Screening anabolic androgenic steroids in human urine: an application of the state-of-the-art gas chromatography-Orbitrap high-resolution mass spectrometry.

Over the past few decades, anabolic androgenic steroids (AASs) have been abused in and out of competition for their performance-enhancing and muscle-building properties. Traditionally, AASs were commonly detected using gas chromatography-mass spectrometry in the initial testing procedure for doping control purposes. Gas chromatography-Orbitrap high-resolution mass spectrometry (GC-Orbitrap-HRMS) is a new technology that has many advantages in comparison with GC-MS (e.g., a maximum resolving power of 240,000 (FWHM at m/z 200), excellent sub-ppm mass accuracy, and retrospective data analysis after data acquisition). Anti-doping practitioners are encouraged to take full advantage of the updated techniques of chromatography-mass spectrometry to develop sensitive, specific, and rapid screening methods for AASs. A new method for screening a wide range of AASs in human urine using GC-Orbitrap-HRMS was developed and validated. The method can qualitatively determine 70 anabolic androgenic steroids according to the minimum required performance limit of the World Anti-Doping Agency. Moreover, the validated method was successfully applied to detect six metabolites in urine after the oral administration of metandienone, and their excretion curves in vivo were studied. Metandienone M6 (17ß-hydroxymethyl-17α-methyl-18-nor-androst-1,4,13-trien-3-one) has been identified as a long-term urinary metabolite which can be detected up to 7 weeks, thus providing a longer detection window compared with previous studies. This study provides a rationale for GC-Orbitrap-HRMS in drug metabolism and non-targeted screening.

Neural stem cell-derived exosomes regulate cell proliferation, migration, and cell death of brain microvascular endothelial cells via the miR-9/Hes1 axis under hypoxia.

BACKGROUND: Our previous study found that mouse embryonic neural stem cell (NSC)-derived exosomes (EXOs) regulated NSC differentiation via the miR-9/Hes1 axis. However, the effects of EXOs on brain microvascular endothelial cell (BMEC) dysfunction via the miR-9/Hes1 axis remain unknown. Therefore, the current study aimed to determine the effects of EXOs on BMEC proliferation, migration, and death via the miR-9/Hes1 axis. METHODS: Immunofluorescence, quantitative real-time polymerase chain reaction, cell counting kit-8 assay, wound healing assay, calcein-acetoxymethyl/propidium iodide staining, and hematoxylin and eosin staining were used to determine the role and mechanism of EXOs on BMECs. RESULTS: EXOs promoted BMEC proliferation and migration and reduced cell death under hypoxic conditions. The overexpression of miR-9 promoted BMEC proliferation and migration and reduced cell death under hypoxic conditions. Moreover, miR-9 downregulation inhibited BMEC proliferation and migration and also promoted cell death. Hes1 silencing ameliorated the effect of amtagomiR-9 on BMEC proliferation and migration and cell death. Hyperemic structures were observed in the regions of the hippocampus and cortex in hypoxia-induced mice. Meanwhile, EXO treatment improved cerebrovascular alterations. CONCLUSION: NSC-derived EXOs can promote BMEC proliferation and migration and reduce cell death via the miR-9/Hes1 axis under hypoxic conditions. Therefore, EXO therapeutic strategies could be considered for hypoxia-induced vascular injury.

[Identifying animal-derived components in camel milk and its products by ultra-high performance liquid chromatography-tandem mass spectrometry].

A method for identifying specific peptide biomarkers of animal-milk-derived components in camel milk and its products was established using proteomics. Samples were prepared by defatting, protein extraction, and trypsin hydrolysis, and proteins and peptides were identified using ultra-high performance liquid chromatography-quadrupole/electrostatic orbitrap-high resolution mass spectrometry (UHPLC-Q/Exactive-HRMS) and Protein Pilot software. Twenty two peptide biomarkers from eight species (i.e., Camelus, Bos taurus, Bubalus bubalis, Bos grunniens/Bos mutus, Capra hircus, Ovis aries, Equus asinus, Equus caballus) were identified by comparing the basic local alignment search tool (BLAST) with the Uniprot database. Verification of these marker peptides were performed quantitatively using a UHPLC-triple-quadrupole mass-spectrometry (QqQ-MS) system by multiple reaction monitoring (MRM). The pretreatment method of casein in camel milk was optimized, such as defatting, protein precipitation, and re-dissolving buffer solution. The effects of various mass-spectrometry parameters, such as atomization gas, heating- and drying-gas flow rates, and desolvation-tube (DL) and ion-source-interface temperatures on ion-response intensity were optimized. Camel milk signature peptides were detected in a mixture of milk from other seven species to ensure specificity for the selected biomarker peptides. The signature peptides of seven other species were also detected in camel milk. No mutual interference between the selected biomarker peptides of the various species was observed. Adulterated camel milk and milk powder were also quantitatively studied by adding 0, 2.5%, 5%, 10%, 25%, 50%, 75%, and 100% bovine milk or goat milk to camel milk. Similarly, the same mass proportion of bovine milk powder or goat milk powder was added to camel milk powder. A quantitative standard curve for adulteration was constructed by plotting the peak areas of characteristic cow or goat peptide segments in each mixed sample against the mass percentage of the added adulterant. The adulteration standard curves exhibited good linearity, with correlation coefficients (r2) greater than 0.99. The limits of detection and quantification (LODs and LOQs, respectively) of the method were determined as three- and ten-times the signal-to-noise ratio (S/N). The minimum adulteration LODs of bovine milk and goat milk in camel milk were determined to be 0.35% and 0.49%, respectively, and the minimum LOQs were 1.20% and 1.69%, respectively. The minimum adulteration LODs of bovine milk powder and goat milk powder in camel milk powder were determined to be 0.68% and 0.73%, respectively, and the minimum LOQs were 1.65% and 2.45%, respectively. The accuracy of the adulteration quantification method was investigated by validating the quantitative detection results for 1∶1∶1 (mass ratio) mixtures of camel milk, bovine milk, and goat milk, as well as camel-milk powder, bovine milk powder, and goat-milk powder, which revealed that this method exhibits good linearity, strong anti-interference, high sensitivity, and good repeatability for adulterated liquid-milk/solid-milk-powder samples. The adulteration results for both liquid milk and milk powder are close to the theoretical values. Finally, 11 actual commercially available samples, including five camel-milk and six camel-milk-powder samples were analyzed, which revealed that only camel signature peptides were detected in 10 samples, while camel and bovine signature peptides were both detected in one camel-milk-powder sample. The ingredient list of the latter sample revealed that it contained whole milk powder from an unidentified source; therefore, we infer that the bovine signature peptides originate from the whole milk powder. These signature peptides also demonstrate the necessity and practical significance of establishing this identification method.

Stable Isotope Labeling-Based Nontargeted Strategy for Characterization of the In Vitro Metabolic Profile of a Novel Doping BPC-157 in Doping Control by UHPLC-HRMS.

Traditional strategies for the metabolic profiling of doping are limited by the unpredictable metabolic pathways and the numerous proportions of background and chemical noise that lead to inadequate metabolism knowledge, thereby affecting the selection of optimal detection targets. Thus, a stable isotope labeling-based nontargeted strategy combined with ultra-high-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) was first proposed for the effective and rapid metabolism analysis of small-molecule doping agents and demonstrated via its application to a novel doping BPC-157. Using 13C/15N-labeled BPC-157, a complete workflow including automatic 13C0,15N0-13C6,15N2m/z pair picking based on the characteristic behaviors of isotope pairs was constructed, and one metabolite produced by a novel metabolic pathway plus eight metabolites produced by the conventional amide-bond breaking metabolic pathway were successfully discovered from two incubation models. Furthermore, a specific method for the detection of BPC-157 and the five main metabolites in human urine was developed and validated with satisfactory detection limits (0.01~0.11 ng/mL) and excellent quantitative ability (linearity: 0.02~50 ng/mL with R2 > 0.999; relative error (RE)% < 10% and relative standard deviation (RSD)% < 5%; recovery > 90%). The novel metabolic pathway and the in vitro metabolic profile could provide new insights into the biotransformation of BPC-157 and improved targets for doping control.

Qualitative and semi-quantitative analysis of melamine in liquid milk based on surface-enhanced Raman spectroscopy.

Melamine is one of the common limited contaminations in dairy products. The traditional detection method has a long period and complicated pretreatment process. The rapid detection method is the better method to solve the screening of limited contaminations. In this paper, taking melamine as the research object, the surface enhanced Raman spectrum of melamine in liquid milk were collected by portable Raman spectrometer, and melamine was qualitatively identified and semi-quantitatively analyzed by Raman characteristic peak and Raman intensity, and a simple and efficient rapid screening method for limited contaminations was developed. The limit of detection is 0.25 mg/kg. The probability of detection is 100% at 2.5 mg/kg, which is the same between the two laboratories, indicating that the semi-quantitative method has good repeatability. The method of melamine proposed in this study can meet the rapid screening requirements of limited contaminations at the maximum residue limit, and has a good application prospect.

Effects of Exponential N Application on Soil Exchangeable Base Cations and the Growth and Nutrient Contents of Clonal Chinese Fir Seedlings.

Nitrogen (N) is an essential macronutrient for plant function and growth and a key component of amino acids, which form the building blocks of plant proteins and enzymes. However, misuse and overuse of N can have many negative impacts on the ecosystem, such as reducing soil exchangeable base cations (BCs) and causing soil acidification. In this research, we evaluated clonal Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) seedlings grown with exponentially increasing N fertilization (0, 0.5, 1, 2 g N seedling-1) for a 100-day trial in a greenhouse. The growth of seedlings, their nutrient contents, and soil exchangeable cations were measured. We found that N addition significantly increased plant growth and N content but decreased phosphorous (P) and potassium (K) contents in plant seedlings. The high nitrogen (2 g N seedling-1) treated seedlings showed a negative effect on growth, indicating that excessive nitrogen application caused damage to the seedlings. Soil pH, soil exchangeable base cations (BCs), soil total exchangeable bases (TEB), soil cation exchange capacity (CEC), and soil base saturation (BS) significantly decreased following N application. Our results implied that exponential fertilization resulted in soil acidification and degradation of soil capacity for supplying nutrient cations to the soil solution for plant uptake. In addition, the analysis of plants and BCs revealed that Na+ is an important base cation for BCs and for plant growth in nitrogen-induced acidified soils. Our results provide scientific insights for nitrogen application in seedling cultivation in soils and for further studies on the relationship between BCs and plant growth to result in high-quality seedlings while minimizing fertilizer input and mitigating potential soil pollution.

Derivatization-Enhanced Analysis of Glucocorticoids for Structural Characterization by Gas Chromatography-Orbitrap High-Resolution Mass Spectrometry.

Glucocorticoids are classified in section S9 of the Prohibited List of the World Anti-Doping Agency, due to a potential risk to improving physical performance and causing harm to the health of athletes. Based on the similar physiological actions of glucocorticoids, both differentiating known glucocorticoids and identifying unknown glucocorticoids are important for doping control. Gas chromatography coupled with mass spectrometry plays an important role in structural characterization because of abundant structural diagnostic ions produced by electron ionization. It also provides a chance to study the fragmentation patterns. Thus, an enhanced derivatization procedure was optimized to produce trimethylsilylated glucocorticoids and structural diagnostic ions of nineteen trimethylsilylated glucocorticoids were obtained by gas chromatography-orbitrap high-resolution mass spectrometry. In our study, glucocorticoids were classified as: 3-keto-4-ene, 1,4-diene-3-keto, 3α-hydroxy with saturated A-ring, 21-hydroxy-20-keto and halo substituent glucocorticoids based on their structural difference. Structural diagnostic ions that contributed to structural characterization were specifically presented and the fragment patterns were demonstrated according to the above categories. This study not only gave new insights into the structural characterization of these glucocorticoids but also provided evidence for tracing unknown glucocorticoids or chemically modified molecules.

Risk assessment and early warning of the presence of heavy metal pollution in strawberries.

Heavy metal pollution is a major threat to agricultural produce and it can pose potential ecological risks which subsequently impacts on human health. Strawberries are an economically important produce of China. The intrinsic link of heavy metal pollution risk in the soil-strawberry ecosystem is of concern. In this study, the pollution index of heavy metal pollutants in farmlands of different provinces were evaluated, and the results showed significantly high levels of cadmium. In addition, Nemerow integrated pollution index analysis showed that low-pollution farmlands only accounted for 14.07% of the total arable land area. Then, the transfer factors were used to calculate the migration of heavy metals from the soil into strawberries. The results showed that cadmium and nickel were relatively high in strawberries from the Guangxi province. Similar results were found for mercury in Jiangxi Province. The pollution index of single food pollution also showed that mercury in strawberries from Jiangxi Province was at a moderate pollution level. The comprehensive pollution index indicated that heavy metal pollution in strawberries in Central China may be severe. In addition, spatial clustering analysis showed that cadmium, chromium, lead, arsenic and zinc in strawberries had significant hotspot clustering in central, south and southwest China. Finally, our studies also suggested that the risk of carcinogenic and non-carcinogenic diseases was higher in the (2, 4] years age group than in other age groups. People in Yunnan Province were also found to have a higher non-carcinogenic risk than those in other provinces and cities in China. This study provides a comprehensive view of the potential risks of heavy metal contamination in strawberries, which could provide assistance in the design of regulatory and risk management programs for chemical pollutants in strawberries, thus ensuring the safety of consumption of these edible fruits.

Online trypsin digestion coupled with LC-MS/MS for detecting of A1 and A2 types of ß-casein proteins in pasteurized milk using biomarker peptides.

Bovine A1-or A2-type ß-caseins have attracted a growing interest due to their variation in beta-casomorphin-7 (BCM-7) formation, which may affect health. In the present work, identification and quantification of A1 and A2 types of ß-casein proteins at the peptide level was achieved for the first time. An automated and online immobilized trypsin digestion system was employed for high throughput digesting of proteins into peptides. Tryptic peptides were separated and analyzed subsequently by liquid chromatography coupled to mass spectrometry platform. Two specific peptides ranging from the position of 49 to 97 in the peptide chain were selected for the identification and quantification of A1 and A2 ß-casein, which covered the different amino acids between them. Synthetic isotopically labeled winged peptides were used for absolute quantification. Compared with traditional in-solution digestion, online digestion shortens digestion times from 2 to 24 h to 4 min. The limits of quantification (LOQ) of A1 and A2 ß-casein in pasteurized milk are 0.8 and 2.4 µg/g, respectively. To further demonstrate the applicability of the proposed method, commercial pasteurized milk tests were performed with satisfactory results. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05376-6.

An Improved POD Model for Fast Semi-Quantitative Analysis of Carbendazim in Fruit by Surface Enhanced Raman Spectroscopy.

The current detection method of carbendazim suffers from the disadvantages of complicated preprocessing and long cycle time. In order to solve the problem of rapid quantitative screening of finite contaminants, this article proposed a qualitative method based on characteristic peaks and a semi-quantitative method based on threshold to detect carbendazim in apple, and finally the method is evaluated by a validation system based on binary output. The results showed that the detection limit for carbendazim was 0.5 mg/kg, and the detection probability was 100% when the concentration was no less than 1 mg/kg. The semi-quantitative analysis method had a false positive rate of 0% and 5% at 0.5 mg/kg and 2.5 mg/kg, respectively. The results of method evaluation showed that when the added concentration was greater than 2.5 mg/kg, the qualitative detection method was consistent with the reference method. When the concentration was no less than 5 mg/kg, the semi-quantitative method is consistent between different labs. The semi-quantitative method proposed in this study can achieve the screening of finite contaminants in blind samples and simplify the test validation process through the detection probability model, which can meet the needs of rapid on-site detection and has a good application prospect.

Risk Assessment of Veterinary Drug Residues in Pork on the Market in the People's Republic of China.

ABSTRACT: Veterinary drugs, including antibiotics, antiparasitics, and growth promoters, are widely used in animal husbandry. Veterinary drug residues are key issues of food safety because they arouse public concern and can seriously endanger the health of consumers. To assess the risk of veterinary drug residues in pork sold in the People's Republic of China, the potential veterinary drug residue risks in imported and domestic pork were analyzed based on regulatory differences and veterinary drug residue safety incidents. For imported pork, a risk assessment model was established based on the differences in veterinary drug residue limits for the People's Republic of China, Brazil, the United States, Australia, Thailand, and Russia combined with comprehensive evaluation methods. The potential risk of veterinary drug residues in U.S. pork was the highest, and that in Brazilian pork was the lowest. For domestic pork, the distribution and aggregation of veterinary drug residue safety incidents in the People's Republic of China was analyzed from 2015 to 2019 with a geographic information system. This study provides new insights into the safety of pork on the Chinese market and a scientific basis for formulating targeted supervision and early warning strategies.

Rapid Detection of Nonprotein Nitrogen Adulterants in Milk Powder Using Point-Scan Raman Hyperspectral Imaging Technology.

To develop a rapid detection method for nonprotein nitrogen adulterants, this experiment sets up a set of point-scan Raman hyperspectral imaging systems to qualitatively distinguish and quantitatively and positionally analyze samples spiked with a single nonprotein nitrogen adulterant and samples spiked with a mixture of nine nonprotein nitrogen adulterants at different concentrations (5 × 10-3 to 2.000%, w/w). The results showed that for samples spiked with single nonprotein nitrogen adulterants, the number of pixels corresponding to the adulterant in the region of interest increased linearly with an increase in the analyte concentration, the average coefficient of determination (R 2) was above 0.99, the minimum detection concentration of nonprotein nitrogen adulterants reached 0.010%, and the relative standard deviation (RSD) of the predicted concentration was less than 6%. For the sample spiked with a mixture of nine nonprotein nitrogen adulterants, the standard curve could be used to accurately predict the additive concentration when the additive concentration was greater than 1.200%. The detection method established in this study has good accuracy, high sensitivity, and strong stability. It provides a method for technical implementation of real-time and rapid detection of adulterants in milk powder at the port site and has good application and promotion prospects.

Four new species of Diaporthe (Diaporthaceae, Diaporthales) from forest plants in China.

Species of Diaporthe inhabit a wide range of plant hosts as plant pathogens, endophytes and saprobes. During trips to collect forest pathogens in Beijing, Jiangxi, Shaanxi and Zhejiang Provinces in China, 16 isolates of Diaporthe were obtained from branch cankers and leaf spots. These isolates were studied by applying a polyphasic approach including morphological, cultural data, and phylogenetic analyses of the nuclear ribosomal internal transcribed spacer (ITS), calmodulin (cal), histone H3 (his3), partial translation elongation factor-1α (tef-1α) and ß-tubulin (tub2) loci. Results revealed four new taxa, D.celticola, D.meliae, D.quercicola, D.rhodomyrti spp. nov. and two known species, D.eres and D.multiguttulata.

Mental health status among non-medical college students returning to school during the COVID-19 pandemic in Zhanjiang city: A cross-sectional study.

The coronavirus disease-2019 (COVID-19) pandemic has brought huge and continuous damage to mental health. The mental health of non-medical college students after returning to school remains largely unknown and the influencing factors were awaited to be deciphered. This cross-sectional study was launched among 1,083 non-medical students in Zhanjiang city by means of online survey (WeChat App) from August 1st, 2022 to August 7th, 2022. Knowledge about COVID-19 and attitude toward COVID-19 were assessed by using 7-items and 5-items questionnaires, respectively. Sleep quality, anxiety and depression symptoms were evaluated by Pittsburgh sleep quality index (PSQI), Hamilton depression rating scale-17 (HDRS-17) and self-rating anxiety scale (SAS), respectively. The results showed that more than half of the participants were knowledgeable about COVID-19. The majority of the participants held positive attitude toward COVID-19. The data demonstrated that 6.8% students had poor sleep quality, and 1.86, 0.37 and 0.37% students had mild, moderate and severe anxiety, respectively. About 26.7, 4.7 and 1.7% students had minimal, mild-moderate and severe depression. Female students showed higher proportions of anxiety (p = 0.02) and depression (p < 0.0001) than male students. Students with monthly household income below 3,000 RMB were more vulnerable to anxiety (p = 0.017) and depression (p = 0.004). Correlation analysis and Multivariate logistic regression analysis results showed that lower grade was positively related with anxiety and depression. Female students, income lower than 3,000 RMB/month, poor knowledge about COVID-19 and negative attitude toward COVID-19 were associated with insomnia, anxiety and depression. This study indicated that during the COVID-19 pandemic, a majority of non-medical students returning to school remained good sleep quality and a small number of students suffered from depression and anxiety. To our knowledge, this is a novel study revealing the mental health of non-medical college students concerning COVID-19 in Zhanjiang.

Multivariate analysis for organic milk authentication.

To differentiate organic milk (OM) from conventional milk (CM), an orthogonal projection to latent structure-discriminant analysis (OPLS-DA) model was constructed using δ13C, δ15N, δ18O, 51 elements and 35 fatty acids (FAs) as the variables. So far, most reported studies barely use three or more types of variables, but more variables could avoid one-sidedness and get stabler models. Our multivariate model combines geographical and nutritional parameters and displays better explanatory and predictive abilities (R2X = 0.647, R2Y = 0.962 and Q2 = 0.821) than models based on fewer variables for differentiating OM and CM. In particular, δ15N, Se, δ13C, Eu, K and α-Linolenic acid (ALA) are found to be critical parameters for the discrimination of OM. These results show that the multivariate model based on stable isotopes, elements and FAs can be used to identify OM, and can potentially expand the global databases for quality and authenticity of milk.

The association between serum CD4 T lymphocyte counts and surgical outcomes in HIV/AIDS patients in Guangxi, China: a retrospective cohort study.

BACKGROUND: HIV/AIDS is a chronic disease leading to complications in infected individuals that often require surgical intervention. These patients' serum CD4 T lymphocyte (CD4) counts represent one of the most important indicators of their ability to tolerate surgical treatment. Previous studies have demonstrated that CD4 cell count (CD4-CC) < 200 cells/µl may increase the risk of surgical complications in these patients, limiting their ability to undergo surgery, which may negatively affect their quality of life. Further investigation into the surgical outcomes of patients with CD4-CC < 200 cells/µl should provide guidance in making appropriate clinical decisions for the optimal healthcare of this patient demographic. METHODS: All enrolled patients were selected from 14 prefecture-level general hospitals in Guangxi, China, and were referred to AIDS outpost hospitals for inpatient surgical therapy. A total cohort of 168 adult patients was retrospectively analyzed. Multifactorial and stratified analyses were performed to evaluate the in surgical outcome differences for patients with CD4-CC < 200 cells/µl (N = 43), using those with CD4-CC ≥ 200 cells/µl (N = 125) as controls. RESULTS: Poor incisional healing was used as the primary outcome indicator, and postoperative complications were used as the secondary outcome indicator. In the patient group with CD4-CC < 200 cells/µl, the risk of surgical complications was significantly increased (OR 2.379; 95% CI [1.049-5.394]) after adjustment. Adjusted stratified analysis of the CD4-CC < 200 cells/µl group revealed that individuals over 60 years (OR 27.504; 95% CI [2.297-329.317]) with erythrocyte counts below 4.00/ml for males or 3.50/ml for females (OR 3.353; 95% CI [1.079-10.419]) had a significantly higher risk of postoperative complications; this finding was statistically different from the control (CD4 ≥ 200 cells/µl) group. However, there was no significant difference between the two groups regarding the risk of poorly healed incision outcomes. CONCLUSIONS: Preliminary findings suggest that a serum CD4-CC < 200 cells/µl is not a definitive contraindication for surgical therapy and that baseline and surgical characteristics may help predict surgical outcomes in these patients. Further studies are needed to confirm these findings.

[Determination of 18 amino acids in three different kinds of milk powder by ultra performance liquid chromatography coupled with pre-column derivatization].

In recent years, goat milk powder and camel milk powder have gained popularity among consumers. Due to their potential low allergenicity, these milk powders have become a substitute for breast milk, especially for infants, and for people with lactose intolerance. In this paper, a method was developed for the simultaneous determination of 18 amino acids (AAs), histidine (His), serine (Ser), arginine (Arg), glycine (Gly), aspartic acid (Asp) combined with asparagine (Asn), glutamic (Glu), glutamine (Gln), threonine (Thr), alanine (Ala), proline (Pro), lysine (Lys), tyrosine (Tyr), methionine (Met), valine (Val), isoleucine (Iso), leucine (Leu), and dimer of cysteine (Cys) combined with cysteine (L-Cys-Cys), phenylalanine (Phe), taurine (Tau) in milk, goat milk, and camel milk power. The aim of the research was to compare the three kinds of milk powder from the perspective of the constituent amino acids. Therefore, the amino acid compositions and contents were compared. Thus, 2.0 g of the sample was accurately weighed, added to 16 mL H2O, and mixed thoroughly. Then, 200 mg of the sample was weighed in a glass tube with a stream of nitrogen to displace oxygen. The samples were hydrolyzed in HCl for 24 h at 110 ℃. Then, the amino acids were pre-column derivatized by 6-aminoquinoline-n-hydroxysuccinimide carbamate (AQC). In precolumn derivatization combined with reverse-phase chromatography, both 2,4-dinitrofluorobenzene (DNFB) and phenylisothiocyanate (PITC) can react with primary amines and secondary amines. However, the derivatization time is approximately 1 h. In contrast, the derivatization time of AQC was greatly shortened. Derivatization led to the conversion of free amino acids into highly stable derivatives, which were separated by ultra performance liquid chromatography (UPLC) with UV detection at 260 nm and quantified by the external standard method. The samples were separated on a BEH C18 column (150 mm×2.1 mm, 1.7 µm) at a flow rate of 0.4 mL/min. The calibration curves showed good linearity, with correlation coefficients greater than 0.999. The limits of detection (LODs) and limits of quantification (LOQs) of the 18 amino acids were 1.3-2.5 (mg/100 g) and 3.9-7.5 (mg/100 g), respectively. Quality control samples of SRM 1849a were used as the reference material. The results were in accordance with the content range. The RSDs ranged from 2.04% to 3.65%. Furthermore, the developed method was successfully applied to determine the types and concentrations of amino acids in 11 samples purchased from local markets in Shanghai and online shops. Abundant amino acids were detected in the three types of milk powder. While all the milk powder samples contained 18 types of amino acids, Tau was not detected in some of the goat and camel milk powder samples. Total essential amino acids (TEAA) in total amino acids (TAA) of milk powder was the highest of all. The TEAA values of TAA in the goat and camel milk powders were similar. The developed method requires only 22 min for the separation of 18 amino acids. This method is suitable for the large-scale analysis of milk powder samples, and it demonstrates high sensitivity and accuracy for the determination and confirmation of the 18 amino acids in different types of milk powders.

Computational design and synthesis of molecular imprinted polymers for selective solid phase extraction of sulfonylurea herbicides.

A high-efficiency approach for the synthesis of molecularly imprinted polymers has been developed and further for the solid-phase extraction of sulfonylurea herbicides in food samples. Molecular simulation approach combined chemometric selected metsulfuron-methyl (MSM) and 2-trifluoromethyl acrylic acid (TFMAA) as the template and the monomer to synthesize the molecularly imprinted polymers (MIPs). Experimental validation confirmed that the MSM-imprinted polymers showed a higher selectivity and affinity to sulfonylurea herbicides. The optimized molecularly imprinted solid-phase extraction (MISPE) conditions, including loading, washing, and eluting conditions, were established. The developed MISPE technology combined HPLC-MSMS was successfully used for the determination of sulfonylurea herbicides in foods. Compared with commercial SPE columns, MISPE showed high affinity, excellent selectivity and low matrix effect. The recoveries of sulfonylurea herbicides spiked in four matrices were between 86.4% and 100.2%, with the relative standard deviations (RSD) in the range of 0.9%-10.5%.

Correction: Determining the geographical origin of milk by multivariate analysis based on stable isotope ratios, elements and fatty acids.

Correction for 'Determining the geographical origin of milk by multivariate analysis based on stable isotope ratios, elements and fatty acids' by Siyan Xu et al., Anal. Methods, 2021, DOI: .

Early mechanical cardiopulmonary resuscitation can improve outcomes in patients with non-traumatic cardiac arrest in the emergency department.

OBJECTIVE: To compare the outcomes of patients with non-traumatic cardiac arrest (CA) who received early versus late mechanical cardiopulmonary resuscitation (CPR) with the Lund University Cardiac Assist System (LUCAS) device in the emergency department (ED). METHODS: This was a retrospective observational study in the ED of a single medical center performed from May 2018 to December 2019; 68 patients with CA were eligible. We grouped the patients according to the time to initiating LUCAS use after CA into an early group (≤4 minutes) and late group (>4 minutes). RESULTS: The rate of return of spontaneous circulation (ROSC) was higher in the early group vs the late group (69.2% vs 52.4%, respectively). The 4-hour survival rate was significantly higher in the early group vs the late group (83.3% vs 45.5%, respectively), and CPR duration was significantly shorter in the early group (23.3 ± 12.5 vs 31.1 ± 14.8 minutes, respectively). CONCLUSION: Early mechanical CPR can improve the success of achieving ROSC and the 4-hour survival rate in patients with non-traumatic CA in the ED, considering that more benefits were observed in patients who received early vs late LUCAS device therapy.