Norah
★    

Tunisia,
2018-12-11 11:30

Posting: # 19677
Views: 683
 

 aspirin degradation [Bioanalytics]

Hi Dears
I'm preparing a BE protocol regarding, enteric delaying release aspirin (acide acetyl salicilique) but because of the instability of ASPIRIN in plasma,
we must take some precautions with anticoagulant, and in sample preparation too.
Could you please tell me what are you recommendations to avoid the degradation of active ingredient in metabolite.
Helmut
★★★
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Vienna, Austria,
2019-02-02 16:56

@ Norah
Posting: # 19848
Views: 295
 

 ASS stabilization

Hi Norah,

» I'm preparing a BE protocol regarding, enteric delaying release aspirin […] Could you please tell me what are you recommendations to avoid the degradation of active ingredient in metabolite.

In my CRO we had two methods (anticoagulant K3EDTA or Li-heparin). Example for 10 mL vacutainers.
  1. Stabilizer H3PO4
    Prepare 5% orthophosporic acid (59 mL 85% o-H3PO4 p.a. diluted to 1000 mL).
    Caution: Even diluted phosphoric acid is strongly acidic; wear gloves and eye protection.
  2. Stabilizer potassium fluoride
    Prepare cold saturated KF solution (100 g KF p.a. in 100 ml water).
    Caution: KF is poisonous. Observe the usual rules.
Penetrate the stopper of 10 mL vacutainers (e.g., by a 200–500 µL HPLC syringe with a thin needle) and inject 100 µl of the respective stabilizer. Use these for all samples.

Handling & storage

Put blood samples immediately after draw in an ice-bath. Allow 10 minutes for equilibration and centrifuge at ~2000×g at +4 ℃ for 20 minutes.

  1. Mix plasma with 5% H3PO4 1:1 (exactly!). Store at ≤20 ℃.
  2. Store at ≤70 ℃.
If you have no problems with sensitivity I would suggest #1. However, the final dilution step is labour-intensive. #2 gives a ~2times lower LOQ but the deep-freezer will suck up a lot of electricity…

Cheers,
Helmut Schütz
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