To normalize major oxides determined by ICP-MS/ES to 100% volatile-free for your analysis of cherts, first determine the Loss on Ignition (LOI) by heating the sample to drive off volatiles like H2O and CO2. Then, recalculate each oxide percentage to a volatile-free basis by dividing by (100 - LOI) and multiplying by 100. Sum the volatile-free oxides, and if the total is not 100%, normalize each oxide to the sum. This process allows for direct comparison of samples with varying volatile contents, which is important for cherts that can have different organic matter and water levels. The LOI can also serve as a proxy for these volatile components.

Normalization Process

Example

Assuming the following data:

• SiO2 = 60%
• Al2O3 = 15%
• Fe2O3 = 10%
• MgO = 5%
• CaO = 5%
• Na2O = 3%
• K2O = 2%
• LOI = 5%

The sum of the normalized major oxides should now equal approximately 100%.

Connection Between LOI and Normalization

LOI is crucial for accurate normalization. By removing the volatile components, we focus on the non-volatile mineral composition of the sample. This allows for better comparison between samples with different water and organic matter contents.

Thank you for your responses. These have been very helpful.

Best

Lorenz

Grad Student