ROX: NHS Ester, Free acid. Select the form for the sample handle and readout.
3 products
3 matching products
| Product / Cat. No. | Chemistry | Excitation / nm | Emission / nm | Pack sizes | Product details |
|---|---|---|---|---|---|
| 6-ROX free acidQH-60-6011 | Free acid | 568 | 585 | 10 mg | |
| 5-ROX NHS EsterQH-60-6016 | NHS Ester | 570 | 591 | 5 mg | |
| 6-ROX Succinimidyl EsterQH-60-6010 | NHS Ester | 578 | 602 | 5 mg |
Need help with reactive forms or detection channels?
QH-60-6010
| Product / Cat. No. | Form | Ex / Em · nm |
|---|---|---|
| 5-ROX NHS EsterQH-60-6016 | NHS Ester | 570 / 591 |
| 6-ROX free acidQH-60-6011 | Free acid | 568 / 585 |
| 6-ROX Succinimidyl EsterQH-60-6010 | NHS Ester | 578 / 602 |
5-ROX NHS Ester; 6-ROX free acid; 6-ROX Succinimidyl Ester have defined positional-isomer and activation identities. Track starting materials and products by isomer and free-acid or NHS-ester form, with separate molar calculations.
Protein N-termini, lysine residues and introduced primary amines
The NHS ester forms an amide bond with a primary amine; hydrolysis competes with coupling. Proteins usually contain multiple accessible sites, and the input ratio is not the final degree of labeling.
Primary amines coupled through a suitable activation route
A free carboxylic acid is not a preactivated NHS ester. Activate it using a sample-compatible method before coupling to an accessible primary amine; do not use it as an NHS reagent without activation.
NHS esters address accessible primary amines; free acids require activation. For nucleic-acid probes, confirm an amino handle, then assess full-length product, free-dye carryover and probe function after purification.
Selection criteria
Compare each product’s excitation and emission with the instrument’s light source, filters and detector. A number in a product name does not replace its specifications.
Select the isomer and form for the intended probe or conjugate. Use molecular weight and optical values for the exact catalog number rather than one value for the entire dye name.
Compare specific signal, negative background and function at matched sample input and acquisition settings. Titrate the purified conjugate.
Sample and experimental preparation
Choose a suitable activation, coupling and separation scheme. Distinguish starting dye, activated intermediate and target product; assess self-crosslinking when the target contains multiple carboxyls and amines.
Record target molecular weight, concentration, available handles and buffer additives. Select a method that separates the target product from free dye, using the product conditions for the actual reactive form.
Retain an unlabeled aliquot from the same preparation. Measure concentration, labeling density and function after purification. Use the actual conjugate for single-color references in multicolor detection.
Tris and glycine consume NHS dye. BSA and gelatin require separation from the target protein; routine buffer exchange is insufficient.
Check NHS hydrolysis and amine-containing additives, then distinguish low labeling from sample loss or reduced binding.
Calculate DOL with absorbance correction, distinguish input ratio from attached dye, and assess recovery and binding.
Distinguish free acids from NHS esters, plan carboxyl activation, amine coupling and product analysis, and retain positional-isomer identity for FAM and ROX.
Compare labeling density, sample recovery, specific signal and background after purification, rather than total fluorescence alone.
Thermo Fisher Scientific · Carbodiimide crosslinker chemistry
Explains carboxyl activation, intermediate hydrolysis and self-crosslinking risks in multi-handle samples, informing free-acid dye activation and product analysis.
Nanda JS, Lorsch JR. · Methods in Enzymology · 536:87–94 · 2014
Uses FAM ester labeling of a protein to explain primary-amine chemistry and labeling-efficiency assessment. It informs NHS workflow design; input and reaction conditions depend on the actual dye and sample.
Vira S, Mekhedov E, Humphrey G, Blank PS. · Analytical Biochemistry · 402(2):146–150 · 2010
Uses FITC-labeled anti-HA antibody to assess changes in labeling density and antigen binding. It informs input-series design and post-purification functional testing; DOL alone is insufficient for selecting a conjugate.
thermofisher.com
Reactive handles, buffer compatibility and method guidance.
Request the manual, SDS or lot-specific CoA by catalog number. Include the vial lot number for a CoA.
Product use, preparation, operating conditions and storage.
Lot-specific test methods and results.
Handling, storage and emergency response information.
Identify the sample handle or required recognition mechanism, then select a matching reactive dye or preconjugated probe. Use preparation, reaction and storage requirements for the exact catalog number.
A free acid is not preactivated and needs a separate activation step. Confirm molecular weight, solubility and product analysis for each form.
Match target concentration, acquisition settings and sample processing. Compare labeling density together with specific signal, negative background, recovery and function; a free-dye or single endpoint measurement does not assess every performance characteristic.
Use molecular weight, an appropriate extinction coefficient and protein-absorbance correction for the exact catalog number after removing free dye. Request parameters not shown on the product page through its Documents tab.
We use cookies and third-party analytics (Microsoft Clarity, Baidu Tongji, Google Analytics) to measure traffic and improve our service. Clarity includes session recording. You may decline — core site functionality is unaffected. View privacy policy
