Term
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Definition
| Sources that imparts enough energy to an analyte molecule to leave them in a highly exited energy state. Relaxation involves rupture of bonds producing fragment |
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Term
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Definition
| source imparts lesser extent of energy resulting fewer fragments |
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Term
| Define molecular ion peak |
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Definition
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Term
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Definition
| represent most stable ion, fix to 100% |
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Term
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Definition
| how the molecule breaks up |
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Term
| Draw the mass spec system |
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Definition
| do on separate sheet of paper |
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Term
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Definition
| How the sample is introduced |
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Term
| What are the two types of inlets for a mass spec? |
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Definition
1) Direct probe
2) connection to separation system |
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Term
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Definition
| introduction of sample manually |
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Term
| Scenarios for direct probe use |
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Definition
-want sample directly in ms
-starting with pure sample
-have minimal sample |
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Term
| Define connection to a separation system |
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Definition
up front separation using
GC- organics
ICP- inorganics
HPLC- anything molecular |
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Term
| What are the two types of ion sources? |
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Definition
1) gas phase source
2) desorption source |
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Term
| What are the two gas phase sources in MS |
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Definition
1) Electron impact
2) Chemical ionization |
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Term
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Definition
-bombard molecule with ton of electrons
-hi detection limit, only 1 per million ionzied
-destructive |
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Term
| Draw the Electron impact system and the chemical reaction involve |
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Definition
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Term
| Describe chemical ionization |
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Definition
| Gaseous atoms of the sample are ionized by collision w/ ions produced by electron bombardment of excess reagent gas |
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Term
| Write out the chemical ionzization reactions(general, proton transfer and hydride transfer). |
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Definition
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Term
| Describe desorption source |
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Definition
-used for non volatile and thermo stable molecules
-used for high molecular weight samples |
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Term
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Definition
1)Evaporate sample on MALDI matrix
2)Place sample matrix in vacuum
3)Hit matrix with laser, matrix absobs photon and transfers energy to sample
4) Ion plume goes to mass azalyzer |
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Term
| What are the three types of mass analyzers |
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Definition
1) quadrapole
2) Time of flight
3) ion trap |
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Term
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Definition
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Term
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Definition
| Altering the RF to DC ratio in the four parallel electrode you can alter the oscillation patterns of the ions and select for a narrow range of m/z |
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Term
| What are the advantages and disadvantages of the quadrapole |
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Definition
advantage: fast scan rate, low detection limit
disadvantage m/z limit of 3000-4000 |
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Term
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Definition
| A spatially tight bunched group of ions produced by MALDI is accelerated in a drift tube where separation occurs based on velocity. (.5mv^2=KE) |
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Term
| What are disadvantages of Time of flight |
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Definition
-Molecules are constantly stream towards detector
-low sensitivity
-requires good electronics |
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Term
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Definition
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Term
| Explain how ion trap works |
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Definition
| Ions with specific m/z are stabilized between two ring electrodes before the RF is change to kick out ions |
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Term
| Define mass selective ejection |
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Definition
| sequentially ejects ions in order of increasing mass by increasing RF-voltage to ring electrode |
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Term
| List the 11 applications for mass spec: |
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Definition
1)Elucidation of the structure of organic and biomolecules
2)determination of the mw of biomolecules
3)ID of components in TLC
4)Determination of aa squence in polypeptide
5)Detection and ID of species separated by chromatography
6)ID of drugs and metabolites in blood urine and saliva
7)Monitoring gases in surgery patients
8)dating archaeological specimens
9)analysis of aerosols
10)determination of pesticide residues in food
11)monitoring volatile organics in water supplies |
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