Which fixative is not mercury-containing and can be used for preserving parasite material in stool?

Which fixative is not mercury-containing and can be used for preserving parasite material in stool?

• A. Formalin
• B. Sodium acetate
• C. Buffered glycerol
• D. Polyvinyl alcohol

Answer: (A)

Formalin is a non-mercury fixative that effectively preserves parasite material in stool by cross-linking proteins and stabilizing cellular and cystic structures, which helps maintain morphology for microscopic identification and for standard concentration techniques like formalin-ethyl acetate. Its widespread use in routine stool parasitology and compatibility with common workflows makes it the best choice among the options when you need a mercury-free preserving agent. Sodium acetate by itself isn’t a fixative; it’s a buffering salt used as part of some fixatives but does not preserve specimens on its own. Buffered glycerol is mainly a mounting/clearing medium rather than a true fixative. Polyvinyl alcohol can be used in some permanent-slide preparations, but it is not the primary, routinely recommended fixative for preserving stool parasites in the way formalin is.

Formalin is a non-mercury fixative that effectively preserves parasite material in stool by cross-linking proteins and stabilizing cellular and cystic structures, which helps maintain morphology for microscopic identification and for standard concentration techniques like formalin-ethyl acetate. Its widespread use in routine stool parasitology and compatibility with common workflows makes it the best choice among the options when you need a mercury-free preserving agent.

Sodium acetate by itself isn’t a fixative; it’s a buffering salt used as part of some fixatives but does not preserve specimens on its own. Buffered glycerol is mainly a mounting/clearing medium rather than a true fixative. Polyvinyl alcohol can be used in some permanent-slide preparations, but it is not the primary, routinely recommended fixative for preserving stool parasites in the way formalin is.