Question

1-You have a sample that is fluid and smells. Which ionization method would you use?
use? Reason?

2-How can you decide if the following fragment ions are OE + · or EE + ions: C4H9N (m / z 71), C4H8NO (m / z 86), C7H5ClBr (m / z 203)

Answer 1

1) Matrix-Assisted Laser Desorption Ionization (MALDI) is used for the ionization of fluid and smell sample.It is generally used for non volatile compound such as fluid and it utilizes nitrogen laser at 337nM as the ionization source.Hence fluid can completely be ionized.

2) R+DB value (ring plus double bond) is ameasure of degree of unsaturation.It is also usefull for the determination of OE oe EE ions.The R+DB value will be the integer number for OE+^. ion & for EE+ion it will be an odd multiple of 0.5.For a molecule for the general formula C_xH_yN_zO_n R+DB is given by

R+DB = x- y/2 + z/2 +1

For C4H9N, R+DB = 1 Hence it is OE+.

For C4H8NO, R+DB= 1.5 hence it is EE+

For C7H5ClBr , R+DB = 5.5 Hence it is EE+