Bendamustine (BD), a volatile anti-cancer drug in Japan, was quantitatively evaluated using solid phase extraction (SPE)-type extraction device designed for the adsorption of gaseous semi-volatile organic compounds. First, the stability of BD was tested in various conditions, including solvent, temperature, and contact with oxygen. Then, the BD standard solution was spiked on filter paper, and the SPE-type extraction device was connected to the filter downstream. The filter and extraction device were then used to collect clean air. The actual volatility of BD was determined in high-performance liquid chromatography. Even after 24 h of air sampling at 7 L/min (10,080 L), the results demonstrated that BD evaporation was not confirmed. Furthermore, BD evaporation was not confirmed in a 7,000 L air sampling volume of heated air at 50°C. The volatility properties of n-alkanes of C26H54, C28H58, and C30H62 in these air sampling conditions were compared. The results show that BD is not volatile at room temperature.
γ-Aminobutyric acid (GABA) is an inhibitory neurotransmitter having anti-anxiety, stress-reducing and sleep-enhancing effects. The blood GABA concentration has the potential to become a diagnostic index for depression and schizophrenia. In this study, we developed a method for the quantification of GABA in human serum by liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) combined with derivatization using a pair of reagents, 4-diethylaminobenzoic acid N-succinimidyl ester (DEABAS) and its deuterated isotopologue (dDEABAS). The deproteinized serum samples were derivatized with DEABAS, to which the dDEABAS-derivatized standard GABA of known amount was then added. The DEABAS-derivatization enhanced not only the ESI-MS/MS sensitivity but also the LC retention, which enabled the separation of GABA from the interfering isomers. Satisfactory assay precision and accuracy were also acquired by adding dDEABAS-derivatized GABA, which served as the internal standard and worked well for correcting the matrix effect and instrument drift. The developed method had satisfactory applicability to the real sample analysis because it was successfully used to quantify the serum GABA of the healthy subjects.