Machine Design

Less oily, tastes great

The Model 6890N gas chromatograph from Agilent Technologies.

Excess fusel oils in cola, whiskey, gin, rum, or brandy produce off-flavors and worse hangovers for consumers. But a new gas chromatograph (GC) from Agilent Technologies, Wilmington, Del., lets bottlers and distillers accurately measure levels of these elementalorganic compounds during production.

Metering samples into the GC is a Pneutronics VSO proportional valve from Parker Hannifin Corp., Hollis, N.H. The VSO is an analytically clean valve that compensates for temperature variations by virtue of a high spring rate and low plunger mass.

After passing through the valve, the sample is heated to vapor and carried by a helium gas stream to an oven. The oven contains a narrow capillary column coated with a special material. The programmed oven temperature is maintained at around 400°C with ramps to 450°C to prevent condensation. The compounds get absorbed along the column wall and are released in time according to their relative affinities for the special material. Data from a detector at the column exit goes to a desktop computer with software that generates a chromatograph for characterizing sample components.

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