Specification for the use of chromogenic substrate DAOS 83777-30-4: Details determine detection accuracy

In the field of in vitro diagnostics (IVD), chromogenic substrates serve as key reagents for enzymatic reactions, and their performance directly affects the sensitivity and accuracy of detection results. N-Ethyl-N - (2-hydroxy-3-sulfopropyl) -3,5-dimethoxyaniline sodium salt (DAOS reagent), as a novel peroxidase substrate, is widely used in clinical biochemical testing due to its high sensitivity and low background interference. However, the strict requirements for operational details during its use often become a key factor determining detection accuracy. This article will analyze the core specifications used in DAOS from four dimensions: dissolution, storage, reaction system optimization, and quality control.

1, Dissolve: Precisely formulated to avoid loss of activity

DAOS is a solid powder reagent, and its dissolution must strictly follow the principles of "low temperature, avoiding light, and slow stirring". Firstly, the dissolution medium should be phosphate buffer solution with a pH of 5.5-7.0 to avoid substrate structure damage caused by acidic or alkaline environments. Secondly, the dissolution process needs to be carried out in an ice bath to prevent local overheating and degradation. When stirring, use a magnetic stirrer to control the speed and avoid generating bubbles due to violent shaking, which can cause oxidation of the active ingredients. After dissolution, it needs to be filtered through a filter membrane to remove insoluble impurities and prevent non-specific absorbance values from occurring in subsequent reactions.

DAOS powder

2, Storage: Package and avoid light, extend shelf life

The stability of DAOS solution is significantly affected by light, temperature, and oxygen. Unused powder should be sealed and stored in a low-temperature environment to avoid clumping caused by repeated freeze-thaw cycles. The dissolved DAOS solution should be divided into brown opaque bottles according to the single use amount, with a capacity of no more than 5 mL per bottle, to reduce the number of bottle openings. It is recommended to control the storage temperature between 2-8 ℃ and use it as soon as possible. If the color of the solution changes from colorless to light yellow or precipitation appears, it indicates that the substrate has been oxidized and is ineffective, and it needs to be replaced immediately. When stored for a long time, suitable antioxidants can be added, but their impact on the detection system needs to be verified through pre experiments.

3, Reaction System: Parameter Optimization, Balancing Sensitivity and Specificity

The reaction efficiency between DAOS and peroxidases (such as horseradish peroxidase, HRP) is influenced by three factors: pH, temperature, and substrate concentration. In terms of pH optimization, it is recommended to use a buffer system with a pH of 6.0-7.0, where enzyme activity and substrate solubility reach the optimal balance. Temperature control must strictly follow the reagent instructions to avoid temperature fluctuations that may cause drift in absorbance values. In terms of DAOS concentration, it is recommended to determine the optimal dosage through chessboard titration. If the dosage is too high, it will increase the background absorbance value, while if it is too low, it will reduce the detection sensitivity.

4, Quality control: Full process monitoring to ensure traceability of results

To ensure detection accuracy, it is necessary to establish a full process quality control system from reagent preparation to result analysis. The preparation process requires recording of dissolution time, temperature, and filtration batch. 10% of each batch of working fluid should be retained as a sample for retesting. The reaction process requires setting up blank controls (excluding enzymes) and positive controls (known concentration standards), and verifying the effectiveness of the reaction through the rate of change in absorbance values.

Product packaging

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