Uric acid, as the end product of purine metabolism in the human body, is an important indicator for evaluating gout, renal dysfunction, and metabolic syndrome in terms of serum concentration. With the rapid development of in vitro diagnostic technology, uric acid detection kits based on enzyme colorimetry have become the mainstream clinical testing solution due to their strong laboratory compatibility and easy operation. In this technical system, the colorimetric reagent TOPS (N-ethyl-N - (3-sulfopropyl) -3-methylaniline sodium salt) has become a key component for improving detection performance due to its unique chemical properties. This article will systematically explain the core role of TOPS in uric acid detection from its chemical properties, reaction mechanisms, application advantages, and extended scenarios.
1, The chemical properties of TOPS: the cornerstone of stability and sensitivity
TOPS is a high-purity (≥ 99%) white crystalline compound, whose sulfonic acid groups in its molecular structure endow it with strong water solubility, solving the problem of uneven detection system caused by the easy precipitation of traditional color reagents (such as phenolic compounds). Experimental data shows that TOPS has high solubility in 25 ℃ aqueous solution, which is much higher than traditional colorimetric reagents. This characteristic not only simplifies the reagent preparation process, but also significantly improves the repeatability of colorimetric reactions.
In addition, the stability performance of TOPS is particularly outstanding. Research has shown that after being stored at 4 ℃ in the dark for 24 months, its color development efficiency can still maintain over 98% of its initial value. This is due to the dual modification of the aniline structure in its molecule by sulfopropyl and ethyl groups, effectively suppressing the occurrence of oxidation side reactions. This stability enables TOPS to adapt to various storage conditions of reagent kits, especially suitable for promotion and use in primary healthcare institutions with limited resources.
2, The color reaction mechanism of uric acid detection
The role of TOPS in uric acid detection is achieved through a two-step enzymatic reaction:
Uricase catalyzed oxidation reaction
Uric acid reacts with water and oxygen under the catalysis of uricase to produce allantoin, carbon dioxide, and hydrogen peroxide (H ₂ O ₂). This reaction has extremely high specificity and is almost unaffected by other metabolites in the blood (such as ascorbic acid), laying a specific foundation for subsequent colorimetric steps.
Peroxidase mediated color reaction
The generated H ₂ O ₂ undergoes oxidative coupling reaction with TOPS and 4-aminoantipyrine (4-AAP) under the catalysis of peroxidase (POD), producing a red quinone imine compound. The maximum absorption peak of the color product is located at a wavelength of 505 nm, and the absorbance is linearly positively correlated with the concentration of H ₂ O ₂ (i.e. uric acid concentration). By measuring the absorbance with a spectrophotometer and combining it with a pre established standard curve, accurate quantification of uric acid can be achieved.
3, Advantages of TOPS application: Breaking through the limitations of traditional reagents
Compared with traditional colorimetric reagents, TOPS exhibits four core advantages in uric acid detection:
Sensitivity improvement
The color development efficiency of TOPS is increased by more than 40% compared to traditional reagents, and even in the face of low concentration samples, it can still produce significant color changes. This feature significantly reduces the risk of false negatives, especially suitable for early gout screening.
Strong anti-interference ability
Due to the highly selective reaction between TOPS and H ₂ O ₂, the influence of common interferences in the blood on its colorimetric efficiency can be ignored. This feature ensures the reliability of the detection results in complex samples.
Wide compatibility of reagents
The pH adaptation range of TOPS covers the needs of most enzyme reaction systems, and can seamlessly integrate the mixed formula of uricase, POD, and stabilizer, providing convenience for the development of freeze-drying process for reagent kits.
5, Future prospects and challenges
Although TOPS has made significant progress in the field of in vitro diagnostics, its application still faces some challenges. For example, in high concentration ascorbic acid samples, the color reaction of TOPS may be slightly inhibited and further optimization is needed by adding anti-interference agents. In addition, the synthesis process cost of TOPS is relatively high, and how to reduce the price of reagent kits through large-scale production will become the key to its grassroots promotion.
Desheng specializes in producing more than the new Trinder's reagents, including TOPS. After more than ten years of research and development, it can ensure that TOPS appears as a powder with a purity of up to 99.5%, strong water solubility, and stable performance to ensure the accuracy of experimental results. Desheng has a place in the market for in vitro diagnostic kit raw materials with high-quality products, and is deeply trusted and supported by customers at home and abroad. If you have any relevant intentions, please click on the official website for consultation!
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