The proficiency test evaluates the performances of laboratories with respect to their ability to quantify dithiocarbamates as CS2 resp. dithianon.
The test materials are prepared of organic pears and spinach. The raw material is free from incurred residues (< 0.01 mg/kg) of dithiocarbamates and dithianon (pear only). The pears resp. spinach are homogenised and spiked thereafter. Liquid nitrogen is used throughout the whole process of preparation, spiking and bottling of the test material to keep the material in deep-frozen condition. The test material consists of a powdery ice. Therefore, sub-samples can be taken without thawing the test samples.
The sophisticated process of test material preparation at very low temperatures avoids a degradation of temperature sensitive parameters like thiram and thus the loss of CS2.
The quantification of dithianon is offered as an additional module in this ring test. A test material of pears is prepared as described above related to the dithiocarbamates.
Reporting limits of 0.01 mg/kg are required related to dithiocarbamates as well as related to dithianon.