H₂SO₄, and oxalic acid) and bases(NaOH, KOH and NH₃) gave the same slope of the calibration curve, respectively. Although a slight gradual increase in the baseline shift could not be avoided, it allowed 500 repetitive determinations of 1M HCl or NaOH with the same 100ml of circulating 0.1M acetate buffer solution.

Journal

BUNSEKI KAGAKU

BUNSEKI KAGAKU 49 (2), 121-124, 2000

The Japan Society for Analytical Chemistry

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