Characterization of the degradation products or intermediates of different types of biomass (Boocock et al. 1980; Yokoyama et al. 1984; Matsumura et al. 2005) dur­ing gasification is important to obtain more detailed information on the chemistry of biomass conversion. When biomass wastes containing heteroatoms such as sul­fur, nitrogen, and halogens are subjected to hydrothermal processes, a series of toxic heteroatom compounds that can cause deterioration to the environment is formed. Previous researches about heteroatomic compounds used nondirect or batchwise measurements where cooling processes were necessary. During this pro­cess, some heteroatomic compounds could change chemically and some analytical information could be lost. The time for collecting the data was also quite long. Mass spectrometry has not extensively been applied to direct measurements. Research conducted by our group where nondirect measurements and cooling pro­cesses were necessary has shown that hydrogen can be formed from various bio­wastes by degrading them using hydrothermal process (Yildiz Bircan et al. 2011; Ishida et al. 2009).

We have developed an online measurement system for heteroatomic compounds at desired temperatures by using a lithium attachment mass spectrometer (Li-IAMS) (Alif et al. 2011, 2012). By this method the cooling process was eliminated and a shorter measurement time was achieved.

Ion-attachment mass spectrometry (IAMS) (Fujii et al. 2001; Tsukagoshi et al. 2012) is a “soft” ionization similar to chemical ionization in which a cation is attached to the analyte molecule. This technique is preferably applied to electro­negative compounds without fragmentation because ionization occurs by attach­ment of a lithium (or alkaline) ion to the gas molecules to be analyzed.

The objective of this study is to determine the mechanism of heteroatomic com­pounds formed through the hydrothermal reaction of biowaste. Specifically, l — cysteine as a model sample and durian fruit as real biomass have been analyzed focused on sulfur compounds. In addition, the effect of alkaline, Ca(OH)2, on the suppression of sulfur compounds has also been studied.