Analysis Application of Soy Sauce
by ionRocket-DART®-MS




Soy sauce is a major condiment in Japan. There are many kinds of soy sauce. Sashimi soy sauce is one kind and is suitable for Sashimi. Sashimi soy sauce is brewed twice, so it takes longer time to produce than standard soy sauce.
The ionRocket is a thermal desorption device for DART®-MS (Direct Analysis in Real Time – Mass Spectrometry). The sample was heated by ionRocket from room temperature up to 600ºC. In this application, we used the ionRocket to analyze soy sauce.



Two types of soy sauce: Standard grade and Sashimi (Commercial items)



ionRocket was mounted on DART®-MS. The 2 μL sample was placed into the POT.
The temperature was raised by the ionRocket from room temperature to 600ºC by 100ºC/min. The total run time was about 7 min.



The analysis results of standard and Sashimi soy sauce were shown in Figure 1 and 2. The tendencies in the heat map were different.
The same kinds of ions were observed in the mass spectra in RT 3.1 min. In the standard grade soy sauce, the intensities of m/z 116 and 118 were the same level, however in Sashimi soy sauce were not.
In the mass spectrum of Sashimi soy sauce at RT 6.0 min, many ions were observed than that of standard grade soy sauce.
These differences would be caused by difference in brewing method.

Figure 1. Standard soy sauce: (A) Heat map (B) The mass spectrum at RT 3.1 min (C) The mass spectrum at 6.0 min
Figure 2. Sashimi soy sauce: (A) Heat map (B) The mass spectrum at RT 3.1 min (C) The mass spectrum at 6.0 min





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