In this experiment, inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) was used to determine the content of 30 elements in rice from six places of production and to explore the relationship between the multielement content in rice and the producing area. The contents of Ca, P, S, Zn, Cu, Fe, Mn, K, Mg, Na, Ge, Sb, Ba, Ti, V, Se, As, Sr, Mo, Ni, Co, Cr, Al, Li, Cs, Pb, Cd, B, In, and Sn in rice were determined by ICP-MS/MS in the SQ and MS/MS mode. By passing H2, O2, He, and NH3/He reaction gas into the ICP-MS/MS, respectively, the interference was eliminated by means of in situ mass spectrometry and mass transfer. The detection limit of each element was 0.0000662–0.144 mg/kg, and the limit of quantification was in the range of 0.000221–0.479 mg/kg, the linear correlation coefficient was greater or equal to 0.9987 (R2 ≥ 0.9987), and the detection results had low detection limit and great linear regression. Recovery of the method was in the range of 80.6% to 110.5% with spike levels of 0.10–100.00 mg/kg, and relative standard deviations were lower than 10%. For the multielement content of rice from different producing areas, the principal component factor analysis can get six principal component factors, 87.878% cumulative contribution rate, and the distribution of the principal component scores of each element and different producing areas. Based on the multielement content and cluster analysis, the samples were accurately divided into two major categories and six subcategories according to the places of production, which proved that there was a significant correlation between the multielement content in rice and the place of production, so that the place of rice origin can be traced.

A method for simultaneous determination of 22 polycyclic aromatic hydrocarbons (PAHs) residues in vegetable oils by gas chromatography-electrostatic field orbitrap high resolution mass spectrometry (Orbitrap GC-MS) was established. The samples were vortexed with acetonitrile, centrifuged at 8,000 r/min for 5 min, and frozen at −70°C for 10 min. The extracts of upper layer were poured out, dried with nitrogen at 40°C, redissolved in dichloromethane, and measured by Orbitrap GC-MS. The matrix interference in vegetable oil could be effectively removed by determining the accurate mass number of target compounds under the full scan mode. Six typical vegetable oil samples (soybean oil, sesame oil, peanut oil, olive oil, rapeseed oil, sunflower oil) were used for method validation. The calibration curve displayed good linearity in the range of 1–100 ng/mL, with correlation coefficients > 0.9950. The limits of detection (LODs) were in the range of 0.10–0.60 μg/kg, and the limits of quantification (LOQs) were in the range of 0.35–2.00 μg/kg. The average spiked recoveries of 22 PAHs in 6 matrices at 5, 50 and 100 μg/kg levels were 76.4–115.4%, and the average relative standard deviations (RSDs) were 1.8–10.8%. The results showed that 22 PAHs were detected in 6 types of 90 edible vegetable oil samples in the Chinese market by this method. Meanwhile, the abundance of light PAHs (LPAHs) was higher than that of heavy PAHs (HPAHs), and its relative contribution of LPAHs to the total PAHs was higher. All levels of BaP conformed to the Chinese requirement of upper limit, 10 μg/kg. However, 13.3 and 11.1% of the samples exceeded the maximum limits of BaP and PAH4 set by EU, 2 and 10 μg/kg, respectively. The total concentrations of 22 PAHs (defined as PAH22) varies greatly among different oil species, and the average PAH22 contents were listed in descending order as follows: peanut oil > sesame oil > olive oil > rapeseed oil > soybean oil > sunflower seed oil. The established method effectively avoided interference from large amounts of lipids and pigments. Therefore, the method is simple, sensitive and suitable for rapid screening and confirmation of PAHs in vegetable oil.

Eugenol compounds are widely used in the circulation and transportation of fresh aquatic products because of their good anesthetic effects. However, some studies have shown that eugenol compounds are potential carcinogens. Therefore, in order to ensure the edible safety of aquatic products, eugenol compounds in aquatic products need to be screened quickly. A method for determination of six eugenol residues in aquatic products was established by multiplug filtration cleanup (m-PFC), combined with gas chromatography-Orbitrap mass spectrometry (Orbitrap GC-MS). Samples were ultrasonically extracted with acetonitrile, and the extracts were frozen at −18°C for 1 h, then purified with the m-PFC column, and detected by Orbitrap GC-MS in full scan mode. The results showed the linear relationships for six eugenols were good in the range of 0.001–0.1 μg/mL, and the correlation coefficients (R2) were above 0.9950. The limits of detection (LODs) were 2–10 μg/kg, and the limits of quantitation (LOQs) were 5–20 μg/kg. The average recoveries at the spiked levels of 5–200 μg/kg were in the range of 76.4%–105.1%, with relative standard deviations (RSDs) of 1.2%–7.5%. Eighty aquatic products were detected by this method, of which only eugenol was detected in 12 samples, and eugenol and isoeugenol were detected in two samples at the same time. The other eugenol compounds were not detected in any sample. The detection rate of positive samples was 17.5%. The method is simple, accurate, and suitable for the rapid screening of eugenol compounds in aquatic products.

These findings show a lower prevalence rate of OCD in Lanzhou general hospitals than that reported for some specialized outpatient clinics in Western countries. Further investigations are required to explore the relationships between OCD and the risk factors identified in the current study. Resolving methodological problems may lead to more accurate prevalence estimates in future epidemiological studies. Our findings suggest that there is an urgent need to improve the ability of clinicians to detect OCD in outpatients.

Shanghai-Hong Kong Stock Connect Program began on July 17th, 2014, aiming to strengthen the cooperation in capital markets and promote the opening of domestic companies to the outside world. Based on DID and PSM-DID method, the article analyzes data sample from 2010 to 2017, exploring the effects of the program on financing constraints. It shows that Shanghai-Hongkong Stock Connect Program alleviates financing constraints of underlying companies: If the institutional ownership is regarded as moderating variable, the financing constraints changes significantly; With the help of this program, enterprises with high investors attention and low tax rate are more likely to get rid of the dilemma of financing. According to the results, the government should keep promoting the development of capital markets and enterprises should learn from the outside world and constantly improve their management skills.