Investigation of residue content of cyanobacterial hepatotoxin in water samples using DLLME method

Hepatotoxins are dangerous biological toxins produced by cyanobacteria. Because of the high consumption of cost and time in the extraction and detection procedure of these toxins, the main aim of the present study is to investigate the performance of a new extraction technique, termed dispersive liquid-liquid microextraction (DLLME) in the extraction of one hepatotoxin with the name Microcystin LR from water samples, using chlorinated organic extraction solvents.

In the first stage, the efficiency of the common method (solid phase extraction) was investigated. Then the mixture of disperser solvents (acetone, ethanol, methanol, and acetonitrile) and extraction solvents (chloroform, dichloromethane, carbon tetrachloride and tetrachloroethylene) were used to investigate the efficiency of DLLME.

The results showed that the efficiency of SPE using a C18 cartridge was 102 %. For high efficiency of DLLME, a cloudy solution should be formed (fine particles of extraction solvent which are dispersed entirely into the aqueous phase). In the present study, only in a mixture of acetone and tetrachloroethylene (with different ratios), a stable cloudy solution was found. The best-observed efficiency was 3 % for DLLME.   

The observations in this study suggest that although based on the obtained efficiency, the chlorinated organic solvents, could not be appropriate extraction solvents in MC-LR extraction, but the DLLME method using other solvents like Ionic liquid extraction solvents is a suitable technique for hepatotoxin extraction because of low consumption of cost, time and solvents in the extraction procedure.