Hi Nadia,

I am not sure why it did not completely dissolve in absolute methanol. I have come across some methods which have a sonication step after the addition of the alcohol to help dissolve the syringaldazine. Maybe this could help?

I have also come across the following re:preparation of syringaldazine using ethanol instead; 

I refer here to the following paper: Gerd Hublik, Franz Schinner, Characterization and immobilization of the laccase from Pleurotus ostreatus and its use for the continuous elimination of phenolic pollutants, Enzyme and Microbial Technology, Volume 27, Issues 3–5, August 2000, Pages 330-336, ISSN 0141-0229, http://dx.doi.org/10.1016/S0141-0229(00)00220-9.

"The assay mixture contained 0.2 mM syringaldazine (dissolved in 60% ethanol) and 40 mM citrate-buffer, pH 5.6. Oxidation of syringaldazine was followed by an absorbance increase at 525 nm (ϵ525 = 65 000 dm3 M−1 cm−1) at a temperature of 25°C".

And here;

Laccase from Myceliophthora thermophila

expressed in Aspergillus oryzae, Revised specifications prepared at the 65th JECFA (2005) and published in FNP 52 Add 13 (2005).

"Syringaldazine, 0.56 mM stock solution: Rinse a 50-ml

volumetric flask with water and ethanol to remove any soapy

residues. Weigh 10.0 mg of syringaldazine in a weighing boat

and transfer to the volumetric flask. Add 96% ethanol to the

mark and stir until the syringaldazine is dissolved

(approximately 3 h). The solution must be stored in a dark

bottle in a refrigerator.

Syringaldazine, 0.22 mM working solution: Rinse a 10-ml

volumetric flask with water and ethanol to remove any soapy

residues. Transfer 4.0 ml of syringaldazine stock solution to the

flask and add water to volume. The solution can be kept in a

dark bottle for up to two hours at room temperature".

Hope this may help you!

Katrina.

Dear Dr. Katrina,

Many thanks for your reply and giving me these information I'll try it, really appreciated :) 

I have tried the method today and it's working, Thanks again for ur help :)

Excellent. I'm glad to hear it is working. Best of luck in your future research.

Kind regards,

Katrina.

hi

I had the problem of precipitation of SGZ_DMF in water.

which way did you try to dissolve SGZ?

I should use the solvent which is highly soluble in water.

what is your suggestion?

I have used this method and it's really working 

Syringaldazine, 0.56 mM stock solution: Rinse a 50-ml

volumetric flask with water and ethanol to remove any soapy

residues. Weigh 10.0 mg of syringaldazine in a weighing boat

and transfer to the volumetric flask. Add 96% ethanol to the

mark and stir until the syringaldazine is dissolved

(approximately 3 h). The solution must be stored in a dark

bottle in a refrigerator.

Hi Maryen, I recommend u to use ABTS for the acidic range from 3 to 6 it will give u better results than SGZ and you can use SGZ for the basic range from 7 to 10. I'm sure if u did that u will not meet this problem. plz feel free if u have more questions 

thanks for your help Nadia.