My research poster I constructed for OK Research Day 2010 that was held at Cameron University November 12, 2010. The title of my research was "Quantitation of Capsaicin Levels in Hot Peppers by Gas Chromatography/Mass Spectrometry."

1. Quantitation of Capsaicin Levels in Hot Peppers by Gas Chromatography/Mass Spectrometry Brandi N. VanAlphen and David von Minden, PhDDepartment of Chemistry, University of Central OK, Edmond, OK 73034 Abstract Capsaicinoids from chili peppers are significantly known for their pungent taste and for causing pain upon skin or eye contact [1]. The most abundantly occurring capsaicinoids are capsaicin and dihydrocapsaicin in the genus Capsicum. The structural characteristic of capsaicin that determines its spicy content is associated with the presence of an amide bond connected to a vanillyl ring and an acyl chain. The development of a rapid, reproducible, and simple method of quantitation by the employment of gas chromatography/mass spectrometry is reported. Mass spectrometry of the fruit-crude extracts indicated that molecular ions at m/z 305 and 307 correspond to capsaicin and dihydrocapsaicin. These two have a common benzyl fragment at m/z 137 which can be used for selective ion monitoring by the use of gas chromatography/mass spectrometry. These two naturally occurring capsaicinoids have been determined and quantified by use of high-purity standards, with an alkylated capsaicinoid derivative as an internal standard. Synthesis of an alkylated capsaicin derivative using tetramethylammonium hydroxide (25% in methanol) and iodoethane produced an internal standard comparable to capsaicin and dihydrocapsaicin. Ethylation of the common benzyl group caused the fragmentation of that group to increase from m/z 137 to 165. Ethylation of these capsaicinoids provided a large enough shift in the retention times of the analytes to avoid interference. The major capsaicinoids in a commercial plant extract and in a variety of chili-pepper fruits were quantified using derivitized ethylated capsaicinoid analogues, not known to ever be employed as internal standards. Derivitization of capsaicin and dihydrocapsaicin and utilization of them as internal standards in hot peppers is presented. Molecular structure of capsaicin, the most common capsaicinoid. Molecular structure of dihydrocapsaicin, the second most abundant capsaicinoid. Spectrum of capsaicin derivative containing m/z 333 as the molecular weight and m/z 165 as the ethylated benzyl fragment. Spectrum of dihydrocapsaicin derivative with m/z 335 as the molecular weight and m/z 165 as the ethylated benzyl fragment. Molecular structure of capsaicin derivative Total Ion Chromatogram of Red Caribbean Pepper. Retention times are as followed: Capsaicin-23.053, Dihydrocapsaicin-23.373, Capsaicin derivative- 24.088. IS is too small to quantify. Molecular structure of dihydrocapsaicin derivative Total Ion Chromatogram of Red Serrano 23.324, Capsaicin derivative-24.085, Dihydrocapsaicin derivative- 24.424. Conclusions It is known that Red Caribbean peppers contain more capsaicin than the Red Serrano peppers. It is suggested that an ethylated capsaicin derivative can be used as an internal standard by gas chromatography/mass spectrometry techniques to quantify the amount of capsaicin and dihydrocapsaicin in these peppers because it gives a reliable MS response. However, a higher scaled derivitization is needed to efficiently quantify capsaicin and dihydrocapsaicin in significantly hot peppers, such as the Caribbean Red. Once an appropriate amount of the internal standard are applied, a calibration curve can be constructed. Dried Red Serrano and Caribbean Red Peppers used in research. References 1. Govindarajan VS, Sathyanarayana MN. Capsicum-production, technology, chemistry, and quality. Part V: impact on physiology. Pharmacology, nutrition, and metabolism; structure, pungency, pain, and desensitization sequences. Food Sci and Nutr 1991;29;435-74. Acknowledgements The authors thank the University of Central Oklahoma for providing the materials, lab space and instruments; Dr. Steven Meier for his invaluable organic chemistry insight; Amanda Bridges for her editing expertise and Monkey Business in Lawton, OK for donating the poster.