Rapid determination of mesotrione, atrazine and its main degradation products in selected plants by MSPD - HPLC and indirect estimation of herbicides phytotoxicity by chlorophyll quantification

A matrix - solid phase dispersion coupled with high-performance liquid chromatography (MSPD - HPLC) method was developed for the isolation and determination of mesotrione, atrazine as well as its degradation products: hydroxyatrazine, deisopropylatrazine, desethyldesisopropylatrazine and deethylatrazine in plant. The method was applied to monitor not only herbicide accumulation levels but also the influence of herbicides accumulation on chlorophyll concentration in crops popular in moderate climate: rape (Brassica napus), radish (Raphanus sativus), carrot (Daucus carota), parsley (Petroselinum sativum), weeds: grass (Gramineae Juss), chamomile (Chamaemelium nobile), thistle, (Carduus L.) and an aquatic plant hornwort (Ceratophyllum demersum L.). Chlorophyll was chosen as a biomarker of plant exposure to triazine and triketone herbicides because these compounds disturb the synthesis of chlorophyll that leads to reduction of this pigment content in plant tissues, which is manifested by whitening of the leaves and finally necrosis of a plant.The MSPD technique coupled with the HPLC-DAD lowers the detection limit of the aforementioned compounds below their maximum residual level (MRLs) 10ng/g, according to European Union (Commission Regulation No 822/2009), the limits of quantitation (LOQ) were in the 1.0-3.0ng/g range, while the recovery of analytes was 67-95%. All investigated herbicides turned out to be toxic for the considered terrestrial plant species. The herbicides at concentration of 100ng/L, the maximum allowable concentration (MAC) in drinking water (Directive 98/83/EC), were innocuous for hornwort, an aquatic plant.