Solid-phase microextraction for the enantiomeric analysis of flavors in beverages.

Solid-phase microextraction combined with gas chromatographic/mass spectrometric analysis and separation on a chiral cyclodextrin stationary phase was a rapid, reliable technique for profiling chiral aroma compounds in flavored alcoholic beverages. Several enantiomeric terpenes, esters, alcohols, norisoprenoids, and lactones were identified in berry-, peach-, strawberry-, and citrus-flavored wine and malt beverages (wine coolers). Using this technique, we were able to confirm the addition of synthetic flavoring to several beverages, consistent with label designations.

Analysis of (+)-catechin, (-)-epicatechin and their 3'- and 4'-O-methylated analogs. A comparison of sensitive methods.

(+)-Catechin and (-)-epicatechin are found in many foods and may have important effects on human health. These compounds, like many other catechols, are thought to be converted to methylated metabolites after ingestion. This paper describes the synthesis of the 3'- and 4'-methyl ethers and their unambiguous identification. These products, along with catechin, epicatechin and an internal standard, (+)-taxifolin, were separated using RP-HPLC with ultraviolet, electrochemical and fluorescence detection. The trimethylsilylated derivatives of the seven compounds were also separated by GC with mass spectrometric detection. The limits of detection and selectivity of the analytical methods were compared with respect to their application in complex matrices such as human plasma.

A simple survival model of volume-controlled hemorrhagic shock in awake rats.

A simple rat model was developed for the study of spontaneous survival after volume-controlled hemorrhage. The objective was to determine in awake, unrestrained rats the shed blood volume (SBV) in ml/100 g body weight that without fluid resuscitation, would result in either a high or a low percentage of survivors within 24 h. About 24 h after cannulation under light anesthesia, the awake rats were insulted with arterial blood withdrawal at a constant rate over 20 min, while mean arterial pressure (MAP) was monitored (N = 78). Then, the arterial catheter was removed, and the rats were observed for 24 h or until death. With increasing SBV, survival rate decreased, SBV of 2.50 ml/100 g (group I) resulted in 74% survivors at 2 h and 24 h; SBV of 2.75 ml/100 g (group II), in 67% survivors at 2 h and 46% at 24 h; SBV of 3.00 ml/100 g (group III), in 35% survivors at 2 h and 20% at 24 h; and SBV of 3.50 ml/100 g (group IV), in no survivors to 2 h. MAP declined similarly over 20 min blood withdrawal in the four insult groups, without difference between ultimate survivors vs. nonsurvivors. All rats survived to the end of 20 min hemorrhage (i.e. hemorrhagic shock [HS] time = 0 min). Deaths at HS time 0-2 h occurred after SBV of 2.50 ml/100 g, at HS time 56 +/- 35 min; after SBV of 2.75 ml/100 g, at HS 81 +/- 26 min; after SBV of 3.00 ml/100 g, at HS 37 +/- 33 min; and after SBV of 3.50 ml/100 g, at HS 11 +/- 2 min. Weight may have affected MAP response and survival. We conclude that a volume-controlled HS model in rats without anesthesia or restraint is feasible. SBV of 2.50 ml/100 g should be suitable for testing additional insults. SBV of 3.00 ml/100 g should be suitable for testing resuscitative therapies. The model should be modified to allow monitoring of key variables after hemorrhage.