BACKGROUND: Methylmercury is an organic form of mercury that is highly toxic to humans. Here, we present and establish a novel method to detect methylmercury concentrations in the blood of Koreans. METHODS: Methylmercury concentration was analyzed with an automated methylmercury analytic system (MERX, Brooks Rand Co., USA) using cold vapor atomic fluorescence spectrophotometry (CVAFS). A variety of biological materials were digested in methanolic potassium hydroxide solution. The analysis method was validated by examination of certified reference material (955c, National Institute of Standard and Technology, USA). We randomly selected 30 Korean adults (age 20 yr or older) to analyze total blood mercury and methylmercury concentrations. RESULTS: The detection limit and methylmercury recovery rate using this method were 0.1 pg/L and, 99.19% (range: 89.33-104.89%), respectively. The mean blood concentration of methylmercury was 4.54+/-2.15 microg/L (N=30). The mean proportion of methylmercury to the total mercury concentration was 78.27% (range: 41.37-98.80%). CONCLUSIONS: This study is the first report to analyze blood methylmercury concentration using CVAFS in Korea. We expect that this method will contribute to the evaluation of mercury exposure and the assessment of the toxicological impact of mercury in future studies.
Adult ; Humans ; Hydroxides/chemistry ; Mercury/blood ; Methylmercury Compounds/*blood ; Potassium Compounds/chemistry ; Reproducibility of Results ; Republic of Korea ; *Spectrophotometry, Atomic

The drug-loading system of DMF (dextran - magnetic layered double hydroxide - fluorouracil) was synthesized by "co-precipitation intercalated assembly - dextran composite in situ - solvent conversion" technology. The crystal-phase characteristic and slow-release performance of DMF were investigated through X-ray diffraction (XRD), infrared spectrum (IR), transmission electron microscopy (TEM), thermogravimetry (TG) and in vitro release experiment. The targeted transshipment and slow-release effect of DMF system were evaluated by in vivo animal experiment. It was showed that the XRD of DMF matched with R-sixtetragonum type layered double hydroxide and Fd-3m cubic type ferrite. IR test demonstrated that the DMF system was a supra-molecular complex consisted of Dextran (DET), magnetic layered double hydroxide (MLDH) and fluorouracil (FU) components. The two-level supra-molecular MLDH-FU presented six-edge lozenge TEM morphology, with layered characteristics. DET on the surface of DMF was capable of protecting the layered structure of MLDH-FU, improving particle dispersion properties, and strengthening the slow-release performance of the drug delivery system. The drug release model of DMF at pH 7.35 of PBS in vitro fit to the zero-order kinetics equation C = 1.1716 x 10(-5) + 4.4626 x 10(-7) t. The drug delivery system DMF could transport drugs principally to in vivo target organs with a local effect, targeted specificity, and excellent circulation transshipment performance. The pharmacokinetic process of DMF presented multi-peak phenomenon with peak attenuation and cyclic growth. The peaks appeared at 0.25, 1, 3, 5 and 9 d separately after dosing intervention. The first peak process of DMF accorded with a pharmacokinetic equation of C(FU) = 14.34 e(-0.530t) + 36.04 e(-0.321t) + 24.18 e(-0.96t), and presented the characteristic of slow absorption and fast elimination. As for subsequent peak processes, half-life increased, bioavailability increased, and plasma clearance decreased. The highest peak value of DMF was 1/37 of original value of FU, and the relative bioavailability was 419% to original FU.
Animals ; Biological Availability ; Delayed-Action Preparations ; Dextrans ; chemistry ; Drug Carriers ; Female ; Fluorouracil ; administration & dosage ; chemistry ; pharmacokinetics ; Half-Life ; Hydroxides ; chemistry ; Magnetics ; Male ; Microscopy, Electron, Transmission ; Rats ; Rats, Sprague-Dawley ; Spectrophotometry, Infrared ; Thermogravimetry ; X-Ray Diffraction