Mass Defect Filtering
Fentanyl and some of its analogs including Acetyl Fentanyl, Para-FluoroIsobutyrfentanyl, and Furanyl Fentanyl.
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Fentanyl analogs are a challenge for forensic laboratories to identify for several reasons. They are constantly modifying compounds as bans for specific drugs go into effect. This creates a moving target for laboratories who struggle to keep up with detecting the latest analog due to lack of certified reference material and validated methods. |
Mass defect is the non-integer portion of the molecular weight. Mass defect filtering (MDF) allows you to filter out the ions that are outside the expected molecular weight range. By using MDF along with common fragment searching, will help to identify new, unknown fentanyl analogs.
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Screening methods are either targeted or untargeted and rely on library identification. However, new analogs will not be a target or in the library and therefore go unidentified. Below is a schematic of the mass defect process for one injection. 
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Fentanyl MW: 336.220154, MDF is centered at 0.23 +/- 20 mDa -47%
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If you want to learn more about targeted drug screening protocols of immunoassays with LC-MS/MS, check out Dinas ASMS poster. If you have any questions about this project, you can contact Dina Swanson.
| targeted_screening_for_drugs_of_abuse_in_postmortem_blood_using_lc-ms_ms.pdf |
DMS of Amphetamines
Examples of designer drugs include amphetamine, methanamphetamine, MDMA and MDEA.
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Current characterization of ‘designer drugs’ and derivatives with conventional sample preparation and chromatographic separation techniques may be laborious and time-consuming. DMS (Differential Mobility Spectrometry) is a more rapid and high-throughput technique that can be used in the characterization of these controlled substances. |
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DMS is a variant of ion mobility spectrometry. It is an emerging technology for post-ionization differentiation and filtration of isobaric interferences. When used before mass spectrometric analysis, DMS provides ion filtration on the order of milliseconds. If you want to learn more about DMS, check out Ife's paper on Rapid Pre-Filtering of Amphetamine and Derivatives by Direct Analysis in Real Time (DART)-Differential Mobility Spectrometry (DMS) published in Analytical Methods. |
Concept of DMS - an asymmetric RF electric field waveform, ofen referred to as dispersion voltage (Vrf) is applied to one of the electrodes across the ion transport channel, perpendicular to the direction of the trans- port gas ow while the other electrode is grounded.
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