Researchers from ARUP Institute for Clinical and Experimental Pathology and the University of Utah have tested to establish if D&S provides acceptable data when compared to an existing, validated, solid phase extraction (SPE) procedure for opioids in urine samples. In their findings, D&S underestimated oxycodone concentrations in a sample as much as 45% compared to the existing method utilising SPE sample preparation.
They emphasize the importance of investigating matrix effects early on in the method validation process on a large number of specimens, in order to determine whether D&S sample preparation is adequate or whether more comprehensive sample preparation such as SPE is necessary.
Or, as an end user puts it: "OK so you’ve just bought a $300k mass spec. Now you're literally going to urinate in the front end of it. Doesn’t sound so good now does it?"
Clark ZD, Strathmann FG, McMillin GA. Diluting and shooting yourself in the foot: Complications with sample-to-sample variations in signal suppression. MSACL 2013 podium presentation.