Pelargonium Oil and Methyl Hexaneamine (MHA): Analytical Approaches Supporting the Absence of MHA in Authenticated Pelargonium graveolens Plant Material and Oil

Abstract

Methylhexaneamine (MHA) has been marketed in dietary supplements based on arguments that it is a constituent of geranium (Pelargonium graveolens) leaves, stems, roots or oil, and therefore qualifies as a dietary ingredient. The purpose of this study is to determine whether P. graveolens plant material (authenticated) or its oil contains detectable quantities of MHA. Two analytical methods were developed for the analysis of MHA in P. graveolens using gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry. The results were further confirmed using liquid chromatography-high-resolution mass spectrometry. Twenty commercial volatile oils, three authenticated volatile oils and authenticated P. graveolens leaves and stems (young and mature, and fresh and dried) were analyzed for MHA content. In addition, three dietary supplements containing MHA that alleged P. graveolens as the source are analyzed for their MHA content. The data show that none of the authenticated P. graveolens essential oils or plant material, nor any commercial volatile oil of Pelargonium (geranium oil) contain MHA at detectable levels (limit of detection: 10 ppb). The dietary supplements that contained MHA as one of their ingredients (allegedly from geranium or geranium stems) contained large amounts of MHA. The amounts of MHA measured are incompatible with the use of reasonable amounts of P. graveolens extract or concentrate, suggesting that MHA was of synthetic origin.

Identification of methylhexaneamine by GC high-resolution TOFMS and soft ionization

“…Other capsules of TB analyzed by low resolution EI GC-MS had concentrations closer to the value reported by the manufacturer which is 30 mg/capsule [13]. If the MHA concentration of 30 mg/ capsule were true and the source of MHA were the geranium extract, according to an estimate made by ElSohly et al [3], in which one kilogram of geranium (P. graveolens) leaves is required to prepare 6 mg of MHA, it will make ''physically impossible'' [14] for the source of MHA in the TB supplement to be from geranium extract. GC-TOF analysis of the underivatized samples also indicated high concentrations of caffeine in all five nutritional supplements.…”

“…The pentafluorobenzoyl derivative of MHA was reported by Lisi et al [2] and derivatization of MHA with heptafluorobutyric (HFB) anhydride was reported by Elsohly et al [3]. In the former case, the most abundant fragments ions in the EI spectra are those at m/z 195 (C 7 F 5 O + ) and m/z 238 (C 9 H 5 F 5 NO + ) corresponding to the pentafluorobenzoyl ion, and the fragment ion formed by elimination of C 5 H 11 radical from the molecular ion of the derivatized MHA, respectively.…”

“…In the former case, the most abundant fragments ions in the EI spectra are those at m/z 195 (C 7 F 5 O + ) and m/z 238 (C 9 H 5 F 5 NO + ) corresponding to the pentafluorobenzoyl ion, and the fragment ion formed by elimination of C 5 H 11 radical from the molecular ion of the derivatized MHA, respectively. Elsohly et al [3], proposed the EI fragmentation pattern of the HFB derivative of MHA in which the ions at m/z 296, m/z 282, and m/z 240 correspond to the elimination of CH 3 , C 2 H 5 , and C 5 H 11 radicals from the molecular ion of HFB-MHA. Derivatization of MHA and tuaminoheptane with cyclohexanone, reported by Perrenoud et al [11], improved the chromatography considerably but the diastereoisomers of MHA were not completely resolved.…”

“…It has been reported that MHA was detected in geranium oil by researchers at the Guizhou Institute of Technology, but a closer scrutiny by Lisi et al [2], Elsohly et al [3], and Zhang et al [4] indicates that the actual compound detected in geranium oil was hexanamide and not MHA. Furthermore, these researchers were unable to find MHA at detectable levels (i.e., 10 ppb [3,4]) in authenticated Pelargonium graveolens essential oils or plant materials, concluding that if MHA is detected in geranium oil then it should be assigned to synthetic origin. Very recently, Fleming et al [5] reported 1,3-DMAA in geranium plants, collected during winter and summer, from three regions of China, and concluded that regional environmental variations could explain the discrepancy in results for the geranium oils.…”

“…It was banned by World Anti-Doping Agency in 2010, although its isomer tuaminoheptane was banned in 2008 [1]. It has been reported that MHA was detected in geranium oil by researchers at the Guizhou Institute of Technology, but a closer scrutiny by Lisi et al [2], Elsohly et al [3], and Zhang et al [4] indicates that the actual compound detected in geranium oil was hexanamide and not MHA. Furthermore, these researchers were unable to find MHA at detectable levels (i.e., 10 ppb [3,4]) in authenticated Pelargonium graveolens essential oils or plant materials, concluding that if MHA is detected in geranium oil then it should be assigned to synthetic origin.…”