Preprocessing was carried out in the following way.
1. Sample 20ml
2. Place the sample on a hot plate and evaporate to 1ml
3. Dilute with 4ml 2% HNO3 in 1ml sample from hot plate
4. Analysis of the final 5ml sample by ICP-MS
Calibration curve
0, 0.1, 0.2, 0.5 1ppb was measured.
The concentration value in ICP-MS was 0.003 ppb.
How can I multiply the pretreatment dilution factor here?
The answer is 0.00075 ng/mL (0.75 pg/mL). Dilution factor = V_final/V_initial = 5/20 = 0.25. 0.25 * 0.003 = 0.00075 ng/mL
Concentration factor is the inverse of the dilution factor and a better way to describe the sample preparation.
The correct answer might actually be "below LOQ" or LOQ, depending on the method and instrument.
In analytical chemistry, the dilution factor is a measure of how much a sample is diluted or concentrated during a series of sample preparation steps. It is used to relate the concentration of the original sample to the concentration of the final solution that is actually analyzed. The dilution factor is calculated by dividing the initial volume of the sample by the final volume after dilution.
In your case, let's go through the steps and calculate the dilution factor at each stage:
Now, you want to know how to multiply the pretreatment dilution factor to the ICP-MS concentration value of 0.003 ppb:
Final Concentration = ICP-MS Concentration × Dilution Factor
For the first dilution step (evaporation), the dilution factor is 20: Final Concentration after evaporation = 0.003 ppb × 20 = 0.06 ppb
For the second dilution step (with 2% HNO3), the dilution factor is 0.2: Final Concentration after dilution with HNO3 = 0.06 ppb × 0.2 = 0.012 ppb
So, after considering both dilution steps, the final concentration of the sample that you would report is 0.012 ppb.
Remember that the dilution factor accounts for how much the sample was diluted or concentrated during the preparation process, allowing you to accurately relate the original sample concentration to the final concentration that was analyzed using ICP-MS.
From the wording, the sample is ultimately concentrated from 20 mL to 5 mL.
The result is 0.003 ng/mL in the autosampler vial.
5 mL vial * 0.003 ng/mL = 0.015 ng analyte in the autosampler vial.
The 0.015 ng is unchanged throughout the sample preparation, so only the volume the analyte is dissolved or suspended in is changing.
0.015 ng in 1 mL = 0.015 ng/mL
0.015 ng in 20 mL = 0.00075 ng/mL
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