Absorbance measurements of oxidation of homogentisic acid accelerated by the addition of alkaline solution with sodium hypochlorite pentahydrate

The urine of patients with alkaptonuria turns dark brown due to the oxidation of homogentisic acid (HGA) to benzoquinone acetic acid (BQA), and this is accelerated by the addition of alkali. We recently reported that alkaptonuric urine and HGA after the addition of alkali showed characteristic peaks...

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Bibliographic Details
Published in:Scientific reports 2018-07, Vol.8 (1), p.11364-9, Article 11364
Main Authors: Tokuhara, Yasunori, Shukuya, Kenichi, Tanaka, Masami, Sogabe, Keisuke, Ejima, Yasukazu, Hosokawa, Sho, Ohsaki, Hiroyuki, Morinishi, Tatsuya, Hirakawa, Eiichiro, Yatomi, Yutaka, Shimosawa, Tatsuo
Format: Article
Language:English
Subjects:
140/131
631/45/320
631/92/507
692/699/317
Absorbance
Acetic acid
Alkaptonuria
Benzoquinone
Humanities and Social Sciences
Ions
Liquid chromatography
Magnetic resonance spectroscopy
multidisciplinary
NMR
Nuclear magnetic resonance
Oxidation
Oxidizing agents
Science
Science (multidisciplinary)
Sodium
Sodium hydroxide
Sodium hypochlorite
Spectrometry
Urine
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Summary:The urine of patients with alkaptonuria turns dark brown due to the oxidation of homogentisic acid (HGA) to benzoquinone acetic acid (BQA), and this is accelerated by the addition of alkali. We recently reported that alkaptonuric urine and HGA after the addition of alkali showed characteristic peaks at 406 and 430 nm. In order to improve the sensitivity of our spectrometric method for the detection of HGA, we accelerated the oxidation of HGA to BQA using sodium hypochlorite pentahydrate (NaOCl·5H 2 O), which is a strong oxidant. In the present study, we measured the absorption spectra of alkaptonuric urine and HGA solution after the addition of sodium hydroxide (NaOH) or NaOH with NaOCl·5H 2 O and analyzed the oxidation reaction of HGA after alkalization using a liquid chromatography time-of-flight mass spectrometer (LC/TOF-MS) and nuclear magnetic resonance (NMR) spectrometry. We accelerated the oxidation of HGA to BQA by adding NaOH with NaOCl·5H 2 O, and this absorbance measurement was useful for more sensitively observing the oxidation of HGA than LC/TOF-MS and NMR spectroscopy. This quick and easy screening method may be suitable for the diagnosis of alkaptonuria.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-018-29769-w