Sample Preparation and Volumes Required per Assay

Proper sample collection is critical to sample processing and achieving valid results from the assays. Each principle investigator (P.I.) is responsible for his or her collection. If in doubt as to the appropriate procedure, please contact the core.

Depending upon specific protocol, a volume of whole blood is usually collected during specific time intervals in an EDTA coated tube. The blood is centrifuged for 15 minutes at 4° C. The plasma is aliquoted into the appropriate size, labeled tube for the core: 12 x75 mm (7 ml pp) for canine and human or 0.5 ml microfuge tubes for mouse. The appropriate protease inhibitor must be added to the sample:

• Catecholamines - EGTA-glutathione
• Pancreatic polypeptide, glucagon, or c-peptide - Trasylol
• GLP-1 - DDP-IV
• Active Ghrelin - call core

Recommended specimen storage tube for studies: Sarstedt tube (#55.526) 12 x75 mm polypropylene with push caps for human or canine studies. Sarstedt tube (#72.699) 30 x 7.8 mm tubes for mouse samples.

1. If samples are in bags, each tube should be labeled with Date, ID, Investigator's name, and type assay requested. The same applies if the samples are brought in boxes except tubes should be organized in the order to be assayed.
2. Complete the order submission form on line, make a copy, and place it in the container with your samples enclosed in a plastic bag if shipping. Place a copy of the form in the log book outside the 713 PRB if you are physically bringing them to the core.
3. Place samples in the designated retainer bins in the -20 freezer in 711 or 758

Samples should be boxed and organized in the order you wish them to be assayed. If they are bagged, the core will put them in chronological order. Do not use long, bulky labels. The sample tubes are placed in a robot for pipetting purposes. If the labels are wrapped around the tubes, they will not fit correctly into the rack for the robot. Please make your labeling as simple as possible.

Note: Patient labels can be denoted with a date and number. We do not need patient names. When samples are identified by name only, additional time is required to prepare the work list.

Samples should be stored at -20 to -70°C. To avoid multiple freeze/thaw cycles, samples must be aliquoted in tubes per assay (i.e.aliquot enough in one tube for insulin, another tube for glucagon, etc.)

Care must be used if heparin is used instead of EDTA as an anticoagulant, since an excess will provide falsely high values in some assays. Use no more than 10 IU heparin per ml of blood collected.

Samples with gross hemolysis or lipemia may yield false results.

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Vanderbilt Hormone Assay & Analytical Services Core
Vanderbilt University
2220 Pierce Ave
713 Preston Research Bldg
Nashville, TN 37232
(615) 936-1624 (V) (615) 936-1667 (F)
wanda.snead@vanderbilt.edu