Sample Preparation Deck (Exam 1) Flashcards
Sample preparation is done for these types of specimens.
Seized drugs & biological
What are the 3 goals of sample preparation?
1) Provide target analyte(s) in solution
2) Provide analyte at concentration appropriate for detection/measurement
3) Remove as many interferants as possible
When are post-mortem specimens collected, and who are they collected by?
They are collected by the pathologist during the autopsy
Post-mortem blood samples can be found in these 2 places.
What are heart and peripheral sites?
These 2 fluids are very useful for alcohol toxicology.
What are vitreous humor and bile?
Why is vitreous humor such an important post-mortem specimen?
It is uncontaminated from decomp and resistant to putrefication
This practice is the decomposition of a sample into liquid form and can be accomplished with strong acids & enzymes/incubation.
What is sample digestion?
This extraction method is accomplished by solidifying proteins and then filtering or centrifuging.
What is protein precipitation?
What is the flowchart for protein precipitation?
Organic solvent > plasma > precipitation > vacuuming
This extraction method is accomplished with organic solvents, polarity, and pH.
What is liquid-liquid extraction (LLE)?
Why is the non-salt form preferred for LLE?
It is unionized and therefore immiscible in polar organic solvents, which is perfect for extracting the analyte
Why are pH adjustments performed in LLE?
To keep target analyte in non-salt form
How should you adjust pH for acidic drugs in LLE?
Move pH 2 units BELOW pKa
How should you adjust pH for basic drugs in LLE?
Move pH 2 units ABOVE pKa
True or False: pKa = 1 always means you are dealing with an acidic molecule.
False; THC is an acidic molecule with a pKa of 10.5
