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The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the biological action of many aromatic environmental pollutants. In this study, we investigated the activation of the AhR by some vegetable constituents using the AhR-based bioassay for dioxins, i.e., the chemical activated luciferase gene expression (CALUX) assay. Ninety-five vegetable constituents, including flavonoids, tannins, saponins, and terpenes, were tested in vitro. Among them, isoflavones such as daidzein, resveratrol having a stilbene structure, and some flavonoids such as naringenin, hesperetin, and baicalein showed AhR activation.

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A method was developed for the determination of trace amounts of acrylamide (AA) in foods. The method includes the addition of 13 C-labeled acrylamide-1-13 C (AA-1-13 C) as an internal standard, extraction with water, bromination, clean-up with a Florisil cartridge column, dehydrobromination and GC/MS analysis in the selected ion monitoring (SIM) mode. Bromination of AA to 2,3-dibromopropionamide (2,3-DBPA) was done using potassium bromide and potassium bromate under an acidic condition. 2,3-DBPA was converted to 2-bromopropenamide (2-BPA) by dehydrobromination with triethylamine before GC/MS analysis. The recoveries of AA from spiked potato chips, corn snack, pretzel and roasted tea were 97ῌ105ῌ, and their relative standard deviations were 0.8ῌ3.9ῌ. The detection limit of AA in foods was 9 ng/g. The method was applied to thirty-one foods purchased from retail markets. AA was found in potato chips at the level of 466ῌ3,340 ng/g, and in other foods at the level of NDῌ520 ng/g.

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The chemical-activated luciferase expression (CALUX) assay is a reporter gene assay that detects dioxin-like compounds based on their ability to activate the aryl hydrocarbon receptor (AhR) and thus expression of the reporter gene. In this paper, the CALUX assay was examined for its application in the screening of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) in retail fish. The sample extracts were cleaned up on a sulfuric acid-silica gel column followed by an activated carbon column, and the AhR activity of the separated PCDD/F and dioxin-like PCB fractions was determined using the assay. The quantitative limit for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) was 0.98 pg ml(-1) (0.19 pg assay(-1) in the standard curve, corresponding to 0.16 pg g(-1) of CALUX-based toxic equivalency (2,3,7,8-TCDD equivalents) in the tested sample. Recovery tests in which dioxins were added to fish samples resulted in acceptable recoveries (77-117%). The CALUX assay performed well in the analysis of dioxins in fish samples and a comparative study revealed a strong correlation between the CALUX assay and high-resolution gas chromatography-high-resolution mass spectrometry analysis for the determination of PCDD/Fs (r = 0.89) and dioxin-like PCBs (r = 0.91) in retail fish (n = 22). These data revealed that the CALUX assay would be a useful screening method for PCDD/Fs and dioxin-like PCBs in retail fish.

The relative standard deviation of measurements in atomic absorption spectrometry for cadmium determination is predicted by the signal fluctuation model, which is made up of the white noise and Markov process. The standard deviation (SD), w̃, of the white noise and SD, m̃, and autocorrelation parameter, ρ, of the Markov process are determined from the power spectrum of the actual signal fluctuation in the system and in turn are put to use for the uncertainty prediction of measurements in the time space. The confidence intervals of the conventional calibration and standard addition method are calculated from the predicted SD of measurements.