GENERAL LABORATORY NOTES for TOXICOLOGY LABORATORY

Studies have shown that thixotropic gels (serum separators) and plasticizers interfere with drug recovery and quantitation.  Therefore serum separator or plastic tubes should not be used for either toxicology or therapeutic drug monitoring studies. 

The Toxicology laboratory does not preserve chain of custody for specimens. hence, forensic studies (including forensic alcohols) should not be submitted to this laboratory. Instead, such samples should be submitted directly to the appropriate legal entity.  
 
Blood samples are saved for one week in the laboratory while urines are retained for three days. Additional (add-on) tests should be requested within these windows, if needed.
 
 It should be noted that the urine immunoassay drug panel is merely a general screen for drugs and drug classes. If it yields positive results, these should be considered to be presumptive only. The urine comprehensive drug panel includes a broad spectrum search for multiple drugs and drug classes. Positive results are confirmed whenever possible. It should be emphasized that, due to its small size and limited scope, the urine immunoassay drug panel may fail to detect many important drugs, including but not limited to tricyclic antidepressants, meperidine, phenothiazines, etc. A detailed listing of the constituents of the urine immunoassay drug panel and the urine comprehensive toxicology panel is included in the Toxicology tables that follow.
 
It should be noted that the plasma alcohol screen is a non- specific screen for ethanol and generally fails to detect other alcohols such as methanol and isopropanol. If the latter agents are suspected, please order the alcohol panel (which includes a quantitative measurement of methanol, ethanol, acetone, and isopropanol). If ethylene glycol is suspected, please order it specifically since it will not be detected by neither of the above.