in an Agilent Ion Trap Mass Spectrometery Capillary exit voltage-induced vs. CID fragmentation behavior of four antiviral drugs in an Agilent Ion Trap Mass Spectrometery Mohamed W Attwa; Nasser Salem; Ali S. Abdelhameed; A. F. M. Motiur Rahman; Adnan A. Kadi Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia OVERVIEW FRAGMENTATION PATTERN FOR ABACAVIR We illustrated Abacavir as an example for comparing two fragmentation techniques (Figure 3 and Figure 4), other three antiviral results are summarized in table 3 and table 4 The fragmentation pathways of antiviral drugs were investigated and data of SID of ESI-Ion Trap and multistage fragmentation ESI-Ion Trap were compared. The detail fragmentation pathways of all ions observed in the in-source fragmentation spectrum of compounds were elucidated by further dissociation of each of these fragment ions using MS2, MS3 and MS4 fragmentation stages. The substructures of all fragment ions were unambiguously assigned.  MS scan for Abacavir applying Capillary Exit Voltage Product ion for 191 Product ion for 174 MS3 for 174 Penciclovir Famciclovir Abacavir MS scan for Abacavir Product ion for 287.2 MS3 for 191 MS4 for 174 MS4 for 164 MS4 for 150 Abacavir Acyclovir INTRODUCTION Mass spectrometry (MS) is a very powerful technique that can be used to analyze a wide range of materials such as proteins, peptides, DNA, drugs and polymers. In an ESI Ion Trap, fragmentation can take place in the source by varying of the capillary exit voltage, whereas CID takes place in the trap to analyze the chemical fragmentations. Due to differences in the methods by which fragmentation is induced, the behavior of compounds subject to these techniques might differ. Here, we present a comparative study of the fragmentation behavior of a group of antiviral drugs, namely Famciclovir, Acyclovir, Penciclovir and Abacavir, to investigate how to extend the qualitative power of ion trap MS and to maximize the benefit from mass analyzer METHODS In Ion trap, product ion scan was performed before the in-source fragmentation to determine each compound’s related fragment ions, the capillary exit voltage was optimized to produce adequate in-source fragmentation. The data was compared with multi stage fragmentation using CID. Capillary exit voltage was 100 V for CID and 200 V for SID Figure 2: MSn Fragmentation pattern of protonated abacavir. Figure 3: In source Fragmentation pattern of protonated abacavir. Table 4: In source Fragmentation of protonated antiviral drugs. In-source fragmentation MS2 MS3 Penciclovir 254.5 152.1 135, 110 110, 135 Acyclovir 226 152 135, 89.2 Famciclovir 322 135 107,116.9 202 186 262 202,136 280 202,238,262 Table 3; MSn Fragmentation of protonated antiviral drugs. MS scan MS2 MS3 Penciclovir 254.5 152.1 135, 110 Acyclovir 226 152 135 Famciclovir 322 136 202 186 262 136,202 280 136,202,238,262 Conclusion Better qualitative information was obtained using capillary exit voltage fragmentation comparing to CID of ESI-Ion Trap MS for antiviral drugs. Figure 1: The Agilent 6320 Ion Trap MS (Figure courtesy of Agilent Technologies) We made all default parameters except capillary exit voltage which was 100V for CID and 250V for SID LC Parameters: MS Parameters: Table 1: LC parameters HPLC Model Agilent 1200. Injection volume 10 µl Column Connector Mobile phase A:H2O B: ACN Flow rate 0.4 ml/min. Run time 5 minutes Table 2: MS parameters Mass detector Agilent Ion Trap 6320 Ion source ESI Drying Gas(N2) Temperature & Flow 350 0C 12 l/min Mode Positive – Ultra scan Nebulizer Pressure 50 psi Scan range 20- 400Daltons Smart target 10,000. Accumulation time 150 ms 62nd ASMS Conference on Mass Spectrometry and Allied Topics, June 15-19, 2014. Baltimore, USA.