Co-contamination and interactions of multiple mycotoxins and heavy metals in rice, maize, soybeans, and wheat flour marketed in Shanghai City.

Mycotoxins and heavy metals extensively contaminate grains and grain products, posing severe health risks. This work implements validated ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and inductively coupled plasma mass spectrometry (ICP-MS) methods to quantify the concentration of 12 mycotoxins and five heavy metals in rice, maize, soybeans, and wheat flour samples marketed in Shanghai. The mixed contamination characteristics were analyzed using correlation cluster analysis and co-contamination index, and the probabilities of all cross combinations of contaminations were analyzed using a self-designed JAVA language program. The results showed that grains and grain products were frequently contaminated with both mycotoxins and heavy metals, mostly with deoxynivalenol (DON), 3-acetyl-deoxynivalenol (3-ADON), 15-acetyl-deoxynivalenol (15-ADON), ochratoxin A (OTA), aflatoxins, fumonisin B1 (FB1), fumonisin B2 (FB2), fumonisin B3 (FB3), arsenic (As), chromium (Cr) and cadmium (Cd). All the samples (100 %) were contaminated with two or more contaminants, and 77.3 % of the samples were co-contaminated with more than four contaminants. In cereals and cereal products, the following combinations were closely associated: (FB3 +3-ADON), (FB1 +As), (FB1 +FB2), (DON+FB1), (DON+Cd), (As+Cd), (DON+Cd+As), (FB1 +FB2 +As), and (DON+3-ADON+15-ADON). The results indicated that mycotoxins and heavy metals frequently co-occurred in Shanghai grains and grain products, and they provided primary data for safety assessments, early warnings, and regulatory measures on these contaminants to protect public health.

[Determination of adenosine content in heart tissue by ultra performance liquid chromatography-triple quadrupole mass spectrometry].

A method based on ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS) was developed and validated for the rapid and accurate determination of adenosine (Ado) in cardiac tissues with high sensitivity and specificity. The samples were dissolved in 1 mL of ultrapure water containing 10 µmol/L 2-hydroxy-3-nonyladenine hydrochloride (EHNA) as a stabilizer, ground at low temperature for 2 min, and then ultrasonically extracted at 60 Hz in an ice-water bath for 40 min. Methanol and 5 mmol/L ammonium acetate solution were used as the mobile phases under a flow rate of 0.4 mL/min, a column temperature of 40 ℃ and an injection volume of 3 µL. The Ado in cardiac tissue was qualitatively and quantitatively analyzed by electrospray ionization (ESI) positive-ion-switching in multiple reaction monitoring (MRM) mode. A solvent standard curve and the external standard method were used for the accurate quantification of Ado. The results showed that the matrix effect of Ado in cardiac tissue was very low. A good linear relationship was obtained in the range of 0.1-160 ng/mL, and the correlation coefficient (r2) was 0.9930. The limits of detection (LOD) and quantification (LOQ) were 0.03 and 0.1 ng/mL, respectively. The spiked recoveries of Ado in murine cardiac tissue were 113.6%, 96.3%, and 102.9% at three spiked levels of low, medium, and high, respectively. The intra-day repeatability (RSDs) were 1.7%-8.4%, and the inter-day reproducibility (RSDs) were 2.6%-7.4%. Based on the correlation and consistency results, a positive bias was observed between the proposed UPLC-MS/MS method and the double-antibody sandwich method. Moreover, the Ado contents detected by these two methods were significantly positively correlated (P<0.0001). Cardiac tissue samples were collected from 17 mice and 17 rats and detected in our laboratory. The content ranges of Ado in the cardiac tissues of mice and rats determined by the developed UPLC-MS/MS method were 3.25-8.78 mg/kg and 10.24-15.19 mg/kg, respectively (average adenosine contents: 5.37 and 12.60 mg/kg, respectively). The developed method is simple, accurate, sensitive, and it is suitable for the determination of Ado in cardiac tissues. It also provides important technical support for cardiac clinical research and disease diagnosis.