511 Address all correspondence to Miao Chen, 530611671@qq.com Simplified Salt-Assisted Solvent Extraction for the Determination of Five Saponins in Toothpastes Using High Performance Liquid Chromatography with Ultraviolet Detector MIAO CHEN, SHIXIONG ZHOU, KUNYUN HE AND YING GAO Technology Research Center, Health Product Division, Yunnan Baiyao Group Co., Ltd., Kunming, Yunnan 650217, China (M.C., Y.G.) Analysis and Testing Center, Pharmaceutical Division, Yunnan Baiyao Group Co., Ltd., Kunming, Yunnan 650500, China (S.Z., K.H.) Accepted for publication July 13, 2021. Synopsis An analytical method for the simultaneous determination of notoginseng R1 (R1), ginsenoside Rg1 (Rg1), ginsenoside Re (Re), ginsenoside Rb1 (Rb1), and ginsenoside Rd (Rd) in different types of silica matrix toothpaste samples has been developed. The determination was performed by high performance liquid chromatography (HPLC) with ultraviolet (UV) detector. The best chromatographic separation was obtained under the following conditions: C18 column was set at 30°C and gradient elution of acetoni- trile with water as mobile phase pumped at 1 mL·min−1. The detection wavelength was set at 203 nm. Toothpastes were vortex-extracted by methanol with anhydrous magnesium sulfate, ultrasonic extraction was set for 30 min at 35 Hz, centrifugation was set at 4,000 rpm for 5 min, and then the supernatant was poured into the evaporating dish. The previous extraction was repeated once, the supernatant was com- bined twice and evaporated by water bath. Quantification was carried out by using the external standard one point method. The method was satisfactorily applied to 17 samples from different manufacturers and batches containing saponins. The spiked recoveries of the five saponins were 84–89%, 91–101%, 85–89%, 89–96%, and 89–96%, respectively. Good repeatability (1.6–5.6%) was obtained. Good analytical features, as well as handleability, make the presented method suitable to carry out the quality control of the finished toothpaste products. INTRODUCTION Panax notoginseng is a traditional Chinese medicine, native to the subtropical mountain forests of Yunnan and Guangxi provinces (1). Modern studies have shown that the saponins in Panax notoginseng are one of its main medicinal ingredients, among which five saponins, namely notoginseng R1, ginsenoside Rg1, Re, Rb1, and Rd, are the main components of Panax notoginseng, accounting for about 80% of the total saponins content (2). J. Cosmet. Sci., 72, 511–518 (September/October 2021)

512 JOURNAL OF COSMETIC SCIENCE Several studies have reported various biological activities of saponins, such as anticarcinogenic (3), immunoregulation (4), cardiovascular protection (5), and anti-inflammatory hemostasia (6), especially as powerful scattered stasis hemostasis agents (7). Therefore, in addition to applications as pharmaceutical active substances, saponins have great potential as oral care ingredients, which have been shown to have significant effects on oral ulcers, gingivitis, and dental plaque. Due to the beneficial properties of saponins, being used as raw material in the manufacture of oral care products is an interesting innovation for chemical industries. However, indicating that an oral care product contains natural ingredients is still a claim to a great extent. Therefore, it is necessary to develop analytical procedures to control industrial processes and to assess the quality of oral care containing saponins. Different analytical methods for the characterization of saponins in Panax notoginseng samples (powder, pieces), Chinese patent medicine, functional foods, and biological samples have been published. HPLC-UV (8) and ultra performance liquid chromatography (9) coupled with electrospray ionization mass spectrometry (10) are the most commonly used detection methods. Methol and n-butyl alcohol are the extractants that have been evaluated for the recovery of saponins (10–12). However, there are few reports describing the determination of saponins in toothpastes, not to mention silica matrix. Toothpaste is a complex system that contains surfactants, abradants, thickeners, humectants, aseptics, essences, active matters, and sweetening agents. Precipitated silica is made of the silicon oxygen tetrahedron three- dimensional network structure. This structure determines use as a toothpaste thickener can provide paste with excellent pseudoplasticity and thixotropy, but when the particle size decreases and the smaller than average distance between the particles and forces increases, the structure is prone to reunite and not to disperse easily, thus increasing the difficulty of toothpaste sample pretreatment. Here, we describe a simple, selective, and highly sensitive HPLC-UV method for the determination of notoginseng R1, ginsenoside Rg1, Re, Rb1, and Rd in different types of silica matrix toothpaste samples. The method was fully validated and applied to the quality control of the finished toothpaste products. EXPERIMENTAL APPARATUS An Agilent 1260 II Infinity LC (Agilent, Santa Clara, CA, USA) system including a UV/visible light detector was employed. The column used was Poroshell 120 EC-C184.6×250 mm, 4μm)(Agilent, Santa Clara, CA, USA). A Kudos SK 5210LC ultrasonic bath (35 Hz) (Shanghai Kudos Ultrasonic Instrument Co., Ltd., Shanghai, China) was used to auxiliary extraction. A high-speed Bioridge TG18.5 centrifuge (Shanghai Lu Xiangyi centrifuge instrument Co., Ltd., Shanghai, China) was used to accelerate separation. A VORTEX-5 (50 W, ≥2,800 rpm) (Qilinbeier, Haimen, China) was used to accelerate the liquid–liquid extraction of toothpaste samples. REAGENTS AND SAMPLES The reference standards of notoginseng R1, ginsenoside Rg1, Re, Rb1, and Rd were purchased from the National Institute for the Control of Pharmaceutical and Biological Products (Beijing, China). Chemical structures are shown in Figure 1. Acetonitrile and