Yes, you can use centrifugation instead of filters. In our lab, we also use centrifugation as a mean to analyse soluble COD.

I don't think there will be much difference. Only that filtration will give you slightly better results.

You need to do a filtration under vacuum and with a 0.45-micron cellulose membrane to separate the dissolved phase from the suspended solid phase which cannot be settled. We can even separate the colloids. Centrifugation is poorer especially if the organic matter is in a colloidal form that may not settle. This can work as long as the suspended matter is settable.

Regards

Yes, you can do centrifugation instead of filtration, but it would be better to use filtration process.

Best of luck.

Hi Raphael,

It depends. Whatever the separation method you will segregate different fractions of your sample. Different filter pore sizes will segregate different fractions of the sample. Different spin speeds, and spin times, will also segregate different fractions of your sample.

So the question is: What use are you going to make with your analysis results? Are you interested in including colloidal fractions in the COD result? And another very important question: are you using the COD method with chromium and silver (and mercury too?). What are you doing with the residue of this analysis? ...

Best Regards,

Markos

It will depend upon the size of the dissociated particles, microns of the filter paper, concentration of the dissolved impurities, concentration of suspended matters in the sample, method/procedure of SCOD estimation. For instance, if we go to analyse pharmaceutical wastewater, its SCOD may be ranged around 250,000-350,000 mg/L. In this case, we required sub-micron filter papers for filtration. For tannery wastewater of TCOD around 5000 mg/L and having total to soluble COD ratio of 0.65-0.75, the results would be better with centrifugation. So, the range of SCOD as well ratio of TCOD to SCOD really matters in order to select either Filtration or Centrigugation.

I guess that I used the same configuration in one of my previous works.

Please check the below link, and I hope it can help you to find your answer.

Article Fabrication and characterization of a novel hydrophobic poly...

In some articles we faced to this method, please kindly read the following reference, may it be helpful for you;

centrifugation replace filtering to analyze dissolved chemical oxygen demand in wastewater samples

I am adding my question here, in case if anyone can help. is there other material of 0.45 micron filter (not the nitrocellulose one) acceptable to use for preparing soluble samples for soluble BOD analysis? the nitrocellulose ones have along lead time and we cannot have it on time.

thanks