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).