Hi!

The results of measurements of the concentrations of individual elements are given in mg/L. The test portion of a given sample taken for analysis was, for example, 0.1 g. The volume of the solution obtained from it was initially, for example, 10 mL, but for measurements this solution was diluted, for example, 10 times, i.e. to a final volume of 100 mL. So the concentration (formal, because the test portion no longer physically exists) of the analyzed sample was in this case 0.1 g/100 mL. And after conversion 1 g/L, i.e. 1000 mg/L. If the measured concentration of an element was, for example, 1 mg/L, then the content of this element in the sample is 1/1000 m/m, i.e. 0.1% m/m. And if 10 mg/L, then 1% m/m. And if 100 mg/L, then 10% m/m. When converting concentration measurement results into contents (mass fractions, e.g. % m/m), try to calculate the formal concentration of the sample in the solution subjected to measurements rather than calculating any numerical values ​​of the dilution ratio.

ZJ

Dear Joohyun:

Sorry for the delay in responding to your request. It was beneficial that you attached the data in an Excel sheet so that we could understand your question clearly, and help you with the calculation using the actual numbers.

Basically, you calculate the Dilution Factors (Dilution Ratios) for each step in the process, say DF1, DF2, DF3, ...... (In your case, there are only two dilution steps, pretreatment and second dilution.)

Then the final Dilution Factor, DFfinal = DF1 x DF2 x DF3 .......

Then, the concentration in the sample,

Csample = Csolution x DFfinal

I have attached the revised spreadsheet with the calculation in your "Summary page".

Please let us know if you have any questions.

Best wishes,

Nimal

PS: (for anyone who may have interest):

I will be presenting a full-day short course at the upcoming FACSS SCIX Conference, North Carolina Oct 20, 2024 ( https://scixconference.org/ )

SciX 135 - Statistics, Calibration Strategies and Data Processing for Analytical Measurements.

Presenter: Dr. Nimal De Silva

First of all you should have a calibration curve according to the know standard sample then you can easily calculate the experimental values in ppm or mg/L.

Thanks

helpful tip is let the units be your guide.. and you should know the serial steps on how you diluted your solutions.

I have attached an example in the attachment.

Good day sorry for the late reply.

Firstly you will have to plot the calibration and use the regression equation to calculate the concentration of the unknown.

Dear colleague,

Sorry for the delay in responding to your request.

I know, that this post is not related with the question of the college. I want to pay attention on the methodology of measurement, which must ensure the accuracy of analytical results in the determination of matrix element by ICP-OES.

There I pay attention on the following:

1. The calculation of the final results is the easiest problem.

2. The accuracy of analytical results is the most important problem!!

There you have two analytical tasks:

I. Determination of Sulphur (S) as impurity in the presence of Li, P and Fe as matrix constituents by ICP-OES

In this case, after dissolution of the sample must study the spectral interferences in the presence of the matrix constituents Li, P and Fe in other to select a prominent line of S, which is free of spectral interferences in the presence of the corresponding matrix constituents .

The calibration solutions for S must be prepared from Merck Titrisols and blank, containing the acids used for digestion. The blank sample containing the acids used for digestion has to preparer in the same way.

There is not necessary to use a dilution factor.

II. Determination of matrix elements Li, P and Fe in two LiFePO4 samples by ICP-OES

In this case, after dissolution of the sample, must be selected an appropriate dilution factor, which permit to measure the corresponding analytical signals of matrix constituents with desire level of precision. I think that the dilution factor cannot be higher than 20.

The calibration solutions for the determination of Li, P and Fe must be prepared on the basis of acid blank, diluted in the same way, as the sample. The acid concentration in reference solution is equal to that in the final sample solution.

The accuracy of analytical results is of prime importance.

Owing to the lack of certified reference materials the accuracy must be evaluated using analysis of a sample with well-known composition.

There is necessary to use and second direct method for determination of Li, P and Fe.

On the basis of the analytical information by ICP-OES, the corresponding stoichiometry of the both samples must be calculated.

My research group has experience in the determination of the content of the major components Sr, Li, Ti, Fe and Nb in single crystals, based on strontium–lithium–titanium oxides by inductively coupled plasma atomic emission spectrometry (ICP-AES) and Electron probe microanalysis (EPMA) as second direct method [1].

References

[1]. A. Detcheva, N. Daskalova*, S. Velichkov, I. Havezov, Analysis of single crystals based on strontium–lithium–titanium oxides by inductively

coupled plasma atomic emission spectrometry, Spectrochimica Acta Part B 58 (2003) 1481–1488

With kind regards, N.Daskalova