Monitoring of cyanotoxins in water from hypersaline microalgae colonies by ultra high performance liquid chromatography with diode array and tandem mass spectrometry detection following salting-out liquid-liquid extraction

Maryam Hemmati; Carmen Tejada-Casado; Francisco J Lara; Ana M García-Campaña; Maryam Rajabi; Monsalud Del Olmo-Iruela

doi:10.1016/j.chroma.2019.460409

Monitoring of cyanotoxins in water from hypersaline microalgae colonies by ultra high performance liquid chromatography with diode array and tandem mass spectrometry detection following salting-out liquid-liquid extraction

J Chromatogr A. 2019 Dec 20:1608:460409. doi: 10.1016/j.chroma.2019.460409. Epub 2019 Jul 29.

Authors

Maryam Hemmati¹, Carmen Tejada-Casado², Francisco J Lara², Ana M García-Campaña², Maryam Rajabi³, Monsalud Del Olmo-Iruela⁴

Affiliations

¹ Dept. of Analytical Chemistry, University of Granada, Av. Fuente Nueva s/n, 18071, Spain; Department of Chemistry, Semnan University, Semnan, 2333383-193, Iran.
² Dept. of Analytical Chemistry, University of Granada, Av. Fuente Nueva s/n, 18071, Spain.
³ Department of Chemistry, Semnan University, Semnan, 2333383-193, Iran.
⁴ Dept. of Analytical Chemistry, University of Granada, Av. Fuente Nueva s/n, 18071, Spain. Electronic address: mdolmo@ugr.es.

PMID: 31399210
DOI: 10.1016/j.chroma.2019.460409

Abstract

In this study two different analytical approaches have been developed to determine the presence of several cyanotoxins in saline water samples from a continental salt marsh. A salting-out assisted liquid-liquid extraction (SALLE) has been used in combination with ultra-high performance liquid chromatography-tandem mass spectrometry and UV-diode array detection (UHPLC-MS/MS and UHPLC-DAD). The target analytes are eight microcystins named MC-RR, MC-YR, MC-LR, MC-WR, MC-LA, MC-LY, MC-LW, MC-LF and nodularin (NOD), covering a wide range of polarities. The separation was achieved using a Zorbax Eclipse Plus RRHD C18 column (50 × 2.1 mm, 1.8 μm) in less than 7.5 and 5.5 min for UV and MS/MS detection, respectively. The mobile phase used consisted of water (solvent A) and acetonitrile (MeCN) (solvent B), both containing 0.01% of formic acid for DAD and 0.4% of formic acid for MS/MS detection, at a flow rate of 0.4 mL min^-1. The temperature of the column was set at 25 °C and 20 μL of sample were injected. The main parameters affecting the SALLE procedure were studied and the following optimum values were obtained: neutral pH, 2 mL of acetonitrile as extraction solvent and 1.2 g of ammonium sulfate as salting-out agent for 4 mL of water sample. The validation protocols for both methods were accomplished with real water samples obtaining LODs ranging from 1.0 to 3.4 μg L^-1 and 0.02 to 0.11 μg L^-1 for DAD and MS/MS respectively. Although the SALLE-UHPLC-DAD methodology is easier and cheaper than UHPLC-MS/MS significantly better detection limits were achieved with tandem mass spectrometry as well as allowing for unambiguous identification. Extraction recoveries were higher than 77.0% (except for MC-RR and NOD which were 53.2% and 54.3, respectively) with satisfactory inter-day and intra-day precisions (RSD below 13.3%).

Keywords: Cyanotoxins; Diode array detection; Saline waters; Salting-out assisted liquid-liquid extraction; Tandem mass spectrometry; Ultra-high performance liquid chromatography.

MeSH terms

Chromatography, High Pressure Liquid*
Environmental Monitoring / methods*
Limit of Detection
Liquid-Liquid Extraction*
Marine Toxins* / analysis
Marine Toxins* / isolation & purification
Microalgae / chemistry*
Microcystins / analysis
Microcystins / isolation & purification
Reproducibility of Results
Seawater / chemistry*
Tandem Mass Spectrometry*
Water Pollutants, Chemical / analysis
Water Pollutants, Chemical / isolation & purification

Substances

Marine Toxins
Microcystins
Water Pollutants, Chemical
microcystin