This is a paragraph from a paper:
'Laccase and peroxidase activities were quantified spectrophotometrically (Agilent, Cary 100 Bio) at 415 nm by detecting the oxidation of 2,20-azino-bis(3-ethylbenzothiazoline6-sulfonate) (ABTS). For laccase activity, 100 μL of sample were mixed with a solution containing 900 μL of 10 mM ABTS and 0.2 M sodium acetate pH 5.0. For peroxidase activity, 100 μL of sample were mixed with a solution containing 800 μL of 10 mM ABTS and 100 M sodium acetate pH 5.0 and 100 μL of 20 mM H2O2.'
10 mM ABTS: 5.48 g ABTS in 1000 mL distilled water or
54.8 mg ABTS in 10 mL distilled water
0.2 M Sodium Acetate: 16.4 g Sodium Acetate , add distilled water to obtain 1000 mL Sodium Acetate solution.
20 mM H2O2: 680 mg or 469 micolitre H2O2 in 1000 mL distilled water.
H2O2 is supplied as a solution, not a solid, typically at 30%, which is 9.8 M when fresh (it degrades over time). You can use that figure to work out how much to add for a final concentration of 20 mM.
Dr. Adam B Shapiro, I have H2O2 stock as 30% (v/v), then I guess 9.8 M is not correct. It should be 12.7 M. Isn't it?
Dr. Mina Karimi-Avargani, sodium acetate is prepared with acetic acid or glacial acetic acid, not just distilled water. pH should be adjusted before use.
Secondly, ABTS is prepared in a suitable buffer, not distilled water. Sodium acetate (pH 5) can be used for it.
It depends on what is meant by 30% - (w/v), (w/w) or (v/v). One product I saw was (w/w). The density was about 1.1 g/mL, so 1 L weighs 1100 g of which 330 is H2O2. The mol. wt. is 34. So the molarity is (330 g/L)/(34 g/mol) = 9.7 M.
However, the concentration of H2O2 in a solution is only approximate, since it is somewhat unstable.
- Badges
- Science topic
- Similar topics
- Filing