An investigation of enhanced secondary ion emission under Au n + (n=1–7) bombardment

We investigate the mechanism of the nonlinear secondary ion yield enhancement using Au(n)+ (n = 1, 2, 3, 5, 7) primary ions bombarding thin films of Irganox 1010, DL-phenylalanine and polystyrene on Si, Al, and Ag substrates. The largest differences in secondary ion yields are found using Au+, Au2+, and Au3+ primary ion beams. A smaller increase in secondary ion yield is observed using Au5+ and Au7+ primary ions. The yield enhancement is found to be larger on Si than on Al, while the ion yield is smaller using an Au+ beam on Si than on Al. Using Au(n)+ ion structures obtained from Density Functional Theory, we demonstrate that the secondary yield enhancement is not simply due to an increase in energy per area deposited into the surface (energy deposition density). Instead, based on simple mechanical arguments and molecular dynamics results from Medvedeva et al, we suggest a mechanism for nonlinear secondary ion yield enhancement wherein the action of multiple concerted Au impacts leads to efficient energy transfer to substrate atoms in the near surface region and an increase in the number of secondary ions ejected from the surface. Such concerted impacts involve one, two, or three Au atoms, which explains well the large nonlinear yield enhancements observed going from Au+ to Au2+ to Au3+ primary ions. This model is also able to explain the observed substrate effect. For an Au+ ion passing through the more open Si surface, it contacts fewer substrate atoms than in the more dense Al surface. Less energy is deposited in the Si surface region by the Au+ primary ion and the secondary ion yield will be lower for adsorbates on Si than on Al. In the case of Au(n)+ the greater density of Al leads to earlier break-up of the primary ion and a consequent reduction in energy transfer to the near-surface region when compared with Si. This results in higher secondary ion yields and yield enhancements on silicon than aluminum substrates.     

Improvement of biological time-of-flight-secondary ion mass spectrometry imaging with a bismuth cluster ion source

A new liquid metal ion gun (LMIG) filled with bismuth has been fitted to a time-of-flight-secondary ion mass spectrometer (TOF-SIMS). This source provides beams of Bi(n)q+ clusters with n = 1-7 and q = 1 and 2. The appropriate clusters have much better intensities and efficiencies than the Au3+ gold clusters recently used in TOF-SIMS imaging, and allow better lateral and mass resolution. The different beams delivered by this ion source have been tested for biological imaging of rat brain sections. The results show a great improvement of the imaging capabilities in terms of accessible mass range and useful lateral resolution. Secondary ion yields Y, disappearance cross sections sigma, efficiencies E = Y/sigma , and useful lateral resolutions deltaL have been compared using the different bismuth clusters, directly onto the surface of rat brain sections and for several positive and negative secondary ions with m/z ranging from 23 up to more than 750. The efficiency and the imaging capabilities of the different primary ions are compared by taking into account the primary ion current for reasonable acquisition times. The two best primary ions are Bi3+ and Bi5(2+). The Bi3+ ion beam has a current at least five times larger than Au3+ and therefore is an excellent beam for large-area imaging. Bi5(2+) ions exhibit large secondary ions yields and a reasonable intensity making them suitable for small-area images with an excellent sensitivity and a possible useful lateral resolution <400 nm.     

Ion yield improvement for static secondary ion mass spectrometry by use of polyatomic primary ions

Static secondary ion mass spectrometry (S-SIMS) is one of the potentially most powerful and versatile tools for the analysis of surface components at the monolayer level. Current improvements in detection limit (LOD) and molecular specificity rely on the optimisation of the desorption-ionisation (DI) process. As an alternative to monoatomic projectiles, polyatomic primary ion (P.I.) bombardment increases ion yields non-linearly. Common P.I. sources are Ga+ (liquid metal ion gun (LMIG), SF5+ (electron ionisation) and the newer Au(n)+, Bi(n)q+ (both LMIG) and C60+ (electron ionisation) sources. In this study the ion yield improvement obtained by using the newly developed ion sources is assessed. Two dyes (zwitterionic and/or thermolabile polar functionalities on a largely conjugated backbone) were analysed as a thin layer using Ga+, SF5+, C60+, Bi+, Bi3(2+) and Bi5(2+) projectiles under static conditions. The study aims at evaluating the improvement in LOD, useful and characteristic yield and molecular specificity. The corrected total ion count values for the different P.I. sources are compared for different instruments to obtain a rough estimate of the improvements. Furthermore, tentative ionisation and fragmentation schemes are provided to describe the generation of radical and adduct ions. Characteristic ion yields are discussed for the different P.I. sources. An overview of the general appearances of the mass spectra obtained with the different P.I. sources is given to stress the major improvement provided by polyatomic P.I.s in yielding information at higher m/z values.     

Use of monoatomic and polyatomic projectiles for the characterisation of polylactic acid by static secondary ion mass spectrometry

The application of polyatomic primary ions is a strongly developing branch of static secondary ion mass spectrometry (S-SIMS), since these projectiles allow a significant increase in the secondary ion yields to be achieved. However, the different limitations and possibilities of certain polyatomic primary ions for use on specific functional classes of samples are still not completely known. This paper compares the use of monoatomic and polyatomic primary ions in S-SIMS for thin layers of polylactic acid (PLA), obtained by spin-coating solutions on silicon wafers. Bombardment with Ga+, Xe+ and SF5+ primary ions allowed the contribution of the projectile mass and number of atoms in the gain in ion yield and molecular specificity (relative importance of high m/z and low m/z signals) to be assessed. Samples obtained by spin-coating solutions with increasing concentration showed that optimal layer thickness depended on the primary ion used. In comparison with the use of Ga+ projectiles, the yield of structural ions increased by a factor of about 1.5 to 2 and by about 7 to 12 when Xe+ and SF5+ primary ion bombardment were applied, respectively. A detailed fragmentation pattern was elaborated to interpret ion signal intensity changes for different projectiles in terms of energy deposition and collective processes in the subsurface, and the internal energy of radical and even-electron precursor ions.     

Quantitative molecular depth profiling of organic delta-layers by C60 ion sputtering and SIMS

Alternating layers of two different organic materials, Irganox1010 and Irganox3114, have been created using vapor deposition. The layers of Irganox3114 were very thin ( approximately 2.5 nm) in comparison to the layers of Irganox1010 ( approximately 55 or approximately 90 nm) to create an organic equivalent of the inorganic 'delta-layers' commonly employed as reference materials in dynamic secondary ion mass spectrometry. Both materials have identical sputtering yields, and we show that organic delta layers may be used to determine some of the important metrological parameters for cluster ion beam depth profiling. We demonstrate, using a C(60) ion source, that the sputtering yield, S, diminishes with ion dose and that the depth resolution also degrades. By comparison with atomic force microscopy data for films of pure Irganox1010, we show that the degradation in depth resolution is caused by the development of topography. Secondary ion intensities are a well-behaved function of sputtering yield and may be employed to obtain useful analytical information. Fragments characteristic of highly damaged material have intensity proportional to S, and those fragments with minimal molecular rearrangment exhibit intensities proportional to S(2). We demonstrate quantitative analysis of the amount of substance in buried layers of a few nanometer thickness with an accuracy of approximately 10%. Organic delta layers are valuable reference materials for comparing the capabilities of different cluster ion sources and experimental arrangements for the depth profiling of organic materials.     

Measurement of sputtering yields and damage in C60 SIMS depth profiling of model organic materials

Sputter‐depth profiles of model organic thin films on silicon using C₆₀ primary ions have been employed to measure sputtering yields and depth resolution parameters. We demonstrate that some materials (polylactide, Irganox 1010) have a constant and high sputtering yield, which varies linearly with the primary ion energy, whereas another material (Alq₃) has lower, fluence‐dependent sputtering yields. Analysis of multi‐layered organic thin films reveals that the depth resolution is a function of both primary ion energy and depth, and the sputtering yield depends on the history of sputtering. We also show that ～30% of repeat units are damaged in the steady‐state regime during polylactide sputtering. Crown Copyright © 2006. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.     

Depth profiling of Irganox‐3114 nanoscale delta layers in a matrix of Irganox‐1010 using conventional Cs+ and O2+ ion beams

Depth profiling of an organic reference sample consisting of Irganox 3114 layers of 3 nm thickness at depths of 51.5, 104.5, 207.6 and 310.7 nm inside a 412 nm thick Irganox 1010 matrix evaporated on a Si substrate has been studied using the conventional Cs⁺ and O₂⁺ as sputter ion beams and Bi⁺ as the primary ion for analysis in a dual beam time‐of‐flight secondary ion mass spectrometer. The work is an extension of the Versailles Project on Advanced Materials and Standards project on depth profiling of organic multilayer materials. Cs⁺ ions were used at energies of 500 eV, 1.0 keV and 2.0 keV and the O₂⁺ ions were used at energies of 500 eV and 1.0 keV. All four Irganox 3114 layers were identified clearly in the depth profile using low mass secondary ions. The depth profile data were fitted to the empirical expression of Dowsett function and these fits are reported along with the full width at half maxima to represent the useful resolution for all the four delta layers detected. The data show that, of the conditions used in these experiments, an energy of 500 eV for both Cs⁺ beam and O₂⁺ beam provides the most useful depth profiles. The sputter yield volume per ion calculated from the slope of depth versus ion dose matches well with earlier reported data. Copyright © 2013 John Wiley & Sons, Ltd.     

Analysis of bone minerals by time-of-flight secondary ion mass spectrometry: a comparative study using monoatomic and cluster ions sources

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is an important tool for the analysis of bone minerals at implant surfaces. Most studies have been performed with monoatomic primary ion sources such as Ga(+) with poor secondary molecular ion production efficiency and only elemental distributions and minor fragments of bone minerals have been reported. By using cluster ion sources, such as Au(1-3) (+) and Bi(1-3) (+), identification of larger hydroxyapatite species at m/z 485, 541, 597 and 653, identified as Ca(5)P(3)O(12), Ca(6)P(3)O(13), Ca(7)P(3)O(14) and Ca(8)P(3)O(15), respectively, became possible. The ions appear to be fragments of the hydroxyapatite unit cell Ca(10)(PO(4))(6)(OH)(2). Each ion in the series is separated by 55.9 m/z units, corresponding to CaO, and this separation might reflect the columnar nature of the unit cell.     

ToF-SIMS Analysis of Adsorbed Proteins: Principal Component Analysis of the Primary Ion Species Effect on the Protein Fragmentation Patterns

In time-of-flight secondary ion mass spectrometry (ToF-SIMS), the choice of primary ion used for analysis can influence the resulting mass spectrum. This is because different primary ion types can produce different fragmentation pathways. In this study, analysis of single-component protein monolayers were performed using monatomic, tri-atomic, and polyatomic primary ion sources. Eight primary ions (Cs(+), Au(+), Au(3) (+), Bi(+), Bi(3) (+), Bi(3) (++), C(60) (+)) were used to examine to the low mass (m/z < 200) fragmentation patterns from five different proteins (bovine serum albumin, bovine serum fibrinogen, bovine immunoglobulin G and chicken egg white lysozyme) adsorbed onto mica surfaces. Principal component analysis (PCA) processing of the ToF-SIMS data showed that variation in peak intensity caused by the primary ions was greater than differences in protein composition. The spectra generated by Cs(+), Au(+) and Bi(+) primary ions were similar, but the spectra generated by monatomic, tri-atomic and polyatomic primary ion ions varied significantly. C(60) primary ions increased fragmentation of the adsorbed proteins in the m/z < 200 region, resulting in more intense low m/z peaks. Thus, comparison of data obtained by one primary ion species with that obtained by another primary ion species should be done with caution. However, for the spectra generated using a given primary ion beam, discrimination between the spectra of different proteins followed similar trends. Therefore, a PCA model of proteins created with a given ion source should only be applied to datasets obtained using the same ion source. The type of information obtained from PCA depended on the peak set used. When only amino acid peaks were used, PCA was able to identify the relationship between proteins by their amino acid composition. When all peaks from m/z 12-200 were used, PCA separated proteins based on a ratio of C(4)H(8)N(+) to K(+) peak intensities. This ratio correlated with the thickness of the protein films and Bi(1) (+) primary ions produced the most surface sensitive spectra.     

Comparison of mono- and polyatomic primary ions for the characterization of organic dye overlayers with static secondary ion mass spectrometry

Organic carbocyanine dye coatings have been analyzed by time-of-flight static secondary ion mass spectrometry (TOF-S-SIMS) using three types of primary ions: Ga(+) operating at 25 keV, and Xe(+) and SF(5) (+) both operating at 9 keV. Secondary ion yields obtained with these three primary ions have been compared for coatings with different layer thickness, varying from (sub)-monolayer to multilayers, on different substrates (Si, Ag and AgBr cubic microcrystals). For (sub)-monolayers deposited on Ag, Xe(+) and SF(5) (+) primary ions generate similar precursor ion intensities, but with Ga(+) slightly lower precursor ion intensities were obtained. Thick coatings on Ag as well as mono- and multilayers on Si produce the highest precursor and fragment ion intensities with the polyatomic primary ion. The yield difference between SF(5) (+) and Xe(+) can reach a factor of 6. In comparison with Ga(+), yield enhancements by up to a factor of 180 are observed with SF(5) (+). For the mass spectrometric analysis of dye layers on AgBr microcrystals, SF(5) (+) again proves to be the primary ion of choice.     

Peptide structural analysis using continuous Ar cluster and C60 ion beams

A novel application of time-of-flight secondary ion mass spectrometry (ToF-SIMS) with continuous Ar cluster beams to peptide analysis was investigated. In order to evaluate peptide structures, it is necessary to detect fragment ions related to multiple neighbouring amino acid residues. It is, however, difficult to detect these using conventional ToF-SIMS primary ion beams such as Bi cluster beams. Recently, C₆₀ and Ar cluster ion beams have been introduced to ToF-SIMS as primary ion beams and are expected to generate larger secondary ions than conventional ones. In this study, two sets of model peptides have been studied: (des-Tyr)-Leu-enkephalin and (des-Tyr)-Met-enkephalin (molecular weights are approximately 400 Da), and [Asn¹ Val⁵]-angiotensin II and [Val⁵]-angiotensin I (molecular weights are approximately 1,000 Da) in order to evaluate the usefulness of the large cluster ion beams for peptide structural analysis. As a result, by using the Ar cluster beams, peptide molecular ions and large fragment ions, which are not easily detected using conventional ToF-SIMS primary ion beams such as Bi₃ ⁺, are clearly detected. Since the large fragment ions indicating amino acid sequences of the peptides are detected by the large cluster beams, it is suggested that the Ar cluster and C₆₀ ion beams are useful for peptide structural analysis.     

TMP与受阻酚Irganox 1010在异辛烷溶液中并用时光稳定作用的研究

本文研究了2,2,6,6-四甲基哌啶醇(简称TMP)和2,2,6,6-四甲基哌啶醇氮氧自由基(简称TMPO·)分别与四[3-(3,5-二叔丁基-4-羟基苯基)丙酸]季戊四醇酯(简称Irganox 1010)在异辛烷溶液中并用时的光稳定作用。结果表明:TMP与Irganox 1010的并用体系有反协同作用:Irganox 1010对异辛烷溶液的光氧化有敏化作用;TMP与Irganox 1010并用时,TMPO·的累积速率变慢,浓度极大值比只含TMP的样品低;TMPO·与Irganox 1010并用时,TMPO·的衰减比只含TMPO·的样品快得多。根据实验事实提出:TMPO·与Irganox 1010之间起了某种反应,该反应引起的氮氧自由基浓度的降低可能是受阻胺与受阻酚并用时产生反协同效应的主要原因。     

Time-of-flight secondary ion mass spectrometric analysis of the interface between bone and titanium implants

Implant healing into bone tissue is a process where the mature bone grows towards and eventually fuses with the implant. In this study we investigated implant healing during 4 weeks with focus on the implant-tissue interface. Our main interest was to study the mineralization process around the implant. Titanium discs were implanted in rat tibia for 2 and 4 weeks. After implantation cross sections of bone and implant were made using a low-speed saw equipped with a diamond wafering blade. One section from each sample was stained with basic fuchsin and micrographed by light microscopy (LM). The other section was analyzed with imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS) using a Bi(3)(+) cluster ion source. This ion source has recently been shown to enable identification of high-mass hydroxyapatite (HA) fragment ions (m/z 291-653) in bone samples. The LM images were used to identify areas suitable for TOF-SIMS analysis. Three areas were selected for mass spectral analysis, corresponding to interface region, bone and soft tissue, from which positive ion spectra were recorded. In the areas identified as bone, high-mass HA fragments ions were found after both 2 and 4 weeks. In the soft tissue area, no high-mass ions were found after 4 weeks. However, after 2 weeks HA-related ions were identified in mineralized spots in areas defined as soft tissue. After 4 but not after 2 weeks, high-mass HA fragment ions were found in the interface region. In conclusion, differences were observed regarding mineralization between 2 and 4 weeks of implantation and between different regions surrounding the implants. Imaging TOF-SIMS analysis using a Bi(3)(+) cluster as ion source enables identification of high-mass HA fragment ions at implant-tissue interfaces in bone. This technique might therefore be useful for biocompatibility assessment and for studying the mineralization process at implant surfaces.     

Bismuth coordination chemistry with allyl, alkoxide, aryloxide, and tetraphenylborate ligands and the {[2,6-(Me2NCH2)2C6H3]2Bi}+ cation

A series of bis(aryl) bismuth compounds containing (N,C,N)-pincer ligands, [2,6-(Me(2)NCH(2))(2)C(6)H(3)](-) (Ar'), have been synthesized and structurally characterized to compare the coordination chemistry of Bi(3+) with similarly sized lanthanide ions, Ln(3+). Treatment of Ar'(2)BiCl, 1, with ClMg(CH(2)CH═CH(2)) affords the allyl complex Ar'(2)Bi(η(1)-CH(2)CH═CH(2)), 2, in which only one allyl carbon atom coordinates to bismuth. Complex 1 reacts with KO(t)Bu and KOC(6)H(3)Me(2)-2,6 to yield the alkoxide Ar'(2)Bi(O(t)Bu), 3, and aryloxide Ar'(2)Bi(OC(6)H(3)Me(2)-2,6), 4, respectively, but the analogous reaction with the larger KOC(6)H(3)(t)Bu(2)-2,6 forms [Ar'(2)Bi][OC(6)H(3)(t)Bu(2)-2,6], 6, in which the aryloxide ligand acts as an outer sphere anion. Chloride is removed from 1 by NaBPh(4) to form [Ar'(2)Bi][BPh(4)], 5, which crystallizes from THF in an unsolvated form with tetraphenylborate as an outer sphere counteranion.     

Is proton cationization promoted by polyatomic primary ion bombardment during time-of-flight secondary ion mass spectrometry analysis of frozen aqueous solutions?

Ion bombardment of pure water ice by Au+ monoatomic and Au3 + and C60 + polyatomic projectiles results in the emission of two series of water cluster ions-(H2O)n + and (H2O)nH+-with n ranging from 1 to >40. The cluster ion yields are very significantly higher under polyatomic ion bombardment than when using an Au+ primary ion. The yield of the protonated water species (H2O)nH+ is found to be enhanced by increasing ion fluence. C60 + bombardment results in a very dramatic increase in the (H2O)nH+ yield and decrease in the yield of (H2O)n +. Au3 + also significantly increased the yield of protonated species relative to the non-protonated but to a lesser extent than C60 +. Bombardment by Au+ also increased the yield of protonated species but to a very much smaller extent. The hypothesis that the protonated species may enhance the yield of [M+H]+ from solute molecules in solution has been investigated using two amino acids, alanine and arginine, and a nucleic base, adenine. The data suggest that the protons produced by the sputtering of water ice are depleted in the presence of these solutes and concurrently the yields of solute-related [M+H]+ and immonium secondary ions are greatly enhanced. These yield enhancements are analysed in the light of other possible contributors such as increased rates of sputtering under polyatomic beams and increased secondary ion yields as a consequence of solute dispersion. It is concluded that enhanced proton attachment is occurring in polyatomic sputtered frozen aqueous solutions.     

Mass spectrometric studies on 4-aryl-1-cyclopropyl-1,2-dihydropyridinyl derivatives: an examination of a novel fragmentation pathway

Examination of the electrospray ionization product ion spectra of 1,2-dihydropyridinyl and 4-aryl-1,2-dihydropyridinyl derivatives bearing a 1-cyclopropyl or 1-trans-2-phenylcyclopropyl group has led to the characterization of unexpected fragment ions. For example, the base peak at m/z 156 present in the product ion spectrum of trans-1-(2-phenylcyclopropyl)-4-phenyl-1,2-dihydropyridine proved not to be the expected 4-phenylpyridinium species but rather the isomeric 3-phenyl-5-azoniafulvenyl species. The results of studies with a series of structural and isotopically labeled analogs require a novel fragmentation pathway to account for the formation of this and related fragment ions. One possible pathway is based on an initial 1,5-sigmatropic shift of a cyclopropylmethylene hydrogen atom that is accompanied by opening of the cyclopropyl ring. The resulting eniminium intermediates then fragment to yield the 5-azoniafulvenyl species.     

Fragmentation characteristics of b(n) (n=2-15) ions from protonated peptides

The fragmentation reactions of protonated oligoalanines (trialanine, tetraalanine and pentaalanine) and the fragments present in the electrospray ionization (ESI) mass spectrum of polyalanine have been studied by collisionally activated dissociation (CAD) mass spectrometry (MS(2) and MS(3) experiments). The MS(n) experiments provided strong evidence that the m/z 71n+1 ion series in the ESI mass spectrum of polyalanine is a b(n) series. These ions are formed via the b(n) -y(m) pathway of amide bond cleavage, which results in the formation of a proton-bound complex of an oxazolone and a peptide/amino acid. Also, the MS(2) spectra of the b(n) series from polyalanine revealed that the chain length of b(n) ions influences significantly the dissociations taking place. For example, b(n) ions start losing H(2)O at n ≥5 and the losses of CO and CO+NH(3) decrease in intensity from b(2) to b(15). The elimination of H(2)O+NH(3) and the elimination of 61 mass (HN=C=O+H(2)O) commence with b(6); their abundances initially increase up to ~ b(8)-b(9) and then gradually decrease until b(15) (largest fragment studied). The tandem mass spectrometry experiments help to elucidate the dissociation mechanisms of the observed structures of biopolymer fragments.     

Investigation of ionic liquids under Bi‐ion and Bi‐cluster ions bombardment by ToF‐SIMS

A systematic study of five different imidazolium‐based room temperature ionic liquids, 1‐butyl‐3‐methylimidazolium acetate, 1‐butyl‐3‐methylimidazolium nitrate, 1‐butyl‐3‐methylimidazolium iodide, 1‐butyl‐3‐methylimidazolium hexafluorophosphate and 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide were carried out by means of time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) in positive and negative ion mode. The compounds were measured under Bi‐ion and Bi‐cluster ions (Bi_2–7⁺, Bi_{3, 5}²⁺) bombardment, and spectral information and general rules for the fragmentation pattern are presented. Evidence for hydrogen bonding, due to high molecular secondary cluster ions, could be found. Hydrogen bonding strength could be estimated by ToF‐SIMS via correlation of the anionic yield enhancement with solvent parameters. Copyright © 2010 John Wiley & Sons, Ltd.     

GC-MS analysis of ring and side chain regioisomers of ethoxyphenethylamines

Mass spectral differentiation of 3,4-methylenedioxymethamphetamine (3,4-MDMA), a controlled drug, and its 2,3-regioisomer from the ring substituted ethoxyphenethylamines is possible after formation of the perfluoroacyl derivatives, pentafluoropropionamides (PFPA), and heptafluorobutyrylamides (HFBA). The ring substituted ethoxyphenethylamines constitute a unique set of compounds having an isobaric relationship with 3,4-MDMA. These isomeric forms of the 2-, 3-, and 4-ethoxy phenethylamines have mass spectra essentially equivalent to 3,4-MDMA; all have molecular weight of 193 and major fragment ions in their electron ionization mass spectra at m/z 58 and 135/136. All the side chain regioisomers of 2-ethoxy phenethylamine having equivalent mass spectra to 3,4-MDMA are synthesized and compared via gas chromatography-mass spectrometry to 2,3- and 3,4-methylenedioxymethamphetamine. The mass spectra for the perfluoroacyl derivatives of the primary and secondary amine regioisomers are significantly individualized, and the side chain regioisomers yield unique hydrocarbon fragment ions at m/z 148, 162, and 176. Additionally, the substituted ethoxymethamphetamines are distinguished from the methylenedioxymethamphet-amines via the presence of the m/z 107 ion. Gas chromatographic separation on relatively non-polar stationary phases successfully resolves these derivatives.