Mass Spectra Of Trimethylsilyl Derivatives Research Articles

Elucidation of electron ionization mass spectrometric fragmentation pathways of trimethylsilyl ether derivatives of vicinal diols deriving from haplamine by collision‐induced dissociation gas chromatography/tandem mass spectrometry and 18O labelling

Formation of vicinal diols was observed after in vitro and in vivo studies of the natural product haplamine (9-methoxy-2,2-dimethyl-2,6-dihydropyrano[3,2-c]quinolin-5-one). These compounds, identified as trans- and cis-3,4-dihydroxy-9-methoxy-2,2-dimethyl-2,3,4,6-tetrahydropyrano[3,2-c]quinolin-5-ones and trans- and cis-3,4,9-trihydroxy-2,2-dimethyl-2,3,4,6-tetrahydropyrano[3,2-c]quinolin-5-ones, have a potential interest in oncology. It is therefore essential to elucidate their electron ionization mass spectrometric (EIMS) fragmentation pathways. EIMS fragmentation pathways of trimethylsilyl (TMS) derivatives of 3,4-dihydroxy- and 3,4,9-trihydroxyhaplamines were investigated. These pathways have been substantiated by: (i) comparison with EI mass spectra of structural homologues (silylated diols obtained from various chromenes and 1,2-dihydronaphthalene), (ii) low-energy collision-induced dissociation (CID) gas chromatography/tandem mass spectrometry (GC/MS/MS) and (iii) (18)O labelling. CID-MS/MS analyses and (18)O labelling demonstrated that EI mass spectral fragmentation of these TMS derivatives involves a transannular cleavage of the pyran ring with formation of a characteristic intense cyclic ion. The study of the mass spectra of TMS derivatives of different chromenes and 1,2-dihydroxynaphthalene allowed to confirm the proposed fragmentation pathways and to show that they act only when the pyran ring is present. Elimination of the neutral element [(CH3)2=C(H)OSi(CH3)3] and formation of cyclic ions play a key role during EI mass spectral fragmentation of the TMS derivatives of 3,4-dihydroxy- and 3,4,9-trihydroxyhaplamines. These fragmentation pathways could be generalized to TMS derivatives of cyclic compounds possessing vicinal diols close to a pyran ring.

Comprehensive two-dimensional gas chromatography, retention indices and time-of-flight mass spectra of flavonoids and chalcones

The applicability of comprehensive two-dimensional gas chromatography (GC × GC) for flavonoids analysis was investigated by separation and identification of flavonoids in standards, and a complex matrix natural sample. The modulation temperature was optimized to achieve the best separation and signal enhancement. The separation pattern of trimethylsilyl (TMS) derivatives of flavonoids was compared on two complementary column sets. Whilst the BPX5/BPX50 (NP/P) column set offers better overall separation, BPX50/BPX5 (P/NP) provides better peak shape and sensitivity. Comparison of the identification power of GC × GC-TOFMS against both the NIST05 MS library and a laboratory (created in-house) TOFMS library was carried out on a flavonoid mixture. The basic retention index information on high-performance capillary columns with a non-polar stationary phase was established and database of mass spectra of trimethylsilyl derivatives of flavonoids was compiled. TOFMS coupled to GC × GC enabled satisfactory identification of flavonoids in complex matrix samples at their LOD over a range of 0.5–10 μg/mL. Detection of all compounds was based on full-scan mass spectra and for each compound a characteristic ion was chosen for further quantification. This study shows that GC × GC-TOFMS yields high specificity for flavonoids derived from real natural samples, dark chocolate, propolis, and chrysanthemum.

Enhanced Detection and Structural Characterization of Flavonoids by Complexation with N,O-Bis(trimethysilyl)trifluoroacetamide Using Electrospray Ionization Mass Spectrometry

Many natural products contain flavonoids that display biological effects when ingested by humans and animals. Flavonoids have received a great deal of research interest, especially for possible cancer and heart disease-preventive properties. The content and the quality of each flavonoid may be a key to their biological effects. The recent development of electrospray ionization mass spectrometry (ESI-MS/MS) has made it possible to use it to study molecular interactions. In the present work, we investigated the derivatization procedures for three flavonoids (chrysin, genistein, and luteolin) by using ESI-MS/MS. Each flavonoid and the derivatization reagent, N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), are mixed using acetonitrile and the mixture is introduced through an electrospray needle. The signal intensities for the derivative ions significantly increased, almost two or three orders of magnitude increased as compared to those for the protonated molecular ions of the flavonoids. Mass spectra of trimethylsilyl derivatives are fragmented at a fixed pattern by collision induced dissociation to obtain the structural relevance of the derivative flavonoids. Further fragmentation studies have been performed and results are discussed in detail. The results in the positive mode detection show that better high intensity data and more simplification of peaks appeared than that for the underivatized cases.

Determination of Sudan dye residues in eggs by liquid chromatography and gas chromatography–mass spectrometry

A sensitive and cheap high performance liquid chromatography (HPLC) with ultraviolet-visible (UV-VIS) was developed for the determination of Sudan dyes (I, II, III, and IV) residues in various types of eggs. The chromatographic separation was achieved on a reverse phase C 18 column with gradient elution, using a mobile phase of 0.1% formic acid acetonitrile/0.1% formic acid aqueous solution; detector was set at 478 nm for Sudan I and 520 nm for Sudan II, III and IV. The suspected egg samples were derivatized with N, O- bis (trimethylsilyl) trifluoro-acetamide and confirmed by gas chromatography–mass spectrometry (GC–MS) in EI. Mass spectra of trimethylsilyl derivatives of the Sudan dyes were built up in EI mode. Recoveries of the Sudan dyes ranged between 79.8 and 95.7% in eggs by HPLC–UV, with all the relative standard deviations of less than 5%. Limit of detection (LOD), limit of quantification (LOQ) were in the range of 4.0–4.8 and 12.3–13.8 μg kg −1 in eggs, respectively. Identification and confirmation could be validated in the range of 2.0–4.2 μg kg −1 with the GC–MS method. This method is suitable for routine fast monitoring, screening and confirmation of Sudan dyes residues in eggs, as mandated by regulatory agencies.

Organic mass spectrometry in archaeology: evidence for Brassicaceae seed oil in Egyptian ceramic lamps

An analytical procedure based on alkaline hydrolysis and silylation followed by GC/MS analysis was employed to study the formation of characteristic acidic compounds and the development of a distinctive chromatographic pattern in the course of accelerated ageing tests on Brassicaceae seed oil. On the basis of mass spectra of trimethylsilyl derivatives, the main degradation products were identified as alpha,omega-dicarboxylic, omega-hydroxycarboxylic and dihydroxycarboxylic acids, including 11,12-dihydroxyeicosanoic acid and 13,14-dihydroxydocosanoic acid. The mass spectra of both these compounds are characterised by fragment ions arising from the alpha cleavage of the bond between the two vicinal trimethylsiloxy groups, resulting in fragments at m/z 215 and 345 for 11,12-dihydroxyeicosanoic acid, and at m/z 215 and 373 for 13,14-dihydroxydocosanoic acid. Other significant fragment ion-radicals from rearrangement process at m/z [M - 90](+*), [M - 142](+*), 204 as well as fragment ions at m/z [M - 15](+), [M - 105](+), 217 are present in the mass spectra of both the compounds. The results obtained for reference materials were compared with those relating to archaeological organic materials recovered in Egyptian pottery lamps. The occurrence of the same characteristic degradation products found in the reference materials subjected to accelerated ageing indicates an unambiguous origin for the organic archaeological remains and represents the chemical evidence for the use of oil from seeds of Brassicaceae as illuminant.

Metabolism of benzoate, cyclohex-1-ene carboxylate, and cyclohexane carboxylate by "Syntrophus aciditrophicus" strain SB in syntrophic association with H(2)-using microorganisms.

The metabolism of benzoate, cyclohex-1-ene carboxylate, and cyclohexane carboxylate by "Syntrophus aciditrophicus" in cocultures with hydrogen-using microorganisms was studied. Cyclohexane carboxylate, cyclohex-1-ene carboxylate, pimelate, and glutarate (or their coenzyme A [CoA] derivatives) transiently accumulated during growth with benzoate. Identification was based on comparison of retention times and mass spectra of trimethylsilyl derivatives to the retention times and mass spectra of authentic chemical standards. (13)C nuclear magnetic resonance spectroscopy confirmed that cyclohexane carboxylate and cyclohex-1-ene carboxylate were produced from [ring-(13)C(6)]benzoate. None of the metabolites mentioned above was detected in non-substrate-amended or heat-killed controls. Cyclohexane carboxylic acid accumulated to a concentration of 260 microM, accounting for about 18% of the initial benzoate added. This compound was not detected in culture extracts of Rhodopseudomonas palustris grown phototrophically or Thauera aromatica grown under nitrate-reducing conditions. Cocultures of "S. aciditrophicus" and Methanospirillum hungatei readily metabolized cyclohexane carboxylate and cyclohex-1-ene carboxylate at a rate slightly faster than the rate of benzoate metabolism. In addition to cyclohexane carboxylate, pimelate, and glutarate, 2-hydroxycyclohexane carboxylate was detected in trace amounts in cocultures grown with cyclohex-1-ene carboxylate. Cyclohex-1-ene carboxylate, pimelate, and glutarate were detected in cocultures grown with cyclohexane carboxylate at levels similar to those found in benzoate-grown cocultures. Cell extracts of "S. aciditrophicus" grown in a coculture with Desulfovibrio sp. strain G11 with benzoate or in a pure culture with crotonate contained the following enzyme activities: an ATP-dependent benzoyl-CoA ligase, cyclohex-1-ene carboxyl-CoA hydratase, and 2-hydroxycyclohexane carboxyl-CoA dehydrogenase, as well as pimelyl-CoA dehydrogenase, glutaryl-CoA dehydrogenase, and the enzymes required for conversion of crotonyl-CoA to acetate. 2-Ketocyclohexane carboxyl-CoA hydrolase activity was detected in cell extracts of "S. aciditrophicus"-Desulfovibrio sp. strain G11 benzoate-grown cocultures but not in crotonate-grown pure cultures of "S. aciditrophicus". These results are consistent with the hypothesis that ring reduction during syntrophic benzoate metabolism involves a four- or six-electron reduction step and that once cyclohex-1-ene carboxyl-CoA is made, it is metabolized in a manner similar to that in R. palustris.

Identification of α-D-Glucosylglycerol in Sake

alpha-D-Glucosylglycerol (GG) was found for the first time in sake (Japanese rice wine) in an amount of about 0.5%. GG was also found in miso and mirin which had been brewed by using koji. GG was hydrolyzed into glucose and glycerol in an equimolar ratio with maltase (EC 3.2.1.20, alpha-glucosidase from yeast), but not with emulsin (EC 3.2.1.21, beta-glucosidase from almond). The retention times and mass spectra of trimethylsilyl derivatives by a GC-MS analysis of GG in sake were comparable to those of various GG samples synthesized by glycol cleavage. It was proven that GG in sake consisted of three components, viz., 2-O-alpha-D-glucosyl-glycerol (GG-II), (2R)-1-O-alpha-D-glucosylglycerol (R-GG-I) and (2S)-1-O-alpha-D-glucosylglycerol (S-GG-I). The ratio of the three components in GG was 6:66:28 for sake. It is considered that GG was formed by transglucosylation of the glucosyl groups to glycerol by alpha-glucosidase from koji in the sake mash.

Simultaneous determination of 5′-deoxy-5-fluorouridine, 5-fluorouracil and 5,6-dihydro-5-fluorouracil in plasma by gas chromatography-mass spectrometry

A gas chromatography-mass spectrometry (GC-MS) method for the simultaneous determination of 5′-deoxy-5-fluorouridine (doxifluridine, 5′-dFUR), 5-fluorouracil (5-FU) and its main catabolite 5,6-dihydro-5-fluorouracil (5-FUH 2) in human plasma has been developed. Sample preparation consisted of protein precipitation with ammonium sulphate followed by analyte extraction with ethyl acetate/isopropanol ( 90 10 , v/v) mixture. Extracts were then analysed by GC-MS in positive electron impact mode after derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide/pyridine ( 1 1 , v/v). The trimethylsilyl (TMS) derivative of 5′-dFUR was proved to be stable so that no interference in 5-FU determination was observed. Mass spectra of TMS derivatives of 5′-dFUR, 5-FU and 5-FUH 2 are discussed. Analyte response was linear over two decades of concentration and detection limits were typically 20 ng/ml of plasma.

Pyrolysis and mass spectra of trimethylsilyl derivatives of monosaccharides

The pyrolysis of trimethylsilyl derivatives of saccharides (1) was investigated by DTA-TG, MS, GC/MS and TG-GC/MS. The DTA-TG/DTG curves showed that the pyrolysis of 1 occurred in one stage. The exothermic peaks were due to sublimation or thermal decomposition by vaporization. The cleavage mechanism by electron impact of 1 was classified into four categories: 1) stepwise elimination of the side-chain, 2) cleavage of the side-chain, 3) cleavage of the pyranose ring, and 4) cleavage of the pyranose ring and side-chain at the same time. The mass-spectrum for 1 revealed the main common four fragment ions, such asm/z 73, 191, 204 and 217, with cleavage of the pyranose ring. These fragment ions were detected with a similar retention time in the gas cromatogram by GC/MS or TG-GC/MS. The retention time for 1 increased in the sequence aldopentose<ketohexose<aldohexose. This result indicates that the trimethylsilyl derivatives are thermally stable. Subsequently, the pyrolysis regime for 1 obeyed apparent 1/2-order kinetics and their apparent activation energy was estimated as 75–100 kJ/mole.

In vitro reactions of 2-cyanoethylene oxide with calf thymus DNA

Acrylonitrile oxide (CEO) is a direct-acting mutagen and the postulated proximate carcinogenic form of acrylonitrile (AN). We have studied the reactions of CEO with 2′-deoxyribonucleosides and in vitro with calf thymus DNA at pH 7.0–7.5 and 37°C for 3 h. Reaction of CEO with dAdo gave 2 adducts, N 6-(2-hydroxy-2-carboxyethyl)-dAdo ( N 6-HOCE-dAdo) (2% yield) and 1, N 6-etheno-dAdo (ε-dAdo) (11%); reaction with dCyd resulted in the isolation of 3-HOCE-dUrd (22%); reaction with dGuo gave 7-(2-oxoethyl)-Gua (7-OXE-Gua) (31%) and reaction with dThd yielded 3-OXE-dThd (3%). Structural elucidation of adducts was accomplished by ultraviolet spectroscopy, high-field proton NMR spectroscopy and mass spectrometry. Structural confirmation was provided by an accurate mass measurement technique where diagnostic ions in the electron impact mass spectra of trimethylsilyl derivatives were measured to within 0.0007 atomic mass units. The facile Dimroth rearrangement of 1-HOCE-dAdo to N 6-HOCE-dAdo and hydrolytic deamination of a dCyd adduct to 3-HOCE-dUrd is postulated to be catalyzed by the hydroxyl group on the 3-carbon side chain of the adduct. Reaction of CEO with calf thymus DNA yielded (nmol/mg DNA) N 6-HOCE-dAdo (2); ε-dAdo (11); 3-HOCE-dUrd (80); 7-OXE-Gua (110) and 3-OXE-dThd (1). Thus CEO, like its metabolic precursor AN, directly alkylates DNA in vitro but at a much more rapid rate.

Mass spectra of trimethylsilyl derivatives of naturally occurring flavonoid aglycones and chalcones

AbstractElectron impact mass spectra of the trimethylsilyl derivatives of a series of flavonoid aglycones and chalcones are reported. The spectra show prominent ions arising from fragmentation of the trimethylsilyl (TMS) groups. Inter‐actions between adjacent TMS groups, and between TMS groups in the 3‐ or 5‐position (6′‐position for the chalcones) and the C‐ring carbonyl, yield structurally significant ions. Few fragments associated with the retro‐Diels‐Alder cleavage of the C‐ring characteristic of the underivatized compounds, are observed. The TMS derivatives thus provide complementary information for the identification of flavonoid aglycones and chalcones in biological systems.

Cyclic ions in the mass spectra of trimethylsilyl derivatives of substituted o‐dihydroxybenzenes

AbstractThe mass spectra of trimethylsilyl (TMS) ethers/methyl esters of phenolic acids containing o‐dihydroxybenzene groups have base peaks at [M−119]+ instead of the usual [M−15]+ and [M−31]+ that are characteristic of TMS/methyl esters of monohydroxyphenolic acids. These ions, formed by the loss of 31+88 u from the parent ion, possess a cyclic moiety as proven by substitution of deuterium atoms for hydrogen atoms in the TMS groups of the methyl esters of 3,4,5‐trihydroxybenzoic (gallic), 3,4‐dihydroxybenzoic (protocatechuic) and β‐(3,4‐dihydroxyphenyl)propenoic (caffeic) acids. Although these cyclic ions are the base peaks in TMS‐derivatized o‐dihydroxyphenolic acid esters, similar ions represent intense peaks but not necessarily the base peak in other derivatized compounds such as 1,2‐dihydroxybenzene, 1,2‐dihydroxy‐3‐methyl‐ and 1,2‐dihydroxy‐4‐methyl‐benzenes and flavan‐3‐ols that possess o‐dihydroxybenzene groups. Compounds possession m‐ or p‐dihydroxybenzene groups do not form these cyclic ions; therefore, this procedure for derivatization and interpretation of mass spectra is valuable for the identification of compounds containing o‐dihydroxybenzene groups in complex mixtures of isomeric compounds.

Cytokinins of the Developing Mango Fruit

The cytokinin activity has been isolated and identified from extracts of immature mango (Mangifera indica L.) seeds. The structures of zeatin, zeatin riboside, and N(6)-(Delta(2)-isopentenyl)adenine riboside were confirmed on the basis of their chromatographic behavior and mass spectra of trimethylsilyl derivatives. Both trans and cis isomers of zeatin and zeatin riboside were also identified by the retention times of high performance liquid chromatography. In addition, an unidentified compound appeared to be a cytokinin glucoside.The concentration of cytokinins in the panicle and pulp of mango reached a maximum 5 to 10 days after full bloom and decreased rapidly thereafter. The cytokinin level in the seed remained high until the 28th day after full bloom. The quantity of cytokinins in pulp per fruit increased from the 10th day after full bloom, the maximum being attained around the 50th day after full bloom. Similarly, the amount of cytokinins per seed increased from the 10th day after full bloom, reaching a peak on the 40th day and decreasing gradually thereafter.A high percentage of fruit set in mango was persistently maintained by supplying 6-benzylaminopurine (1.5 x 10(3) micromolar) onto the panicle at the anthesis stage and by supplying gibberellic acid (7.2 x 10(2) micromolar) and naphthalene acetamide (3.1 x 10 micromolar) at the young fruit stage.

Mass spectrometric identification of intermediates in the biosynthesis of cyanogenic glucosides

Mass spectra of trimethylsilyl derivatives of the following compounds, which are related to the biosynthesis of the cyanogenic glucoside dhurrin, are described: tyrosine,N-hydroxytyrosine,p-hydroxyphenylacetaldoxime,p-hydroxyphenylacetonitrile,p-hydroxybenzaldehyde, tyramine,p-hydroxyphenylpyruvic acid oxime, andp-hydroxyphenylpyruvic acid. Accurate mass measurements and metastable transitions support the proposed fragmentation mechanisms. Based on the mass spectrometry data presented, a method is described by which compounds possibly involved as intermediates in the biosynthesis of cyanogenic glucosides can be identified in biosynthetic reaction mixtures.

Cytokinins in tRNA Obtained from Spinacia oleracea L. Leaves and Isolated Chloroplasts

Cytokinin-active ribonucleosides have been isolated from tRNA of whole spinach (Spinacia oleracea L.) leaves and isolated spinach chloroplasts. The tRNA from spinach leaf blades contained: 6-(4-hydroxy-3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine (cis and trans isomers), 6-(3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine, and 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-beta-d -ribofuranosylpurine (cis and trans isomers). A method for isolation of large amounts of intact chloroplasts was developed and subsequently used for the isolation of chloroplast tRNA. The chloroplast tRNA contained 6-(3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine and 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-beta-d -ribofuranosylpurine (the cis isomer only). The structures of these compounds were assigned on the basis of their chromatographic properties and mass spectra of trimethylsilyl derivatives which were identical with those of the corresponding synthetic compounds. The results of this study indicate that ribosylzeatin was present in spinach leaf tRNA, but absent from the purified chloroplast tRNA preparation.

The study and characterization of nucleosides by mass spectrometry. 3. Comparison between the mass spectra of trimethylsilyl derivatives of purine 2'-and 3'-linked anhydro, thioanhydro, and aminoanhydro nucleosides.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCharacterization of nucleosides by mass spectrometry. III. Comparison between the mass spectra of trimethylsilyl derivatives of purine 2'- and 3'-linked anhydrothionanhydro, and aminoanhydro nucleosidesDenis C. K. Lin, L. Slotin, K. K. Ogilvie, and J. B. WestmoreCite this: J. Org. Chem. 1973, 38, 6, 1118–1123Publication Date (Print):March 1, 1973Publication History Published online1 May 2002Published inissue 1 March 1973https://doi.org/10.1021/jo00946a012RIGHTS & PERMISSIONSArticle Views58Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (738 KB) Get e-Alerts Get e-Alerts

Some Aspects of Intra- and Inter-Molecular Reactions of Siliconium Ions in the Vapor Phase

Abstract Intramolecular rearrangement processes in the mass spectra of trimethylsilyl derivatives of hydroxy steroids are discussed in terms of the reaction of a siliconium center and a heteroatom. The reaction is shown to be stereospecific. The reactivity of siliconium cations also results in the occurrence of intermolecular reactions under electron impact ionization conditions. Tetramethylsilane is used as a precursor for the production of siliconium ions and examples of chemical ionization mass spectra employing this reagent are shown.

Mass spectra of trimethylsilyl derivatives of homogeneous cerebrosides (monoglycosylceramides)

Mass spectra of trimethylsilyl derivatives of a series of homogeneous cerebrosides have been recorded. The compounds studied had a d-galactopyranose in β-glycosidic linkage to different ceramides (containing dihydroxy or trihydroxy long-chain base and normal or hydroxy fatty acid). The composition of some fragments was established by high resolution analysis. Molecular ions were found for all compounds ( m/e 863–1265). Fragments of the silylated hexose were of relatively low intensity (at m/e 451, and 451 minus trimethylsilanol at m/e 361). Specific fragments of medium intensity were obtained from primary cleavage of the long-chain base and of a hydroxy fatty acid. Two rearrangement ions were specific for the fatty acid. Fragments of the base plus fatty acid were also obtained. Trimethylsilyl derivatives should therefore be useful in the analysis of long-chain bases and fatty acids and combinations thereof in natural mixtures of cerebrosides.

Mass spectra of trimethylsilyl derivatives of pyrimidine and purine bases.

Mass spectra of trimethylsilyl derivatives of pyrimidine and purine bases.

The mass spectra of the trimethylsilyl derivatives of glycerophosphoric acids. Inter- and intra-molecular rearrangements of siliconium ions

The trimethylsilyl derivatives of several glycerophosphoric acids are taken as model compounds for an investigation of the fragmentation mechanisms producing the characteristic ions present in the mass spectra of trimethylsilyl derivatives of organic phosphates of this type. A considerable number of rearrangement ions formed by migration of hydrogen atoms and/or trimethylsilyl groups are observed. The presence of a fully substituted phosphonium system is thought to contribute to the stability of these ions. A close similarity between the migratory properties of hydrogen atoms and trimethylsilyl groups is apparent. The spectra of the trimethylsilyl derivatives of the diphosphates exhibit ions produced by the interaction and rearrangement of intact trimethylsilyl phosphate groups. Ion–molecule reactions involving the combination of a neutral molecular species with an abundant fragment ion containing a siliconium centre are also observed. These ion–molecule reactions provide additional information regarding the structure of some of the fragment ions.