W.M. Keck Facility at Yale - Recommended and Optimal Sample Amounts for Protein Chemistry and Mass Spectrometric Analyses

Analysis	Minimum Recommended Amount	Optimal Amount	Notes
Amino acid analysis	0.5 痢	3 - 5 痢	Samples should contain as little non-volatile salts, buffers, primary amines, and detergents as possible. The maximum permissible amount is the equivalent of 0.1 ml 0.5M non-volatile buffers/salts, 10 mM Tris (or other primary amines), 2% glycerol, or 0.01% SDS or other detergent (More information).
N-terminal Edman protein/peptide sequencing	1 pmol	10 - 100 pmol	Samples may be submitted on PVDF (maximum size is 15 mm²) or in <0.1 ml of volatile solvents that are free of primary amines such as Tris. The maximum amount of SDS permitted is the equivalent of 0.1 ml 0.01% and the maximum sample load is < 1 nmole (More information).
Digest/HPLC/ Internal Edman sequencing	5 pmol	25 pmol	Samples may be submitted as Coomassie Blue stained gel bands or in solution. We do not recommend submitting PVDF blotted samples (More information).
Identification of posttranslational modifications via HPLC/Edman sequencing	10 pmol	50 pmol	Within reasonable limits, the more protein is submitted the greater will be the fraction of predicted peptides that are isolated and the greater will be the probability that the modified peptide of interest will be isolated (More information).
Radioactive samples for HPLC/Edman sequencing	100,000 cpm/site	1 x 10⁶ cpm/site	These samples must also contain the minimum recommended amount of protein and may not contain significantly more than the optimal number of cpm. (More information).
MALDI-MS Protein Identification (following digestion)	0.1 pmol	0.5 pmol	Samples may be submitted as Coomassie Blue stained gel bands or in solution. We do not recommend submitting PVDF blotted samples (More information).
LC MS/MS Protein Identification (following digestion)	10-20 fmol	1 pmol	Samples may be submitted as Coomassie Blue stained gel bands or in solution. We do not recommend submitting PVDF blotted samples (More information).
Q-Tof ES MS: Protein Mass	5 pmol	20 pmol	Samples should be submitted at concentrations above 1 然 in volatile solvents that are free of non-volatile buffers,detergents, salts, urea, glycerol, etc. Suitable solvents are water, acetonitrile/water or methanol/water mixtures. Dilute, volatile buffers (e.g., 1 mM NH₄HCO₃) may be used also (More information)
Q-Tof ES: Peptide MS/MS	10 fmol	1 pmol