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The Nose Knows, But So Does the Gas Chromatograph One of the greatest tools for analyzing a scent's components is the gas chromatograph (GC). For perfumers, the GC is perhaps the most important invention—days of organic chemistry research are now performed in a few hours. How does it work? Even Jolique can't understand all the particulars, but one chemist explained it to her like this: First, imagine a long, thin tube with one end connected to a detection device similar to an EKG or a lie detector, called a mass spectrometer (MS). Flowing through the tube is an inert "carrier gas," such as helium or nitrogen, as well as millions of oil-coated beads, each about the size of a grain of sand. Now imagine that a bunch of odor molecules—lemon and hyacinth, for example—are blown through the tube. (Remember: these are lemon and hyacinth molecules—they can't be seen with the naked eye.) The carrier gas "carries" each of these molecules through the tube, but because the oily beads obstruct their passage somewhat, the molecules are slow to reach the end of the tube. Also, some of the molecules are heavier than others, and therefore move even more slowly. The amount of time it takes each molecule to move from one end of the tube to the other is recorded on the EKG-like printout. These time measurements are unique to each type of molecule: lemon odor molecules travel at a rate that is different from lavender's rate. So by reading the amount of time it takes for an odor to travel along the tube, you can tell what kind of odor it is. These printouts are the blueprints to a scent's entire chemical make-up. They are as closely-guarded by perfumers as is the Hope Diamond by the National Gallery! |
 Above: The fragrant hyacinth |
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| Another method for analyzing odors is called "headspace technology." Headspace technology allows chemists to examine and identify an odor's components without directly extracting the oil from the plant source, thus preventing the destruction of rare botanicals. The technology comes from beer brewing (the term 'headspace' refers to the area just above the foam of beer, where a brew master would sniff the batch to determine if had properly fermented). Like the airborne molecules in the headspace above a beer's foam, so do the odor molecules of a rose hover in the air around its petals. But rather than crushing the rose to extract its oil for analysis, a balloon-like gadget encloses the living rose and "vacuums" the molecules into a GC/MS, which analyzes its odor make-up. Next >> | |
