i have prepared stock solution for chromium,zinc,nickel,lead and copper(1ppm,5ppm,10ppm,50ppm,100ppm) from their respective salts.now i dont know that how to make all this elements together for analysing into heavy metals in ICP-AES?
These elements may be mixed together in a 5-10% HNO3 solution. Merck even does so in their reference "ICAL" solution (20 ppb I think). Good pipetting is critical.
Dear karthika,
You can prepare your "multiple elements stock solution" by adding specific volumes of your standard in order to obtain the desired concentrations. the trick is to put every standard in the same flask (same final volume) and at the end taking your dissolution to the meniscus mark.
You can use the next rule for calculate your volumes:
C1*V1 = C2*V2
and
C1= Initial concentration (element stock dissolution)
V1= Initial volume (element stock dissolution)
C2 = Final concentration
V2= Final volume;
C1= (C2*V2)/V1
for each element you can calculate how many mL (V1) of your "Stock dissolution" you need and transfer it to a volumetric flask (V2), wich will contain all your elements in the same volume.
At the end you will have in the same flask all the elements with your selected concentrations.
Hope it will help,
Regards
Mario
PS Be careful with the transference of your dissolutions. Every drop count!!
To prepare a mixed solution of heavy metals should be done as follows. First, prepare the intermediate standard solution from the stock solution of each metal with a concentration of 1 g/l (1 mg/ml). For example, place 0.1 ml of the stock solution of Cr, 0.5 ml of the stock solution of Zn, 1.0 ml of the stock solution of Ni, etc. into a flask of 100 ml, add 8 - 10 ml of nitric acid and bidistilled water to the mark. Concentrations of metals in this solution are 1; 5; 10 µg/ml, respectively. The solution is stable for a long (up to 1 year) time. To prepare working standard solution with concentrations 1; 5; 10 µg/l, etc. dilute the intermediate solution to 1000 times. For example, 0.05 ml of intermediate standard solution place in a flask of 50 ml, add 4 - 5 ml of nitric acid and bidistilled water to the mark. Prepare this solution every day before work.
Look up USEPA SW846 method 6010b or c (https://www.epa.gov/sites/production/files/2015-07/documents/epa-6010c.pdf); it will have all of the requirements, interferences, standards, QA/QC and other qualifiers for what you're looking for.
First you should make 1000 ppm of the mentioned ions from their respective salts. Keep the final volume to be 1000 ml which would contain all the respective ions with desired concentrations. Applying the formula C1V1=C2V2, you can arrive at your objective. If you take 1 ml , 5 ml, 10 ml, 50 ml and 100 ml from the stock solutions of chromium, zinc, nickel, lead and copper respectively and mix the solution thoroughly to make the final volume to 1000 ml, the fresh solution would contain the mixed elements of the mentioned concentrations.
Example:
if 10 ml of Nickel is taken from the stock solution, then going by the formula,
1000*10=C2*1000
C2=10 ppm
Similarly the process can be repeated for other elements.
Caution to be taken is that the final volume should not exceed 1000 ml, or else it would result in a lower targeted concentrations.
I have a problem with ICP-OES results. I measured 50ppm but the ICP-OES results do not exactly reflect 50ppm. The solution was prepared from a metal salt say Pb(NO3)2. Before measurement, the sample was diluted 10 times to meet the detection limit. What could be the problem?
The dilution should be a "serial dilution" process. If diluted directly then there is some error in the dilution factor, which if not taken into account then you get an underestimated value of the concentration. If the dilution factor is properly estimated then the concentration should be exactly 50 ppm. Otherwise kindly cross-check the calibration and the standard preparations.
Hope this helps.
Im going for same, but im confused if i need to prepare 100ppm solution, then can i prepare at according ppm calculation of metal salt or pure metal ? Someone please guide me
Dear Munir
you can visit at
http://delloyd.50megs.com/1000ppm.html
to prepare 1000 ppm std. solution from pure metal or salt.
For preparing 100 ppm solution just take 1/10 g of given value in the above procedure and diluted to 1000 ml.
Hope this help you.
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