Formaldehyde is a gas at room temperature and one atmosphere of pressure. A saturated solution of formaldehyde in water is 37% w/w formaldehyde and this solution is properly called “formalin.” The commonly used laboratory fixative is a neutral buffered 1:10 dilution and has a formaldehyde concentration of 4% w/v. Common usage is to call this “formalin,” meaning the neutral buffered 4 w/v solution. It is also called NBF formalin. The 1:10 formalin is almost a universal tissue fixative but for special procedures, bouin’s fixative or zinc formalin are preferred. For immunohistochemistry staining zinc/formalin is preferred. Our zinc/formalin contains 10.9 g/l formaldehyde, 2 g/l zinc sulfate and is buffered with sodium acetate to a pH of 5.5. our catalog number is 909A. Medical chemical sells this reagent in plastic bottles of 1 gal. and 5 gal. sizes. We also sell pre-filled biopsy containers that are half filled with this fixative. Available biopsy containers are:

Catalog # 909A-20. 20 ml. fixative/40 ml. jar, 50 jars/case.
Catalog # 909A-30. 30 ml. fixative/60 ml. jar, 50 jars/case.
Catalog # 909A-90_6OZ_JAR. 90 ml. fixative/6 oz. jar, 50 jars/case.
Catalog # 909A-90_6OZ_JAR. 90 ml. fixative/6 oz. jar, 50 jars/case.
Catalog # 909A-100_6OZ_JAR. 100 ml. fixative/6 oz. jar, 50 jars/case.
Catalog # 909A-100_. 20 ml. fixative/40 ml. jar, 50 jars/case.
Catalog # 909A-250. 250 ml. fixative/16 oz. jar, 24 jars/case.
Catalog # 909A-16OZ_VPET. 500 ml. fixative/32 oz. jar, 12 jars/case.
Catalog # 909A-1000. 1000 ml. fixative/32 oz. jar, 6 jars/case.
Catalog # 909A-3L/2GL_BKT. 3 L/2 gal. bucket.