- The main goal of effectively analyzing Nonoxynol-9 in its Nonoxynol-n mixture by the Aviv Analytical 5975-SMB GC-MS with Cold EI was easily achieved as demonstrated in Figure 1.
- Abundant molecular ions were observed for all the Nonoxynol-9 isomers as well as for all the other Nonoxynol-n (N=3-14) mixture compounds, which is in marked contrast with standard EI results in which already for N>5 no molecular ions are observed.
- Reasonable chromatographic separation of the various Nonoxynol-9 isomers was achieved, without peak tailing, as demonstrated in Figure 3 below, despite the use of short column. In contrast, with standard GC-MS ion source peak tailing (and poor sensitivity) completely eroded the isomer separation for Nonoxynol-9.
- The Cold EI mass spectra of Nonoxynol compounds were characterized by having abundant molecular ions plus five other characteristic high mass fragments with relative abundances which were highly isomer specific (Figures 1 and 3).
- All other nonylphenol polyethoxilate compounds (Nonoxynol-n) were detected, from Nonoxynol-3 up to Nonoxynol-14, while Nonoxynol-9 was the most abundant peak in the TIC mass chromatogram. Note that the molecular ion of Nonoxynol-14 m/z=836.7 was easily observed. In contrast, standard GC-MS analysis of the same Nonoxynol mixture ended with Nonoxynol-9 being the last to elute compound. Thus, the 5975-SMB proved again its feature of having uniform response to all the mixture compounds. The use of short column (5 m) and high column flow rate (5 ml/min) enabled the elution of these large, semi-polar compounds with molecular weight of up to m/z=836, which are incompatible for analysis by standard GC-MS, while the use of fly-through ion source eliminated ion source peak tailing and resulted in having uniform compound independent response, in marked contrast to standard EI.
- Isotope abundance analysis with the Tal-Aviv Molecule Identifier (TAMI) software helped in the unambiguous identification of Nonoxynol-9 and its correct elemental formula C33H60O10 was listed as number one in the TAMI software hit list, as shown in Figure 4 below. This identification is in addition to the possibility to add Nonoxynol-9 Cold EI mass spectrum to the NIST library for library based identification. For further information on the powerful TAMI software please visit its website and/or contact us for its manual and demonstration on your files.
- The analysis took 26 min which is reasonable and over three times faster than with standard GC-MS analysis of these heavy compounds (Figures 1 and 2).
- Excellent full scan TIC sensitivity was obtained with TIC S/N>500 (peak to peak) for 2 µg Nonoxynol-9 mixture. Thus, we demonstrated over 500 lower TIC LOD with the 5975-SMB GC-MS with Cold EI for this compound than what was obtained with standard GC-MS, which is important for forensic applications. This superior TIC sensitivity combined with an estimated over 1000 times more abundant molecular ion (>70% vs undetected)) implies that the S/N gain on the molecular ion could approach the staggering value of 1,000,000.
- Excellent five ions SIM sensitivity was demonstrated with S/N of >2000 (peak to peak noise) for 2 ng Nonoxynol-9 mixture while using its molecular ion m/z=616.4 which should be very selective. In Figure 5 below this SIM analysis is shown. Thus, 1 pg extrapolated Nonoxynol-9 mixture LOD Milestone was achieved.