Detection Of Sulfur Fumigated TCM Decoction Pieces Using SERS & Study Of The Raman Substrates’ Application

The Raman Spectrometry technology is a molecular structure characterization technique that based on Raman effect, which signals are from rotations and vibrations of molecules. The surface-enhanced Raman scattering(SERS) effect is that when some molecules are adsorbed by coarse metals(such as silver, copper and gold, etc.), the Raman scattering signals from adsorbed molecules are much stronger than normal Raman scattering(NRS), which greatly improves the limit of detection(LOD) for 4 to 10 orders of magnitude higher. Nowadays, SERS becomes an important detection method of analytical fields, and its applications cover food and drug industries, etc.In this article, SERS was applied to rapidly detect Traditional Chinese Medica(TCM) decoction pieces, in order to judge whether it is sulfur fumigated. The Raman substrates were also preliminarily investigated, and an innovative method using SERS without any pretreatments was built to detect residual sodium sulfite in TCM decoction pieces. The main contents are listed below.1.Reviewed the development of SERS, as well as its applications in fields of food and drug industries,which are relevant to TCM.2. A new Surface-Enhanced Raman Scattering(SERS) was developed for direct detection of residuary sodium sulfite in TCM decoction pieces only by dropping solution of gold particles onto surface of them. No pretreatment process in this simple method, and so the method is extremely suitable for on-site rapid detection. 10 groups of TCM decoction pieces including sulfur fumigated and non-sulfur fumigated ones were detected, and dramatic difference were obtained.3. Preliminary investigation of SERS to detect sulfur fumigated TCM decoction pieces on quantitative aspect was carried out, which involved two attempts:(1). Used SERS to detect sulfur fumigated TCM decoction pieces solutions extracted by water, and compared the result with calibration curves of sodium sulfite standard solutions that built based on the same method, in order to achieve quantitative detection;(2). Dropped sodium sulfite standard solutions with different concentrations on non-sulfur fumigated TCM decoction pieces, and calibration curves were obtained by using SERS detection. These calibration curves were compared with the result of sulfur fumigated TCM decoction pieces’, in order to achieve quantitative detection. However, both attempts did not achieve the expected goal.4.SERS detection is affected by numerous factors. One of these important factors was the performance of nanoparticles that used to enhance the intensity of Raman signal. On account of opinions above, studies on the applications of shell-isolated nanoparticles, a new Raman substrates, produced by a new method-Atomic Layer Deposition, to detect pigment, were carried out as steppingstones for future works on quantitative detection.