In chronic arsenic poisoning the following samples can be sent for laboratory examination,except -

Arsenic is rapidly cleared from the blood and is distributed to various organs and tissues, where it is detectable for prolonged periods. Blood sample is thus of use only in a case of acute poisoning, but not in chronic poisoning. In chronic poisoning arsenic is found in hair, nails, bones, skin etc. and its detection is possible when any of these structures is available - Parikh