Page 508 - Tandem Techniques

Page 494

Figure
13.8 Extracted Electropherogram of Some
Bioactive Peptides (A) and Some Hormones (B)
Reprinted with permission from J. R. Perkins and K. B. Tomer,
Anal. Chem., 66(1994)2835 Copyright 1994 American Chemical Society.

This will also cause the direction of the osmotic flow to be reversed, so that it will flow from a high
negative potential to ground. The use of buffers below pH 10.6 will result in the wall having a positive
charge and will thus repel the positively charged analytes. The spectrometer was the Kratos Concept
ISQ, fitted with an electrospray attachment. The probe was modified to accommodate a zero dead
volume T, which permitted the coaxial introduction of the make-up flow (50% methanol and 50% water
containing 3% of acetic acid). A diagram of the modified probe is shown in Figure 13.7. The
electrospray needle comprised a piece of stainless steel tubing, 0.028 in. O.D. and 0.017 in. I.D. (22
gauge). The use of the larger needle allowed columns with greater outer diameters to be employed,