Frequency-modulated simultaneous Atomic Absorption Spectrometry (FremsAAS): Determination of As, Se and Sb.

The evaluation of accuracy and efficiency of the frequency-modulated simultaneous Atomic Absorption Spectrometry (FremsAAS) has been extended to an arrangement with EDL as light sources. Fundamental calibrations have been worked out for As, Se and Sb using a graphite furnace as well as hydride generation in combination with a heated quartz tube as atomization unit. The characteristic data are in good agreement with results obtained by conventional single-channel AAS instruments. Determinations in three standard reference materials with different complex matrices resulted in complete agreement with the certified values.

The strength characteristics of internal and external rotator muscles in professional baseball pitchers.

The purpose of this study was to establish a data base regarding the isokinetic muscular performance characteristics of the external/internal rotator muscles of professional baseball pitchers. One hundred fifty healthy professional baseball pitchers were evaluated by use of a Biodex isokinetic dynamometer. The subjects tested had a mean age of 23.4 years and a mean body weight of 199 pounds. Isokinetic tests were performed concentrically at 180 and 300 deg/sec for both the throwing and nonthrowing shoulders. Testing procedures regarding positioning and stabilization followed established guidelines. The testing protocol and actual test repetitions were standardized for each subject. Statistical analysis was performed using the Pearson Product Moment Correlation and paired t-tests. Determination of the correlation coefficient was made at the P < 0.05 level of significance. Test results for bilateral comparison of mean peak torque for the throwing and nonthrowing shoulders indicated no statistically significant difference between the internal rotators at both test speeds, or for the external rotators at 300 deg/sec. There was a significant statistical difference at the 180 deg/sec test speed for the external rotators. The external/internal rotator strength ratio indicated a 65% ratio at 180 deg/sec and a 61% ratio at 300 deg/sec. Data were also collected for mean peak torque/body weight ratios of the throwing shoulder to establish a data base in professional throwers. This study offers clinical relevance in establishing a muscle performance profile for the professional thrower. This data base can therefore be used as criteria that should be met before an injured pitcher can be returned to throwing at the professional baseball level.

Investigations for the determination of lead by in situ hydride trapping within a graphite electrothermal atomizer for routine analysis.

A new commercial system consisting of a flow injection analysis system for hydride generation coupled with a transversely heated graphite atomizer-atomic absorption spectrometer for the determination of lead is investigated in detail. The hydride generation is optimized by using an ammonium peroxodisulphate-hydrochloric acid system as oxidant and sodium borohydride as reducing reagent. The addition of sodium cumol sulphonate as surface active substance shows advantages considering efficient plumbane production. The hydride trapping and atomization in a graphite electrothermal atomizer is also optimized. The characteristic concentration was 0.74 mug/l, the detection limit was 0.70 mug/l for 500 mul sample volumes. The relative operation standard deviation of this method was smaller than 2%. Further examinations demonstrate the influence of several heavy metals on the determination of lead. Finally, the measurement of standard reference materials shows the efficiency of the method in combination with decomposition with aqua regia solutions.

Is there a hazard to health by mercury exposure from amalgam due to MRI?

The local magnetic fields from computer monitors are well known. Recently a hypothesis was published that these magnetic fields may lead to a 400% increase of mercury dissolution from dental amalgam fillings. In MRI the exposure to the magnetic field exceeds by far the exposure from computer monitors. Therefore, this study examined the amalgam-related mercury release for typical MRI conditions, separated for both the static and the variable magnetic fields in a 1.5 T MR-unit. First, 20 dental cavities were filled with a non-gamma-2 amalgam, and the mercury release was measured for 14 days in a non-magnetic environment. Second, one half of the specimens were exposed to a static magnetic field for 24 hours (group A), while the other specimens were exposed to a repetitive gradient echo sequence for 60 minutes (group B). In both experiments there was no significant increase in mercury release due to MRI. This in vitro study demonstrated no evidence of an elevated mercury dissolution from a non-gamma-2 amalgam during magnetic field exposure by MRI; therefore, there is no increased risk to health.