PMC

Schematic and component details of the GC×GCC-IRMS system constructed and used in this work.

The (A) m/z 44 and (B) m/z 45/44 ratio trace 2D contour chromatograms of the GC×GCC-IRMS of Urine A (from athletes’ pooled urine) with a 6s modulation rate. The (C) m/z 44 and (D, E) m/z 45/44 ratio trace 3D chromatograms of the GC×GCC-IRMS of Urine A (from athletes’ pooled urine) with a 6s modulation rate.

The m/z 44 trace GC×GCC-IRMS chromatogram in the E–AC and A–AC region of the Urine A extract (from athletes’ pooled urine) with a (A) no modulation and (C) 6s modulation. The m/z 45/44 ratio trace of the same chromatogram with (B) no modulation and (D) 6s modulation.

Linearity of δ¹³C measurements by GC×GCC-IRMS for the steroids A–AC, 11-KE–AC, and Cne contained in the isotopic standard CU/USADA 33-1 over a large mass range (4–80 ng) injected on column (n=9). The mean ± standard deviation for each steroid is also reported. (One outlier was removed).