Question

use figure $\mathbf{25}\mathbf{-}\mathbf{17}$to suggest which type of liquid chromatography you could use to separate compounds in each of the following categories.

(a)Molecular mass <2000,soluble in octane

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

(c) Molecular mass <2000 ,weak acid

(d)Molecular mass<2000 ,soluble highly polar

(e) Molecular mass <2000 ,ionic

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

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

(h) Molecular mass<2000,soluble in tetrahydrofuran

Short answer

which type of liquid chromatography you could use to separate compounds.

a)We would use normal-phase chromatography

b)We would use bonded reverse-phase chromatography

c)We would use bonded reverse-phase chromatography.

d)We would use hydrophilic interaction chromatography

e)We would use ion-exchange or ion

f)We would use molecular-exclusion

g)We would use ion-exchange with wide pore stationary phase chromatography

h)We would use molecular-exclusion chromatography.

Step-by-step solution

Molecular mass

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.

soluble highly polar

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.