TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Arrangement: The side outlet port of the purification column is above or below the side inlet port of the purification column. Side outlet port (24) of the column (20) is below or above (preferably above) the side inlet port (21) of the column (20). Side outlet port (34) of the column (30) is below or above (preferably below) the side inlet port (31) of the column (30). Side outlet port (54) of the column (50) is above side inlet port (51) of the column (50). Preferred Process: The purified composition is passed through additional purification device(s) to form purified product. The boron-containing contaminant is partially removed from the composition by feeding the composition into column (10) through upper inlet port (11), and removing top boron-containing contaminant stream (1T) through top outlet port (13), and partially purified composition (1B) through bottom outlet port (12) from the column (10). The partially purified composition (1B) is fed into column (20) through side inlet port and top boron-containing contaminant stream (2T) through top outlet port (23), bottom boron-containing contaminant stream (BS2) through bottom outlet port (22) and the partially purified composition through side outlet port are removed from the column (20). The boron-containing contaminant stream(s) is recycled. The purified composition (2S) is passed into column (30) through side inlet port, top boron-containing contaminant stream (3T) through top outlet port (33), bottom boron-containing contaminant stream (BS3) through bottom outlet port (32) and partially purified composition (3S) comprising trichlorosilane through side outlet port are removed from the column (30), the purified composition (3S) is treated with metal oxide(s) in a treatment container (40) to form treated composition (4), removing treatment contaminant stream, the treated composition is fed into column (50) through side inlet port and top boron-containing contaminant stream (5T) through top outlet port (53), bottom boron-containing contaminant stream (BS4) through bottom outlet port (52) and purified product comprising trichlorosilane are removed through side outlet port from the column (50). Preferred Composition: The additional purification device is treatment container comprising metal oxide(s) or bed of the metal oxide.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The metal oxide is silica gel. The purified product has boron content of 0.5 ppb or less.