Abstract: A probe adapter for converting a thermospray equipped LC/MS analyzer to an electrospray equipped LC/MS analyzer. The probe adapter includes structure defining an elongated and hollow first chamber opened at one end to atmosphere and closed at the other end by a first partition. Additional structure is provided defining a hole through the first partition and an elongated and hollow probe shaft is connected to and extends from the first partition on a side thereof remote from the opened end. A central axis of the probe shaft is coaxial with a central axis of the first hole. A second partition is provided in the first chamber and is spaced from the first partition and defines a second chamber therebetween. Adjusting structure is provided for selectively adjusting the spacing between the two partitions. A second hole is provided in the second partition and is coaxially aligned with the first hole.