| Natural animal silks, mainly from spiders and silkworms, have outstanding comprehensive mechanical properties. However, the artificial silk fibers are rather poor and cannot compete with the natural ones. The main reason is thought to be the difference between the ariticial and natural spinning process. Nowadays, the studies of the spinning mechanism are focus on B. mori silkworm and spider and lots of evidences have proved that metallic ions play an important role during such a spinning process. Antheraea pernyi silkworm is kind of wide silkworm that can produce large amount of silks. The use and properties of A. pernyi silk is similar to Bombyx mori silk (domestic silkworm silk), but its amino acid sequence is similar to that of major ampullate silk of spider. Thus it is necessary to know more about the metal elements and their content in A. pernyi silkworm to make it clearer about the spinning mechanism, and provide more accurate theoretical guidance on the artificial spinning.Dry ashing and acid digestion method tried on the sample preparation were studied, but only the dry ashing was adopted. The technique of dry ashing showed low blank values and had little interference, thus could detect the metal elements in A. pernyi silk gland and fiber effectively.In this thesis, Na, Mn, Mg, K, and Ca in A. pernyi silk gland and fiber were determined by FAAS (Flame Atomic Absorption Spectrometry), while Cu, Fe, and Al were determined by GFAAS (Graphite Furnace Atomic Absorption Spectrometry). Operating parameters were optimized for the metal elements introduced to the instrument. The calibration graphs of standard curve and linear equations were also conducted. The recovery of these elements was87.5%-120.0%and the detection limit was0.2-45μg/g, respectively.In this thesis, deuterium lamp was used to correct background absorption. During the measurement, calcium may form stable CaO compound in the air/acetylene flame, therefore a hotter nitrous oxide/acetylene flame was used to overcome such a kind of chemical interference. In addition, when determining calcium, ionization interference was observed in nitrous oxide/acetylene flame, so an excess of easily ionizable metal, such as cesium was added to eliminate such interference. Moreover, the blank values were strictly controlled during the sample analysis to ensure the accuracy of the results.The results indicated that there were at least eight metal elements, i.e., Na, K, Mg, Ca, Mn, Cu, Al, and Fe in A. pernyi silk gland and fiber. In the silk gland, K had the highest content, Ca, Mg, and Mn were in the middle, and Na, Cu, Al, and Fe were very low. The distribution of K, Ca, Mg, and Mn in A. pernyi silk gland was found to be similar to that of B. mori, indicating the K ions were favorable to the conformation transition of silk fibroin and the formation of silk fiber, and Ca, Mg, and Mn ions was favorable for the silk fibroin to be stably stored in sol state. In addition, Fe and Al were also favorable for the fiber formation. Furthermore, Na and Cu seems have little effect on the silk formation of A. pernyi silkworm.The most contents of these eight metal elements in the cocoon silk of A. pernyi silkworm had the same magnitude as they were in silk gland, only Mg and Ca had a large difference that may due to the complicated wide environment. However, by considering the similar effect of Mg and Ca in the spinning process of A. pernyi silkworm, these two metal elements may be replaced from each other. In the meantime, the contents of metal elements in sericine were also measured briefly. The results showed that the content of most metal elements, especially those had low content, such as Na, Cu, Fe, and Al did not have obvious difference to the value in the silk gland. However, the contents of K, Mg, and Ca in sericine were one magnitude lower than that in silk gland, which was suggest the importance of K, Mg, and Ca ions in the spinning process of A. pernyi silkworm. |
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