An ultrasensitive gold nanoparticles improved real-time immuno-PCR assay for detecting diethyl phthalate in foodstuff samples.

A specific polyclonal antibody targeting diethyl phthalate (DEP) with the higher antibody titer at 1:120,000 has been obtained, and an ultrasensitive and high-throughput direct competitive gold nanoparticles improved real-time immuno-PCR (GNP-rt-IPCR) technique has been developed for detecting DEP in foodstuff samples. Under optimal conditions, a rather low linearity is achieved within a range of 4 pg L(-1) to 40 ng L(-1), and the limit of detection (LOD) is 1.06 pg L(-1). Otherwise, the GNP-rt-IPCR technique is highly selective, with low cross-reactivity values for DEP analogs (<5%). Finally, the concentrations of DEP in foodstuff samples by the GNP-rt-IPCR method range from 0.48 to 41.88 µg kg(-1). Satisfactory recoveries (88.39-112.79%) and coefficient of variation values (8.38-12.77%) are obtained. The consistency between the results obtained from GNP-rt-IPCR and gas chromatography-mass spectrometry (GC-MS) is 98.3%, which further proves that GNP-rt-IPCR is an accurate, reliable, rapid, ultrasensitive, and high-throughput method for batch determination of trace amounts of DEP in foodstuff samples.

[Induction of free radicals after dietary exposure by mercury contaminated rice and protective effect of coexisting selenium].

Sprague-Dawley rats were reared by environmental mercury contaminated rice to survey the potential health risk of Wanshan mercury mining area. Electron spin resonance (ESR) was introduced to detect the species and the intensities of free radicals, using spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). The results showed that the mercury-contaminated rice significantly increased the levels of free radicals and MDA in rat brain at 7 days (p < 0.05). ESR spectrums showed that the principal spin adducts resulted from the trapping of alkyl free radical (alphaH = 22.7 x 10(-4)T +/- 1.6 x 10(-4)T, alphaN = 15.5 x 10(-4)T +/- 0.5 x 10(-4)T), and hydroxyl radical. Levels of free radicals and MDA increased slowly until after 90-day exposure period (83%, 100%). Element correlation analysis showed high correlations of mercury and selenium in the brain of rat fed with Wanshan rice, suggesting that the coexisting selenium in rice exhibited antagonistic effects on both mercury accumulation and toxicity. The slight increases of free radicals in rat brain at 7, 20 and 30-day exposure periods should be related with the scavenger effect of Se.

Kinetic spectrophotometric determination of rutin by its inhibitory effect on the oxidation of amaranth by potassium periodate.

A novel kinetic spectrophotometric method is described for the determination of rutin. The method is based on the inhibitory effect of rutin on the oxidation reaction of amaranth by potassium periodate in acidic media at 100 degrees C. The linear range for the determination of rutin is 0.02 - 0.50 microg/ml, and the detection limit is 0.014 microg/ml. The method has been successfully applied to the determination of rutin in medicine of rutin tablet and traditional Chinese medicine.