Uptake and elimination of aflatoxins (AFs) by rainbow trout ( Oncorhynchus mykiss ) during a long-term (21 days) dietary exposure were studied to assess contamination by AFs in aquaculture fish fed AF-containing feed. The uptake factor (UF) of aflatoxin B(1) (AFB(1)) in muscle ranged from 0.40 × 10(-3) to 1.30 × 10(-3). AFB(1) concentrations in liver were 165-342 times higher than in muscle. AFs from feed were more highly accumulated in liver than in muscle. Aflatoxicol (AFL) and aflatoxin M(1) (AFM(1)) were detected in muscle and liver and also in the rearing water. AFL concentrations were higher than AFM(1) by 2 orders of magnitude in muscle, and AFL was a major metabolite of AFB(1). The elimination rate constants (α) of AFB(1) and AFL in muscle (1.83 and 2.02 day(-1), respectively) and liver (1.38 and 2.41 day(-1), respectively) were very large. The elimination half-life (t(1/2)) of AFB(1) was 0.38 days (9.12 h) in muscle and 0.50 days (12.00 h) in liver. The elimination half-life of AFL in muscle and liver was 0.34 day (8.16 h) and 0.29 day (6.96 h), respectively. These data show that AFs are eliminated rapidly and are not biomagnified in fish. Thus, AFB(1) concentration in muscle of fish fed AFB(1)-containing feed (ca. 500 μg/kg) decreased to below the detection limit (20 ng/kg) of the most sensitive analytical method at 1.54 days (36.96 h) after the change to uncontaminated feed.

In order to demonstrate the activation effects of a Pt electrode by laser pulse irradiation, the electro-oxidation of glucose was tested at an activated Pt electrode by cyclic voltammetry. A fixed potential was applied to the electrode, and then the electrode was irradiated with laser pulses from a Nd:YAG laser at 20 Hz for 20 s. Activation by the laser pulse irradiation gave two remarkable effects on cyclic voltammograms from the electro-oxidation of glucose in a 0.1 mol dm -3 NaOH solution, i.e., surface modulation and cleaning effects. Significant differences were found in the cyclic voltammograms at the activated and at the simply polished electrodes. Such differences in the oxidation waves are attributed to a crystallographic change of the electrode surface induced by a laser ablation, accompanied by laser pulse irradiation. Due to the cleaning effect, the activated Pt electrode gave a sharp oxidation wave at -0.3 V even in real samples containing various organic compounds that could foul the electrode, though the activated Pt electrode lacked selectivity to the electro-oxidation of glucose.

A highly sensitive analysis method for six aflatoxins (aflatoxin B 1 , B 2 , G 1 , G 2 , M 1 and aflatoxicol) in rainbow trout muscle and liver was developed. Aflatoxins (AFs) were extracted with acetonitrileῌwater (9 : 1), purified on an immunoa$nity column, and subjected to HPLC with fluorescence detection after post-column photochemical derivatization. The recoveries of AFs at 0.05 ῌg/kg spiking levels were 71.4ῌ82.4̮ in muscle and 80.1ῌ93.0̮ in liver, and the repeatability relative standard deviations (RSDr) were 0.87ῌ4.6̮ in muscle and 2.0ῌ6.2̮ in liver. Limits of quantitation (LOQs) and limits of detection LODs of AFs were estimated to be 0.004ῌ0.029 ῌg/ kg, and 0.002ῌ0.012 ῌg/kg, respectively.

New analytical methods for the determination of free asparagine Asn , which is a precursor of acrylamide, in grains were developed using LC-MS and LC-MS/MS. Asn was extracted from a sample with 5 w/v aqueous trichloroacetic acid solution, appropriately diluted with 0.1 v/v formic acid solution, and then analyzed by LC-MS or LC-MS/MS. HPLC separation was performed by isocratic elution on a Penta Fluoro Phenyl PFP column using 0.1 v/v formic acid and acetonitrile mixture as the mobile phase. The calibration curve was linear in the range of 0.005-0.1 μ g/mL. The mean recoveries from potato starch, non-glutinous rice flour and whole wheat flour ranged from 95.4 to 100.9 , repeatability RSD ranged from 0.9 to 6.0 , and within-laboratory reproducibility RSDwr ranged from 2.8 to 7.1 . Limits of quantitation LOQs were 7 mg/kg for potato starch, and 5 mg/kg for non-glutinous rice flour. In addition, an inter-laboratory study was performed in 10 laboratories using 5 kinds of grains non-glutinous brown rice flour, corn flour, strong flour, whole wheat flour, and whole rye flour , which naturally contained free asparagine. The HORRAT R values ranged from 0.4 to 1.0. These results are within the range of the procedural manual of the Codex Alimentarius Commission, confirming the effectiveness of the developed procedures.

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