From the testing perspective, it is easier to predict whether
the amount of drug found in a blood sample was likely to be
pharmacologically significant (i.e. likely to have produced an
effect on the subject). However, the flip side is that many drugs
are present in such low concentrations in blood samples that they
could be pharmacologically active, but labs might not be able to
detect the drug in the blood.
Because the kidneys collect, excrete, and concentrate drugs in
the urine, laboratories can detect most drugs in urine samples
much longer than in blood samples. Therefore, urine is the
preferred type of sample to test and is used for almost all
testing.
From the collection perspective, blood samples are easy to
obtain, while urine samples can be more difficult. If a urine
sample cannot be collected, then a blood sample is available.
Alcohol analysis is ideal for DUI/DWI case or suspected alcohol
consumption and the type of test used may have legal implications.
A specimen of whole blood is usually preferred. Serum may also be
used. However, the alcohol level is between 16%-18% higher than
whole blood.
1. Whole Blood: 5 ml whole blood, or 7 ml serum. Use EDTA
(lavender top tube) for most drug test(s).
2. Serum or Urine; 3.0 ml serum or 15 ml urine with Sodium
Fluoride preservative.
Method: Gas Chromatograph Flame-Ionization Detection (GC-FID).