Chemistry Guide

Therapeutic Drug Level Monitoring

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Trace Metal Analysis

Collection Instructions

Patients should refrain from eating seafood or taking antacids, vitamins with mineral supplements or herbal preparations for at least 3 days prior to specimen collection.

Fingerstick specimens: can be falsely elevated due to skin contamination; venipuncture is preferred for sample collection. First wash the draw site with soap and water, then dry thoroughly with a clean towel (not a recycled paper towel). Disinfect the draw site with isopropyl alcohol; do not use an iodine containing disinfectant. Use powderless gloves.

Whole blood or plasma: Use only a EDTA containing Navy blue top (trace metal free) vacutainer for collection. Navy blue top vacutainers are available from the Clinical Labs in room M521 (Moffitt Hospital). 

Do not use a plastic syringe to collect the specimen: the black rubber seals of the syringes contain varying amounts of contaminant metals. 

24 hour or random urine: Collect the sample directly in the acid-washed container obtained from Specimen Receiving. Do NOT use a metal bedpan or urinal. If an acid-washed container has not been supplied by the reference laboratory it must be prepared, using only devices made of polyethylene or polypropylene with metal-free plastic caps. Fill the device with a solution made from equal parts of metal-free 6N nitric acid (HNO3) and metal-free deionized water and let it stand for 30 minutes. Use ONLY nitric acid. Then rinse the containers or pipettes with 5 volumes of metal-free water to remove metal and acid residues.

Processing Instructions

Blood: Do not centrifuge or transfer to another container.

24 hour urine: To avoid contaminating the colleced specimen, do not measure the total urine volume until the aliquot has been obtained. Mix the urine collection vigorously, then pour the urine aliquot directly into an acid-washed shipping container or transfer it only with an acid-washed pipette. After the aliquot has been poured off, the volume of the remainder of the urine collection should be measured in the usual way (if the volume of the remainder is < 300 mL, increase the volume recorded by the amount of the aliquot sent for analysis

For additional information, see: Trace element analysis in biologic specimens in Techniques and Instrumentation in Analytic Chemistry, Vol. 15 Heuber, RFM and Stoeppler, M. Elseuier 1994

Additional Information

Trace metals are ubiquitous and often contaminate the apparatus employed for specimen collection and processing in amounts which can significantly alter the results, particularly if the sample is collected at a site of potential exposure such as the place of employment. The extent of contamination can be minimized by rigorous adherence to proper technique