(a)

(b)

1.21 Z48 3J5 5~ΌΓ Time (min)

MW = 286

6.28 7.54

(M + H)+

2 N N H C H Î

M. > α -ν γ,Ν M W = 2 9 g

""—' • 1 • • · " ' ' i " — • " i -t i "

(M + H ) +

t " • • - •

to TO

03

J? Φ or.

(M + H)+

4 CHiV·: (M + H)+

MW = 284

•f τ τ r

(M + H)+

100 125 150 175 200 225 250 275 300

m/z

Figure 3. LC/APIMS separation and detection of a synthetic mixture containing 25 ng each of five benzodiazepines using a heated pneumatic nebulizer, (a) Full-scan LC/MS background subtracted total ion current (TIC) chromatogram and (b) posit ive ion APCI mass spectra. The total isocrat ic f low of 1.2 mL /m in CH 3 CN/CH 3 OH/H 2 0 (40:25:35, v /v ) , 10 m M ammo­nium formate buffer f rom a 4.6 m m X 250 m m Zorbax-Rx co lumn was passed through the LC/MS inter­face whi le the mass spectrometer was scanned f rom m/z 100 to m/z 350 at a scan rate of 3 s/scan wi th corona discharge ionizat ion. The APCI mass spectra in (b) were taken f rom the corresponding chromato­graphic peaks in (a). Peak ident i f icat ion: 1, oxazepam; 2, chlordiazepoxide; 3, nordiazepam; 4 , alprazo­lam; and 5, d iazepam.

shows the TIC chromatogram, UV chromatogram, and two plotted full-scan mass spectra for the packed-col­umn SFC separation and APIMS de­tection of the components in a syn­thetic mixture of five corticosteroids. Approximately 25 ng of each compo­nent were injected to obtain the TIC

chromatogram shown in Figure 4a. For additional structural details, SFC/MS/ MS experiments were performed to provide the full-scan product ion mass spectra for each of these compounds, which yield abundant ions indicating the structure of these compounds (not shown here). This interface is also

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