November 16, 2015

Tryptophan Analysis

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This time of year, our thoughts turn to tryptophan, a chemical associated with the perceived sleep-induced nature of turkey. Tryptophan is an essential amino acid (see the NH2 and COOH above), meaning that we do not naturally produce this compound, but that it is a necessary part of our diet in order for protein synthesis to occur. Tryptophan is found in many protein-based food products, including oats, chocolate, red meats, milk products, and many seeds and nuts. While tryptophan is found in turkey, the quantities are no more than what you find in chicken or other fowl. For example, 100 grams of turkey has 0.24 grams of tryptophan, the same as chicken, while cod has 0.7 grams, and an egg white has 1.0 grams. It is true, however, that tryptophan can cause drowsiness, so monitor your protein intake prior to driving.
Tryptophan and other amino acids are normally analyzed with HPLC.  However, GC-MS can be used on more volatile amino acids, which provides more identification capabilities than offered by HPLC. The polar nature of tryptophan requires that the amino acid is derivatized prior to GC-MS analysis, however, which increases the volatility of the compound, a necessary property for GC-MS. Often times, silylation is performed to derivatize the amino acid. In this process, a silicon-alkyl compound reacts with the hydroxyl group, creating an Si-O bond where the hydroxyl group used to be. This reaction results in a volatile, and more stable, compound for GC-MS analysis. Identification and quantification can now occur.
Contact CPG for more information on chromatography. Our scientists specialize in custom test development to identify and quantify compounds.