Infusion devices, comparison

Comparison of Infusion Devices with Different Driving Mechanisms... 

A comparison of the low-frequency sensitivity drift is also difficult to do directly, but a reasonable analogy can be drawn. A variation in sensitivity over a series of sample spots is a situation similar to infusion and observation of baseline drift with ESI. Using ideal conditions of sample deposition and crystallization with pure standards and solvents establishes some idea of reproducibility limits. An example is shown in Figure 13.12, where a series of spots from a sample of the dmg Propanolol were created with an electrostatic deposition device." The spots were rastered at a speed such that each spot was traversed in 600 ms. Absolute area reproducibility of approximately 6% was achieved— that is, worse than the infusion data of NanoESI and the high flow techniques, but still reasonable, particularly if referencing the signal to an internal standard (not done here) in the same spot that is ionized at the same time as the analyte. Suffice it to say that good quantitation is possible when an internal standard is cocrystallized with the analyte. ESI or APCI do not require coelution of the internal standard and analyte. 

---