Formaldehyde-Free Parasite Fixative Composition for Reliable Staining
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Solution Overview
Problem
Existing fixative solutions for biological samples, particularly parasitological samples, are hazardous and struggle to effectively kill organisms like helminths with tough outer layers, and their impact on staining properties is unpredictable.
Innovation Solution
A fixative solution comprising C2 to C6 carboxylic acid, C2 to C6 carboxylate salt or halide salt, and optionally biocidal essential oils, which rapidly kills organisms and preserves cellular structure without toxic additives, facilitating good staining properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If formaldehyde is used in fixative solutions, then fixation effectiveness is improved, but toxicity and carcinogenicity increase
Solution Approach 1:
The patent changes the chemical parameters of the fixative solution by replacing formaldehyde with a specific combination of carboxylic acid (acetic acid at 0.5-3.5M), carboxylate salt, and halide salt (calcium chloride/magnesium chloride at 0.02-0.5M). This parameter substitution maintains fixation effectiveness while eliminating the toxic and carcinogenic properties of formaldehyde.
Solution Approach 2:
The patent creates a composite fixative system combining multiple components: carboxylic acid, carboxylate salt, and halide salt. This composite formulation works synergistically to achieve effective fixation of parasitic organisms without requiring toxic substances like formaldehyde, thereby maintaining reliability while reducing harmful factors.
2Reliability
If highly toxic chemicals are used to kill parasitical organisms, then killing effectiveness is improved, but safety hazards increase
Solution Approach 1:
The patent changes the chemical composition parameters by using non-hazardous carboxylic acid and halide salt combinations at specific concentrations. This allows achieving effective killing of parasitic organisms with tough outer layers without the safety hazards associated with highly toxic chemicals, while maintaining reliable fixation.
3Object-affected harmful factors
If non-hazardous fixatives are used, then safety is improved, but killing effectiveness against resilient organisms decreases
Solution Approach 1:
The patent develops a composite non-hazardous fixative system combining carboxylic acid, carboxylate salt, and halide salt that works together to effectively kill resilient parasitic organisms. This composite formulation achieves reliable killing effectiveness while maintaining safety by avoiding toxic additives, thus resolving the contradiction between safety and killing effectiveness.
4Manufacturing precision
If fixative formulation is modified, then staining properties may be improved, but predictability of staining results decreases
Solution Approach 1:
The patent establishes specific parameter ranges for the fixative components (carboxylic acid at 0.5-3.5M, carboxylate salt at 0.02-0.5M, halide salt at 0.02-0.5M) that have been optimized to produce consistent and predictable staining results. By defining precise concentration ranges rather than allowing arbitrary modifications, the patent maintains both improved staining properties and result predictability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves rapid organism killing, preserves cellular structure, and ensures excellent staining properties, even after prolonged periods, making it suitable for microscopic examination.
Implementation Method 1
a C2 to C6 carboxylic acid at a concentration of 0.5M or greater... It has been found that such concentrations of carboxylic acid (particularly acetic acid) result in a rapid killing of biological organisms such as helminth ova
Implementation Method 2
The carboxylate salt or halide salt of component b) may for example be the salt of an alkali or alkaline earth metal or of ammonium other cation that confers reasonable solubility... It has been found that such halide salts help preserve the cellular structure, possibly an osmoregulatory effect involving the halide salts counteracting the turgor effect of the carboxylic acid
Data Source
AI summary
A fixative contains carboxylic acid, preferably acetic acid, for parasitological samples. An exemplary aqueous fixative solution for parasitological samples comprises: a) a C2 to C6 carboxylic acid (preferably acetic acid) at a concentration of 0.5M or greater; and b) a C2 to C6 carboxylate salt or halide salt at a concentration of 0.02M or greater, preferably 0.04M or greater. An optional composition comprises 1.3M acetic acid, 12 mM sodium benzoate, 0.9% calcium chloride, 0.9% calcium bromide, 100 μg/ml menthol and 350 μg/ml thymol. The fixative is free of formaldehyde or other hazardous compounds, and exhibits good killing and staining properties when used with parasitological samples such as ova and helminths.