There is a time lapse between aliquot withdrawn from the system, separation of adsorbent by filtration and determination of the amount of metal in the filtrate. As we separate out the biomass, tominimize interaction between the adsorbent and the metal containing system, the extracellular material still remains in the filtrate and may be acting on the metal present. Thus, when the amount of metal present is actually determined we may not get the true reading for that particular time interval. Is there anything we could add (chemical) or do to stop the reaction at the particular time interval to get accurate readings.
Dear Kruti. If you're doing removal of heavy metal cations I would recommend you to filter fast by using a filtrating disk (0.45 micrometer) similar to those of chromatography. Yo can use a syringe to directly extract the volume of sample from the reactor. Once done this, I recommend you to add few microliters of concentrated acid (10, for instance of HCl or nitric) to get a pH about 1.5-2.By doing so, if any extracellular material passes the filter, the high protons concentration avoids the uptake of metal cations because of the competence of the H+ with them. The addition of acid will also avoid the precipitation of some metals by ageing and it is strongly recommended for the further analysis in any atomic technique.
Hope it will help you!!
Carlos
Dear Carlos,
Thank you so much for your valuable suggestions and inputs. I guess this will help me.
Kruti Shah
Dear Kruti Shah,
Maybe I did not fully understood. It seems to me that it does not matter what happens in the filtrate as long as analysis of metals is done in a destructive way. It will detect bound and free metals alike. Only if you use titration, spectrophotometric or ion selective electrodes it would be a problem.
Dear Titus Sobisch,
You got things right. Just that I had some doubt if interaction of the metal with the cell free extract would not give true results may b due to immobilisation of the metal by extracellular metabolites released by the biomass.
Thank you so much for your valuable suggestion and input. I m sure it will help me.
Regards,
Kruti Shah
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