中医临床常用生石膏(CaSO4·2H2O)治疗发热疾病, 通过对石膏显微晶体特征和微量元素特征的研究, 提出了微量元素锶(Sr)是石膏降温重要影响元素的假说。 实验通过偏光显微镜(optical polarized light microscopy, OPLM)、 X射线衍射(X-ray diffraction, XRD)、 电子探针微区分析(electron probe microanalysis, EPMA), 电感耦合等离子体质谱(inductively coupled plasma mass spectrometry, ICP-MS)等方法分析了来自五个产地33批石膏药材的显微晶体结构和微量元素组成。 OPLM分析结果显示: 石膏的显微晶体形态主要为长柱状和纤维状, 且和石膏的产地密切相关。 按传统要求认为品质好的样品, 其显微颗粒较大。 XRD分析结果显示: 除1批样品含有石英杂质, 其余样品在XRD下均未见其他矿物杂质。 EPMA分析结果显示: 石膏样品中主要矿物为石膏, 次要矿物为硬石膏, 两者呈现共生关系。 微区图像中的硬石膏矿物没有确定的晶形, 硬石膏和石膏的接触面都是不规则状曲线, 推测样品中包含的硬石膏不是原生的硬石膏, 而是石膏矿物在成矿后期转化而来。 ICP-MS分析结果显示: 微量元素锶(Sr)在石膏中含量较高, 是所有微量元素中绝对含量最高的, 与原始地幔中微量元素含量的对比结果显示, Sr元素在石膏样品中是最为稳定富集的微量元素, 它比原始地幔富集6倍以上, 最高到176倍。 石膏微区点位的CaO/SrO分析结果显示锶(Sr)元素在石膏中呈统计式均匀分布, 在石膏中主要以类质同象混入物的形式存在。 在随后进行的石膏水溶液中Sr元素含量测定的结果显示, 锶(Sr)在石膏煎煮液及石膏混悬液中的溶出量达到了理论值的2～4倍。 临床上大剂量使用石膏并先煎的方法, 可以促进Sr2+的溶出。 因为Sr2+具有抑制Na+的作用, 据此提出石膏降温的假说: 应用石膏降温时, Sr2+和Ca2+同时溶出, Sr2+抑制机体对Na+的吸收, 同时增加对机体Ca2+的供给, 共同调节发热的正调节介质Na+/Ca2+的比值, 石膏降温的物质基础是Sr元素和Ca元素共同的作用。

Clinical Chinese Medicine commonly used gypsum (CaSO4·2H2O) to treat febrile diseases. Based on the study of microscopic crystal characteristics and trace element characteristics of gypsum, the hypothesis that trace element strontium (Sr) is an important influential element for gypsum cooling is proposed. We analyzed the microscopic crystal structure and trace element composition of 33 batches of gypsum herbs from five producing areas by optical polarized light microscopy (OPLM), X-ray diffraction (XRD), electron probe micro-analysis (EPMA) and inductively coupled plasma mass spectrometry (ICP-MS). The results of OPLM analysis show that the microscopic morphology of gypsum is mainly long columnar and fibrous, and is related to the original area of gypsum. According to the traditional requirements, the samples with good quality have larger micro-particles. XRD analysis showed that except for one batch of samples containing quartz impurities, the other samples showed no other mineral impurities. The results of EPMA analysis showed that the main mineral in the gypsum sample was gypsum and the secondary mineral was anhydrite, which showed a symbiotic relationship. The anhydrite in the micro-area image has no definite crystal form, and the contact surfaces of anhydrite and gypsum are irregular curves. It is speculated that the anhydrite is converted from the gypsumin the later stage of mineralization rather than native. The results of ICP-MS analysis showed that the trace element strontium (Sr) was higher in gypsum, and the highest absolute content of all trace elements. The comparison with trace elements in the primitive mantle showed that the Sr element is the most stable and enriched trace element in the gypsum sample, which is more than 6 times more than the primitive mantle, up to 176 times. The analysis of the value of CaO/SrO in the micro-site of gypsum shows that the strontium (Sr) element is statistically uniformly distributed in the gypsum and exists mainly in the form of isomorphic mixtures in gypsum. The results of the determination of the Sr element content in the aqueous gypsum solution showed that the dissolution amount of strontium (Sr) in the gypsum decocted fluid and the gypsum suspension reached 2～4 times of the theoretical value. Gypsum was used in large doses in the clinic, and decocted first can promote the dissolution of Sr2+. Because Sr has the effect of inhibiting Na. The hypothesis of gypsum cooling: when gypsum is used for cooling, Sr2+ and Ca2+ are simultaneously dissolved. Sr2+ inhibits the absorption of Na+ to the body, increases the supply of Ca2+ to the body, and regulates the ratio of Na+/Ca2+ one of the positive regulation medium of fever. The material basis for the cooling of gypsum is the joint action of Sr and Ca.