internal stanard

[aniket]

i got one qiestion, why do we use internal standard for biological samples?
what hapeens if we dont use internal stanards? why we dont use internal stanards for regular use?

aniket

[jitender]

The objective of using Internal Standards (IS) is to improve precision and accuracy of method. IS is used

1. To account lose of sample in extraction stages (from matrix) or derivatisation.
2. To remove the error associated with inconsistencies in injection volume (especially in manual injectors), volumetric dilution errors (pipetting).
3. To account for detector response variation (may be detector cleanliness, Temperature)


With ther use of newer auto injectors, pipetes, the second case may nt be very importrant. However, IS shall minimize errors related with extraction steps.

IS need to have some desired physical and chemical properties and should get resolved from analytes of interests.

One need to weigh the advantage associated with use of IS and efforts needed to find and resolve suitable IS.

[Mark Tracy]

This subject has been discussed before on this forum.

http://www.sepsci.com/chromforum/viewtopic.php?t=1245

covers most of the points