An on-line method for S-isotope analysis is described. Samples are combusted in an elemental analyzer. SO2 is separated from other combustion gases by gas chromatography, and the gases enter the ion source of the mass spectrometer through a split interface. Integrated peak areas for 32S02+ and 34SC>2+ are compared to the response for a standard gas sample to determine the S^S value. 534S values of samples analyzed using the on-line method correspond linearly with those achieved from the same sample prepared off-line, where Kiba reduction followed by oxidation of the sulfur to SO2 is carried out prior to S-isotope analysis against a known standard. With the described on-line method, the amount of sulfur necessary for S-isotope analysis is reduced to about 10 #tg of S per analysis. The time needed for on-line preparation and measurement is less than one-third of the off-line procedure.Stable sulfur-isotope analysis is often associated with many problems concerning sample preparation and mass spectrometric determination. The 34S/32S ratios are most commonly determined after SO2 has been generated out of natural materials. Sample preparation always requires several chemical transformation steps to finally produce SO2 out of the S-containing compounds. The standard preparation techniques used for most sulfur-bearing samples start with conversion of all sulfur to BaSO*, which is then reduced to H2S by one of the following three procedures: graphite reduction at 1000 °C,' reduction with tin(II)-strong phosphoric acid (Kiba's reagent) at 300 °C in a stream of nitrogen,2 or application of a HI-H3PO4-HCI reduction solution.3 The generated H2S is converted to Ag2S, which is finally oxidized to SO2. One major disadvantage of these methods is that they all need relatively large amounts of the original material to obtain sufficient sulfur as the numerous chemical processes require rather high amounts of sulfur (3-7 mg of S). Although

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Guidelines for the performance and analysis of bioequivalence studies are not very specific. The advantages and disadvantages of the following methods and tests are discussed: analysis of variance by summation or by use of general linear models, nonparametric procedures, aposteriori probabilities and tests on the normality of residuals and on the variability of the results. Arguments for or against an analysis of data after logarithmic transformation versus analysis of untransformed data are presented. If the confidence intervals lie within certain limits, preparations may be considered equivalent. The criteria leading to those limits are discussed. It is recommended that concentration-dependent data of bioequivalence studies be evaluated by analysis of variance after logarithmic transformation, applying general linear models. Data that by theoretical reasons cannot be normally or log-normally distributed should be analysed by nonparametric methods. Otherwise these methods can only be recommended if a significant deviation from normality has been noted and only for two-way cross-over designs. For a geometric evaluation (after logarithmic transformation) the regions of acceptance should be symmetrical in the logarithm, e.g. (80%, 125%).

PurposeA variety of elastographic techniques have been developed to facilitate the non-invasive assessment of tissue properties. The goal of the study was to examine the influence of gender, age, BMI, alcohol consumption, and smoking in healthy volunteers.MethodsOf the 263 participants who met all the study inclusion criteria, 234 had successful measurements. The examination was performed with the Siemens Acuson S3000 (Siemens Healthcare, Erlangen, Germany), using the 6C1 curved array transducer with the virtual touch tissue quantification (VTQ) method.ResultsThe values determined with the curved array in the head of the pancreas were 1.44 ± 0.39 m/s for women and 1.19 ± 0.29 m/s for men; in the body, the results were 1.49 ± 0.37 m/s for women and 1.26 ± 0.30  m/s for men; in the tail, the corresponding values were 1.29 ± 0.36 m/s for women and 1.05 ± 0.30 m/s for men. Comparison of gender showed that men have significantly lower mean values than women. There were significantly higher values in all parts of the organ with the increasing age of the participants (p < 0.0001). For BMI, there was a significant correlation with the values only when considering the BMI in continuous form. Alcohol consumption and smoking did not have any significant effects.ConclusionsARFI-VTQ is qualified for use on pancreatic tissue. Further studies are required to examine the influence of other factors in larger populations.

Twenty-four healthy volunteers participated in a study on the disposition of ergotamine following oral and rectal administration. Plasma samples were collected surrounding each dose of medication and a new mass spectrometry method was used for quantitation of the samples. A mean peak plasma concentration of 454 pg/ml was measured an average of 50 min following a 2 mg rectal dose. In contrast, the 2 mg oral dose produced a mean peak plasma concentration of 21 pg/ml an average of 69 min following the dose. Area under the concentration time curve indicated a relative bioavailability of 5% for the oral dosage form. Conflicting data on ergotamine disposition highlight the factors which may be responsible for determining bioavailability and pharmacologic activities of the compound.