For tissue:

Weigh out 40mg of tissue in liquid nitrogen making sure the samples remain frozen until delivery. Please ensure that all samples are within 10mg of each other. Samples should be delivered in 1.5ml micro-centrifuge tubes.

For plasma and serum:

Provide 40µl plasma/serum frozen in 1.5 ml micro-centrifuge tubes and deliver on dry ice. Please ensure that all volumes are consistent.

For plated cells:

Whole cells should be washed twice on plates with ice-cold PBS, then twice with ice-cold water. Freeze cells by floating the plate on liquid nitrogen: hold the plate above the liquid phase for a few seconds to prevent the plate from cracking. Well-powered experiments generally require at least 6 replicates per condition. For many cell lines, nearly-confluent 6-well plates provide enough sample to obtain full metabolite coverage.