Alcohols Two common effects 1)Loss of water 入入oH m/z74 m/z56 100 H5-n-5439 60 40 20 0-mm4444m4444hthr4mmmh 10 15 20 25 30 35 40 45 5055 60 70 75 m/z
Alcohols Two common effects OH m/z 74 m/z 56 H2O 1) Loss of water
Alcohols 2)a-cleavage [则”一[8+|· CHCH m/z74 m/z45 100 h5-n-0335 % 60 40 20 10 15 20 25 30 35 40 5 50 55 60 70 75 m/z
Alcohols 2) α-cleavage m/z 74 OH O H O H m /z 4 5 C H 2 C H 3
McLafferty Rearrangement Any ketone containing a y-hydrogen can rearrange to the enol form in a MS H1+ m/z100 m/z58 100 H5-e-0337 80 60 20 0、 [mt 20 30 40 50 60 70 80 90 100 m/z
McLafferty Rearrangement Any ketone containing a γ-hydrogen can rearrange to the enol form in a MS H O m/z 100 O H m/z 58
Ketones Ketones can also do a-cleavage similar to alcohols ”一+叫 ·CH2CH2CH2CH3 m/z100 m/z43 100 3-0-0337 80 60 40 20 0 10 20 30 40 50 60 70 80 90 100 m/z
Ketones Ketones can also do α-cleavage similar to alcohols O m/z 100 O O CH2CH2CH2CH3 m/z 43
High Resolution Mass Spectrometry(HRMS) These high sensitivity mass spectrometers,called HRMS, can be used to determine molecular formula a HRMS can detect particle masses with an accuracy of 1/20,000 therefore >0.0001 amu (atomic mass units) Can use this to distinguish compounds with a similar rough mass but with a different molecular formula 12C 12.0000 amu (by definition) H 1.0078amu 16O 15.9949amu Many structures may have the same integer value molecular weight, but different molecular formulas For example: HN人NH CH。O1 CsH1o C.HoN2 70.0418amu 70.0783amu 70.0531amu
High Resolution Mass Spectrometry (HRMS) These high sensitivity mass spectrometers, called HRMS, can be used to determine molecular formula a HRMS can detect particle masses with an accuracy of 1/20,000 therefore > 0.0001 amu (atomic mass units) Can use this to distinguish compounds with a similar rough mass but with a different molecular formula !!!12C ! !12.0000 amu (by definition) !!!1H ! ! 1.0078 amu !!!16O ! !15.9949 amu For example: Many structures may have the same integer value molecular weight, but different molecular formulas O C4H6O1 70.0418 amu C5H10 70.0783 amu HN NH C3H6N2 70.0531 amu