[Determination of sodium, magnesium, calcium, lithium and strontium in natural mineral drinking water by microwave plasma torch spectrometer with nebulization sample introduction system].

The microwave plasma torch (MPT) was used as the emission light source. Aqueous samples were introduced with a nebulizer and a desolvation system. A method for the determination of Na, Mg, Ca, Li and Sr in natural mineral drinking water by argon microwave plasma torch spectrometer (ArMPT spectrometer) was established. The effects of microwave power, flow rate of carrier gas and support gas were investigated in detail and these parameters were optimized. Under the optimized condition, the experiments for the determination of Na, Mg, Ca, Li and Sr in 11 kinds of bottled mineral drinking water were carried out by ArMPT spectrometer. The limit-of-detection (LOD) of Na, Mg, Ca, Li and Sr was found to be 4.4, 21, 56, 11 and 84 µg x mL(-1), respectively. Relative standard deviation (n = 6) was in the range of 1.30%-5.45% and standard addition recoveries were in the range of 84.6%-98.5%. MPT spectrometer was simpler, more convenient and of lower cost as compared to ICP unit. MPT spectrometer demonstrated its rapid analysis speed, accuracy, sensitivity and simultaneous multi element analysis ability during the analysis process. The results showed that MPT spectrometer was suitable for metal elements detection for natural mineral drinking water. This approach provides not only one way for resisting the illegal dealings, but also a security for the quality of drinking water. Moreover, the usability of MPT spectrometer in the field of food security; drug safety; clinical diagnostic is promised.

Calix[4]arene crown-4 ether modified glassy carbon electrode for electrochemical determination of norepinephrine.

A sensitive and selective electrochemical method for the determination of norepinephrine (NE) was developed by using a calix[4]arene crown-4 ether (CACE) film modified glassy carbon electrode (GCE). The fabrication of the CACE film and its electrocatalytic effect for electrochemical oxidation of NE were investigated by electrochemical impedance spectroscopy (EIS) and voltammetric methods. It was found that the electrochemical behavior of NE on the CACE film modified electrode depended on the film thickness of CACE. Based on the electrochemical data, the CACE film surface coverage (theta), the charge transfer number (z) and the amount of the surface-bound NE (Gamma) were calculated. The effects of the experimental variables such as the solution pH and the applied potential were investigated for optimum analytical performance. Excellent linear relationships were obtained in two concentration ranges of NE: one was from 0.55 to 9.7 microM and the other was 9.7 to 230 microM. The detection limit (S/N = 3) of NE obtained by steady-state amperometry was 0.28 microM. The relative standard deviation (RSD) for 10 successive measurements of 0.05 mM NE was 2.2%. This method could be applied for the direct determination of NE in injection samples. In addition, effects of possible interferences (e.g. ascorbic acid, AA) were investigated. The present work provides an effective method for amperometric determination of NE by using a CACE modified electrode.

[Distribution and drug resistance of the isolated bacteria from children with acute respiratory infection].

OBJECTIVE: To study the distribution and drug resistance of the isolated bacteria from children with acute respiratory infection (ARI) in Dalian. METHODS: Between January 2006 and February 2007, 930 children with ARI were enrolled, including 364 with acute upper respiratory infection (AURI), and 566 with acute lower respiratory infection (ALRI). The AURI children, who did not receive antimicrobial agent treatment or received oral antimicrobial agents 1-2 times, had bacterial cultures of pharyngeal swab. The ALRI children, who received intravenous antibacterial agents more than 3 days, had bacterial cultures of sputum and bronchoalveolar lavage fluid (BALF). Isolated bacteria were identified by the ATB system (Bio-Merieux, France). Antimicrobial susceptibility testing was carried out by means of Kirby-bauer. RESULTS: A total of 404 isolates (43.4%) were identified. Haemophilus influenzae, Haemophilus parainfluenzae and Streptococcus pneumoniae accounted for 22.5%, 12.1% and 7.4% respectively. In the isolates from AURI, Haemophilus influenzae, Haemophilus parainfluenzae and Streptococcus pneumoniae accounted for 43.9%, 22.0% and 9.1% respectively; Escherichia coli, Klebsiella pneumonia and Nonfermenters accounted for 4.5%, 8.3% and 3.0% respectively. In the isolates from ALRI, Haemophilus influenzae, Haemophilus parainfluenzae and Streptococcus pneumoniae accounted for 12.1%, 7.4% and 6.6% respectively; Escherichia coli, Klebsiella pneumoniae and Nonfermenters accounted for 16.9%, 13.2% and 21.8% respectively. The resistant rates of Haemophilus to ampicillin and TMP-SMZ were 29.3% and 32.9% respectively, and to amoxicillin-clavulanic acid, cefalotin, cefaclor, cefuroxime and cefotaxime were 12.1%, 10.0%, 10.0%, 11.4% and 5.7%, respectively. The resistant rate of Haemophilus to ampicillin, amoxicillin-clavulanic acid, cefaclor, tetracycine and TMP-SMZ in the ALRI group were significantly higher than that in the AURI group (P<0.05 or 0.01). CONCLUSIONS: In Dalian, Haemophilus was the main isolate of children with ARI. The distribution of bacteria was different between ALRI and AURI. In ALRI, Gram-negative bacilli were in a higher proportion, and the resistant rates of Haemophilus influenzae and Haemophilus parainfluenzae to ampicillin, amoxicillin-clavulanic acid and cefaclor were higher.

An amperometric hydrogen peroxide biosensor based on immobilization of horseradish peroxidase on an electrode modified with magnetic dextran microspheres.

A new kind of magnetic dextran microsphere (MDMS) with uniform shape and narrow diameter distribution has been prepared from magnetic iron nanoparticles and dextran. Horseradish peroxidase (HRP) was successfully immobilized on the surface of an MDMS-modified glassy-carbon electrode (GCE), and the immobilized HRP displayed excellent electrocatalytic activity in the reduction of H(2)O(2) in the presence of the mediator hydroquinone (HQ). The effects of experimental variables such as the concentration of HQ, solution pH, and the working potential were investigated for optimum analytical performance. This biosensor had a fast response to H(2)O(2) of less than 10 s and an excellent linear relationship was obtained in the concentration range 0.20 micromol L(-1)-0.68 mmol L(-1), with a detection limit of 0.078 micromol L(-1) (S/N = 3) under the optimum conditions. The response showed Michaelis-Menten behavior at larger H(2)O(2) concentrations, and the apparent Michaelis-Menten constant K(M)(app) was estimated to be 1.38 mmol L(-1). Moreover, the selectivity, stability, and reproducibility of the biosensor were evaluated, with satisfactory results.

The immobilization of hepatocytes on 24 nm-sized gold colloid for enhanced hepatocytes proliferation.

Bioartificial liver and hepatocyte transplantation is anticipated to supply a temporary metabolic support for candidates of liver transplantation or for patients with fulminant liver failure. An essential restriction of this form is the inability to acquire an enough amount of hepatocytes. Enhancement of the proliferation and differentiated function of hepatocytes is becoming a pursued target. Here, porcine hepatocytes were successfully immobilized on nano-sized gold colloid particles to construct a "hepatocyte/gold colloid" interface at which hepatocytes can be quickly proliferated. The properties of this resulting interface were characterized and confirmed by scanning electron microscopy and atomic force microscopy. The proliferative mechanism of hepatocytes was also discussed. The proliferated hepatocytes could be applied to the clinic based on their excellent functions for the synthesis of protein, glucose and urea as well as lower lactate dehydrogenase release.