Cloud-point extraction of nodularin-R from natural waters

HongXia YU, Ben Kwok-Wai MAN, Lily Lee-Ni CHAN, Michael Hon-Wah LAM, Paul K. S. LAM, Liansheng WANG, Hongjun JIN, Shiu Sun Rudolf WU

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32 Citations (Scopus)


A cloud-point extraction (CPE) technique for the determination of a cyanobacterial hepatotoxin, nodularin-R, in aqueous media using a cationic surfactant, tricaprylmethylammonium chloride (Aliquat-336), was developed. Cloud-point phase separation of Aliquat-336 at ambient temperature was induced by the addition of sodium sulfate. The Aliquat-336/Na2SO4 CPE system displayed large preconcentration factor, FC, for nodularin-R. At the operational CPE conditions, FC of 709.2 was achieved. Distribution constant, KD, of the distribution of nodularin-R between the surfactant-rich and aqueous phases of the CPE system was estimated to be (4.94±0.8)×103. Coupled to liquid chromatography with UV detection, the CPE method offered a detection limit of 330pgml-1 (in freshwater)/1.3ngml-1 (in seawater) and a repeatability of 6.4% (in freshwater) (n=7, P<0.05) for nodularin-R in a sample of 25ml. The CPE is a rapid process and no cleanup step is required. Effects of pH, natural abundant anion (chloride) and dissolved organic matters (DOM, humic acid, HA) on the extraction efficiency were evaluated. A double CPE technique was developed to overcome interferences encountered in the analysis of environmental samples. Applicability of the new method to the determination of nodularin-R in real coastal marine water samples has also been demonstrated. Copyright © 2003 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)63-70
JournalAnalytica Chimica Acta
Issue number1
Publication statusPublished - 29 Apr 2004


Yu, H., Man, B. K.-W., Chan, L. L.-N., Lam, M. H.-W., Lam, P. K. S., Wang, L., . . . Wu, R. S. S. (2004). Cloud-point extraction of nodularin-R from natural waters. Analytica Chimica Acta, 509(1), 63-70. doi: 10.1016/j.aca.2003.12.019


  • Cloud-point extraction
  • Nodularin-R
  • Natural waters
  • Cyanobacterial toxin


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