Determination of freely dissolved polycyclic aromatic hydrocarbons in human serum using core-shell Fe3O4@polyacrylate magnetic microspheres by exclusive volume effect.

Freely dissolved concentration is an important parameter for evaluating the bioavailability of compounds. Negligible-depletion solid-phase microextraction (nd-SPME) has been widely used for the determination of freely dissolved compounds but suffered from long equilibrium time. Multifunctional mesoporous composite microspheres have large specific surface area and therefore extraction equilibrium could be reached in a short time. In this study, a novel method was developed for quick determination of freely dissolved polycyclic aromatic hydrocarbons (PAHs) in human serum using core-shell polyacrylate-ferriferous oxide magnetic microspheres (Fe3O4@PA). Mass transfer of PAHs from sample solution to Fe3O4@PA was greatly increased owing to unique properties including large surface area (58.5 m2 g-1), high pore volume (0.10 cm3 g-1) and thin coating layer (50 nm). Freely dissolved PAHs can be selectively extracted because of the mesoporous structure of PA coating layer with uniform pore size of 7.08 nm. However, bound forms of PAHs would not be able to access into pore channels due to size exclusion. In comparison with long equilibration time (139 h) by nd-SPME, equilibrium can be reached within 29 min (t90%) using Fe3O4@PA as novel sorbents. The sorption coefficients (log KBSA) of PAHs to bull serum albumin (BSA) ranged from 3.36 to 4.87, which are consistent with the values measured by nd-SPME (log KBSA = 3.64-5.12). Finally, the freely dissolved PAHs (Cfree) measured by the proposed method (0.69-1.92 µg L-1) have a good agreement with that by nd-SPME (0.56-2.11 µg L-1), indicating that it is feasible for rapid determination of free forms of compounds in real samples by Fe3O4@PA.

[Relationship between three neuropsychological tests and cerebral glucose metabolism in Alzheimer's disease].

OBJECTIVE: To study the relationship between the scores of 3 neuropsychological scales: MMSE, extended scale of dementia (ESD) and Blessed dementia scale (BDS) and cerebral glucose metabolism in Alzheimer's disease (AD) indicated by positron emission tomography (PET). METHODS: Brain scanning was performed with SIEMENS ECAT 47 PET scanner among 21 AD patients, aged 60 - 83 (10 mild, 6 moderate, and 5 severe), and 15 healthy persons, aged 57 - 73. The ratio of mean radioactivity of cerebral lobe to that of cerebellum as semi-quantitative parameters was used to evaluate the cerebral glucose metabolism. Cognitive function was assessed by three neuropsycholigical scales: MMSE, ESD and BDS. RESULTS: The average MMSE score was 13.3 +/- 6.3 (range 2 - 25), the average ESD score was 120.5 +/- 54.8 (range 28 - 200), and the average BDS score was 4.7 +/- 3.1 (range 0.5 - 10) in the AD patients. The decreases of glucose metabolism in parietal, frontal and temporal lobes were significantly positively correlated with MMSE and ESD scores, and negatively correlated with BDS scores in AD patients (P < 0.05). The correlations between MMSE and ESD (r = 0.886), MMSE and BDS (r = -0.763), and ESD and BDS (r = -0.773) were significant in AD patients (all P < 0.01). Taking the ratio of radioactivity of cerebral lobe to that of cerebellum as an independent variable X, the MMSE, ESD and BDS scorsas dependent variable Y, three regression equations were established as follows: Y = 40.11 * X- 25.32, Y = 309.19 * X- 180.9, Y = 19.97 - 16.53 * X. The independent variable entering the three regression equations was always the ratio of radioactivity of left parietal lobe to that of cerebellum. The ratio of radioactivity of left parietal lobe to that of cerebellum was a significant predictor for cognitive dysfunction measured by MMSE, ESD and BDS in AD patients (P < 0.01). CONCLUSION: MMSE, ESD and BDS scores correlate well with impaired cerebral glucose metabolism in AD. The function of left parietal lobe may play an important role in the progress of the disease. MMSE, ESD and BDS are good measures for cognitive dysfunction.

Rapid and direct determination of iodide in seawater by electrostatic ion chromatography.

An electrostatic ion chromatographic (IC) method for rapid and direct determination of iodide in seawater is reported. Separation was achieved using a reversed-phase ODS packed column (250x4.6 mm I.D.) modified by coating with Zwittergent-3-14 micelles, with an eluent comprising an aqueous solution containing 0.2 mM NaClO4 and 0.3 mM Zwittergent-3-14 and using UV detection at 210 nm. Samples prepared by dissolving NaIO3, NaNO2, NaBr, NaBrO3, NaNO3, NaI, and NaSCN in artificial or real seawaters were analyzed using this IC system. Nitrite, iodate, bromide, bromate, and nitrate showed very little or no retention, while iodide and thiocyanate were well separated, being eluted within 6 and 16 min, respectively. The detection limit for iodide obtained by injecting 400 microL of sample was 0.011 microM (S/N = 3), and the precision values obtained by analyzing samples containing 0.1 or 0.3 microM iodide in real seawater samples were 2.3% RSD and 1.2% RSD, respectively. Direct determination of iodide in real seawater samples was possible using this proposed IC system.