Titania nanotube arrays (NTA) generated from anodizing processes are tested as the substrate for surface-assisted laser desorption/ionization mass spectrometry (SALOl MS). The background generated from titania NTA is very low, making the approach suitable for the analysis of small molecules. The upper detectable mass is -29 kOa. Homogeneous sample deposition leads to good shot-to-shot reproducibility and suitability for quantitative analysis. Additionally, phosphopeptides can be selectively trapped on the titania NTA substrate, as illustrated by simply depositing a tryptic digest of f3-casein followed by titania NTA SALOl MS analysis. The detection limit for small organics and peptides is in low fmol. atrix-assisted laser desorption/ionization mass spectrometry (MALOl MS) has been extensively used in the analysis of different types of analytes since its development [1,2]. However, employing MALOl MS in the analysis of molecules with a mass of <600 Oa is difficult because of the interference from matrix ions appearing in this mass region. A low background interference in the low mass region is generally obtained when using inorganic materials as the assisting substrate for laser desorption/ionization mass spectrometry. Tanaka et al.[3] first employed nano-sized cobalt powder mixed with glycerol for the analysis of proteins in laser/desorption ionization mass spectrometry. Sunner and coworkers [4] alternatively used micro-sized carbon materials such as graphite and active carbon powder [5][6][7][8] mixed with glycerol for the analysis of peptides and proteins in laser/desorption ionization mass spectrometry. This was named as surfaceassisted laser desorption/ionization mass spectrometry (SALOl MS) because the surface structure was critical to obtaining mass spectra [9,10). Furthermore, the enhanced surface area and altered electric and thermal properties [9,10] [26] has attracted a great deal of attention because of its suitability for the analysis of small organics with low background interference. Thus, most of these studies have addressed the suitability of these approaches to the analysis of small analytes.When using sol-gel derived 2,5-dihydroxybenzoic acid (OHB) [27][28][29][30] as the SALOl substrate, not only can the absence of background interference in the mass spectra when analyzing small organics be observed but the detectable mass range can also be extended to > 10 kDa. To make the fabrication of sol-gel films easier, titania films capable of absorbing laser energy in the ultraviolet (UV) region were then proposed to be used as the SALOl substrate [31,32]. The detectable mass range was further extended to -24 kDa. Alternatively, the titania substrate can easily be generated from titanium sheets via electrochemical etching. Effective OIOS [26] and SALOl substrates [10] have been generated from electrochemical approaches. Although porous silicon can readily be generated from silicon wafer via electrochemical etching and directly used for OlOS analysis, [26] the etched silicon substrate is easily oxidiz...