I do not which where the problem lies. In detection or quantification? You could try Western Blotting with vacuum-assisted detection protocol. See the document attached. Article A new approach to detect small peptides clearly and sensitiv...

I do not which where the problem lies. In detection or quantification? You could try Western Blotting with vacuum-assisted detection protocol. See the document attached. Article A new approach to detect small peptides clearly and sensitiv...

Ninhydrin can detect amines at the picomolar level - but it is not selective.

https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/ninhydrin

Please look at the following below links which may help you in your analysis:

https://www.ncbi.nlm.nih.gov/books/NBK22571/

https://www.hplc.eu/Downloads/ACE_Guide_Peptides.pdf

https://scholarworks.wm.edu/cgi/viewcontent.cgi?article=5264&context=etd

Thanks

Small peptides are generally lack of chromophores thus they won't give enough signal at UV based detection, LC separation, and MS detection is the reasonable solution. otherwise, FLD or UV detection can be accomplished by applying derivatization methods using agents like OPA, FMOC, ninhydrin, chloroformates, etc. Protein quantitation assays based on dye binding or Cu reduction would not give responses if the amount and/or amino acid sequences of the peptides are improper. Thereby HPLC based separation and MS detection are critical. Polar natures of the small peptides are also a bottleneck for chromatographic retention and separation. You should consider like they are single amino acids as an analytical method development approach and tagging with hydrophobic molecule aforementioned as derivatizing agents would be a good choice for quantitation.

To selectively determine, resolve and quantify different peptides, consider HPLC. HPLC will provide much better resolution and selectivity than Western blot, plus add better quantitation. Depending on the amino-acids present in each one of your peptides, HPLC coupled to Diode Array Detection (DAD) may work fine. Many peptides can be detected by low wavelength UV alone using the DAD. The sample concentration and complexity of the matrix limit this. If you require concentration measurements at higher sensitivity levels, then deriv and final detection using DAD/FLD may be needed.

• To provide the best advice, we would need to know exactly which peptides (and their AA composition) you wish to measure, what type of matrix they will be in AND the expected concentrations. *Successful project design requires that we first understand the specific problem and goals.