Elaboration and application of a graphite furnace atomic absorption spectrometry-based method to quantify chromium in tubers of Dioscorea polystachya

The Chinese yam (Dioscorea polystachya) is of interest as a foodstuff and as a medicinal plant due to its blood sugar mediating potential. Given the importance of its cultivation, four different cultivation techniques were investigated concerning the chromium content of yam tubers. A method was developed to quantify chromium (λ = 357.8687 nm) by graphite furnace atomic absorption spectrometry (GF AAS). During method optimization, the focus was on improving the pyrolysis and atomization temperatures using various modifiers. Magnesium nitrate was found suitable for the analysis. The pyrolysis and atomization temperatures were 1300 °C and 2300 °C, respectively. The elaborated method exhibited a limit of detection and quantification of 0.57 µg L−1 and 1.36 µg L−1, respectively. The characteristic mass amounted to 1.77 pg. In addition, an accuracy rate of 95–105% (precision 2–5%) documents the performance of the method. The analytical procedure was ultimately applied to determine the chromium content in tubers of yam. For this purpose, tubers from the four cultivation techniques mobile raised beds (MRBT), trench cultivation (TCT), mound beds (MBT), and gutter cultivation (GCT) were used. Absolute differences in chromium concentrations were found in extracts from these tubers, ranking in the order GCT < TCT < MRBT ≪ MBT. The varying contents of chromium could be attributed to the different cultivation techniques. Thus, GF AAS contributes to monitoring the quality of yam. A way to make yam cultivation more productive has been paved, and hopefully, this will also further expand its potential as a medicinal plant in the future.