Solid Urine Preservative Composition for Fast Dissolution and Stable pH
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Solution Overview
Problem
Existing urine preservatives in solid form face challenges such as low dissolution rates, difficulty in precise dosing, and inconsistent bacteriostatic effects, particularly with boric acid, which are exacerbated by the use of PET tubes that allow water vapor passage, leading to unreliable additive/sample volume ratios.
Innovation Solution
A urine preservative composition in solid form is developed using boric acid, D-mannitol, sodium bicarbonate or carbonate, polyvinylpyrrolidone, and optionally sodium citrate or potassium sorbate, which enhances solubilization rates and stability without freeze-drying, and allows easy dosing with volumetric/gravimetric systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid preservatives are used in urine sampling tubes, then the reliability of the preservative/sample ratio is improved, but the dissolution rate becomes slow
Solution Approach 1:
The patent changes the physical state of the preservative from crystalline to amorphous form, which fundamentally alters the dissolution parameters. Amorphous boric acid lacks the ordered crystal structure, enabling rapid dissolution in urine samples while maintaining the correct preservative/sample ratio in PET tubes.
Solution Approach 2:
The patent creates a composite preservative system combining amorphous boric acid with buffer substances (sodium bicarbonate, sodium carbonate, potassium phosphate, or ammonium hydroxide) and optionally antioxidants. This composite approach ensures both rapid dissolution and reliable preservative performance in PET tubes.
2Reliability
If crystalline boric acid is used, then the bacteriostatic effect is maintained, but the dissolution difficulty increases
Solution Approach 1:
The patent transforms boric acid from crystalline to amorphous form by controlling the drying process (lyophilization or spray drying), which removes the ordered crystal structure while preserving the bacteriostatic properties. This parameter change enables easy dissolution without sacrificing effectiveness.
Solution Approach 2:
The patent introduces buffer substances as intermediaries that facilitate the dissolution of amorphous boric acid in urine samples. These buffers (sodium bicarbonate, sodium carbonate, potassium phosphate, or ammonium hydroxide) create a favorable chemical environment for rapid dissolution while maintaining the bacteriostatic effect.
3Speed
If preservatives in aqueous solution are used, then the dissolution is fast, but the solubility limitation of boric acid restricts effectiveness
Solution Approach 1:
The patent changes the physical state from crystalline to amorphous, which dramatically increases the effective concentration achievable in solution. Amorphous boric acid dissolves rapidly and completely, allowing higher effective concentrations within the solubility limit compared to crystalline forms.
Solution Approach 2:
The patent uses buffer substances as intermediaries that enhance the solubility and dissolution rate of boric acid, enabling maximum utilization of the solubility limit and achieving effective preservative concentrations without exceeding it.
4Device complexity
If PET tubes are used instead of glass, then the device complexity is reduced, but water vapor passage alters the additive/sample volume ratio
Solution Approach 1:
The patent changes the preservative form to amorphous solid that dissolves rapidly upon contact with urine, ensuring the correct ratio is established before any PET tube permeation effects can occur. This speed advantage compensates for the PET tube's water vapor passage characteristics.
Solution Approach 2:
The patent performs preliminary dissolution of the amorphous preservative in the urine sample itself during the collection process, ensuring the correct preservative/sample ratio is achieved in situ before the sample is stored in the PET tube, thereby preventing ratio alteration from tube permeation.
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 composition achieves rapid dissolution within 5-10 minutes, maintains pH stability, and provides broad-spectrum bacteriostatic effects, ensuring reliable preservation of urine samples for microbial analysis.
Implementation Method 1
The composition achieves rapid dissolution within 5-10 minutes
Implementation Method 2
maintains pH stability
Implementation Method 3
provides broad-spectrum bacteriostatic effects, ensuring reliable preservation of urine samples
Data Source
AI summary
A urine preservative composition in solid form, based on boric acid and D-mannitol is disclosed. The urine preservative composition consists of boric acid from 37.0 to 69.7% by weight, D-Mannitol from 9.6 to 16.2% by weight, sodium bicarbonate and/or sodium carbonate from 18.0 to 25.0% by weight, polyvinylpyrrolidone from 0.1 to 2% by weight and sodium citrate and/or potassium sorbate from 0% to 24.2% by weight.