Jeanne Carr wasn't always in charge of a major clinical lab facility with automated instruments — and that may be her greatest strength. Carr, technical director of molecular microbiology and virology at St. Jude Children's Research Hospital, says that her experience in performing these kinds of assays manually in the past is a great asset when it comes to troubleshooting problems that crop up in the lab today.
"I draw on a lot of knowledge from doing things manually," says Carr, whose lab mostly works on homebrew molecular microbiology assays and some FDA-cleared kits. "That has helped over the years." That experience also means she's in demand for doling out words of wisdom about how to figure out what may be causing issues in other people's clinical labs — something she did during a presentation at this year's American Association for Clinical Chemistry conference. With highly automated instruments that make calls for you, there may be problems behind the scenes that you can't see unless you can get at the raw data, Carr says. Understanding the principles of how the machines are supposed to work can help you tell whether the raw data is actually on target and a match for the auto-call.
For anyone who's gotten a questionable result, Carr says the first step is to ask whether a reagent, control, or standard changed on this particular run "compared to the last one that was successful." If nothing did change, you'll want to look into maintenance records for the instrument in question. Is it in compliance with the manufacturer-recommended maintenance protocols? Following those guidelines as closely as possible can save a lot of headaches down the road.
Carr says the next step is to look into the experiment itself to identify a problem. In work with microtiter plates and other low-volume substrates, "anything out of the ordinary with volumes" can mess up the work. Check for pipetting errors and calibration, and also look at the reaction vessels "for bubbles or anything that might interfere with the detector," she adds.
When all else fails, check the factors that you might not normally consider — room temperature, power supply, and water quality. With larger analyzers, electrical requirements are more precise, and some machines will need dedicated circuits, Carr says. Instruments sharing a circuit might be cycling at the same time, for instance, and could derail your assay without your knowing it.