Direct monitoring of laser absorption of MALDI matrices by fast piezoelectric transducer

The absorption of laser energy by recently found matrices used in matrix assisted laser desorption ionization (MALDI) detection of large DNA segments: 3-hydroxypicolinic acid (3-HPA), picolinic acid (PA), composite matrix (PA + 3-HPA) and 3-aminopicolinic acid (3-APA), was studied by using a fast piezoelectric transducer for solid matrices and for their aqueous solutions. A nonlinear dependence of acoustical signal on laser fluence was found for PA, PA + 3-HPA and 3-APA matrices at 266 nm. Near linear dependence was found for 3-HPA at 266 nm. There was no strong deviation from linear power dependence for any of these matrices at 355 nm. Possible mechanisms to account for the observed nonlinearity are discussed.