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What to ask your Antibody vendor about Stability and Consistency?

Currently, assessing the stability and lot-to-lot consistency is left to the scientist purchasing a reagent.  It might sound crazy, but we think that time is better spent in running, analyzing and designing experiments.  To that end, Phitonex has compiled this handy checklist of items to ask your antibody vendor about the reagents you are purchasing.


What is the shelf life stability?

Have you tested room temp stability?

What is the stability under different fixative conditions?

Are there any spectral changes when you use fixatives?


Can you share your lot-to-lot data for both conjugated antibodies and fluorophores?

Do you see any vial to vial variability?

How much lot-to-lot variance is tolerated?

Why ask the questions above?

The Problem with Traditional Dyes

Tandem Dye Instability

Setting aside their issues with cross-excitation and spillover, tandem dyes exhibit instability in solution, leading to false positives [1] and decouple differently on cell phenotypes [2].  Additionally, they break down very quickly in fixative solution [3].

Lot to Lot Inconsistency

In addition to these issues, traditional dyes like the tandems [4] and we have observed that polymer dyes exhibit significant lot-to-lot variability.


The new standard for stability + consistency

Room Temperature, Fixative Stable – across the Spectrum

In contrast to traditional dyes, antibodies conjugated to NovaFluors™ are room temperature and fixative stable for at least 2 weeks, and are stable across the spectrum. [5].

Making Lot-to-Lot Inconsistency a Thing of the Past

We openly share our manufacturing lot-to-lot data and have shown that NovaFluors labels exhibit less than 5% variance anywhere in the spectrum [6], and that there was no statistically significant difference in CD4 conjugates of these lots in a study performed by an outside laboratory. [5]


  1. Maecker, H.T., Frey, T., Nomura, L.E., and Trotter, J. (2004). Selecting fluorochrome conjugates for maximum sensitivity. Cytometry A 62, 169–173.
  2. Le Roy, C., Varin-Blank, N., Ajchenbaum- Cymbalista, F., and Letestu, R. (2009). Flow cytometry APC-tandem dyes are degraded through a cell-dependent mechanism. Cytometry A 75, 882–890.
  3. Tario & Wallace. “Reagents and Cell Staining for Immunophenotyping by Flow Cytometry” 2014, Pages 3678-3701
  4. P. Rogers. “Standardizaton of the MoFlo Astrios for Long Term Clinical Research Sortng Projects.” MoFlo Users Group Meeting. 19 Sept 2017.
  5. M.D. Stadnisky “Let’s geek out about stability, consistency, and applications.”  Presentation. 21 October 2020.
  6. S.Y. Thomas, C.D. LaBoda, S. Burrows, D. Daley, A. Stroud, M.D. Stadnisky. “Above + Beyond 40 Colors.” Phitonex, Inc. 2020