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- Posts: 10
- Joined: Tue May 12, 2020 12:50 pm
I'm looking for some advice.
I am trying to optimize a method to extract olamine piroctone from solid soap.
I'm basing it on a method that requires extraction in methanol and dichloromethane (+ ultrasonic bath), then in a volumetric flask, the methanol/acetic acid mixture is filled to the mark.
The soap is averaged on a cryogenic mill before analysis.
I get very reproducible results. where RSD% = 1-2%, even between a series of 12 replicates, and Recovery of 90-100% (spike sample)
The problem is that the declared content is about 1% [g/100g], another lab gets a result of about (for example) 0.97, I get 0.86.
It uses a certified reference material, the calibration curve is stable. The peaks are reproducible. HPLC-UV/DAD method.
Is it possible that I am losing some % of analyte somewhere? If so, where? I have heard that analyte can form complexes with iron if it has been in direct contact somewhere.