Clotted Blood specimens are not acceptable.
Avoid seafood consumption for 48 hours prior to sample collection. Tubes containing Heparin based anticoagulants are not acceptable. Studies have shown that cyanide has variable instability in biological specimens and is particularly unstable in some postmortem specimens. The loss of cyanide can be minimized by shipping the sample to the laboratory for analysis as soon as possible, preferably using refrigerated transportation and preservation using sodium fluoride / potassium oxalate (grey-top tube). The potential for increases in cyanide concentrations, although rare, have also been demonstrated and may be due to microbial action. Preservation with sodium fluoride may reduce this possibility. Tubes should be filled to prevent loss of volatile analytes into headspace. Ensure that container remains tightly sealed.