New Method for Analysis of Trimethylamine Oxide Using Ferrous Sulfate and EDTA

In the analysis of trimethylamine oxide (TMAO) in fish tissues, an equimolar mixture of ferrous sulfate (FeSO₄) and disodium ethylenediaminetetraacetic acid (EDTA) (0.1 M) in acetate buffer (0.8 M, pH 4.5) was found to be a satisfactory replacement for titanium chloride (TiCl₃). The TiCl₃ method for TMAO was usually conducted at 80°C; the FeSO₄-EDTA reaction at 50°C appeared complete in 5 min and yielded comparable results. The use of an acetate buffer alleviated any interference from the trichloroacetic acid used for extraction of TMAO and trimethylamine (TMA) from fish tissue.     

ESTIMATION OF ARRHENIUS MODEL PARAMETERS USING THREE LEAST SQUARES METHODS

The effectiveness of three least squares regression methods has been assessed for the estimation of Arrhenius model parameters. The performance of each method was assessed by comparing the relative sizes and positions of the 90% confidence regions for the parameter estimates and the degradation predictions. The traditional regression scheme, Method I, of sequentially regressing concentration data to obtain rates followed by a regression of the rates versus temperature to obtain the Arrhenius parameters was shown to be the least desirable method. Method II was similar to Method I, but used a multiple linear regression to regress the concentration data through a single co value. This provided more precise estimates, but a bias was indicated due to the fact that the individual rate estimates were not independent. Method III utilized a nonlinear regression which did not evaluate the individual rates. This method was less precise than Method II, but showed no bias. Method III was superior to Method I in every respect.     

Relation Between Multiregion Crack Growth and Dynamic Fatigue of Glass Using Indentation Flaws

The influence of transport-limited kinetic crack growth on the fatigue properties of soda-lime glass was examined. Dynamic fatigue data were taken on specimens with controlled indentation flaws and were compared with the predicted response from measured crack velocity characteristics. Heptane was used as the operational test environment because of its pronounced crack velocity plateau; control tests in water served to establish a baseline reference for comparing the results. Frac-tographic observations using a stress wave marker technique showed a complex growth history for flaws broken in heptane compared to that for flaws broken in water. The magnitude of the predicted region II influence is too small to be detected in the dynamic fatigue results, even allowing for the relatively high degree of data reproducibility. The implications of this conclusion for lifetime predictions are discussed.     

COMPARISON OF TWO ANALYTICAL METHODS FOR THE DETERMINATION OF DIMETHYLNITROSAMINE IN BEER AND ALE, AND SOME RECENT RESULTS

The results obtained by a rapid Celite column extraction method for the determination of dimethylnitrosamine (DMN) in beer and ale were compared with those obtained by a more elaborate vacuum distillation method. The end determination in both cases was done by gas-liquid chromatography using a thermal energy analyzer (TEA) detector. The two sets of results for 28 samples of beers from various countries were highly comparable. Recent survey results for both Canadian and imported beer and ales suggest a significant decrease in the levels of DMN in these beverages from that observed 2–3 years earlier. This decrease is probably due to the improvements in the malt drying techniques instituted in Canada as well as in other countries.     

Synthesis and Aroma Properties of New Alkyloxazoles and Alkylthiazoles Identified in Cocoa Butter from Roasted Cocoa Beans

Previous work provided evidence for the occurrence of new alkyloxazoles and alkylthiazoles in the volatiles of cocoa butter from roasted cocoa beans. The synthesis, mass spectral data and sensory properties of these compounds are reported.