The present invention relates, in part, to a biocompatible hydrophobic-core carrier comprising a carrier, and a plurality of hydrophobic groups covalently linked to the polymeric carrier. In the invention, absorbed current detectors are mounted in a vacuum specimen chamber and capacitance of a signal wire from each probe to corresponding one of the absorbed current detectors is reduced to the order of pF so that even an absorbed current signal with a high frequency of tens of kHz or higher can be detected. Comparison circuits 36A, 36B and 36C compare pieces of data read out from databases 50A, 50B and 50C with the comparison target data. The image processing unit corrects the pixel data of the phase-difference detecting pixel. In one exemplary embodiment, recovery of metals from a leached metal-bearing material is controlled and improved by providing a high grade pregnant leach solution and a low grade pregnant leach solution to a single solution extraction plant comprising at least two solution extractor units, at least two stripping units, and, optionally, at least one wash stage.