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PRESENTED BY
SUBODH S SATHEESH
MPHARM
PHARMACEUTICS
ECPS
1
PHARMACEUTICAL ANALYSIS-GAS
CHROMATOGRAPHY
 It is expressed by the number of theoretical plates
 It is determined by the formula
 The number of theoretical plates...
where tr is the retention time measured from the instant of injection
w is the peak width
W is determined by SD= σ ie w=4σ...
 Resolution is the ability to seperate two signals
 In chromatography its the ability to seperate two peaks.ie
seperatio...
Greater the distance more resolution and vice versa.
5
PHARMACEUTICAL ANALYSIS-GAS
CHROMATOGRAPHY
 The rates of migration of substances in chromatographic
procedures depend on the relative affinity of the substances for...
7
PHARMACEUTICAL ANALYSIS-GAS
CHROMATOGRAPHY
 It is the volume of carrier gas required to elute
components from the column to the time the peak
maximum is obtained.
...
 It is the ratio of partition coefficient of two components to be
separated.
 S= Kb/Ka = K’a/k’b= (tb-to)/(ta-to)
If pea...
 HETP is numerically equal to the column length divided by
the number of theoretical plates in the column
 It varies fro...
11
PHARMACEUTICAL ANALYSIS-GAS
CHROMATOGRAPHY
 A chromatographic peak should be symmetrical about its
centre to follow gaussian distribution
 Asymetric factor is the ...
The chromatographic peak in (a) is an example of tailing, which
occurs when some sites on the stationary phase retain the ...
 Its function is to separate sample components to
discrete peaks
 It should have reasonable chemical and thermal
stabili...
 Liquid phase should not permeate too deeply into the fine
pores of the support structure as slow diffusion in and out of...

Stationary Phase Trade Name Max Temp Common
Applications
Dimethyl Polysiloxane OV – 1, SE – 30 350oC Hydrocarbons,
Polyn...
 Nonpolar solutes like pentane butane etc can be effectively
separated by nonpolar solvents like squalene. And polar
solu...
 H KAUR Instrumental methods of chemical analysis
ninth edition 2013 ;1091-1092
 Skoog holler crouch Instrumental analys...
MANY THANKS
19
PHARMACEUTICAL ANALYSIS-GAS
CHROMATOGRAPHY
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Column efficiency parameters

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A presentation on column efficiency parameters in chromatography.. A part of gas chromatography in pharmacutical analysis..will be helpful for all mphrm students

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Column efficiency parameters

  1. 1. PRESENTED BY SUBODH S SATHEESH MPHARM PHARMACEUTICS ECPS 1 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  2. 2.  It is expressed by the number of theoretical plates  It is determined by the formula  The number of theoretical plates is a measure of the “goodness” of the column  If the retention time is high and peak width is narrow then it shows excellent chromatograms 2 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  3. 3. where tr is the retention time measured from the instant of injection w is the peak width W is determined by SD= σ ie w=4σ 3 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  4. 4.  Resolution is the ability to seperate two signals  In chromatography its the ability to seperate two peaks.ie seperation of constituents where tr1 and tr2 and w1 and w2 are the times and widths, respectively, of the two immediately adjacent peaks.  If the peaks are sufficiently close w is nearly the same for both peaks and resolution may be expressed as  4 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  5. 5. Greater the distance more resolution and vice versa. 5 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  6. 6.  The rates of migration of substances in chromatographic procedures depend on the relative affinity of the substances for the stationary and the mobile phases  Its the difference in time between the point of injection and the time of emergence of separation of component from the column.  It is actually the time required for 50% of the component to get eluted.  It is measure in minutes or seconds 6 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  7. 7. 7 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  8. 8.  It is the volume of carrier gas required to elute components from the column to the time the peak maximum is obtained.  Retention volume depends upon flowrate and retention time  VR= tR-FC 8 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  9. 9.  It is the ratio of partition coefficient of two components to be separated.  S= Kb/Ka = K’a/k’b= (tb-to)/(ta-to) If peaks are far apart ie there is more difference in partition coefficient between compounds hence more seperation factor and viceversa Less seperation factor More seperation factor 9 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  10. 10.  HETP is numerically equal to the column length divided by the number of theoretical plates in the column  It varies from to one column to another as well as one solute to other  The more efficient the column the better the resolution and the smaller the HETP.  HETP=Length of column / no of theoretical plates 10 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  11. 11. 11 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  12. 12.  A chromatographic peak should be symmetrical about its centre to follow gaussian distribution  Asymetric factor is the measure of peak tailing or fronting.  It is defined as the distance from the centre line of the peak to the back slope divided by the distance from the centre line of the peak to the front slope. 12 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  13. 13. The chromatographic peak in (a) is an example of tailing, which occurs when some sites on the stationary phase retain the solute more strongly than other sites. The peak in (b) is an example of fronting, which most often is the result of overloading the column with sample. For both (a) and (b) the green chromatogram is the asymmetric peak and the red dashed chromatogram shows the ideal, Gaussian peak shape. 13 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  14. 14.  Its function is to separate sample components to discrete peaks  It should have reasonable chemical and thermal stability  There are a lot liquid stationary phases available for gas chromatography. But there is no solvent that meet all the requirements of a perfect stationary phase 14 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  15. 15.  Liquid phase should not permeate too deeply into the fine pores of the support structure as slow diffusion in and out of pores affects column efficiency  It should be chemically inert  It should be a good solvent for sample component  Liquid phase should have low volatility and high stability at elevated temperatures otherwise they can contribute to interference in analysis 15 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  16. 16.  Stationary Phase Trade Name Max Temp Common Applications Dimethyl Polysiloxane OV – 1, SE – 30 350oC Hydrocarbons, Polynuclear aromatics, PCB’s Poly(phenyl methyl) siloxane OV – 17 250oC Steroids, Pesticides, Glycols Poly (Trifluoro propyl dimethyl) siloxane OV – 210 200oC Chlorinated Aromatics, Nitro Aromatics, Alkyl substituted Benzenes Polyethylene Glycol Carbowax 20 M 250oC Free acids, Alcohols, Essential Oils, Glycols 5% Diphenyl – 95% Dimethyl polysiloxane DB – 5 325oC Flavors, environmental samples and aromatic hydrocarbons Typical liquid stationary phases 16 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  17. 17.  Nonpolar solutes like pentane butane etc can be effectively separated by nonpolar solvents like squalene. And polar solutes can be easily separated by polar solvents eg; PEG.  Boiling point is also a factor of consideration. among solutes with similar polarity if there is sufficient difference in BP effective separation can take place.  Eg. Squalene min/max temp= 293/423 SE4 423/573  A solvent that could generate different partition ratios among solvents can only be useful in GLC 17 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  18. 18.  H KAUR Instrumental methods of chemical analysis ninth edition 2013 ;1091-1092  Skoog holler crouch Instrumental analysis 2012 841- 846  B K sharma Instrumental methods of chemical analysis twenty fourth edition 2005 c188-191  En.wikipedia.org gas chromatography 18 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY
  19. 19. MANY THANKS 19 PHARMACEUTICAL ANALYSIS-GAS CHROMATOGRAPHY

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