[Mattschke]

Hi!
For a project work (school for chemical technician) i need to quantify Selenium in nuts. I found a good recipe for photometric analysis.

But the thing is: When i homogenize nuts, isn't the matrix too fatty to isolate Selenium? How do i do that?

[Borek]

I found a good recipe for photometric analysis.

Doesn't the recipe tell how to prepare the sample?

If the recipe doesn't give any suggestions in general you need to decompose the sample either by roasting or boiling it with some oxidizing stuff (perhaps with microwaving or ultrasounds). There are some general techniques, which is best depends mainly on the volatility of the analyte.

[Mattschke]

The probe needs to be pH-neutral in the beginning. When the probe starts with being in a fatty matrix, the fat dissolves into carbonic acids, so the probe isn't neutral.

Otherwise, the recipe would function with any Selenium probes, up to 5μg.

[Corribus]

It would be helpful to have more information about "photometric analysis". But in general, prepping samples for metal/metalloid analysis involves acid digestion to get rid of organics (including fats). Take care, selenium can be difficult because of its tendency to form gaseous compounds during digestion. You might find an EPA or other regulatory method that fits your needs.