Metal element contents in silk gland and silk fiber of Bombyx mori silkworm

The contents of metal elements in silk gland and silk fiber of B. mori silkworm have been detailedly analyzed by proton induced X-ray emission (PIXE), inductively coupled plasma mass spectroscopy (ICP-MS) and atomic adsorption spectroscopy (AAS). The results showed that Na, Mg, K, Ca, Cu, Zn, Fe and Mn were found in both silk gland and silk fiber, while Rb and Sr were also possibly contained. The contents of these elements varied from silk gland to different kinds of silk fibers (i.e. cocoon silk, forced-drawn silk and degummed silk), and the changes of element content might correspond to the effect of these metal elements on the spinning process (conformation transition of silk fibroin) of B. mori silkworm.