A few years back during my 3 month trip to China I remember noticing enormous number of pharmacies that sold traditional Chinese medicine. Everywhere I went in China they looked more or less the same just like an old-fashion pharmacy of the 1920s here in the West with its wooden drawers and cabinets full of dried herbs, flowers, insects, animal body parts, and other things that were truly scary looking. The “prescriptions” are filled on the spot by grounding ingredients in a traditional stone mortar and pestle.
Traditional Chinese medicine or TCM, being natural materials, appeal to many people, because they are believed to have high activity, low toxicity, and rarely cause complications. This growing popularity drives the research of TCM in China especially in the field of analytical chemistry in order to control the quality of medicine.
Analytical chemists from Fudan University (Shanghai) developed a new method to characterize active ingredients in chrysanthemum flower – the dried flower head of Chrysanthemum morifolium. It has reportedly been used in China since 1500 BC to cure wind-heat, the liver’s hyperactivity (in terms of Qi), and improve eyesight. Dry Chrysanthemum flower contains about 0.3% of essential oil consisting of 31 components including three active compounds: eucalyptol, camphor, and borneol.
The conventional quality control of Chrysanthemum is GC/MS ( Gas Chromatography/Mass Spectrometry) analysis of eucalyptol, camphor, and borneo from steamed distilled essential oil. This method requires a relatively larger amount of sample (50â?? 1000 g) and takes about 8 hours due to a steam distillation process, not a very friendly method.
However, the team from Fudan University used a novel approach by employing a fast and powerful sample preparation technique known as pressurized hot water extraction (PHWE ) that was recently developed by a group of American scientist. The novelty of this method enabled Chinese chemists to reduce the extraction time to 5 min , reduce sample size to 0.005 g and completely eliminate the need for organic solvents.
The hot water extraction process yields about 10 ml of the aqueous extract that is cooled and filtered. Then 2 ml of it undergoes 15 min headspace solid-phase microextraction followed by GC/MS of analytes desorbed from polydimethylsioxane (PDMS) fibers. The method validation including relative recovery, repeatability, detection limit, and relative accuracy was also studied. The relative recoveries were: 86% for eucalyptol, 90% for camphor, and 87% for borneol. The results indicated that this method provided a good recovery.
In the end , the Fudan University group should be proud of their work. This new method significantly cut the analysis time to 20 min from 6-8 hours and reduced the sample size to only 50 mg.