INSULIN

Insulin, a hormone, plays a key role in catalyzing the processes by which glucose (carbohydrates) furnishes energy or is stored in the body as glycogen or fat. The absence of insulin not only interrupts these processes, but produces depression of essential functions and, in extreme cases, even death. Insulin protein is characterized by a high sulfur content in the form of cystine and it is unstable in alkaline solution.

Insulin is isolated from the pancreas of beef or pigs and by extraction with acidified alcohol, followed by purification. In the process (Fig. 1), the crude alcoholic extract is run from two strong extraction-centrifuge units into a collection tank from which the extract is neutralized with ammonia and filter aid added. In a continuous precoat drum filter, the cake is separated and washed, the clear liquor going to the reacidification tank. In evaporators, the first stage removes alcohol, with subsequent waste-fat separation. The extract goes to a chill tank, with filter aid added, through a filter press and into the second evaporator. From the second evaporator, the concentrated extract is filtered and conducted to the first salting-out tank, followed by filter-press filtration with filtrate to sewer and salt cake to purification for the second salting out. The second-salting-out product is crystallized twice to furnish Iletin (insulin) crystals.

Figure 1: Manufacture of insulin.

IODINE

Iodine (melting point: 113.5 C, boiling point: 184.4 C, density: 4.93) is a red to purple solid that sublimes readily under ambient conditions. Iodine can be produced...