AWWA WQTC60549

This study reports on a rapid and sensitive method for the determination of six algal toxins that was developed using liquid chromatography separation with tandem mass spectrometric detection (LC/MS/MS). Six algal toxins (Cylindrospermopsin toxin, Anatoxin-a, Nodularin, and Microcystins LR, YR and RR) were separated using reverse phase chromatography using a formic acid/methanol gradient. Electrospray ionization in both negative and positive mode was used for all compounds. For the determination of soluble algal toxins, two mL of water were filtered through a 0.45 µm membrane filter then stored at 4°C until analysis. To determine total algal toxins, 125 mL of sample were frozen at -80°C then thawed three consecutive times, and then filtered as with the dissolved fraction. An injection volume of 20 µL was used for all analyses. A reporting limit of 0.50 µg/L has been established for all target algal toxins. Water samples were collected from Lake Mead, Nevada where a Cylindrospermopsin algal bloom had been reported. Despite the fact that the sampling took place after the bloom had receded, Cylindrospermopsin toxin was still detectable, yet less than the reporting limit of 0.05 µg/L. An extensive monitoring program has now been established at Lake Mead, and preliminary results are presented. Includes tables, figures.