Summary
An electron spin resonance (ESR) method already in use for the quantitative analysis of paraquat was applied to the analysis of diquat in blood, serum, urine, tissue homogenates and several drinks without purification of the samples. The diquat radical produced with ascorbic acid at alkaline pH was much more stable than that produced with the commonly used sodium dithionite. Radical decay in solutions covered with n-hexane was less than 5% after 60 min over a wide range of ascorbic acid concentrations. In 0.2N NaOH solution 85% of the radicals was present even after 24h. The limit of detection was 0.3 μg/ml and the required amount of sample was 0.1 ml. When both diquat and paraquat were present in a sample the diquat was first extracted with 1-butanol prior to the ESR measurement, because both species were converted to the radicals.
Zusammenfassung
Eine ESR-Methode, bereits fur die quantitative Analyse von Paraquat entwickelt, wird zur Analytik von Diquat in Blut, Serum, Urin, Gewebshomogenisaten and verschiedenen Getränkeproben ohne besondere Reinigung des Materials herangezogen. Das mit Ascorbinsäure gewonnene Diquatradikal war im alkalischen Milieu stabiler als das üblicherweise eingesetzte und mit Natriumdithionit hergestellte Radikal. Der Abfall der Radikalkonzentration in n-Hexanlösungen lag bei weniger als 5% nach 60 Minuten in weiten Bereichen der Ascorbinsdurekonzentration. Beispielsweise lagen in 0,2 N-NaOH noch 85% nach 24 Stunden vor. Die Nachweisgrenze beträgt 0,3 μg/ml and das benbtigte Probenvolumen 0,1 ml. Liegen sowohl Diquat als auch Paraquat in der Probe vor, so wird empfohlen, Diquat durch Extraktion mit 1-Butanol vor der ESR-Messung abzutrennen, da beide Verbindungen in Radikale überführt werden.
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Minakata, K., Suzuki, O., Kumazawa, T. et al. Determination of diquat in biological materials by electron spin resonance spectroscopy. Z Rechtsmed 103, 599–607 (1990). https://doi.org/10.1007/BF00202721
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DOI: https://doi.org/10.1007/BF00202721