It was based on the biomolecules present in the plant extrract...may (1ml, 2ml,....10ml li9ke that)

It varies depends on the plant extract. Normally 1:9ml is preferred.

Thanks a lot

One more query.the ratio 1:9 indicates 1 unit of plant extract to 9 units of precursor-right?is an opposite protocol possible i.e. 9:1=9 units of plant extract to 1 unit of precursor?what can be the predictable/possible consequences?

Actually the ratio isn't cont. it depends on seasonal variation,time of day during which plant part collected,temp. of reaction mixture and the conc. of precursor viz 100ppm,200 ppm etc. so we have to correlate all this and set standard to obtain NPs.

I tried this ratio with silver nitrate and got better result. If you try with reverse ratio there may be agglomeration of particles or particles may be of larger size.

you can try 5 ml of leaf extract against 95 ml of 1 mM of AgNO3 solution. It gave good results with me

Ok

you can use Qualitech 4 software. it work Taguchi equation basically. choose some factor as temp. , PH , con.and ... then examine ways . you can find your optimum situation.

insha allah