This is consistent with previous studies on the composition of VO (12). In order to obtain reproducible MALDI TOF composite spectra with acceptable signal/noise ratio (>1,000) for the most abundant molecular species (m/z 949.7), we found that a matrix/VO mole ratio of 44:1 was optimum. With this mole ratio, more than 20 composite spectra were obtained (100 shots per composite spectrum), and each composite spectrum gave a resolution greater than 8000. A matrix/VO ratio less than 40:1 resulted in high noise level, making it difficult to identify the minor TAG component (VLS, VLO, VLL). On the other hand, a matrix/VO ratio of greater than 50:1 produced poor sample crystallization, resulting
in low and unreproducible ion count. The identified TAG gave sodiated molecular ions (Fig. 1) rather than protonated,
thus providing very uncomplicated MALDI TOF spectra. To further confirm that cationization was the norm under
our experimental conditions, we tried two other matrices, sinapinic acid and dithranol, both of which gave spectra similar
to that with CHCA.