NEW: 'Kairos' cLDEP Particle Sorter   More info...

ApogeeMix: A Reference for Flow Cytometry Performance Assessment & Calibration

ApogeeFlow offers a wide range of beads which can be purchased by sending an email to Payment will be handled via credit card (secure payment link) for new customers or invoice for our existing clients.

The complex relationship between particle size and the amount of light scattered at different collection angles makes it difficult to infer particle size from a flow cytometer's light scatter data. A population may be described as scattering an amount of light equal to a reference particle (e.g. a polystyrene or silica bead of known size) but same sized particles of different refractive index (ɳ) give different signal strengths. When comparing data between flow cytometers the difficulties are compounded by differences in light scatter collection angles. Ideally it would be possible to produce stable reference particles of known size and of a refractive index and structure similar to the bacteria or microvesicles of interest, but such particles are not commercially available, expensive or relatively unstable.

Due to the refractive index difference, polystyrene beads on their own do not offer an accurate means to assess a flow cytometer's light scatter performance for the study of biological particles. Silica (SiO2) beads can be used as a better reference particle because silica's refractive index is closer to the refractive index of biological vesicles 1,2,3,4.

Product range

 Content per microlitre
+/- 20% 
14081000 UVViolet300040
14162000 BlueGreen1000040
1419500 BlueGreen500040
14211000 VioletYellow/Green500040
14261000 BlueYellow/Green500040
1446500  Yellow/Green1000040
14641000 GreenRed500040
1465200 BlueYellow/Green500040
14782000 RedDeep Red (>650nm)200040
14841000 BlueYellow/Green5000010
1488110 BlueGreen1000025
1493110/500180/240/300/590/880/1300  see belowsee below25
14942000 GreenRed200040
1502 880NoneNone250040
1503 300  250040
1506 1300  250040
1507 180  250040
1508 590  250040
1512 240  250040
151380 405nmGreen1000040
1518500 RedDeep Red500040
1525500 VioletYellow/Green500040
152780/110/500180/240/300/590/880/1300  see belowsee below25
15281000 RedDeep Red (>650nm)500040

To purchase please send an email to Payment will be handled via credit card (secure payment link) for new customers or invoice for our existing clients.

Most purchased: ApogeeMix #1493 & 1527

The ApogeeMix products (Cat #1493 & 1527) are a convenient mixture of non-fluorescent silica beads and fluorescent polystyrene beads, with diameters 180nm, 240nm, 300nm, 590nm, 880nm and 1300nm diameter with refractive index ɳ=1.43 (Silica, SiO2). It also contains 80nm (#1527 only), 110nm and 500nm green fluorescent beads with refractive index ɳ=1.59 (Polystyrene).

The product is intended to assess a flow cytometer's light scatter and fluorescence performance. It will provide useful points of reference for light scatter data and prepare flow cytometers for the analysis of small particles by providing points of reference.

The fluorescent polystyrene beads may be used to assess the fluorescence sensitivity and to assess the performance of the flow cytometer's optics at a different refractive index.

Approximate particle concentrations (lots vary):

 Content per microlitre
+/- 20% 
80 (#1527 only)  405nmGreen 500025
110  405nm / 488nmGreen 5000
 180  None 5000
 240  None 10000
 300  None 9000
500  405nm / 488nmGreen 3600
 590  None 2700
 880  None 3900
 1300  None 3400

Data from ApogeeFlow standard "Micro” Cytometer

The resolution of the peaks indicates the flow cytometer's performance. The below image is from #1493 ApogeeMix measured on a standard ApogeeFlow "Micro” Cytometer. A "MicroPLUS” model would offer more than an extra decade of light scatter sensitivity. Ideally eight populations will be resolved from each other and resolved from instrument noise:

  • 6 populations with refractive index 1.43 (silica, SiO2)


  • 2 green fluorescent (405nm or 488nm laser) populations (110nm and 500nm) with refractive index 1.59 (polystyrene), middle graph. Product #1527 also contains 80nm polystyrene beads (green fluorescent from 405nm laser excitation, not shown in data below).

ApogeeMix Chart

Ordering Information

Please email purchase orders and price requests to

Product Safety

Caution: Product contains 0.05% sodium azide.

MSDS available on request (


  1. Journal of Thrombosis and Haemostasis 2011 Jun, 9(6):1216-24

A new microparticle size calibration standard for use in measuring smaller microparticles using a new flow cytometer Chandler, W., Yeung, Wandy, Tait, Jonathan.

  1. Water Research 42 (2008) 3757 - 3766

Use of silica microspheres having refractive index similar to bacteria for conversion of flow cytometric forward light scatter into biovolume Paola Foladori, Alberto Quaranta, Giuliano Ziglio.

  1. J Thromb Haemost 2014; DOI:10.1111/jth.12602 van der Pol E, Coumans FAW, Grootemaat AE, Gardiner C, Sargent IL, Harrison P, Sturk A, van Leeuwen TG, Nieuwland.

Particle size distribution of exosomes and microvesicles determined by transmission electron microscopy, flow cytometry, nanoparticle tracking analysis, and resistive pulse sensing.

  1. American Chemical Society 2014 Oct, 2 p.6195-6201 Edwin van der Pol et al

Refractive index determination of nanoparticles in suspension using nanoparticle tracking analysis.

...performance where it counts

Get In Touch
Visit our Facebook page Follow us on Twitter Connect with us on LinkedIn