Abstract

Since the discovery of matrix-assisted laser desorption for protein detection, laser desorption mass spectrometry (LDMS) has been successfully used to detect very- large proteins. However, when it was initially applied to DNA, the success was very limited. Using a custom-designed time-of-flight mass spectrometer with very high ion energy (~70 KeV), we increased the detection efficiency significantly. In addition, a few new matrices were discovered to enhance the efficiency of desorption and ionization of DNA. Recently, we succeeded in detecting oligonucleotides up to 500 nucleotides in size with detection sensitivity at the femtomole region. In addition, double- strended DNA was also successfully detected by using polymerase chain reaction (PCR) and LDMS. The major advantages of developing laser desorption mass spectrometry for DNA analysis is that it is much faster than conventional gel electrophoresis methods. It usually takes less than one millisecond for the LDMS method compared to hours using a gel electrophoresis method. In addition, there is no need for radioactive or toxic materials. Due to the ultrafast analysis speed, LDMS can be very valuable to the human genome program for sequencing the whole human genome.

© 1996 Optical Society of America