Prior to the analysis, plasma samples were mixed with the equal volume methanol and then centrifuged at 12,000 rpm/min in 4 °C for 10 min.
Twofold serial dilutions of the plasma samples were mixed with an equal volume of calpox virus.
Plasma samples were mixed with an aqueous solution of ammonium sulfate and ethanol (1 1) and then extracted with hexane.
For analysis of epirubicin and epirubicinol, plasma samples were mixed with an internal standard (daunorubicin) and 1 ml of 0.02 M sodium biphosphate buffer (pH 4.0).
Plasma samples were mixed with an internal standard (camptothecin) in acidified acetonitrile to precipitate plasma proteins, then incubated for 15 min at 40°C to convert analytes to their respective lactone forms.
Before the measurements, thawed plasma and urine samples were mixed by inversion, centrifuged with cooling (1500 rpm for 10 min, 4°C, or 2000 rpm for 5 min, 4°C, resp).
In this study, 0.6 mL of CSF, 0.5 mL of plasma, and 0.05 mL of urine samples were mixed with 100 pg, 250 pg, and 330 pg of the internal standards, respectively, for each sample preparation.
Samples were mixed every 5 min.
The samples were mixed by gentle tapping.
Subsequently, the labeled samples were mixed.
