Stomach contents, liver, urine, feed, and any other suspected source of toxicant are the best samples for the detection of organophosphorus insecticides. This is an exception to the general rule of never freezing whole blood samples. Stomach contents and feed are the preferred samples when carbamate toxicity is suspected. The specimens needed to aid in the diagnosis of herbicide or fungicide poisoning are stomach contents, feed, other suspected sources of poison, liver, and kidney. Paraquat , a herbicide, has been implicated in a number of veterinary and human toxicoses.
Preferred specimens are urine, gastric fluid, and feedstuffs.
Liver, kidney, lung, and brain may also be analyzed. When checking for poisoning by metals such as lead, arsenic, or copper, samples of liver, kidney, urine, and gastric content are preferred. Heparinized whole blood, feed, and any suspected materials may also be helpful. Except in very immature plants, prussic acid accumulates largely in the leaves. It is best if samples submitted are not finely chopped.