Seldom do researchers deliberately include samples of a well-analyzed material disguised as an unknown, although we encourage them to do so. We are seldom asked to analyze replicate subsamples. We provide an estimate of the analytical uncertainty with each datum we obtain. The estimate is based both on counting statistics and our experience with analyzing each particular element. Actual precision can only be judged by analyzing replicate samples, however.
Extra samples cost extra money, which researchers are usually reluctant to spend.
We are similarly reluctant, after the fact, to speculate on the actual accuracy and precision of the data we provide when a better-designed experiment could have provided data that would have avoided the need for speculation. The goal of these GRS analyses is to obtain high-precision data so that we can check the accuracy of a particular batch of samples against averages obtained over many years. We also suggest, especially if you intend to submit a large batch of samples, that a few duplicate samples be included in each batch. Feel free to include samples of GRS's. If it is important to you to know what subtle compositional differences may exist among a small set of related samples, identify these samples for us and we will attempt to radioassay the samples in a way that optimizes precision.