[Determination of 22 mycotoxins in milk by liquid chromatography-quadrupole/orbitrap mass spectrometry].

Mycotoxins have carcinogenic, mutagenic, hepatotoxic, nephrotoxic, immunotoxic, neurotoxic, and teratogenic properties. Thus, these substances have attracted significant attention because they pose a threat to human health. As research on mycotoxins deepens, new structural analogues of mycotoxins are constantly being discovered. In this study, a method based on high performance liquid chromatography-quadrupole/orbitrap mass spectrometry was established for the simultaneous determination of 22 mycotoxins in milk. A simple, effective, and rapid pretreatment method was optimized by focusing on the solvent type, extractant volume, and extracting salt based on the characteristics of the mycotoxins and sample matrix. The analytes were extracted using 0.5% formic acid acetonitrile solution and added with sodium chloride to separate fats from water. The samples were centrifuged at 8000 r/min (4 ℃) for 5 min using a centrifuge and then concentrated using nitrogen. The dry residue was dissolved with 50% methanol aqueous solution. Twenty-two mycotoxins were separated on a ZORBAX Eclipse Plus C18 chromatographic column (100 mm×2.1 mm, 1.7 µm), and quantitative analysis was performed using the isotope internal standard method. The analytes were determined by liquid chromatography-quadrupole/orbitrap mass spectrometry in positive electrospray ionization mode. Qualitative analyses of the compounds were performed in full mass spectrometry/data-dependent tandem mass spectrometry (MS/dd-MS2) mode. Good linearities in the range of 0.5-100.0 µg/L were observed for the 22 mycotoxins, and the correlation coefficients (R2) were greater than 0.999. The limits of detection (S/N=3) and quantification (S/N=10) ranged from 0.3 to 0.5 µg/kg and from 1.0 to 1.5 µg/kg, respectively. The average recoveries of the 22 mycotoxins at three spiked levels of 1.5, 5.0, and 15 µg/kg were between 84.7% and 100.8%, with relative standard deviations (RSDs) of 1.2%-9.9%. These findings indicate that the method has high sensitivity and accuracy as well as good precision. Finally, the method was applied to the detection and analysis of mycotoxins in 25 actual commercial milk samples. The results revealed that the selected samples were not contaminated with any of the mycotoxins analyzed. Thus, the proposed method is useful as a quick preprocessing and confirmatory method for the simultaneous determination of mycotoxins in milk.

Catalytic spectrophotometric determination of trace aluminium with indigo carmine.

A new catalytic spectrophotometric method is described for the determination of trace amounts of Al(III). The methods based on catalytic action of Al(III) on the oxidation of indigo carmine (IC) by ammonium persulfate in hexamethylene tetramine-hydrochloric acid ((CH2)6N4-HCl) buffer medium (pH 5.4) and in the presence of surfactant-TritonX-100. The effects of some factors on the reaction speed were investigated. Aluminium concentration is linear for 0-1.2x10(-7) g/ml in this method. The detection limit of the proposed method is 1.96x10(-8) g/ml. Most of the foreign ions except for Cu(II), Fe(III) do not interfere with the determination, and the interference of Cu(II) and Fe(III) in this method can be removed by extraction with sodium diethyldithiocarbamate-carbon tetrachloride (DDTC-CCl4). This system is a quasi-zero-order reaction for Al(III), but it is a quasi-first-order reaction for IC. The apparent rate constant is 2.62x10(-5) s-1 and the apparent activation energy is 6.60 kJ/mol in the system. The proposed method was applied to the determination of trace aluminium(III) in real samples with satisfactory results.

[New development of modern photometric determination of trace aluminium in environmental samples].

In this paper, new development of modern photometric determination of aluminium in environmental samples in recent years was reviewed and discussed. The new development in modem photometric determination of aluminium in environmental samples was emphasized, including micelle photometric method, dual-wavelength photometric method, derivative photometric method, catalytic photometric method, solid phase photometric method and flow injection photometric method. Reaction systems of determination and it's conditions, molar absorption coefficient (epsilon) or the limit of detection, the scope of determination and applications of the ordinary photometric method, and the micelle photometric method were summarized. Advantages and disadvantages of all kinds of photometric methods were discussed. The development trend of photometric method was prospected for the detection of trace aluminium in environmental samples.

[Study on preparation of lanthanum-doped TiO2 nanometer thin film materials and its photocatalytic activity].

In this paper, lanthanum-doped TiO2 nanometer film materials coated on glass were prepared in Ti(OBu)4 precursor solutions by sol-gel processing. Transmittance and photocatalytic activity were respectively investigated and tested for these nanometer thin films prepared with different amount of lanthanum (La), different amount of polyethylene glycol (PEG), and different coating layer times. Some reactive mechanisms were also discussed. For one layer La-addition had little effect on the film transmissivity; but the photocatalytic activity was significantly improved due to La-addition. With increasing PEG, the transmittance of the film decreased for one layer film; but its photocatalytic activity did not rise. Increasing layer number did not affect the transmissivity of multilayer film. After coating two times, increasing layer number did not significantly improve the photocatalytic activity. The highest photocatalytic activity and best transmissivity were obtained for two layer TiO2 film when the dosage of lanthanum was 0.5 g and the dosage of polyethylene was 0.2 g in the precursor solutions. These materials will probably be used in the protection of environment, waste water treatment, and air purification.

[Biosence technology applied to environment monitoring].

The applications of biosensors and sensing technology in environment analysis and monitoring in water, air and others are reviewed, and the prospects of biosensor and sensing technology are discussed in this paper, including the determinations of BOD, phenols, nitrate and organophosphorous compounds, and the monitoring of red tides in water, the detections of carbon dioxide, sulfur dioxide and nitrogen oxide in atmosphere; the detections of poisonous residue and persistent organic pollutants; toxicity assessment and the determination of bacteria population.