Sample Preparation for the Matrix Urine

Activate the FPE cartridge with 3 ml methanol and condition with 3 ml phosphate buffer 

Mix urine with 3 ml 0.1 M phosphate buffer and pass through the cartridge using a slight vacuum 0 

Treat with 0.5 ml 0.1 M acetic acid, pH 3, using a slight vacuum 

Pass 50 pi methanol through the cartridge using a slight vacuum 

Elute the acidic fraction with 4 ml acetone/chloroform (1 1) 

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