Strawberry leaves are not only for herbal teas with a beneficial effect on human health, but are also now helping analytical chemists in checking the accuracy of laboratory sample analyses. The R-lab control laboratory of the Department of Analytical Chemistry, UP Faculty of Science, cooperated with the company Analytika on the characterization of matrix certified reference material (CRM) from strawberry leaves. Via the CRM, chemists can compare their own results of analyses of this material. In case of any discrepancies, the sample analysis procedures can be corrected to give the most accurate results.
“A good analytical chemist often wonders if the results of their analyses are reliable. In addition to careful work or good knowledge of the methods and devices used, the reliability of the results can also be verified independently, precisely through the analysis of CRM samples,” David Milde explained, on the role of certified reference materials. CRMs can be simply imagined as real samples for which the exact result is known even before the analysis of their composition in the laboratory. “After analysing the CRM sample, the laboratory’s results are compared with the values stated in the certificate for this matrix material,” added Milde.
For example, for the analysis of elements in plant samples, the R-lab control laboratory has already obtained CRM samples for cabbage, green algae, corn flour, tea, pine needles, and lichen. “The CRM of strawberry leaves will help us expand the portfolio. Not all CRMs have certified values of concentrations or content of all elements that we analyse,” noted Radka Pechancová.
There are several groups of certified reference materials. Probably the most important are “matrix reference materials”, which due to their composition are most similar to ordinary samples. The demand for matrix reference materials now exceeds their supply on the market. “Most analytical chemists would like to choose from several corresponding CRM samples for their specific area of research or analysis, but they are not often available. Therefore, it is desirable to perform certification of other CRMs, including biological and environmental matrices,” added Pechancová.
According to Jitka Součková, the reference material certificate can be compared to a birth certificate. In addition to the certified composition values, an analytical chemist can find an abundance of necessary information there, such as laboratory storage conditions, data on the minimum amount of sample required for analysis, or how long the certified values are valid. “Some certificates also provide details on the preparation of the CRM and the methods used to obtain certified values. This information helps us in choosing a suitable CRM. Due to the relatively high price of reference materials, it is necessary to have as much information as possible before purchasing, and this can be obtained from certificates,” specified Součková.
The use of CRMs plays a key role in analytical chemistry, which is why R-lab experts participated in the inter-laboratory certification study of the matrix CRM of strawberry leaves. “In the Czech Republic, we could count the number of manufacturers of reference materials on the fingers of one hand, so we decided to support one of the manufacturers, the Analytika company. We consider the invitation to this inter-laboratory study to be a recognition of our expertise and analytical skills. By successfully involving the R-lab control laboratory, we also verified the correctness of setting up a quality management system for the determination of metals in plant materials, with which we have many years of experience in our laboratory,” added Tomáš Pluháček.