United States Department of Agriculture Investigation of Inkberry Ilex glabra L. Gray (Aquifoliaceae) Solvent Fractions using Two-Dimensional Gas Chromatography Technology Roderquita K. Moore Doreen Mann Second dimension (s) First dimension (s) Forest Forest Products Research Note September Service Laboratory FPL–RN–0388 2020 Abstract Contents Comprehensive two-dimensional gas chromatography Introduction ..........................................................................1 (GC×GC) is an important technique used to investigate Experimental ........................................................................1 complex mixtures with pharmaceutical potential. GC×GC expands the peak capacity of the separation, which Results and Discussion ........................................................2 increases the resolution for more targeted characterization Conclusions ..........................................................................8 of analytes of interest and trace chemicals. Traditional gas chromatography–mass spectrometry is used to investigate Acknowledgments ................................................................8 extracts; however, when the mixture is complex, there is References ............................................................................8 a need for higher resolution power to identify the extracts profile completely and discover new extracts of interest. In this study, inkberry chemical compounds were characterized using GC×GC. Inkberry was chosen because of the lack of literature on its chemical components. Two solvent solutions were used to isolate chemicals from inkberry leaves, acetone and hexane. From the acetone extracts, 2,986 chemicals were identified and 1,653 of them were unknowns. From the hexane extracts, 1,726 chemicals were identified and 698 were unknowns. NIST and Wiley libraries were used for identification. Keywords: GC×GC, extractives, bushes, fractions, solvent extraction September 2020 Moore, Roderquita K.; Mann, Doreen. 2020. Investigation of inkberry Ilex glabra L. Gray (Aquifoliaceae) solvent fractions using two- dimensional gas chromatography technology. Research Note FPL-RN-0388. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 9 p. A limited number of free copies of this publication are available to the public from the Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI 53726-2398. This publication is also available online at www.fpl.fs.fed.us. 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Submit your completed form or letter to USDA by: (1) mail: U.S. Department of Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Washington, D.C. 20250–9410; (2) fax: (202) 690–7442; or (3) email: [email protected]. USDA is an equal opportunity provider, employer, and lender. Investigation of Inkberry Ilex glabra L. Gray (Aquifoliaceae) Solvent Fractions using Two-Dimensional Gas Chromatography Technology Roderquita K. Moore, Research Chemist Doreen Mann, Physical Science Technician USDA Forest Service, Forest Products Laboratory, Madison, Wisconsin, USA Introduction of interest to scientific research. The free radicals created from reducing phenolic compounds give rise to antioxidant Comprehensive two-dimensional gas chromatography activity, which has many health benefits. The similarity (GC×GC) consisted of two tandem columns with different of these phenolic compounds will cause co-eluting and chemical stationary phases. These phases separate complex decrease the similarity match between chemicals in the mixtures with a thermal modulator to divert one effluent sample and the library (Moore and others 2015a, 2015b, from a one-dimensional to a two-dimensional column. 2017a, 2017b, 2017c). The complexity and similarity This technique has been available for more than 30 years between the chemicals require more resolving power to and was first reported by Lui and Phillips (1991). The two identify trace chemicals in the samples. different stationary phases increase the peak capacity in which co-eluting chemicals are easy to identify in complex Comprehensive two-dimensional gas chromatography time mixtures (Lui and Phillips). GC×GC was chosen for this of flight (GC×GC-TOF) was chosen for this investigation investigation because of the complexity and similarities of because of the complexity and similarities of the chemicals the chemicals in inkberry. found in inkberry extractives. Acetone and hexane extracts were characterized and categorized based on the Inkberry (Ilex glabra (L.) Gray) is an ornamental plant molecular chemical mapping on the chromatogram. The of the Holly family (Aquifoliaceae) and is also known as chromatograms of these solvent fractions were categorized gallberry. The name inkberry gives reference to the fruit that based on their functionality. Chemical mapping provided a is produced by the shrubs, which was once used to produce fingerprint of inkberry extractives in both solvent fractions. ink. It is an evergreen native to the coastal plain of eastern North America. Inkberry leaves are used for an herbal tea called Appalachian. The name gallberry was derived from Experimental the galls of oaks, which can be used to make black ink. In Materials addition to its application in ink production, this plant is resistant to pollutants in urban areas and does not have any Inkberry plants were purchased at a local nursery. These serious problems with insects or diseases. Bees and bird are plants were maintained with moisture content above 30%. drawn to it as a source for food. Solvents were purchased from Thermo Fisher Scientific (Waltham, Massachusetts, USA). Tetracosane 99% was used The holly plant family has been studied for their for the calibration standard and was purchased from Sigma- phytochemicals. Jaiswal and others (2014) detected Aldrich (St. Louis, Missouri, USA). and characterized 32 phenolic compounds by liquid chromatography tandem mass spectrometry. They Extraction Procedure reported for the first time full characterization of Inkberry leaves were extracted by two solvent solutions. 3,4-dihydroxybenzoyl glucosides; 3,4-dihydroxybenzyl Leaves were removed from the freezer and slightly thawed. glucosides; 4-hydroxybenzoyl glucosides; chlorogenic They were weighed and placed in a 250-mL Erlenmeyer acid glucosides; and vanillic acid glucosides. Polyphenols flask with 100 mL of acetone and water (90:10) solvent are the largest and most complex group of phytochemicals solution. The second extraction was performed with found in most human and animal diets. Biomass such as isopropyl alcohol and hexane (50:50). The solvent solution plants and wood are constructed with multiple chemical extractions were filtered, filled with fresh solvent every structures of phenolic derivatives. The phenolic compounds 24 hours, and shaken for a total of 48 hours. Solvent can range from very toxic to nontoxic. These properties are Research Note FPL–RN–0388 Table 1—Two-dimensional gas chromatography Table 2—Number of chemicals detected by two- (Pegasus BT 4D) instrument parameters dimensional gas chromatography and identified by Gas chromatograph agilent 7890B with LECO dual stage quad jet NIST and Wiley libraries modulator and LPAL 3 autosampler Total Peaks Peaks >800 >800 a Injection 1 uL, split 20-150:1 at 250 °C Extract >700 unknown known known known Carrier gas He at 1.4 mL/min iba 2,986 1,653 1,333 659 183 Primary column Rxi-5 ms, 30 m by 0.25 mm i.d. by ibh 1,726 698 1,029 558 141 0.25 μm coating (Restek, Bellefonte, aNumber of known chemicals after removing shared and isomers. PA, USA) Secondary column Rxi-17SilMS, 0.60 m by