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About Us
Durastab Medtec LTD has always adhered to the mission of "making diagnostic reagents more stable and more accurate" since its establishment, and is committed to providing excellent ready-to-use reagent solutions to global advanced medical diagnostic companies.
To date, Durastab has successfully provided products to over 600 companies and research teams at thousands of universities and scientific research institutions worldwide, among which are more than 50 listed IVD companies.
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- +86-0755-32813268
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Flagship Product: Safer, More Stable, and More Versatile – ProCide 300 Preservative!
Newly Upgraded 3rd-Gen TMB Substrate: Enhanced Stability with Multiple Freeze-Thaw Tolerance!
New Product Launch – Bovine Serum Albumin (BSA) for Clinical Biochemistry, Immunoassays, and Molecular Detection!
Flagship Product: Safer, More Stable, and More Versatile – ProCide™ 300 Preservative!
Newly Upgraded 3rd-Gen TMB Substrate: Enhanced Stability with Multiple Freeze-Thaw Tolerance!
New Product Launch – Bovine Serum Albumin (BSA) for Clinical Biochemistry, Immunoassays, and Molecular Detection!
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TMB Substrate Reading Guide: 450 nm vs 650 nm, Wavelength & Best Practices
What Wavelength Do You Read TMB At?
TMB gives two reliable readings depending on how you run the assay:
| Readout | Condition | What You Measure |
|---|---|---|
| 450 nm | After adding stop solution | The stopped yellow chromophore — most common endpoint |
| 650 nm | Without stopping | The blue reaction product — used for kinetic reading and O.D.-limit checks |
Why 450 nm and 650 nm?
After stopping, the blue product converts to a yellow chromophore whose absorbance peaks near 450 nm — read this for the final endpoint value. Before stopping, the blue form absorbs strongly near 650 nm, which is convenient because it avoids overlap with the detector and lets you monitor color development in real time. Reading at 650 nm without stopping is a common way to run a kinetic (time-course) assay.
Why does TMB change from blue to yellow after stopping?
The blue species is a charge-transfer complex of oxidized TMB. Adding an acid stop solution protonates this complex into a stable yellow diimine, whose absorbance is measured at 450 nm. The absorbance before stopping (650 nm) is proportional to the blue form, while after stopping (450 nm) it measures the yellow form — both correlate with analyte amount, so you can choose either endpoint or kinetic readouts.
Stop Solutions for TMB
To fix the endpoint you can use a dedicated stop solution. Durastab offers TMB Stop Solution 450 and TMB Stop Solution 650 for convenient stopping across different plate formats.
Reading Best Practices
Read within a defined window after stopping to keep results comparable (e.g. read within 30 min).
Subtract blank or read against blank wells for accurate OD values.
Minimize bubbles before reading — they scatter light and inflate absorbance.
Keep temperature consistent between kinetic measurements.
Watch for saturation: if OD exceeds the linear range, shorten development or choose a less sensitive formulation.
Figure 1 | TMB wavelength reading comparison: 450nm vs 650nm
Quality First
We have established a comprehensive quality management system and use stringent standards to make our products more reliable.
We can achieve excellent batch-to-batch consistency and a maximum single-batch output of 1950L, ensuring a stable supply to companies worldwide.
Our Advantages
- Strong R&D capabilities
- Strong supply capacity
- Product boasts Excellent performance and Stability
- Further reduce your costs
- We have GMP-Standard production workshops
Our Mission：Make Diagnosis more Accurate and Stable Serving the Life.
Durastab Medtech Co., Ltd.
Our Vision：To become a globally renowned manufacturer of key raw materials for diagnostic kits.
Advocating Green and environmentally friendly solutions
We are committed to developing green and environmentally friendly reagents, using environmentally friendly materials, and reducing pollution.
We advocate against using environmentally harmful components, especially VOCs such as methanol and DMF, to protect the ecosystem and create a safer working environment.
Environmentally Friendly Components: Our product line offers a variety of environmentally friendly reagents that are free of any organic solvents, toxic substances, animal-derived ingredients, BSA, or other components that may have adverse effects on the ecological or working environment.
Top Choice for Leading Companies: We have long been committed to developing green and environmentally friendly reagent products. Nevertheless, our products do not sacrifice quality, sensitivity, and accuracy, making us the preferred choice for most leading immunoassay kit manufacturers.
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Committed to providing excellent ready-to-use reagent solutions to global advanced medical diagnostic companies.
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