Georg Heinrich Friedrich Armbrust (March 17 1818 - May 2 1869)
This is from drei Orgelstücke Opus 4;
1. Moderato (on IMSLP)
3. Einleitung und Fuge
Geog was father of Carl Armbrust who composed Orgelsonate d-moll "Nun danket alle Gott" recently uploaded by hauptwerker.
Not many details to hand about Georg but he was the organist of the St. Petri-Kirche in Hamburg and accompanied Brahm's Frauenchor.