Method and composition for controlling formaldehyde fixation by delayed quenching

Abstract

A method and composition for quenching formaldehyde fixation of cell and tissue specimens. The composition includes a formaldehyde-reactive agent. The formaldehyde-reactive agent reacts with the formaldehyde to quench the fixation of the cell or tissue specimen. The method involves contacting a formaldehyde fixative solution with the composition.

What is claimed is:  
     
         1 . A composition comprising formaldehyde fixative and an effective formaldehyde fixative quenching amount of at least one ammonium salt.  
     
     
         2 . A composition according to    claim 1    wherein the ammonium salt is selected from the group consisting of ammonium bicarbonate, ammonium hydrogen phosphate, ammonium benzoate, ammonium alginate, ammonium bitartrate, ammonium citrate, dibasic, ammonium chloride, ammonium gluconate, ammonium valerate, ammonium thiocyanate, ammonium phosphate, monobasic, ammonium acetate, ammonium nitrate, ammonium sulfate, ammonium sulfamate, ammonium purpurate, ammonium tartrate, ammonium hippurate, ammonium iodide, ammonium bromide, ammonium fluoride, ammonium carbonate, ammonium citrate and ammonium acetate.  
     
     
         3 . A composition according to    claim 1    wherein the composition includes an effervescent agent.  
     
     
         4 . A composition according to    claim 3    wherein the effervescent agent is an intrinsic anion of an ammonium salt.  
     
     
         5 . A composition according to    claim 1    wherein the composition includes a buffering agent.  
     
     
         6 . A composition according to    claim 5    wherein the buffering agent is an intrinsic anion of an ammonium salt.  
     
     
         7 . A composition according to    claim 4    wherein the ammonium salt is ammonium bicarbonate.  
     
     
         8 . A composition according to    claim 5    wherein the buffering agent is ammonium bicarbonate.  
     
     
         9 . A quenching composition comprising a formaldehyde-reactive agent and an effervescent agent.  
     
     
         10 . A quenching composition according to    claim 9    wherein the formaldehyde-reactive agent is selected from the group consisting of ammonium salt, amino acid, urea hydrogen peroxide, thiourea, carbamic ester, cyanamide, dicyanamide, melamine, sodium bisulfite, hydrogen sulfide, sugar in alkaline solution, malonic ester, phenylhydrazine, aniline, solid hydrazine and hydroxylamine.  
     
     
         11 . A quenching composition according to    claim 9    wherein the formaldehyde-reactive agent is ammonium salt.  
     
     
         12 . A quenching composition according to    claim 9    wherein the formaldehyde-reactive agent and the effervescent agent are one or more ammonium salts.  
     
     
         13 . A composition for quenching a fixative which includes formaldehyde comprising a core and a coating layer around the core, the core including a formaldehyde-reactive agent.  
     
     
         14 . A composition for quenching a fixative which includes formaldehyde according to    claim 13    wherein the formaldehyde-reactive agent is ammonium salt.  
     
     
         15 . A composition for quenching a fixative which includes formaldehyde according to    claim 13    wherein the core includes an effervescent agent.  
     
     
         16 . A composition for quenching a fixative which includes formaldehyde according to    claim 15    wherein the effervescent agent is selected from the group consisting of sodium bicarbonate and ammonium bicarbonate.  
     
     
         17 . A composition for quenching a fixative which includes formaldehyde according to    claim 13    wherein the core includes a disolution aid.  
     
     
         18 . A composition for quenching a fixative which includes formaldehyde according to    claim 17    wherein the disolution aid is selected from the group consisting of carbon dioxide gas, citric acid, tartaric acid, malic acid, fumaric acid, acetic acid, glutaric acid, or succinic acid.  
     
     
         19 . A composition for quenching a fixative which includes formaldehyde according to    claim 13    wherein the core includes a pH neutralizer.  
     
     
         20 . A composition for quenching a fixative which includes formaldehyde according to    claim 19    wherein the pH neutralizer is a buffer or a base.  
     
     
         21 . A composition for quenching a fixative which includes formaldehyde according to    claim 19    wherein the pH neutralizer is ammonium salt.  
     
     
         22 . A composition for quenching a fixative which includes formaldehyde according to    claim 13    wherein the formaldehyde-reactive agent includes ammonium bicarbonate and ammonium phosphate dibasic.  
     
     
         23 . A composition for quenching a fixative which includes formaldehyde according to    claim 22    wherein the mole ratio of anions from ammonium bicarbonate and ammonium phosphate dibasic ranges from about 50:50 to about 90:10.  
     
     
         24 . A composition for quenching a fixative which includes formaldehyde according to    claim 13    wherein the coating is formed from a material selected from the group consisting of polymethylacrylate, ethyl cellulose and poly(ortho) ester.  
     
     
         25 . A composition for quenching a fixative which includes formaldehyde according to    claim 13    wherein the coating includes at least a first layer and a second layer, the first layer being a subcoating for protecting moisture sensitive materials in the core prior to application of the second layer.  
     
     
         26 . A composition for quenching a fixative which includes formaldehyde according to    claim 25    wherein the subcoating includes hydroxypropylmethylcellulose.  
     
     
         27 . A method for quenching a formaldehyde containing fixative comprising contacting the fixative with a composition containing an ammonium salt.  
     
     
         28 . A method for quenching a formaldehyde containing fixative according to    claim 27    wherein the ammonium salt acts as an effervescent agent.  
     
     
         29 . A method for quenching a formaldehyde containing fixative according to    claim 27    wherein the ammonium salt is selected from the group consisting of ammonium bicarbonate, ammonium phosphate dibasic and mixtures thereof.  
     
     
         30 . A method for quenching a formaldehyde containing fixative comprising contacting the fixative with a composition including a core, the core having a coating, the core including a formaldehyde-reactive agent.  
     
     
         31 . A method for quenching a formaldehyde containing fixative according to    claim 30    wherein the formaldehyde-reactive agent is selected from the group consisting of ammonium salt, amino acid, urea hydrogen peroxide, thiourea, carbamic ester, cyanamide, dicyanamide, melamine, sodium bisulfite, hydrogen sulfide, sugar in alkaline solution, malonic ester, phenylhydrazine, aniline, solid hydrazine and hydroxylamine.  
     
     
         32 . A method for quenching a formaldehyde containing fixative according to    claim 30    wherein the fixative, after the contacting, has a formaldehyde residual concentration of about 0.25M or less.  
     
     
         33 . A method for quenching a formaldehyde containing fixative for fixing a biological sample comprising: 
 contacting the sample with a fixative including formaldehyde;    contacting the fixative with a composition including a core including a formaldehyde-reactive agent, the core having a coating.    
     
     
         34 . A method for quenching a formaldehyde containing fixative according to    claim 33    wherein the formaldehyde-reactive agent is an ammonium salt.  
     
     
         35 . A method for quenching a formaldehyde containing fixative according to    claim 33    wherein the core includes an effervescent agent.  
     
     
         36 . A method for quenching a formaldehyde containing fixative according to    claim 35    wherein the effervescent agent is selected from the group consisting of sodium bicarbonate and ammonium bicarbonate, dibasic.