DNA arrays are typically prepared by microcontact printing of DNA on a glass surface that has been modified by an aminosilane. The DNA immobilization on the modified glass surface relies on direct contact between DNA and amine groups supplied by the silane layer. The presence of surfactants such as Triton even at trace level can completely inhibit attachment of DNA. Given the tendency of this molecule to segregate at interfaces, its detection by surface sensitive techniques such as ToF-SIMS is facilitated; in other words, the sample preparation method and ToF-SIMS analysis constitute a very sensitive analytical procedure to detect trace levels of surfactant molecules in DNA preparations. To further corroborate the impact of surfactants, pure DNA solutions were intentionally contaminated with Triton X-100 in varying concentrations. The resulting mixtures were used for printing on modified glass slides. It was demonstrated that the presence of Triton reduces the amount of immobilized DNA and above a certain concentration (10-100 ppm by volume) can completely inhibit DNA printing. In another application of ToF-SIMS, we demonstrate the ability to study fluid flow and evaporation dynamics in a drying droplet in microarrays. Evaporation behavior of the drop strongly influences the solute transport and hence the uniformity of the dot. We have utilized ToF-SIMS analysis of printed DNA dots to determined the final distribution of the solute by mapping the sodium concentration in the drop. Three different kinds of effects were observed: the first kind having higher concentration of solute on the outer edge of the drop (rim effect); the second kind having higher concentration at the center of the drop (pinprick) and the third having uniform distribution.