珍珠是名贵的装饰品和中药材, 在我国对其已有2000多年的应用历史。 研究发现, 贝壳内层的化学组成与珍珠相似, 主要含有碳酸钙和各种氨基酸。 贝壳粉也可在临床上做药用, 但其药用价值远低于珍珠粉。 然而, 珍珠粉和贝壳粉外观特性极为相似, 元素组成和形貌检测无法对其进行有效地鉴别。 由于贝壳粉的成本低, 常常冒充珍珠粉流入市场, 侵害了消费者的利益。 本研究通过珍珠粉和贝壳粉在不同温度下煅烧一定时间后显微红外反射光谱的差异实现珍珠粉真伪鉴别。 实验结果表明, 在一个大气压下经过400 ℃煅烧30 min后, 珍珠粉中文石型碳酸钙部分转化为方解石型, 而贝壳粉中文石型碳酸钙完全转化为方解石型。 这种不同的相转变过程可以被显微红外反射光谱很好的区别。 因此, 可在此条件下利用红外反射光谱鉴别珍珠粉和贝壳粉相变差异。 和传统的透射式红外光谱法相比, 这种显微反射红外光谱法无需压片制样、 快速灵敏。 本研究也讨论了该方法针对其他常见伪品的适用性, 如牡蛎粉和石决明粉, 结果表明该方法能够简单、 高效和准确地鉴别珍珠粉真伪。

Pearl is a precious ornament and traditional Chinese medicine, which application history in China is more than 2000 years. It is well known that the chemical ingredients of shell and pearl are very similar, which all of them including calcium carbonate and various amino acids. Generally, shell powders also can be used as medicine; however, its medicinal value is much lower than that of pearl powders. Due to the feature similarity between pearl powders and shell powders, the distinguishment of them by detecting chemical composition and morphology is very difficult. It should be noted that shell powders have been often posing as pearl powders in markets, which seriously infringes the interests of consumers. Identification of pearl powder was investigated by microscopic infrared reflectance spectroscopy, and pearl powder as well as shell powder was calcined at different temperatures for different time before infrared reflectance spectroscopy analysis. The experimental results indicated that when calcined at 400 ℃ for 30 minutes under atmospheric pressure, aragonite in pearl powder partly transformed into calcite, while aragonite in shell powder completely transformed into calcite. At the same time, the difference in phase transition between the pearl powders and shell powders can be easily detected by using the microscopic infrared reflectance spectroscopy. Therefore, based on the difference in their phase transition process, infrared reflectance spectroscopy can be used to identify phase transformation differences between pearl powder and shell powder. It’s more meaningfully that the proposed infrared reflectance spectroscopy method was also investigated for the applicability to other common counterfeits, such as oyster shell powders and abalone shell powders, and the results show that the method can be a simple, efficiently and accurately method for identification of pearl powder.