Determination of triazine herbicides in seaweeds: Development of a sample preparation method based on Matrix Solid Phase Dispersion and Solid Phase Extraction Clean-up

A method using dual process columns of Matrix Solid Phase Dispersion (MSPD) and Solid Phase Extraction (SPE) has been developed for extracting and cleaning-up of nine triazine herbicides (ametryn, atrazine, cyanazine, prometryn, propazine, simazine, simetryn, terbuthylazine and terbutryn) in seaweed samples. Under optimized conditions, samples were blended with 2g of octasilyl-derivatized silica (C8) and transferred into an SPE cartridge containing ENVITM-Carb II/PSA (0.5/0.5g) as a clean up co-sorbent. Then the dispersed sample was washed with 10mL of n-hexane and triazines were eluted with 20mL ethyl acetate and 5mL acetonitrile. Finally the extract was concentrated to dryness, re-constituted with 1mL methanol:water (1:1) and injected into the HPLC-DAD system. The linearity of the calibration curves was excellent in matrix matched standards, and yielded the coefficients of determination>0.995 for all the target analytes. The recoveries ranged from 75% to 100% with relative standard deviations lower than 7%. The achieved LOQs (