text: Sinapinic acid is most commonly used for this procedure. It often requires helium to be pumped into a collision cell in an intermediate step.
full_question: Sinapinic acid is most commonly used for this procedure. It often requires helium to be pumped into a collision cell in an intermediate step. This technique is done twice in a row, or in tandem, to sequence proteins. In a common method of prepping this procedure, a laser is fired at a matrix to desorb a sample. The output of this procedure is commonly shown as a bar graph with an M+1 signal right next to the (*) base peak, which is the radical cation formed in this procedure's first step. This technique measures the abundance of each m-over-z ratio in a sample by subjecting fragments to a magnetic field. For 10 points, name this form of spectrometry which distinguishes between isotopes because of the difference in ions' molecular weights.
first_sentence: Sinapinic acid is most commonly used for this procedure. It often requires helium to be pumped into a collision cell in an intermediate step.
raw_answer: mass spectrometry