Chromatography Forum

Hello guys, I'm have some trouble in plote a calibrate curve for ICP OES ICAP Pro Serie with autosampler ASX-560.

The samples are from soils and sediments, which we extracted by EPA 3051 (0.25+ digest to 10 mL of Nitric Acid destilled ).
The calibration curve is range to 0,5 to 300 ppm, prepared by taking : MULTIELEMENTAR STANDARD +5 mL of Nitric Acid 2%+ 50 microliters of Ytrium.

AFTER THE READING WE FOUND VALUES TO HIGH FROM THE CONTENT, LIKE :
FOR 2 ppm --> 65 ppm
5 ppm ---> 25 ppm

We very lost about those signal of concentrations, we have repeat the curve yet found very similar concentrations.

My range limits for calibration curve must attend the maximum limit allowed by a standard for soil and sediment that we intend to use in the laboratory, which is :
As 4 mg/ kg,
Cd 0.4 mg/kg,
Pb 35 mg/kg,
Cu 34 mg/kg,
Cr 37, 3 mg/ kg,
Hg 0.17 mg/ kg,
Ag 18 mg /kg
Zn 123 mg/kg

My stock solution is :
Multielementary Solution MATRIX 5% HNO3
Be, Cd,Co,Mn --> 10 mg.L-1
Cr, Cu,Ni--> 20 mg.L-1
Al, As, Ba, Pb, V--> 10 mg.L-1
B,Fe,Se,Tl,Zn--> 100 mg.L-

Multielement Solution Acid Matrix 5 %
Ag,Al,Ba,Be,Bi,Cd,Co,Cr,Cs,Cu,Ga,In,Li,Mg, Mn, Mo, Ni, Pb,Rb,Sr, Tl,V, Zn --> 10 mg .L-1
I'm using Ytrium as internal standard 10 ppm.

Can you guys helping me?

We normally calibrate in a range from 1-5ppb up to 1-2ppm on our ICPOES. The high ppm levels will saturate the detector.

You may need to calibrate to lower concentrations of standards, then dilute the samples with your dilute acid so they are in the same concentration range as the calibration standards.

Always dilute the samples with the same concentration of acid as the standard. If you have a different concentration of acid the response of the analyte can vary.

Thank you James, we seen to be take the right path now, this new experient lead us to great results.