Determination of Fosetyl and Phosphonic Acid at 0.010 mg/kg Level by Ion Chromatography Tandem Mass Spectrometry

A new sensitive, fast, and robust method using ion chromatography tandem mass spectrometry (IC-MS/MS) for the determination of fosetyl and phosphonic acid in plant-derived matrices was developed. For compensation of matrix effects and differences in recovery rates the isotopically labeled internal standard (ILIS) ¹⁸O₃-labeled phosphonic acid was added to the samples prior to the extraction of the target compounds. The validation of the method for the matrices tomato, apple, lemon, sultana, avocado, and wheat was performed according to the actual EU guidance document SANTE/11945/2015. The precision and accuracy were determined in five replicates at spiking levels of 0.010 and 0.100 mg/kg with recovery rates between 76 and 105% and RSDs between 1.2 and 17.8%. In this paper, it was achieved for the first time to detect both fosetyl and phosphonic acid at the reporting level of 0.010 mg/kg most relevant for organic plant food commodities.

Organotin levels in seafood from Portuguese markets and the risk for consumers

Because of their ubiquity in the aquatic environment, the antifouling agent tributyltin (TBT) and other organotins (OTs) accumulate through the food chain, resulting in the occurrence of OTs in seafood products. Despite a high number of studies on the negative impact of TBT in female prosobranch gastropods, few works exist in Europe reporting the levels of these compounds in edible parts of marine organisms used in Human diet. Therefore, within the scope of an EU project OT-SAFE the levels of several OTs were evaluated in the most relevant seafood products for Portuguese consumers. Butyltins (BTs) have been detected in all analysed groups (fish, crustaceans, bivalves, cephalopods), whereas triphenyltin, tricyclohexyltin, monooctyltin and dioctyltin could not be detected and tetrabutyltin was present above detection limits in a single sample. In general, levels of BTs in edible parts of fish, crustaceans and cephalopods collected in Portuguese markets during this study are in the lower range of that reported for these animal groups from other locations (i.e. below 30ngg(-1) wet weight). In contrast, moderate to high concentrations have been observed in bivalves (up to 275ng TBTg(-1) wet weight). While most samples showed TBT plus DBT levels below the tolerable average residue levels (TARL), which may indicate low risk for consumer, four bivalve samples displayed BT levels above TARL, thus indicating that higher bivalve consumer groups may be at risk. The results found are discussed in relation to the potential risk for consumers and integrated with recent finds on the molecular targets of OTs in mammals.

Discovery of a transalkylation mechanism--identification of ethylmercury+ at a tetraethyllead-contaminated site using sodiumtetrapropylborate, GC-AED and HPLC-AFS

Although organolead as a gasoline additive is banned in most countries, contamination by organolead compounds is still present. Little is known about transformation reactions of organolead compounds and especially transalkylation reactions with other metals. Laboratory experiments to clarify transalkylation reactions between organolead and inorganic mercury, and investigations of sites, where organolead compounds were emitted, are reported. Under laboratory conditions, inorganic mercury is ethylated to ethylmercury+ in presence of tetraethyllead. These transalkylations take place very fast and almost completely. In soil samples from an industrial site contaminated with organolead compounds and inorganic mercury, EtHg+ was clearly identified in high concentrations (up to 46 mg Hg/kg dw). Furthermore, methylmercury+ was found in concentrations up to 27 mg Hg/kg dw. It is the first time, that a transethylation of an organolead compound to an organomercurial compound in the environment is reported. It must be assumed, that this transalkylation takes place at sites, where organolead compounds occur and Hg2+ is available. Thus, it will be necessary to assess the risk of these sites.