Name: Sulforhodamine B (Highly Pure)
Brand: Molecular Depot
SKU: B2012336
Price: 395.00 USD
Availability: InStock

<h2 data-section-id="1vnrtbv" data-start="0" data-end="40">What are fluorescent labels and dyes?</h2>
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Fluorescent labels and dyes are reactive fluorophores, most commonly containing N-hydroxysuccinimide (NHS) ester or isothiocyanate functional groups, that covalently attach to primary amines on lysine residues of proteins or antibodies to generate custom fluorescent conjugates. They are used either as standalone reactive dyes for &ldquo;do-it-yourself&rdquo; labeling or as part of complete kits that include optimized buffers and protocols for controlled and reproducible conjugation. Related entities include fluorophore-to-protein (F:P) ratio, lysine-based amine coupling chemistry, IgM-specific labeling workflows, and downstream applications such as flow cytometry, immunofluorescence, and ELISA.
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<h2 dir="ltr">What you will find: </h2>
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Reactive Core Fluorophores: High-grade chemical tags configured with functional groups to form durable covalent links with target molecules like proteins, peptides, or nucleic acids.
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Selective Cellular Tracers: Membrane-permeable staining compounds developed to delineate specific structural architectures and monitor localized biological mechanisms.
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Responsive Molecular Sensors: Sensitive indicator dyes tailored to track real-time changes in physiological parameters, environmental gradients, and target activity shifts.
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<h2 data-section-id="fyqbla" data-start="905" data-end="949">How to choose fluorescent labels and dyes</h2>
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Reactive dye only vs. complete labeling kit
Standalone reactive dyes provide maximum flexibility for users with established conjugation protocols and optimized in-house workflows. Complete labeling kits include pre-optimized buffers, reaction conditions, and sometimes purification components, making them better suited for first-time labeling or when standardization and reproducibility are important.
Buffer compatibility for direct labeling
Some modern labeling kits allow conjugation directly in common antibody storage buffers containing components such as BSA, gelatin, sodium azide, or low concentrations of Tris. This reduces or eliminates the need for buffer exchange prior to labeling, improving workflow efficiency.
IgG vs. IgM antibody compatibility
Most labeling chemistries are optimized for IgG antibodies, which are structurally simpler and more uniform. IgM antibodies have a pentameric structure and different reactivity, and therefore often require specialized IgM-optimized labeling kits to maintain antigen binding and achieve consistent labeling efficiency.
Reaction speed and post-labeling purification
Rapid labeling kits can complete covalent conjugation within approximately 15 minutes and may require minimal or no post-labeling purification. Standard chemistries may take longer reaction times and typically require additional steps to remove unreacted dye to ensure clean signal and low background.
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<h2 data-section-id="1fljvas" data-start="3232" data-end="3257">Specifications context</h2>
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Fluorescent dyes are characterized by excitation and emission maxima (in nanometers), and their performance is often benchmarked relative to standard dyes such as fluorescein in terms of brightness. Labeling kits typically specify expected fluorophore-to-protein (F:P) ratios and recommended antibody input amounts, usually ranging from micrograms to milligram-scale reactions. Reaction times vary from minutes in rapid systems to several hours in conventional chemistries, with reported recovery rates indicating how much functional conjugate is retained after labeling and purification.&nbsp;
This sub-category is part of MBP's fluorescent reagents catalog alongside fluorescent conjugates, which provide ready-to-use labeled antibodies and proteins. MBP&rsquo;s specialist team can help confirm dye chemistry, antibody compatibility, and expected F:P ratio for a specific labeling workflow before order placement.
<a href="https://mbpinc.net/contact-us">Contact the helpful team</a> at MBP today to request a quote.

Fluorescent Labels & Dyes

Molecular Depot

Key Specifications

Sulforhodamine B (Highly Pure)

Sulforhodamine B (Highly Pure) by Molecular Depot is a sulforhodamine B sodium salt, an aminoxanthene dye. Its sulfonate groups make it highly water-soluble and membrane-impermeant. It is used in the SRB cytotoxicity assay, as a fluorescent tracer in hydrology and microfluidics and as a counterstain. Each unit contains 5 mg. MBP supplies Molecular Depot dye reagents to research labs in the United States, Canada and worldwide.