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Building a Better Column for Measurement of Trans Fats

potato chips

Heart disease is the leading cause of death in the United States, contributing to the demise of more than 500,000 people per year. Recent medical research has linked the consumption of trans fatty acids or "trans fats"—typically found in snack and convenience foods—with increases in LDL (low-density lipoprotein) or "bad" cholesterol and decreases in HDL (high-density lipoprotein) or "good" cholesterol. Both of these changes can increase the risk of heart disease.

In 2003, Denmark addressed the health effects of trans fats, effectively banning their use in packaged foods sold within its borders. Recently, regulators in both the U.S. and Canada took action, too, mandating the labeling of trans fat content in all processed foods sold in those countries—and both set January 2006 as the deadline for compliance. In the U.S., this regulation will cause a change in the familiar Nutrition Facts panel found on food labels: the Total Fat section will include a new line that lists the amount of trans fat contained in a product.

Around the world, leading food manufacturers and food testing labs are gearing up for this new requirement. Most will use gas chromatography (GC) to measure trans fats, but the most suitable types of capillary GC columns are not always readily available because they can be difficult to manufacture.

Improving shelf life and flavor stability

Trans fat occurs naturally in some plant- and animal-based foods. However, most of the trans fat found in packaged food is manufactured through a process called hydrogenation: hydrogen gas is bubbled through unsaturated vegetable oil in the presence of a catalyst, creating partially hydrogenated oil. This substance is commonly used to produce vegetable shortenings and some types of margarine.

Partially hydrogenated oil is also widely used in processed foods because it increases flavor stability and extends shelf life. Those benefits make it a popular ingredient in snack foods such as chips, crackers, cookies and candies, convenience foods such as frozen entrees and pizza, and fast foods such as French fries, onion rings and chicken nuggets.

Designed for reliable manufacturing

The most practical way to measure trans fat is GC through a capillary column that has high cyanopropyl content. Trans fat analysis also requires a high-polarity column with specific selectivity and very high efficiency. In the past, columns with those characteristics have been difficult to manufacture, limiting their availability.

Agilent recently introduced the HP-88 column, designed especially for the traditional method of determining trans-fat content via GC analysis of cis/trans Fatty Acid Methyl Esters (FAMEs). Cis/trans FAME separations require very high column polarity and specific selectivity to separate molecules that have extremely subtle vapor pressure differences. These separations also require a very high number of theoretical plates (more than 300,000), which means the column coating must be applied evenly and efficiently. The HP-88 column is optimized to ensure that its stationary-phase polymer will coat properly, minimizing the production problems that can cause long waiting times and unpredictable delivery.

 HP-88 internal chemistry 
The small amount of phenyl in the backbone of the polymer increases thermal stability while maintaining excellent elution order

The HP-88 is comparable to the previous generation of cyanopropyl-containing columns, providing equivalent (excellent) resolution and nearly identical elution order. What's more, its innovative internal chemistry (see diagram) provides a temperature range that is 20° Celsius higher than similar columns. The improved thermal stability of the HP-88 reduces column bleed and increases column lifetime.

This long-lasting, high-resolution column enables efficient, reliable analysis of trans fat content in food. For food makers who are already listing trans fat content on their labels—and the manufacturers and labs that are gearing up for January 2006—the HP-88 column is available now.

For more information

Recently, Agilent worked with Lipomics Technologies, leaders in lipid metabolite analysis, to co-author the most comprehensive characterization of 67 individual fatty acid esters on any GC column to date. The poster was presented at the AOAC International meeting and exposition, held September 2004 in St. Louis, MO. To request a copy of the poster, please send us an email message with "HP-88 poster" in the body.

To learn more about the HP-88 and other Agilent GC columns, please see the Columns & Accessories section of our Web site. For additional information about Agilent chemical analysis products and resources, please visit the Life Sciences/Chemical Analysis main page.

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