Electrospray ionization tandem mass spectrometry of 3-phenyl-N-(3-(4-phenylpiperazin-1-yl)propyl)-1H-pyrazole-5-carboxamide derivatives: unusual fragmentation involving loss of 11 u. - Purna Chander C; Raju G; Mathai G; Srinivas R; Gaikwad HK; Bantu R; Nagarapu L (Rapid communications in mass spectrometry : RCM, 2012)