Bacteria can be identified by using a time-of-flight mass spectrometer to measure their chemical composition. First, a very short laser pulse vaporizes and ionizes a bacterial sample. The positive ions are accelerated, in vacuum, through a -15 kV potential difference, and then they travel at constant speed through a 1.5-m-long drift tube to a detector that records their arrival times. An ion's time of flight depends on its mass, so a record of the arrival times can be used to determine the masses of the biomolecules that were released from the bacteria. Each type of bacteria has a unique set of proteins with different masses, so the mass spectrum is a fingerprint for identifying bacteria. Part A What is the mass in kDa of an ionized protein that is detected 51 us after the laser pulse? You can assume that the protein is singly ionized (q=+e) which is mostly true in practice. You can also neglect the time needed to accelerate through the potential difference because it is very small compared to the drift time. Express your answer in kilodaltons. m= Submit V ΑΣΦ Provide Feedback Request Answer kDa Next >

Bacteria can be identified by using a time-of-flight mass spectrometer to measure their chemical composition. First, a very short laser pulse vaporizes and ionizes a bacterial sample. The positive ions are accelerated, in vacuum, through a -15 kV potential difference, and then they travel at constant speed through a 1.5-m-long drift tube to a detector that records their arrival times. An ion's time of flight depends on its mass, so a record of the arrival times can be used to determine the masses of the biomolecules that were released from the bacteria. Each type of bacteria has a unique set of proteins with different masses, so the mass spectrum is a fingerprint for identifying bacteria. Part A What is the mass in kDa of an ionized protein that is detected 51 us after the laser pulse? You can assume that the protein is singly ionized (q=+e) which is mostly true in practice. You can also neglect the time needed to accelerate through the potential difference because it is very small compared to the drift time. Express your answer in kilodaltons. m= Submit V ΑΣΦ Provide Feedback Request Answer kDa Next >