Are analytical standards and reagents really reliable?

Quality assurance is one of the major challenges in analytical chemistry, whatever the scope of application. The quality of analytical standards is very seldom questioned; however, sometimes odd results are obtained, and all the other potential sources of discrepancies are eliminated. So, we investigated the reliability of three analytical standards and reagents implemented for radiochemical and chemical characterizations of nuclear waste. In particular, this work examined the purity of a source of tritiated dodecane, the trueness of a certified concentration value and the purity for a diethylenetriaminepentaacetic acid (DTPA) reagent and the trueness of a certified concentration value for a multi-anion standard used in an interlaboratory comparison exercise. It was shown that the source of tritiated dodecane contains 60 % of tritiated impurities. The trueness of the DTPA concentration certified by the supplier was questioned due to the presence of impurities in the solution. It was proven that the long-term stability of the multi-anion standard was not guaranteed for nitrite. The results clearly demonstrated that, despite the certificates delivered by the suppliers, caution has to be taken toward the reliability of the analytical standards and reagents.