by Joseph R. Swider, Jeffrey A. Jankowski and Antonio Sobevski


AL


Direct, Real-Time Mass Spectrometry Analysis of Cinnamon


To ensure food safety, rapid detection of adulterated and counterfeit food products is critical. One such method, Direct Analysis in Real Time-Mass Spectrometry (DART-MS) (IonSense, Saugus, Mass.), quickly screens and analyzes a wide array of samples for mass spectral information1–3


and does


not require sample preparation. As an example, several recent studies4–8


detail the analysis of cinnamon,


mostly using chromatographic methods. High concentrations of couma- rin in cinnamon have prompted numerous investigations as well, as its presence is suspected of being harmful.9–11 sample derivatization and long analysis times.


All of these studies require Cinnamomum verumb


In the current study, DART-MS was used to analyze cinnamon (see Table 1) and detect the presence of coumarin.


Materials and methods


Instrument and chemicals The analytical instrument comprised a DART ion source (IonSense) and JMS-T100LC AccuTOF time-of-flight mass spectrometer (JEOL, Peabody, Mass.).12


Standard compounds typically found in cinnamon were analyzed


as references (Sigma Aldrich, St. Louis, Mo.): coumarin, cinnamaldehyde (natural), trans-cinnamaldehyde, cinnamic acid (natural), trans-cinnamic acid and eugenol. When necessary, these were diluted with HPLC-grade methanol (Fisher Scientific, Pittsburgh, Penn.). All neat solutions and powders were administered using melting-point capillaries (90 mm, 0.2 mm wall, Fisher Scientific).


Commercial samples Samples of ground cinnamon and cinnamon bark and sticks (solids) (brand A) and one sample each of ground and sticks (brand B) were tested.


Analysis methods Standards and their dilutions were analyzed as neat solutions using a capillary dipped in solution and placed in the helium plasma stream. Blank capillaries in solvent were also analyzed for background compounds. All standards in their original concentrations were analyzed in both negative and positive ion modes at temperatures of 100, 150, 200, 250, 350 and 450 °C. These analyses were evaluated for an ion mode and temperature that produced the best response for each compound. Grid voltages were set to 350 °C for negative and positive ion modes for all analyses.


AMERICAN LABORATORY 36 , Cinnamomum zeylanicum


Table 1 – Four cinnamon sources Species name


Cinnamomum cassiaa ,


Cinnamomum aromaticum Cinnamomum burmannii


Cinnamomum loureiroi Common name Cassia, Chinese cinnamon


Indonesian cinnamon, Korintje cinnamon, Padang cassia


Vietnamese cinnamon, Vietnamese cassia, Saigon cinnamon


Ceylonese cinnamon, Sri Lankan cinnamon


aCassia (Cinnamomum cassia) from China is the most common type


of cinnamon used in food products. b


Ceylon (Cinnamomum verum) is considered “true” cinnamon.


Sample introduction is accomplished by dipping a capillary into a liquid or powder and placing this end in the helium stream, not by administering a known volume. As such, DART-MS used in this manner is not quantita- tive. This study analyzed successive dilutions of 1:10 in methanol until no analyte was detected for a sense of relative detection limits.


Ground cinnamon samples were analyzed by dipping glass capillaries into the powder and placing the small amount of powder adhered to the capillary in the helium stream. Bark and commercial product samples were sectioned to sample sizes so that they could be gripped with a pair of tweezers and held in the helium stream.


Results


Standard cinnamon compounds The six standards shown in Table 2 produced the best response using 350 °C plasma in positive ion mode. These conditions were used for all subsequent analyses. Table 2 shows each compound’s exact mass, base mass peak and lowest concentration detected after sequential dilutions in methanol. Additional masses and their most likely corresponding compounds identified in the standard analyses are shown. The responses for the same standard from different sources (i.e., natural and trans-) dem- onstrated similar results. Coumarin and cinnamaldhydes were detected at 100 µg/L, while the detection of cinnamic acid and eugenol was less sensitive at 10 mg/L.


APRIL 2016


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