The ornamental design for a polymerasechainreactioninstrument, as shown and described.
FIG. 1 is a front perspective view of a polymerase chain reaction instrument.
FIG. 2 is a perspective view of the polymerase chain reaction instrument shown in FIG. 1.
FIG. 3 is a front view of the polymerase chain reaction instrument shown in FIG. 1.
FIG. 4 is a back view of the polymerase chain reaction instrument shown in FIG. 1.
FIG. 5 is a side view of the polymerase chain reaction instrument shown in FIG. 1.
FIG. 6 is a side view of the polymerase chain reaction instrument shown in FIG. 1.
FIG. 7 is a top view of the polymerase chain reaction instrument shown in FIG. 1; and,
FIG. 8 is a bottom view of the polymerase chain reaction instrument shown in FIG. 1.
Portions of the polymerase chain reaction instrument shown in broken lines form no part of the claimed design. The evenly dashed broken lines in the drawings illustrate the portions of the design that form no part of the claim. The dot-dot-dash broken lines in the drawings define the bounds of the claim and form no part thereof.