The matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometric study of DNA detection using 2,3,4-trihydroxyacetophenone, 2,4,6-trihydroxyacetophenone, and their combination has been carried out systematically. The results show that a mixture of 2,4,6-trihydroxyacetophenone, 2,3,4-trihydroxyacetophenone and ammonium citrate with molar ratios of 2:1:1 serves as a good matrix for the detection of DNA, especially for samples containing a small quantity of DNA such as polymerase chain reaction product. The resolution and shot-to-shot reproducibility using this matrix are better than, and the MALDI sensitivity comparable to, that obtained when using 3-hydroxy picotinic acid (3-HPA), PA and ammonium citrate matrix (9:1:1). The mechanism of desorption/ionization using this matrix is discussed.

Infrared spectra of hydroperoxymethyl formate indicate that the open-form conformer decomposes to formic-acid anhydride, but the hydrogen-bonded one does not.

The reactions of Criegee intermediates with HNO3 are important in the polluted urban atmosphere because of their large rate coefficients and the significant concentration of HNO3. Employing a step-scan Fourier-transform spectrometer, we recorded infrared spectra of transient species and end products in the reaction CH2OO + HNO3 upon irradiation of a flowing mixture of CH2I2/HNO3/N2/O2 at 308 nm. Eight bands at 1686, 1426, 1348, 1294, 1052, 965, 891, and 825 cm–1 were assigned to the absorption of the adduct nitrooxymethyl hydroperoxide (NMHP, NO3CH2OOH). Additional products from two dissociation channels were observed. Four bands at 1709, 1325, 1276, and 886 cm–1 were assigned to H2C­(O)­ONO2 (with coproduct OH), produced from the fission of the O–O bond of internally hot NMHP (NMHP*). Simultaneous detection of H2CO (1746 cm–1), NO2 (1617 cm–1), and HO2 (1392 and 1098 cm–1) indicated a direct cleavage of the N–OC and C–OO bonds of NMHP*. The relative yields of these three channels in pressure range 10–150 Torr were estimated. At 10 Torr, the absorption of internally excited HNO3 near 885 and 1320 cm–1 was also detected at an early stage of the reaction. We investigated also the rate coefficient of the reaction CH2OO + HNO3 by probing the temporal profiles of the formation of NMHP and NO2 under total pressures of 40 and 70 Torr at 298 K. The rate coefficient k HNO3 = (2.4 ± 0.4) × 10–10 cm3 molecule–1 s–1 is less than half the only literature value, (5.4 ± 1.0) × 10–10 cm3 molecule–1 s–1, reported by Foreman et al. (Angew. Chem. Int. Ed. 2016, 55, 10419–10422).

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The DNA sequence of a single-stranded and double-stranded template was determined. The templates were sequenced using the chain termination method and cycle sequencing method and detected by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The sequencing products were analyzed successfully without the laborious and expensive methods for removal of the template. Direct sequencing of the double-stranded template was achieved with minimal post-reaction purifications, which could be extremely important for mutation analysis and clinical diagnosis. A systematic study of the mechanisms and kinetics of sequencing reactions was also performed. The details of this analysis and directions for future improvements of the quality of sequencing are presented.