Monitoring Lipophilic Toxins in Seawater Using Dispersive Liquid—Liquid Microextraction and Liquid Chromatography with Triple Quadrupole Mass Spectrometry

Abstract

The use of dispersive liquid–liquid microextraction (DLLME) is proposed for the preconcentration of thirteen lipophilic marine toxins in seawater samples. For this purpose, 0.5 mL of methanol and 440 µL of chloroform were injected into 12 mL of sample. The enriched organic phase, once evaporated and reconstituted in methanol, was analyzed by reversed-phase liquid chromatography with triple-quadrupole tandem mass spectrometry. A central composite design multivariate method was used to optimize the interrelated parameters affecting DLLME efficiency. The absence of any matrix effect in the samples allowed them to be quantified against aqueous standards. The optimized procedure was validated by recovery studies, which provided values in the 82–123% range. The detection limits varied between 0.2 and 5.7 ng L−1, depending on the analyte, and the intraday precision values were in the 0.1–7.5% range in terms of relative standard deviation. Ten water samples taken from different points of the Mar Menor lagoon were analyzed and were found to be free of the studied toxins.

Development of an Efficient Extraction Method for Harvesting Gymnodimine-A from Large-Scale Cultures of Karenia selliformis

“…Thus, dichloromethane was the most suitable extraction solvent for GYM-A used in this study because of its high extraction efficiency, low cost, and relatively low toxicity compared to other chlorinated solvents. [27]. In this study, a satisfactory GYM-A extraction efficiency was achieved in the cultures of the initial seawater pH, and the effect of pH on extraction was not considered any further.…”

“…Different letters (a, b, ab) indicate significantly different values at p < 0.05.The pH of the sample can also affect the extraction efficiency. It was found that an acidic pH favored the extraction of acidic toxins (PTX2, DTXs and OA), while an alkaline pH favored the extraction of other toxins (AZAs, SPXs and GYM) during dispersive liquidliquid microextraction[27]. In this study, a satisfactory GYM-A extraction efficiency was achieved in the cultures of the initial seawater pH, and the effect of pH on extraction was not considered any further.…”

“…Therefore, the dispersed solvent can be discarded in the LLE procedure and the satisfactory recovery of GYM-A could still be obtained without these solvents. Good recovery of GYM-A in the spiked seawater was also achieved using chloroform as an extraction solvent in an optimized dispersive liquid-liquid microextraction by Oller-Ruiz et al [27]. In some previous studies, dichloromethane was also used as an extractant to extract GYM from digestive glands and microalgae [4,28].…”

“…With the advantages of a rapid reaction, a high enrichment factor, and simple steps, LLE can be used to separate hydrophobic compounds from the culture medium. The LLE method has been used to separate a wide range of hydrophilic and hydrophobic marine phycotoxins, enabling the comprehensive extraction and analysis of marine toxins [25], in addition to being a rapid pre-treatment method for sample pre-concentration and purification for the detection of marine lipophilic toxins [26,27]. For example, Marrouchi et al [28] reported the use of dichloromethane and diethyl ether when extracting the GYM toxin in clams using LLE method.…”

Selection, Characterization, and Optimization of DNA Aptamers against Challenging Marine Biotoxin Gymnodimine-A for Biosensing Application

“…For example, the establishment of the liquid chromatography–high-resolution mass spectrometry (LC–HRMS) approach is conducive to the discovery of new derivatives of GYMs and the in-depth investigation of the metabolic characteristics of shellfish samples [ 36 ]. The combination of the dispersive liquid–liquid microextraction (DLLME) with the liquid chromatography with triple quadrupole mass spectrometry (LC–QqQ-MS/MS) allowed for the sensitive and selective analysis of thirteen lipophilic marine toxins, including GYM in seawater samples [ 37 ]. Although the performance of LC–MS/MS methods, including specificity, sample consumption, detection time, or the low limit of detection (LOD), continues to improve, these methods are still expensive, complex, time-consuming, and need special personnel, sophisticated instrument, or certified toxin of various congeners of GYMs [ 28 , 38 ].…”