Fig 3. UV traces at 214 nm and EICs over time (5–25 min) of external protein standards.

Standards were prepared at the same concentration, run independently and overlaid to illustrate that ionisation efficiency varied from one protein to the other. All external standards purchased from Sigma (aCN, bCN, kCN, aLA, bLG, BSA, and myoglobin) were dissolved in 50% Solution A to a 10 mg/mL concentration. The coloured arrows in between the UV traces and the EICs represent the elution windows of the bovine protein standards.