For many compounds, excellent analytical results can be obtained with a quick-and-easy SLE cleanup. As shown in this comparison, accurate and precise results—with performance matching a leading supplier—were obtained for acidic, basic, and neutral analytes following a simple Resprep SLE cleanup of plasma samples.
Experimental detail: Gender-pooled and K2EDTA-treated human plasma samples were fortified at concentrations ranging from 0.0125 µg/mL to 2.18 µg/mL. Acidic compound aliquots were diluted in 2% formic acid (aqueous) while basic compound aliquots were diluted in 5% ammonium hydroxide (aqueous). A 200 µL diluted sample (1:1 dilution with pretreatment solutions) was loaded onto a 200 mg Resprep SLE well plate. After five minutes, the samples were eluted with 1 ml of 50:50 dichloromethane:ethyl acetate. Then, 100 µL 50 mM HCl was added to the basic pretreated wells, and, all wells were blown down to dryness and reconstituted in 1:1 methanol:water. Recovery values were determined using matrix-matched calibration. N≥36 wells for each treatment; 4.7–14.4 %RSD across all compounds.
