Dot-it-Spot-it® Protein Assay

Step by step


  • Detection sheet
  • Apply 1 uL of sample and dry


  • 1 mL Detection solution
  • 4 min
  • 1 mL Washing solution
  • 4 min


  • Dry and mount
  • Scan with an image scanner
  • Quantify the blackness intensity


Along the 11 cm Detection sheet you can apply 24 dots with 1-μL aliquots of protein sample. The kit contains the black Detection solution, the Washing solution and 20 Detections sheets, sufficient for 480 estimations.

 Add detergent


SDS or Triton X-100 seems useful for diluting samples and standard. They give different measuring range.

The handling of low concentrations of protein is difficult. Proteins will bind to every surface, which reduce the concentration in the solution.

Detergents reduce the ability for proteins to bind to surfaces. Some of them are recommended to use for dilution of your samples before assay application.

Se below the difference in protein distribution when applying HSA (ug/mL) with and without detergent.




1% SDS                              No detergent



Handling of low concentrations of protein solutions require the addition of detergents. The detergents SDS (sodium dodecyle sulfate) and OPG (n-octyl-beta-D-Glucopyranoside) in 1 % concentration are suitable for dilution of samples and standard when high sensitivity is required. Triton X-100 seems useful when a measuring in the range 1-100 ug/mL.

Detection tools





March 2015. Download the file ”Detection recommendations for Dot-it-Spot-it protein assay, 01.03.2015” showing the way to use eye, smartphone and scanner for detection.

We recommend use of the affordable scanner Epson Perfection V600 Photo, together with the software Epson Scan.

We also tested iPhone 5s as detection tool with good results.