This would result in an increase in the gradable PT challenges. The requirements for PT state that for each regulated analyte, there must be at least three yearly challenges consisting of five samples each for a total of 15 yearly samples per analyte. Most PT samples for quantitative analytes are received in a lyophilized form. It is critical that reconstitution instructions are followed precisely. Well calibrated pipettes and reagent grade water, if no diluent is supplied, should be used to reconstitute the sample and are critical to good PT results.
Some samples require time to dissolve after reconstitution and before analysis.
Analysis should occur on the same day as reconstitution in case any of the analytes have limited stability. The PT samples should be refrigerated when not undergoing analysis. Any unused portion of the PT sample should be frozen in case there is a PT failure and troubleshooting of the analysis is necessary. Unsatisfactory performance can also occur if the laboratory fails to participate in a PT program for an analyte that is performed. This assumes that there is a PT program available for that analyte.