Simultaneous Determination and Health Risk Assessment of Four High Detection Rate Pesticide Residues in Pu'er Tea from Yunnan, China.

Four pesticides with a high detection rate in Pu'er tea have been determined by a QuEChERS (quick, easy, cheap, effective, rugged, safe) method with multiwalled carbon nanotubes (MWCNTs), and combined ultrahigh-performance liquid chromatography-triple quadrupole linear ion trap-tandem mass spectrometry (UHPLC-QTRAP-MS/MS). MWCNs have been compared with other common purification materials, and found to be superior. The matrix effect was systematically studied, and the results show that the MWCNs can quickly and effectively reduce matrix interference values, which were in the range from -17.8 to 13.8. The coefficients (R2) were greater than 0.99, with the limit of quantification ranging from 0.1 to 0.5 µg/kg, and the recovery rate ranging from 74.8% to 105.0%, while the relative standard deviation (RSD) ranged from 3.9% to 6.6%. A total of 300 samples, taken from three areas in which Yunnan Pu'er tea was most commonly produced, tested for four pesticides. The results show that the detection rate of tolfenpyrad in Pu'er tea was 35.7%, which is higher than other pesticides, and the lowest was indoxacarb, with 5.2%. The residual concentrations of chlorpyrifos, triazophos, tolfenpyrad and indoxacarb ranged from 1.10 to 5.28, 0.014 to 0.103, 1.02 to 51.8, and 1.07 to 4.89 mg/kg, respectively. By comparing with China's pesticide residue limits in tea (GB 2763-2021), the over standard rates of chlorpyrifos, tolfenpyrad, and indoxacarb were 4.35%, 0.87% and 0%, respectively. The risk assessment result obtained with the hazard quotient (HQ) method shows that the HQ of the four pesticides was far less than one, indicating that the risk is considered acceptable for the four pesticides in Pu'er tea. The largest HQ was found for tolfenpyrad, 0.0135, and the smallest was found for indoxacarb, 0.000757, but more attention should be paid to tolfenpyrad in daily diets in the future, because its detection rate, and residual and residual median were all relatively high.

Comparison of the chemical constituents of raw Fructus Aurantii and Fructus Aurantii stir-baked with bran, and the biological effects of auraptene.

ETHNOPHARMACOLOGICAL RELEVANCE: Fructus Aurantii (FA) is a Chinese herbal medicine commonly used in clinical practice to improve gastrointestinal motility, treat dyspepsia, and relieve constipation. More than 20 processing methods of FA have been recorded, among which FA stir-baked with bran is the earliest, most time consuming, and the most popular one. Raw FA has a strong ability to promote qi-moving and has middle-energizer-soothing effects; therefore, it is often used to relieve hypochondrium distension and pain, and to relax the stagnation of the liver Qi. FA stir-baked with bran is more effective in nourishing the stomach and curing indigestion. AIM OF THE STUDY: In this study, the chemical composition and differences between raw FA and FA stir-baked with bran were systematically compared. The chemical components that increased after stir-baking FA and bran were separated and their pharmacodynamic characteristics were determined. Lastly, the processing mechanism of FA was further explained. MATERIALS AND METHODS: Twelve main chemicals in raw FA and FA stir-baked with bran were compared using high-performance liquid chromatography (HPLC). The main differential components were identified, separated, purified, and then analyzed using pharmacodynamic tests. The intestine-pushing test, in vitro smooth muscle test, and in vitro acetylcholinesterase (AchE) activity test in mice were performed to explain the mechanism of auraptene in improving gastrointestinal motility. RESULTS: Using HPLC, the primary chemical that differed between raw FA and FA stir-baked with bran was identified as auraptene. The processed FA was extracted, separated, and purified to obtain pure auraptene. The intestine-pushing test in mice showed that low (0.6 mg·kg-1) and medium doses (1.2 mg·kg-1) of auraptene could promote peristalsis of the small intestine, whereas a high dose (2.4 mg·kg-1) inhibited peristalsis. In vitro studies on the smooth muscle of mice showed that a low dose of auraptene (0.2 mmol·L-1, 10-800 µL) could promote contraction, whereas a high dose (0.2 mmol·L-1, >1000 µL) had the opposite effect. Auraptene has a mechanism of action similar to that of the acetylcholinesterase inhibitor, neostigmine. Additionally, auraptene could inhibit AchE activity in vitro. CONCLUSIONS: Auraptene is the main chemical constituent that differs between raw FA and FA stir-baked with bran. Pharmacodynamic tests showed that auraptene has a cholinergic effect, by virtue of its role as an acetylcholinesterase inhibitor. Moreover, auraptene could dually regulate the gastrointestinal smooth muscle. Auraptene was present in low levels and its content varied in FA stir-baked with bran, depending on the origin and source of FA, and the treatment procedures it was subjected to. In the Chinese Pharmacopoeia, the recommended dose of FA stir-baked with bran is a low dose of 3-10 g, which effectively promotes small-intestinal peristalsis. The mechanism of action is attributed to an increase in the relative content of acetylcholine by the inhibition of AchE activity to promote gastrointestinal motility. The increased levels of auraptene in FA stir-baked with bran are the main reason and the primary purpose for the change in its medicinal properties. This technique, therefore, has potential to be used as one of the main processing mechanisms of raw FA.

[Removal of Antibiotics During In-situ Sludge Ozone-reduction Process].

Two sequencing batch reactors were established at bench-scale, with one used as an in-situ sludge ozone-reduction system and the other as a control system. Both systems were continuously operated for 90 days to comparatively investigate the elimination of nine typical antibiotics (i.e., tetracycline, oxytetracycline, doxytetracycline, norfloxacin, ofloxacin, ciprofloxacin, lomefloxacin, enrofloxacin, and azithromycin) during the in-situ sludge ozone-reduction process. Results indicated that the presence of target antibiotics in the influent (100 µg·L-1 each) had an insignificant influence on the removal of COD, total nitrogen, ammonia, and total phosphorus by the activated sludge. The antibiotic concentrations in the effluent of the reduction system remained fairly stable over the entire operation period, and were similar to those in the effluent of the control system; however, the antibiotic concentrations in the sludge of the reduction system were obviously lower than those in the control system sludge. Mass balance calculations revealed that the input and output of target antibiotics gradually approached balance in both the systems. Ozone degradation and excess sludge discharge were the main pathways for target antibiotic removal in the reduction and the control systems, respectively. The influent antibiotics could be degraded by 83% in the sludge ozonation module of the reduction system, while 82% of the influent antibiotics were discharged with excess sludge in the control system. Therefore, the in-situ sludge ozone-reduction process could greatly reduce the release of antibiotics from the activated sludge system, which is of great importance in practice.

Simultaneous quantification of polymethoxylated flavones and coumarins in Fructus aurantii and Fructus aurantii immaturus using HPLC-ESI-MS/MS.

The major lipid-soluble constituents in Fructus aurantii (zhiqiao) and Fructus aurantii immaturus (zhishi) are polymethoxylated flavones (PMFs) and coumarins. In the present study, a high-performance liquid chromatography with electrospray ionization tandem mass spectrometry method was developed to quantify PMFs (nobiletin, tangeretin, 5-hydroxy-6,7,8,4'-tetramethoxyflavone, and natsudaidai) and coumarins (marmin, meranzin hydrate, and auraptene) simultaneously. PMFs and coumarins were detected by electrospray ionization tandem mass spectrometry in positive ion mode and quantified with multiple reaction monitor. Samples were separated on a Diamonsil C18 (150 mm × 4.6 mm, 5 µm) column using acetonitrile and formic acid-water solution as a mobile phase in gradient mode with a flow rate at 0.5 mL/min. All calibration curves showed good linearity (r² > 0.9977) within the test ranges. Variations of the intraday and interday precisions were less than 4.07%. The recoveries of the components were within the range of 95.79%-105.04% and the relative standard deviations were less than 3.82%. The method developed was validated with acceptable accuracy, precision, and extraction recoveries and can be applied for the identification and quantification of four PMFs and three coumarins in citrus herbs.