Visualisation of sampling error effects in near infrared analysis - comparison betwen Petri dish, roll bottle and spiral sampler

With spectroscopic methods, e.g. near infrared (NIR) analysis, using a constant beam aperture, the effective scanning footprint will be different for a spinning Petri dish, a rolling bottle and a new spiral sampler configuration. This will significantly influence the analytical accuracy and precision of a NIR analytical determination of heterogeneous materials, for example barley with differing protein contents. Here we present the results from a bench-top experiment that evaluates the total analytical bias and precision characteristics for three alternative sample presentation approaches using a mixture of two plastic polymer pellets as a test material with significant heterogeneity. After removal of all incorrect sampling errors (ICS), there are still significantly varying correct sampling error [Fundamental Sampling Error (FSE) and Grouping and Segregation Error (GSE)] uncertainties associated with these standard analytical approaches—but there is a clear winner.