Sigfrid Karg-Elert - Sonata in F-sharp Minor 'Appassionata' for Solo Flute. Sigfrid Karg-Elert’s Sonata 'Appassionata' in F-sharp Minor, Op. 140, was composed on August 10, 1917, during the later years of the composer’s career. Written for unaccompanied flute, the work reflects Karg-Elert’s fascination with the expanded harmonic language of the early twentieth century, employing chromaticism, unexpected harmonic shifts, and an intensely expressive melodic style. In a single continuous movement, the sonata explores the flute’s capacity for both dramatic virtuosity and lyrical expression, creating the impression of a much larger musical texture from one instrument.