The Application Study Of MSP Technique In The Chromatographic Analysis Of Effective Components In TCM And DHA In Milk Powder

Sample preparation is a very important and essential step in. chromatographic analysis, it assists to improve separation and detection and hence affect the final analytic results. With the development of analytical chemistry, numerous novel techniques have been developed for sample preparation, among which, microwave sample preparation technique, which possesses significant advantages over conventional ones, such as a shorter sample preparation time, a reduction in organic solvent consumption, a supposed better recovery and reproducibility, amenable to automation, and the possibility of running multiple samples, has been widely accepted. In this thesis, the application of microwave sample preparation technique in chromatography analysis of medicinal materials and food samples was studied.The studies in this thesis are summarized as follows:1. For the first time, a microwave-assisted hydro-distillation (MAHD) method was compared with a conventional technique, hydro-distillation (HD), for the extraction of essential oil from traditional Chinese medicine (TCM) rhizoma atractylodis. The MAHD method was better than HD method in terms of rapidity (30 min versus 6 h), energy saving and product yield. By using gas chromatography-mass spectrometry (GC-MS) system the compositions of essential oils extracted by both methods were identified, and no obvious difference in the compositions and contents was observed, which indicate that MAHD can be a good alternative for the extraction of essential oils from plants.2. To analyze and compare the compositions of two traditional Chinese medicines Schisandra chinensis and Schisandra sphenanthera, Both volatile constituents (essential oil) and nonvolatile component (lignans) were extracted simultaneously by microwave-assisted extraction (MAE) followed by GC-MS analysis. Compared to the conventional methods, which use hydro-distillation (HD) and ultrasonic extraction (UE) for extraction of essential oils and lignans, respectively and individually, MAE method showed the significant advantages of rapidity (only 90 s was required) and convenience. This method was proven to be useful for the rapid comparison analysis of the compositions of Schisandra chinensis and Schisandra sphenanthera and can be used for quality control.3. Microwave-assisted extraction (MAE) as an efficient sample preparation technique coupled with gas chromatography (GC) with electron capture detection (ECD) for fingerprint analysis of Schisandra chinensis and Schisandra sphenanthera was reported for the first time. The developed analytical procedure was proved to be a rapid, simple and reliable method for identifying and differentiating samples by geographical origin and quality control.4. A microwave sample preparation procedure was developed for the determination of docosahexaenoic acid (DHA) in milk powder and dairy product samples. The developed procedure, which combined microwave-assisted digestion, microwave-assisted extraction and microwave-assisted denvatization into one single step, gave comparable results to the standard method (GB/T 5009.168-2003) involving separate hydrolysis, extraction and transesterification steps, but with less effort, time and organic solvent.