Matrix-assisted laser desorption/ionization mass spectrometry has been used for diagnosis, for monitoring disease progression, for drug discovery and for toxicology studies. It can reliably detect hundreds of proteins with molecular weights up to 30,000.

Richard M. Caprioli and colleagues at Vanderbilt University Medical Center in Nashville, Tenn., reviewed advances in the technique. In their labs, they have employed time-of-flight mass spectrometers from Applied Biosystems of Framingham and from Bruker Daltonics of Billerica, both in Massachusetts.

To obtain the best-quality data, the reviewers recommend using fresh tissue and freezing it in liquid nitrogen, while carefully avoiding contamination. They suggest cutting the tissue into 5- to 20-μm sections, completely drying them, applying a fixative and placing the tissue on a glass slide coated with indium tin oxide. They recommend using sinapinic acid as the matrix solution and depositing it using the electrospray method. The matrix can be deposited automatically using a robotic printer, such as the one they used from Labcyte of Sunnyvale, Calif. (Journal of Proteome Research, published online Oct. 19.)