Use of multiple lines for improving accuracy, minimizing systematic errors from spectral interferences, and reducing matrix effects in MIP OES measurements

Bismuth-based medicines, which are generally available without prescription, are used for a variety of purposes including stomach relief, diarrhea, and cold sores. The determination of Bi in these types of medicines using MIP OES is considered easy, due to the relatively high concentrations of this element. However, high dilution factors can lead to systematic errors and thus low precision. Furthermore, the drugs, excipients, and other active pharmaceutical ingredients (APIs) present in these products can cause spectral and matrix interferences. The present study evaluates the use of multiple spectral lines as a strategy to avoid analytical difficulties. For comparative purposes, hydride generation and standard additions techniques were also evaluated. The results demonstrated the feasibility of using the sum of the intensities of multiple lines to improve accuracy, minimizing systematic errors from spectral interferences and matrix effects, employing simple calculations in a data spreadsheet. The accuracies, calculated based on labeled values, varied from 89.2 to 98.8% and from 72.2 to 124% for direct analysis without and with standard additions, respectively, from 73.2 to 114% for hydride generation, and from 89.8 to 101% for the multiple lines sum method.