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The figure shows the separation of two enantiomers on a chiral stationary phase.


Sepation of enantiomers of Ritalin by HPLC with a chiral stationary phase.[Data from R.Bakhitar,L.Ramos,and F.L.S.Tse, 鈥淨uantification of methlylphenidate in plasma using chiral Liquid-chromatography/Tandem mass spectrometry: Application to Toxicokinetric studies,鈥滱nal Chim Acta 2002,469,261.]

(a)From trandw1/2 find N for each peak.

(b) Fromtrandw1/2find the resolution.

(c)Giventm=1.62min, use Equation23-23with the average N to predict the resolution.

Short Answer

Expert verified

The separation of two enantiomers on a chiral stationary phase.

tr=470minw1/2=0.28minN=5.554.70min0.28min2

=0.589(5.37-4.70)min0.28min+0.35min=0.626=1435.134(1.22-1)1.222.311+2.31=1.19a)1306.49b)0.626c)1.19

Step by step solution

01

definition of enantiomers

In chemistry, an enantiomer 鈥 also known as an optical isomer, antipode, or optical antipode 鈥 is one of two non-superposable stereoisomers that are mirror images of each other.

Find N for each peak

a) Use this formula to find the N by substituting the known value for both enantiomers

b)Find the resolution

The resolution equation goes:

Resolution=0.589trw1/2LD=0.589.(5.37-4.70)min0.28min+0.35min=0.626

02

equation resolution

The average N to predict the resolution

c) This is the equation we are going to use for resolution:

Resolution=N4-1k21+k2=N4-1k21+k2

The average N

N=Nl+Nd=1563.77+1306.492=1435.13tm=1.62min

Now to calculate the resolution find the retention factor for the second peak by first finded

=2.31NowfindthetrfortheLenantiomer:trr,l=tr,l-tm=4.70min-1.62min=3.08minAndsubstitutealltheknownvaluesintheresolutionequation:ResolutionResolution=N4-1k21+2.31=1435.1341.22-11.222.311+2.31=1.19Hence,a)1306.49b)0.626c)1.19

01

equation resolution

The average N to predict the resolution

c) This is the equation we are going to use for resolution:

Resolution=N4-1k21+k2=N4-1k21+k2

The average N

N=Nl+Nd=1563.77+1306.492=1435.13tm=1.62min

Now to calculate the resolution find the retention factor for the second peak by first finded

t'r,D=tr,d-tm=5.37min-1.62min=3.75mink2=trr,dtm=3.75min1.62min=2.31NowfindthetrfortheLenantiomer:trr,l=tr,l-tm=4.70min-1.62min=3.08minAndsubstitutealltheknownvaluesintheresolutionequation:ResolutionResolution=N4-1k21+2.31=1435.1341.22-11.222.311+2.31=1.19Hence,a)1306.49b)0.626c)1.19

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Most popular questions from this chapter

The chromatogram in Box 25-3 shows the supercritical fluid chromatography separation of seven steroids monitored by three detectors.

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(d) Polar solutes were separated by normal-phase chromatographyon bare silica using methyl t-butyl ether and 2-propanol solvent. How would retention times be affected if eluent were changed from 40 vol% to 60 vol% 2-propanol? (Hint: See Table 25-4.)

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