Heavy metal toxicity will hinder the activity of enzymes. I hope the reduction may be due to certain bacterial activity. 

What is the enzyme used? Did you calculate enzyme activity before and after treatment? Mechanism of action of enzyme on copper removal should be studied.

Dear Selvaraj thank you for your answer. I am using tannase enzyme. calculated before treatment the value is 10.22U/mg and after treatment it become less.I have confused that enzyme have the property to which reduced the heavy metal?

Thank u sundarrajan, i had used fungal tannase for my heavy metal determination.

Cadmium and nickel are determined in Coal, Coal Fly Ash and Urban Particulate Matter Reference Materials using solid sampling graphite furnace AAS. The evaluation of integrated absorbance is required to overcome the effect of the matrix on the rate of atomization. The homogeneity of the samples under investigation in the range between 0.3 mg and 1.5 mg sample weight is good enough to make possible relative standard deviations around 10% for cadmium and between 10 and 20% for nickel. Cadmium can be determined against reference solutions; the nickel results are slightly lower than the certified value if calibration is performed against aqueous solutions. Calibration against a solid reference is therefore recommended. Less sensitive resonance lines and an internal gas flow through the tube are required for some of the samples to keep the absorbance in the linear calibration range. The direct determination of chromium in these samples is hampered by the lack of less sensitive resonance lines. Due to high concentrations of chromium in the samples, direct determination without dilution of the sample e.g. by spectrally pure graphite powder is impossible. The peak for the refractory carbide forming element vanadium is strongly suppressed by the Coal and the Urban Particulate matrix. Integration of the signal within a reasonable time and at an atomization temperature of 2650 °C is impossible.

Thank u nadwiga and ahamad for your contribution. is there detoxification?

Thank u Gul. i had digest the sample before the experiment. the level of chromium reduction has done when treated with tannase enzyme. But dont know what is the action behind this.

Ok lets check it. i have write the paper, but i dont know what conclusion i put, in the case of copper conc when treated with my enz.

Yes, It can be analysed using AAS, but it depends upon the metal you use and the availability of lamp for that particular metal

Yes, It can be analysed using AAS, but it depends upon the metal you use and the availability of lamp and standard solution for that particular metal.

Yes, It can be analysed using AAS, but it depends upon the metal you use and the availability of lamp and standard solution for that particular metal.

thank u anusha and astatkie.. Gul i need your paper for reference. Pls send the paper into my [email protected]

There are some enzyme which absorbs the heavy metals in water. please check the literature and you will see this.

Yes. it means that your adsorbent has some adsorption capacity because the initial concentration of Cu in tannery effluent was 1.05 mg/L. After treatment with your enzyme (i.e with ur adsorbent), it came down to 0.34 mg/L. That means it has 67% removal. Although its not that efective but if you modify it further, may be the adsorption capacity increse and then it can bring the tannery effluent to permissible. & then it can be discahrged into the aqueous streams safely. In AAS, for every heavy metal, we hace cathode lamps which need to be selected. But, if you are working with ICP, then u need not to change anything as ICP analyses all the heavy metals simultaneosly. You need to select only the heavy metals from the periodic table and the instrument will give you the final conc. in triplicate.

Depending on enzyme used it could act as a copper adsorbent as already mentioned. I also agree that using AAS can be a good method for determining metal ion concentrations. However, good standard solutions need to be used and proper HCL lamps as well. Results could also vary depending on whether F-AAS or ET-AAS was used.

Thank u Jain and Bieganska....

AAS is the one the precision and accuracy method in determining Cu in trace levels. I'm using since 1990.Certainly both mobilises and ind immobilised enzymes adsorb metal ions. What is the enzyme you used? 

thank u muthu sir..I am using tannase enzyme...

You can not conclude only by decreased concentration of Cu (measured by AAS) in your experiment that the enzyme has adsorption properties. Detailed characterisation and further experiments are required for establishing the enzyme to be an adsorbent. , Off course metal concentration measured by AAS would be enough for quantification.

Thank u Navaneet. Chromium removal from tannery effluent treated with tannase enzyme are there.. whether metal have the capacity to degrade?

Are you using background correction?  It is possible that there is something in the untreated sample that decrease that energy resulting in a higher  apparent Cu level.  If you do not have background correction capabilities on your instrument, you can dilute the sample and see if the Cu levels decreases more than you would expect for the dilution.  This may or may not work depending on the level of the interfering matrix component.  As mentioned you you can explore the possibility that the Cu is being lost during your treatment process.  You can try some standard addition experiments to see if this is the case.

Thank you. Francis and victor. I am using AAS (flame type: Air-C2H2). I have confused that whether there is any adsorption process is done in my experiment.

I think that the difference between initial and final concentration of a metal ion in solution is not enough to decide that adsorption has been occurred. Type and nature of metal ion solution, whole system solution (containing both adsorbent and adsorbate), experimental characteristics of solution like pH, concentration and temperature and adsorbent (enzyme) characteristics are all collective information used to decide the occurrence of adsorption reactions. Metal ions may precipitate as hydroxide or other precipitate type and/or may chemically react with the enzyme in a mode other than adsorption.

Dear Rama and james thanks for giving the answers. In present none of teliterature says copper having the adsorption capcity when treated with tannase enzyme in tannery effluent, but in the case of chromium the reduction had done when treated with same enzyme. Nebulizer uptake was 4 sec and burner height was 7.0mm. the reaction product is gallic acid. the product i had conformed through NMR.  Presently i cant interpret the result.

It cant be possible. After treating the enzyme, Cu may be convert or bind with other molecules, but total amount cant be change. But after enzyme treatment, you follow the filtartion on centrifugation process that can happen. Mainly, I guess that problem with your AAS

Thank u Jinadasa..

Absolutely, provided that you stand by the results. The surface active groups on the enzyme (I have no idea which one did you use) may be instrumental in binding the heavy metals on it. You can find out which heavy metals are competitively bound and the loading of the metals on to enzyme as well as the rate of the reaction as well as other properties such as which model will fit the adsorption characteristics and thermodynamic data of adsorption of a particular heavy metal - INTERESTING!

Thank u Aly..i am using tannase enzyme. the model is fit.i had construct 3d model of the tannase gene.