i have a solution that contain the plant extract and don't have any standard solution of this extract. is there anyway that help me to determine the concentration of this solution?
As per my knowladge, Spectrophotometric method is only useful if solution contains known phytochemical as you suggested but in this case the solution contains plant extract that means lot of different chemicals present in solution. In such case I am agree to Lalrinzuali. In this way we can measure "Total Dissolved Solids" .
Take a empty beaker. Weight it and pour some know quantity of solution. Evaporate on steam bath or electric heater. Keep in to dryer at 80 to 100 degree centigrade for half an hour so that any moisture remain will remove out. Put beaker in dessicator to cool and weight again. Difference in weight is equivalant to dissolved solids in solution. This is general protocol of analysis
i agree with Dr. Rajani...... if you want to know the concentration of a particular compound, you can use HPLC but i cant think of any instrument that can measure the concentration of plant extract since plant extract contains several compounds