Research Article

Quantitative Measurement of Plasma Free Metanephrines by a Simple and Cost-Effective Microextraction Packed Sorbent with Porous Graphitic Carbon and Liquid Chromatography-Tandem Mass Spectrometry

Figure 4

Dot, box, and whisker plots illustrating the concentrations of plasma free metanephrines in clinical specimens. Dotted lines represent the upper cutoff values.
(a)
(b)