Pesticide and Antibiotics residues in food 

Pesticides in the broader sense are considered crop protection products. To combat blight on grape vines a crop protection product is used, and to combat worms in apples, pears or also the cankers in cabbage, a pesticide is used. These substances are applied directly onto the plant and also pass through the soil along with the nutrients, inside the plant and therefore inside the fruits.

Residues of drugs or transformation products of those are often found in human excretions. Also leftovers of drugs are often discarded into the wastewater by the public. The drawn from the wastewater sewage sludge is partially distributed as fertiliser onto fields. It is also common knowledge that antibiotics are added to animal feed.

Remainders of these again are applied across fields as dung and liquid manure. Up until now it was not clear though, if these substances are absorbed by plants and passed along in the food chain.

Tomato plants are treated with various pesticides. The spray chemicals end up directly on the fruit, as well as directly inside the soil and therefore indirectly via the nutrient transport inside the fruit.  Also the use of organic fertilisers from animal husbandry is widely spread.

Consequently the necessity arises to inspect food in regards to possible residues. Often the sought after substances are temperature sensitive. This plays a major part during the preparation of the sample.

Preparing tomatoes cryogenically for analytical purposes is possible with the Mortar Mill PULVERISETTE 2, if the tomatoes are chopped into small chunks and embrittled with liquid nitrogen. For this particular application Fritsch offers as accessories for the mortar mill a stainless steel mortar bowl. This bowl can be cooled down with liquid nitrogen and even during the comminution additional liquid nitrogen may be added. Hereby a complete cryogenic comminution with liquid nitrogen is possible. After a few minutes a fine homogenous powder is obtained. From a sample prepared in this manner, a small representative amount can be weighed in for analysis or for the further processing steps.