ACS Congressional Fellowship
ANALYTICAL APPROACH
Available Fall 1994 T h e Fellowship places an ACS m e m b e r in a staff position in Congress to • Gain firsthand knowledge of t h e o p e r a t i o n of t h e legislative b r a n c h of t h e federal government, • Make scientific a n d technical e x p e r t i s e available to t h e government, and • Forge links b e t w e e n t h e scientific a n d g o v e r n m e n t communities. Applications d u e J a n u a r y 1,1994. For m o r e information c o n t a c t : Mr. William Gray D e p a r t m e n t of G o v e r n m e n t Relations and Science Policy American Chemical Society 1155 Sixteenth Street, N.W. Washington, DC 20036, (202) 8724467. Applications consist of a letter of intent, a resume, and two letters of reference. Arrangements should be made to send the letters of reference directly to ACS. Candidates should contact ACS prior to submitting an application to determine the type of information needed in the letter of intent.
Mft 'Ail « ! * • '
Figure 5. Analysis of liquid-liquid extract from an oleander leaf by (a) LC/LC with UV detection and (b) LC/LC/MS/MS under SRM conditions. techniques and equipment suggest t h i s approach m a y h a v e m e r i t for common applications in which large numbers of biological samples (e.g., plasma and urine) must be analyzed. As a postscript, when this project was completed we proposed that the use of antibodies for isolating oleand r i n a n d i t s r e l a t i v e s m i g h t be a more selective m e a n s for trace enrichment of the target analytes (17). For example, a high-pressure immunoaffinity column could have been coupled on line as column 1 in Figure 4. After pumping a relatively high volume of a q u e o u s t i s s u e e x t r a c t through an immunoaffinity column d u r i n g t r a p p i n g a n d t r a c e enrichment conditions, the column could be rinsed with phosphate-buffered saline. Then the pH could be lowered to unfold the antibody protein and allow release of t h e t r a p p e d a n a l y t e from this column with s u b s e q u e n t
862 A · ANALYTICAL CHEMISTRY, VOL. 65, NO. 19, OCTOBER 1, 1993
t r a p p i n g on column 2 in Figure 4. Back-flushing column 2 with an appropriate eluent could then elute the trapped analytes and any additional m a t r i x components r e s u l t i n g from nonspecific binding onto column 3, which would provide a n analytical separation followed by M S / M S detection. We have demonstrated the feasibility of an immunoaffinity chromatography (IAC) and LC/MS approach with several simple drug and environmental applications. For example, a polyclonal antibody specific for propranolol was used to trace-enrich this drug from h u m a n urine. When we u s e I A C / L C / M S on a modified single quadrupole mass spectrometer operated in the SIM mode, we determined propranolol at a concentration of 2.5 ng/mL directly from urine ( 18). Other applications in our laboratory include the IAC/LC/MS deter-
