Boric acid powder

The phase composition of the as-prepared powders was analyzed by powder X-ray diffraction (XRD) analyses (Philips X’ Pert diffractometer) with CuKα radiation. Environmental scanning electron microscopy (ESEM, Helios Nanolab 600i) and high-resolution transmission electron microscopy (HRTEM JEM-2100) were used to observe the morphology of the graphene sheets. The TEM specimens were prepared by dropping ethanol/water (38 v/v%) solution containing 1 wt % N-doped graphene onto a copper grid and drying at 100 °C. Raman spectra were obtained using a Raman Station (B&WTEK, BWS435-532SY) with a 532 nm wavelength laser corresponding to 2.34 eV, 30% of the laser power (total power: 240 mW) was used on the samples. X-ray photoelectron spectroscopy (XPS, Thermo Fisher) was utilized to determine the bonding characteristics of the samples. All XPS peaks are calibrated according to the C 1 s peak (284.6 eV). The composition was confirmed using X-ray fluorescence (XRF, AXIOS-PW4400) in order to determine the presence of any metallic elements. 2 milligrams of N-doped graphene powder was spread out on the surface of boric acid powder (99.0%, Sinopharm Chemical Reagent Co., Ltd.), the effective test zone is a disk surface with a diameter of 20 mm. The magnetic properties were measured using a Quantum Design MPMS magnetometer based on a superconducting quantum interference device (SQUID).

Dry slices of Chinese yam (CY), cassava (CS), and rhizome of winged yam (RY) were authenticated and provided by Hubei University of Chinese Medicine. CY is from Wen County, Henan Province in China, which belongs to one of the most popular varieties tiegun yam, famous for its nutrients and active ingredients [22 ]. CS and RY are from Xiangtan City, Hunan Province and Nanning City, Guangxi Province in China, respectively, and they are common varieties in the market. These slices were placed in a 60 °C drying baker around 6 h until the quality had no change, and they were ground into powder to pass through a 100-mesh sieve. According to the market research, the price of CS is lower than that of RY, so incorporating CS into CY can better meet the interests of illegal traders. Pure powders (CY, CS and RY) and CY powder adulterated by CS powder in the range of 0–100% at a 5% gradient were used for identification and quantitation tests, respectively. The details of samples are shown in Table 1. Various powders (1 g) assisted by boric acid powder (Sinopharm Chemical Reagent Co., Ltd., Shanghai, China; 9 g) were pressed into pellets of 40 mm diameter by a pressure of 30 tons. For each category, 3 pellets were made to do the repeated experiments. In total, 72 pellets were prepared for experiment.