Agilent 500 Ion Trap LC/MS with Enhanced Charge Capacity (ECC) Manual
Contents
1. 00 The ion cluster at mass to charge 1122 was selected as the test ion The fixed ionization time dura tion was increased and the mass shift and mass resolution full width at half maxi mum FWHM was measured The ion times were adjusted to give approximately the same signal to noise on both instruments Figure 1 Competitive lon Trap 200 psec lon Time Agilent 500 lon Trap 100 psec lon Time a i 4 m Fe 10 m E m m m E 40 m Fe 10 Oo Figure 1 Similar S N ratios with only half the ionization time for the Agilent 500 lon Trap Note that this latter system Is baseline resolved while the competitive ion trap has a 10 valley The ion times were then adjusted to values that produced similar mass resolution Figure 2 It was observed that the Agilent 500 lon Trap could tolerate a 100 fold increase in the ion time equivalent to increasing the charge in the trap by a factor of 100 with little noticeable decrease in the mass resolution The competitive ion trap on the other hand could only tolerate an increase in ion time of 10 before the mass resolution was noticeably degraded Therefore the Agilent 500 lon Trap could store 10 times the number of ions without affecting its performance Competitive lon Trap 2 000 usec lon Time Agilent 500 lon Trap a m 1 000 usec lon Time vn Figure 2 Excellent mass resolution and extended charge capacity for the Agilent 500 lon Trap versus degraded mass resolution and limited ch2. Agilent 500 lon Trap LC MS with Enhanced Charge Capacity ECC Technical Overview Introduction Historically ion traps were limited by the amount of charge that could be stored in them If too much charge was in the trap the electric field from the trapped charge would influence the ion ejection process and shift the apparent mass position In addition the mass resolution would be degraded Software techniques were devel oped to ensure that the trap would always have a relatively constant amount of charge by controlling the ionization time Although this automatic charge regulation was able to limit the charge in the trap to values that did not cause unacceptable mass shifts and resolution losses it required limiting the total number of sample and matrix ions Modifying the electrical multipole content of the trapping field can have dramatic effects on the performance of the ion trap 1 2 The Agilent 500 lon Trap LC MS employs a trapping field that has additional mechanically formed octapole and elec trically generated hexapole components to the trapping field resulting in significant increases in the number of ions that can be trapped and therefore an EEC A rela tive comparison was made between an Agilent 500 lon Trap and a competitive ion trap ae Agilent Technologies Experimental Conditions The test sample was the mass calibration compound Ultramark a perfluorinated amine having ions with mass to charge ratios m z up to 22
3. Allied Topics Portland OR May 12 16 1996 p 126 www agilent com chem Agilent shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material Information descriptions and specifications in this publication are subject to change without notice Agilent Technologies Inc 2011 Printed in the USA February 24 2011 SI 0242 Ee Agilent Technologies
4. arge capacity for the competitive ion trap Discussion and Results Figure 3 shows a plot of peakwidth at half height as a function of ion time for both the Agilent 500 lon Trap and the competitive ion trap The figure illustrates how the 500 lon Trap blue trace maintains 0 5 peakwidth at half height while the competitive ion trap starts to increase peakwidth significantly after only a 10 fold ion concentration increase Agilent 500 lon Trap LC MS a DECA XP Plus 3 2 5 _ Peakwidth at half height Normalized ion time Figure 3 Peakwidth versus normalized ion time for the Agilent 500 lon Trap and a competitive ion trap Figure 4 shows mass shift versus normalized ion time for the 500 lon Trap and com petitive ion trap Reliable detection of trace amounts in the presence of high con centration of coeluting analytes and heavy matrix requires the ion trap to have a large charge capacity Alprazolam with a parent ion at m z 309 at 500 fg level and alprazolam d5 with parent ion at m z 314 at 50 pg level extracted from bovine serum albumin BSA was injected into the 500 lon Trap LC MS The two analytes coeluted under the conditions we used Despite the 100 fold concentration differ ence between the db analog and native compound the signal to noise ratio obtained for alprazolam is excellent The 500 lon Trap signal was not suppressed due to the large amount of matrix the coeluting d5 analog Figure 5 The 500
5. fg alprazolam extracted from BSA is present only at 1 100 of the concen tration of the coeluting labeled compound alprazolam d5 at 50 pg This coelution is a manufactured matrix contribution present at 100 fold concentration and only five masses away from the target analyte mass which produced good detection on the Agilent 500 lon Trap LC MS Agilent 500 lon Trap LC MS 07 DECA XP Plus Mass shift m z So E a 70 40 60 a0 100 120 Normalized ion time Figure 4 Mass shift versus normalized ion time for the Agilent 500 lon Trap and a competitive ion trap kCounts S N PP 75 07 N 11 Agilent 500 lon Trap 500 fg alprazolam lons 274 281 ne P eee eee ee Agilent 500 lon Trap 50 pg alprazolam d5 lons 279 286 25 be ee ee a Pee eo Scans Figure 5 No signal suppression observed with the Agilent 500 lon Trap for alprazolam with the presence of large amount of coeluting compound Benefits Enhanced charge capacity EEC provides the ion trap with the capability to reliably detect trace amounts in a high concentration of coeluting analytes in heavy matrices References 1 A new ion ejection method employing an asymmetric trapping field to improve mass scanning performance of an electrodynamic ion trap International Journal of Mass Spectrometry Vol 190 191 1999 129 143 2 Mass scanning in an asymmetric trapping field Proc 44th Ann ASMS Conf on Mass Spectrometry and
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Agilent 500 Ion Trap LC/MS with Enhanced Charge Capacity (ECC) Manual