You've just decided to develop a solid phase extraction (SPE) method for a new assay in your lab. However, there are so many decisions to be made! Which company to choose? Which product to use? Polymer based sorbent or silica based? Cation or anion exchange? While this seems incredibly difficult, it doesn't have to be that hard!
Evaporative crosstalk is contamination that occurs during evaporation of the elution solvent after SLE or SPE extraction. Volatile analytes evaporate, then redistribute in adjacent wells in a 96-well plate. This can generate false positive results and require re-extraction of patient specimens. Addition of HCl in methanol (MeOH) to produce the salt of volatile compounds like sympathomimetic amines is used to control crosstalk. The type of evaporator, conditions and solvents used can all contribute to crosstalk.
Before we get into our extractions, we need to set up our LC/MS to detect our analytes of interest. The LC will provide the chromatography - or separation of our analytes - and the MS will support detection. So which one do we evaluate first? Well, if you can’t “see” the analytes, what good is perfecting their chromatography? So, first, let’s get the MS focused, or tuned, for optimum analyte detection.
When trying to develop a new method for the detection of a drug panel, you need to refer to reliable sources to learn all you need to know regarding your analytes. For this post, we’ll go in detail through the search process with analytes like naloxone, buprenorphine, norfentanyl and methadone using urine as our matrix of focus.
The sole purpose for method development is to construct a robust and analytically sound method that will not just pass the barriers of validation, but provide physicians and patients with sound and reliable results. But where to start?
