91Ó°ÊÓ

Figure $25-17$is used to solve this.

If the analyte's molecular mass is less than 2 000 , we use the upper part of the figure. We use the lower part if the molecular mass is greater than 2 000 .Table $25-4$can also be used to determine the polarity.

a)Molecular mass <2000,soluble in octane.

We would use normal-phase chromatography to separate compound that has molecular mass below 2 000 and it is soluble in octane.

b)Molecular mass <2000,soluble in methanol-water mixtures

We would use bonded reverse-phase chromatography to separate compound with molecular mass below 2 000 and it is soluble in methanol-water mixtures.

c)Molecular mass <2000,weak acid

We would use bonded reverse-phase chromatography with buffered mobile phase to separate compound with molecular mass below 2 000 and it is weak acid.

d)Molecular mass <2000,soluble highly polar

We would use hydrophilic interaction chromatography to separate compound with molecular mass below 2 000 and it is highly polar.

e)Molecular mass <2000,ionic

We would use ion-exchange or ion chromatography to separate compound with molecular mass below 2 000 and it is ionic.

f)Molecular mass <2000,soluble in water in nonionic various

We would use molecular-exclusion chromatography to separate compound with molecular mass greater than 2 000 and it is soluble in water, nonionic, various sized solutes.

g)Molecular mass >2000,soluble in water in water, variety of changes

We would use ion-exchange with wide pore stationary phase chromatography to separate compound with molecular mass greater than 2000 and it is soluble in water, variety of charges.

h)Molecular mass >2000,soluble in tetrahydrofuran

We would use molecular-exclusion chromatography to separate compound with molecular mass greater than 2 000 and it is soluble in tetrahydrofuran.