Abstract
The toxic glycoalkaloids α-solanine and α-chaconine are produced in all parts of the potato plant, and post-harvest potato tubers may represent a source of soil and water contamination. A new method was developed for extraction and purification of α-solanine in soil samples. Soil samples were extracted with THF : H2O : ACN : CH3COOH (50 : 30 : 20 : 1) and the extract purified by SPE before HPLC determination of α-solanine. The limit of detection was 2.4 mg of α-solanine kg−1 soil. The new procedure was used for determination of α-solanine in spiked soils with varying content of organic matter and texture. Recovery for soil samples spiked with α-solanine 1 h before extraction was 61–68% for soils low in organic carbon (<2.2% C), and to 47% for soil high in organic carbon. Similar recoveries were obtained for α-chaconine. The reproducibility of the method shown by the relative standard deviation varied from 1.7 to 10.1%, depending on the soil type. No decrease in extractable α-solanine was observed until day 17 for soil samples spiked with pure α-solanine kept at 5°C, while the content in samples spiked with potato materials showed a faster decline. This indicates that the degradation and/or ageing processes proceed relatively slowly for glycoalkaloids in soil matrices. This is the first method reported for determination of potato glycoalkaloids in soil.
Acknowledgements
The authors wish to thank Kristina Egede Budtz for skilled technical assistance with the laboratory experiments.