Procedures to make ICP-MS Standard Solution

Procedures to make ICP-MS Standard Solution

Since Standard solutions determine the data accuracy in chemical analyses, it is very important to make good and accurate standard solutions.  ICP-MS analysis needs at least 3 standard solutions: blank, high, and QC.  But, it is better to have more than 3 standard solutions, 5 standards will be a good number of standards.

1. Blank should be your matrix solution for your unknown samples and this solution should be used to make other std solutions.

2. Hi and QC should contain all the elements you want to analyze. The concentrations of all elements in the hi-std should be higher than the highest expected concentration in your unknown samples but not too much higher. For this part, please check with us if you are not sure. The concentration of each element in QC should be about half of that in the hi-std or less. DO NOT recommend to just dilute your hi-std solution for making QC.  You should make hi and QC independently from your stock solutions.  KEEP your standard solutions in bottles, which you know it is ABSOLUTELY clean. The accuracy of your standard solutions determines your data accuracy.  PLEASE BE VERY CAREFUL WHEN YOU MAKE THEM!

3. Procedure:

   • Stock solution: You should purchase either multi-elements stock solution or single element stock solutions from Fisher, VWR, or other vendors. 

   • Using multi-elements stock solutions: all you need is carefully diluting your stock to the concentration you need with dilute (2 to 5%) HNO3 or HCl. HNO3 is preferred for ICP analysis.

   • Using single element stock solution:

     • Add pre-calculated amount of acid (HCl or Nitric Acid) to a CLEAN volumetric flask. The amount of acid should be based on the volume you are making but final acid concentration should be about 3 to 5% of concentrate acid.

     • Add each stock solution to the v-flask by weighing the solution on an analytic balance.  The weight of the solution you transfers will be used to calculate the final concentration of each element.  The calculation should be based on the density of the stock solution if it does not have a density of 1 g/ml. Here is the formula to calculate the volume based on none-1 density. V (ml) = wt.(g) x density.

     • Make the volume with DI-water to the mark of the v-flask.

     • Mix the solution very well and transfer to a plastic bottle, which you know it is absolutely clean even it is a brand new one.  If you are not sure, clean it with dilute HCl acid and rinse with DI water at least 3x.  Then, rinse with a small amount of your standard solution.

   • Making other standards: To improve the data quality, esp. at trace level, you should make more standards than 3.  Do a serial dilution on your Hi-Std.  It will be better do 2x diluttion, then 2x again...

================================================

Another way to make your standard solutions is to use 50 ml falcon tubes with a analytic balance.  This is very accurate and produce great standard curve:

1) Make 500 ml of 3% nitric acid with trace metal grade acid and DI water.

2) Place a 50ml tube on balance and tare it.

3) Add precalculated amount of stock solution.  This can be calculated by using our online calculator.

3) Record the weight. If the density of the stock solution was not 1 g/ml, convert it by this formula: V (ml) = wt.(g) x density.

4) Add the 3% acid to the tube to full or any amount, record the weight.   This is the volume of the "Vol. to make". This solution should have a density very close to 1 g/ml. For most analysis, the error here small enough to be ignored. 

5) Plug the values of the weight from step 4 and weight or the V from step 3 and stock solution conc. to the online calculator and click on the final con.  This is the conc. of the new solution. 

6) Follow the steps 2 to 5 to do another lower conc.  by using the new solution in stp 5.  Continue until you get all standards ready. 

If you have any questions on making standard solutions please contact us.