Acid Trimethylsilyl Research Articles

GC-MS-Guided Antimicrobial Defense Responsive Secondary Metabolites from the Endophytic Fusarium solani Isolated from Tinospora cordifolia and Their Multifaceted Biological Properties.

Medicinal plants are hosts to an infinite number of microorganisms, commonly referred to as endophytes which are rich in bioactive metabolites yielding favorable biological activities. The endophytes are known to have a profound impact on their host plant by promoting the accumulation of secondary metabolites which are beneficial to humankind. In the present study, the fungal endophyte, Fusarium solani (ABR4) from the medicinal plant Tinospora cordifolia, was assessed for its bioactive secondary metabolites employing fermentation on a solid rice medium. The crude ABR4 fungal extract was sequentially purified using the solvent extraction method and characterized using different spectroscopic and analytical techniques namely TLC, UV spectroscopic analysis, HRESI-MS, FTIR, and GC-MS analysis. The GC-MS analysis revealed the presence of pyridine, benzoic acid, 4-[(trimethylsilyl)oxy]-trimethylsilyl ester, hexadecanoic acid trimethylsilyl ester, and oleic acid trimethylsilyl ester. The cytotoxic ability of ABR4 was evaluated by MTT assay against lung cancer (A549) and breast cancer (MCF-7) cell lines. The compounds did not exhibit significant cytotoxicity against the tested cell lines. The endophytic ABR4 extract was evaluated for its antimicrobial potential against human pathogens (S. aureus, B. cereus, E. coli, S. typhimurium, P. aeruginosa, and C. albicans) by recording 47 to 54% inhibition. Taken together, the endophytic fungal strain ABR4 demonstrated a remarkable antimicrobial activity against the tested pathogens. Furthermore, the functional metabolites isolated from the endophytic strain ABR4 reveal its broader usage as antimicrobial agents for newer drug development in the pharmaceutical industry.

Benzo[a]pyrene degradation from hydrocarbon-contaminated soil and their degrading metabolites by Stutzerimonas stutzeri (LOBP-19A)

Polycyclic aromatic hydrocarbons (PAHs) are considered as harmful pollutants for the environment and human health system. The most prevalent PAHs in the environment is benzo[a]pyrene when present in high concentrations are potentially hazardous because it is carcinogenic. The objective of the current study was to identify and screen benzo[a]pyrene-degrading bacterial strain that is adapted for various environmental and nutritional requirements in order to determine how well they can decompose the benzo[a]pyrene. The results showed that, after 45 days of incubation at 140 rpm in a temperature-controlled shaker, benzo[a]pyrene (initial concentration of 1000 mg/L) was degraded 87.5% by the isolated strain LOBP-19A at 37 °C, pH 9 in the presence of glucose (1%), and peptone (0.5%) from. Isolated strain performed worse when temperature and pH are different from optimal conditions. Enzymes were screened using bacterial strain (LOBP-1A) and also produced biosurfactant by different method. GCMS studied and characterized metabolites of benzo[a]pyrene of LOBP-19A strain are 1-(3-methylbutyl)-2,3,4,6-tetramethylbenzene, Tetrazole, 1-(2-flourophenyl)-5-[4-(1,1-dimethylethyl) benzythio], 1,4-Benzenediol,2,6-bis(1,1-dimethylethyl)-(CAS), Octadecanoic acid trimethylsilyl ester and 1-naphthalene-sulfonic acid. The isolated strain was identified as Stutzerimonas stutzeri (LOBP-19A) OP389146 based their 16s-rRNA sequencing. Thus the current study demonstrated the great potential of isolated bacterial strain for use in water bodies and field scale bioremediation of benzo[a]pyrene and PAHs contaminated sites.

In-vitro assessment of biological properties and antioxidant activity of leaf extracts of Moringa oleifera L.

Moringa oleifera is native to India and being used as medicinal and nutritive plant for thousands of years. The plant is an important source for essential nutrients and biochemical constituents. The present study is carried out to investigate the biochemical constituents through FT-IR, GC-MS analysis. The antimicrobial and antioxidant activity of the M. oleifera leaves extract are studied using DPPH assay and antimicrobial activity is observed by selecting various indicator microorganisms. In the present study, the methanolic extract is evaluated for its antioxidant activity and free radical scavenging activity was found through DPPH assay. The IC50 value is found to be 275μg/ml. The antimicrobial activity is studied through well diffusion assay and highest inhibitory activity is observed for E. coli and K. pneumoniae. Further, the biochemical constituents are identified through FTIR and GC-MS analysis and the presence of fatty acids such as dodecanoic acid, n-hexadecanoic acid, 11-octadecanoic acid, hexadecanoic acid trimethyl silyl ester and α-Linolenic acid trimethylsilyl ester are found. The fatty acids occupied major portion of the leaves and the other compounds identified through this analysis are diterpenoids, carotenoid pigments, silanes and diterpene alcohol. The leaves consist of a rich source of bioactive components with antimicrobial and antioxidant activity. The carotenoid pigments and omega fatty acids are considered as food supplements for boosting the immunity and also for scavenging of free radicals.

Assessment of insecticidal, phytotoxicity, and fungistatic potential of chemically characterized Elaeis guineensis (Jacq) kernel oil

Palm kernel fixed oil (PKO) extracted by heat (HPKO) and cold-press (CPKO) was evaluated for contact toxicity against Callosobruchus chinensis (L.) at 0–1.5 mL/25 g of cowpea (Vigna unguiculata (L.) Walp) seeds and fungistatic potential against Aspergillus species. In addition, biochemical compounds in the oils were obtained using gas chromatography and mass spectrometric (GC-MS) analysis. One hundred percent mortality of C. chinensis was achieved with ≥1 mL HPKO dose levels while the same mortality was achieved with ≥0.75 mL CPKO dose levels at 24, 48, 72 and 96 h post treatment. Zones of inhibitions (cm) of A. niger (0.93 ± 0.07) and A. flavus (1.27 ± 0.15) with HPKO were comparably higher than zones of inhibitions of A. niger (0.20 ± 0.06) and A. flavus (1.13 ± 0.03) with CPKO. The relative abundance of major compounds in HPKO was Lauric acid > caprylic acid > capric acid while 9-Octadecenoic acid -, 2,3-bis[(trimethylsilyl)oxy]propyl ester > Butanoic acid trimethylsilyl ester > Tetradecanoic acid trimethylsilyl ester in CPKO. The higher percentage of lauric acid in HPKO may account for its greater insecticidal and fungistatic potentials.

Electron ionization mass spectrometric fragmentation and multiple reaction monitoring quantification of ferulic and p-coumaric acid trimethylsilyl derivatives in deposited atmospheric particles.

Ferulic and p-coumaric acids are important biological and structural components of plant cell walls and possess antioxidant and antimicrobial properties. These phenolic acids are widespread in environmental samples. However, when they are present at very low concentrations or in very complex lipid extracts, their identification and quantification can be challenging. The electron ionization mass spectrometry (EI-MS) fragmentation pathways of ferulic and p-coumaric acid trimethylsilyl (TMS) derivatives were investigated. These pathways were deduced by (i) low-energy collision-induced dissociation (CID) gas chromatography (GC)/EI-MS/MS, (ii) accurate mass measurement, and (iii) 13 C labelling. These compounds were then characterized and quantified in multiple reaction monitoring (MRM) mode in total lipid extracts of deposited atmospheric particles using highly specific transitions based on the main fragmentation pathways elucidated. Low-energy CID-MS/MS analyses, accurate mass measurement and 13 C labelling enabled us to elucidate EI-MS fragmentations of ferulic and p-coumaric acid TMS derivatives. Some specific fragmentations proved useful for subsequent characterization and quantification of these compounds. As an application of some of the described fragmentations, trace amounts of these phenolic acids were characterized and quantified in MRM mode in wet- and dry-deposited atmospheric particles containing low proportions of organic matter. EI-MS fragmentations of ferulic and p-coumaric acid TMS derivatives exhibit specific fragment ions that can be very useful for the quantification of trace amounts of both phenolic acids in environmental samples.

Synergistic effect of oilseed cake and biocontrol agent in the suppression of Fusarium wilt in Solanum lycopersicum.

The antagonistic efficacy of a biocontrol agent in combination with oilseed cake against fungal phytopathogens has been sparsely explored. The present study aimed to evaluate the antifungal activity of a biocontrol agent (Trichoderma harzianum MTCC 3928) formulated with oilseed cake (OSC) against Fusarium oxysporum f. sp. lycopersici responsible for causing vascular wilt in Solanum lycopersicum. In in vitro studies, OSC of mustard (Brassica juncea) exhibited significant mycelial inhibition against the pathogen. The volatile plate assay showed mycelial inhibition of 70 and 40% with unautoclaved and autoclaved mustard cakes, respectively. The aqueous extract (10%v/v) of the mustard cake was the most effective with 47.3% mycelial inhibition of pathogen over control. In addition, volatiles and aqueous extract of mustard cake subjected to GC-MS analysis revealed a range of antifungal bioactive compounds with hexanedioic acid, dioctyl ester (16.57%), and oleic acid trimethylsilyl ester (12.41%) being predominant compounds. In in vitro studies, it was noticed that the T. harzianum strain was compatible with mustard cake, and hence used as a growth substrate for its mass multiplication. SEM analysis revealed no distortion in spores and mycelium of T. harzianum grown on the mustard cake. Further, seed germination assay suggested the optimum concentration of mustard cake (10%) supporting the germination rate and economics of formulation development. In in planta assay, the combination of biocontrol agent and mustard cake showed 48% disease reduction, and ~ 40% with T. harzianum alone in comparison to untreated control. Also, the combination of mustard cake and T. harzianum significantly enhanced the growth parameters of S. lycopersicum. The findings of the current study identified an environmentally friendly alternative for mitigation of Fusarium wilt, thereby providing a sustainable option for mitigation of wilt disease and enhancement of plant health.

UPLC-ESI-MS/MS and Various Chromatographic Technique for Identification of Phytochemicals in Populus euphratica Oliv. Leaves Extract

The aim of this study is to screen the phytochemicals found in Populus euphratica leaves since this type of trees are used traditionally by many villagers as treatment for eczema and other skin disease and also this plant is poorly investigated for their phytochemicals especially in Iraq. Phytochemical screening of the extracts obtained from the n-hexane and chloroform fraction of leaves of Populus euphratica was done by Thin-layer chromatography and various spraying reagents to test if alkaloids, sterols and other compounds are present. UPLC-electrospray ionization –tandem mass spectroscopy along with GC-MS and HPTLC are used to identify the phytochemicals present in the plant leaves.UPLC-ESI-MS/MS method 20 compounds have been identified in various fractions among which are protopine alkaloids. salicin, salicortin, tremulacin. GC-MS showed that the observed data obtained are matched with that in NIST library and confirmed the presence of Hexadecanoic acid trimethylsilyl ester in 43.80% beta-Sitosterol in 37.14% and Diisooctyl phthalate 11.46%.UPLC-ESI-MS/MS is a powerful method for the identification of compounds in mixture based on comparison of their molecular, weight retention time and MS/MS fragmentation. Protopine alkaloid is identified for the first time in Populus euphratica and genus Populus. GC-MS is a valuable method for both qualification and quantification of various phytochemicals that are volatile in nature
 Keywords: Populus euphratica, GC-MS, phytochemical, UPLC-ESI-MS/MS

Electron ionization mass spectrometry fragmentation and multiple reaction monitoring quantification of bacterial metabolites of the sea ice biomarker proxy IP25 in Arctic sediments.

3,9,13-Trimethyl-6-(1,5-dimethylhexyl)tetradecan-1,2-diol and 2,8,12-trimethyl-5-(1,5-dimethylhexyl)tridecanoic acid appear to be produced during the bacterial metabolism of IP25 , a highly branched isoprenoid lipid often employed for past Arctic sea ice reconstruction. Characterization and quantification of these metabolites in sediments are essential to determine if bacterial degradation may exert a significant influence on IP25 -based palaeo sea ice reconstructions. Electron ionization mass spectrometry (EIMS) fragmentation pathways of 3,9,13-trimethyl-6-(1,5-dimethylhexyl)tetradecan-1,2-diol and 2,8,12-trimethyl-5-(1,5-dimethylhexyl)tridecanoic acid trimethylsilyl (TMS) derivatives were investigated. These pathways were deduced by: (i) low-energy collision-induced dissociation (CID) gas chromatography/tandem mass spectrometry (GC/MS/MS), (ii) accurate mass measurement, and (iii) deuterium labelling. CID-MS/MS analyses, accurate mass measurement and deuterium-labelling experiments enabled us to elucidate the EIMS fragmentations of 3,9,13-trimethyl-6-(1,5-dimethylhexyl)tetradecan-1,2-diol and 2,8,12-trimethyl-5-(1,5-dimethylhexyl)tridecanoic acid TMS derivatives. Some specific fragment ions useful in addition to chromatographic retention times for further characterization could be identified. As an application of some of the described fragmentations, the TMS derivatives of these metabolites were characterized and quantified in MRM mode in different Arctic sediments. EIMS fragmentations of 3,9,13-trimethyl-6-(1,5-dimethylhexyl)tetradecan-1,2-diol and 2,8,12-trimethyl-5-(1,5-dimethylhexyl)tridecanoic acid TMS derivatives exhibit specific fragment ions, which appear to be very useful for the quantification of these bacterial metabolites of the palaeo tracer IP25 in sediments.

Development of a simple extraction and oxidation procedure for the residue analysis of imidacloprid and its metabolites in lettuce using gas chromatography

Simple extraction and optimised oxidation procedures were developed for the determination of the total residues of imidacloprid and its metabolites (containing the 6-chloropicolyl moiety) in lettuce using a gas chromatography-micro electron capture detector (GC-μECD). Samples were extracted with acetonitrile, and the extract was then evaporated. The remaining residues were dissolved in water and oxidised with potassium permanganate to yield 6-chloronicotinic acid (6-CAN). The acid residues were further dissolved in n-hexane:acetone (8:2, v/v) and then silylated with MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamide) to 6-chloronicotinic acid trimethylsilyl ester. Calibration curves were linear over the concentration ranges (0.025–5μgmL−1) with a determination coefficient (r2) of 0.991. The limits of detection and quantification were 0.015 and 0.05mgkg−1, respectively. Recoveries at two fortification levels ranged between 72.8% and 108.3% with relative standard deviation (RSD) lower than 8%. The method was effective, and sensitive enough to determine the total residues of imidacloprid and its metabolites in field-incurred lettuce samples. The identity of the analyte was confirmed using gas chromatography–tandem mass spectrometry (GC–MS/MS).

Synthesis and some physicochemical properties of the carbazine acid silyl esters

Structure of the dimethylcarbazine acid trimethylsilyl ether and pyrolysis of its derivative, the trimethylsilyl ester of N,N-dimethyl-N′-trimethylsilylcarbazine acid, were studied by the metods of X-ray diffraction and gas chromatography/mass spectrometry. The presence of the bifurcated hydrogen bonds between the trimethylsilyl dimethylcarbazinate molecules was detected. It was revealed why impossible to obtain dimethylaminoisocyanate even by the low-temperature pyrolysis.

Sulfated Zirconia: An Efficient Catalyst for Solvent-Free Synthesis of Silyl Ethers Under Mild Conditions

Oximes, allylic, aliphatic, aromatic, cyclic, acyclic, and hetero alcohols are silylated in short reaction times with good yields in the midst of a catalytic amount of sulfated zirconia solid acid catalyst and trimethylsilyl cyanide under nonbasic, solvent-free, and ambient temperature conditions. Selectivity toward O-silyl ether rather than N-silyl ether has been observed. This simple experimental procedure, combined with easy recovery and reusability of the catalyst, is expected to contribute to the development of a clean and environmentally friendly strategy for the synthesis of O-silyl ethers.

Bimetallic amidinate aluminum methyl complexes: Synthesis, crystal structure and activity for ε-caprolactone polymerization

Four novel bridged-amidines H2L (1,4-R1[C(NR2)(NHR2)]2 (R1=C6H4, R2=2,6-iPr2C6H3 (H2L1), R1=C6H4, R2=2,6-Me2C6H3 (H2L2), R1=C6H10, R2=2,6-iPr2C6H3 (H2L3), R1=C6H10, R2=2,6-Me2C6H3 (H2L4)) were prepared in 65–78% isolated yields by the condensation reaction of dicarboxylic acid with four equimolar amounts of amines in the presence of PPSE (polyphosphoric acid trimethylsilyl ester) at 180°C. Alkane elimination reaction of AlMe3 with 0.5 equivalent of the bridged-amidines (H2L) in THF at room temperature afforded the corresponding bimetallic aluminum methyl complexes Me2AlLAlMe2 (L1 (1), L2 (2), L3 (3), L4 (4)) in 83–93% isolated yields. In order to understand whether the bimetallic complexes could show cooperative effect in the polymerization, their related mononuclear analogues LAlMe2 (L5 (5), L6 (6), L7 (7), L8 (8)) had also been synthesized in 85–91% isolated yields by treatment of AlMe3 with 1 equivalent of amidines HL ([PhC(N-2,6-iPr2C6H3)2]H (HL5), [PhC(N-2,6-Me2C6H3)2]H (HL6), [CyC(N-2,6-iPr2C6H3)2]H (HL7), [CyC(N-2,6-Me2C6H3)2]H (HL8)) in THF at room temperature. All these complexes were characterized by elemental analysis, FT-IR, and NMR spectroscopy. The crystal structures of H2L3, 1, 3, 5 and 7 were determined by X-ray diffraction. In all these amidinate aluminum methyl complexes, Al is four-coordinated by two nitrogen atoms from the dihapto-amidinate ligand and two methyl groups to adopt a distorted tetrahedral geometry. These complexes showed activity towards the ring-opening polymerization of ε-caprolactone at room temperature to give unimodal molecular weight distribution polyesters.

Application of aminopropyltriethoxysilane and N-[2-(aminoethyl)-N-3-(trimethoxysilyl)propyl]amine to the synthesis of linear and heterocyclic compounds

Reaction of 3-aminopropyltriethoxysilane and N-[2-(aminoethyl)-N-3-(trimethoxysilyl)propyl]-amine and their derivatives with diethylcarbamic acid trimethylsilyl ether and trimetisilylisocyanate proceeds through the stage of formation of intermediate products which under conditions of the synthesis undergo intramolecular (in the case of formation O-silylcarbamates) and intermolecular (in the case of the formation of carbamide trimethylsilyl derivatives) desilylation leading to the cyclic and linear products respectively.

Hydrogen and Trimethylsilyl Transfers During EI Mass Spectral Fragmentation of Hydroxycarboxylic and Oxocarboxylic Acid Trimethylsilyl Derivatives

This paper, describing electron ionization mass spectral fragmentation of some hydroxycarboxylic and oxocarboxylic acid trimethylsilyl derivatives, focuses on the formation of fragment ions resulting from the interactions between the two functionalities of these compounds. These interactions result in the formation of fragment ions at [CH2=C(OTMS)2]+., [CH2=CHC(OTMS)=OTMS]+, [M-31]+, [M-105]+, and [M-RCHO]+. in the case of hydroxycarboxylic acid trimethylsilyl derivatives of formula RCHOTMS(CH2)nCOOTMS and at [RC(OTMS)=CH2]+., [RC(=OTMS)CH=CH2]+, and [M-RC(=O)CH2]+ in the case of oxocarboxylic acid trimethylsilyl esters of formula RC(=O)(CH2)nCOOTMS. Some of these fragmentations appeared to be sufficiently specific to be used to characterize these compounds. Several fragmentation pathways involving trimethylsilyl and hydrogen transfers were proposed to explain the formation of these different fragment ions and were substantiated by deuterium labeling.

Elimination of C-8-functional groups from driman-8α,11-diol-11-monoacetate and-diacetate

The dehydration products of driman-8α,11-diol-11-monoacetate that are formed upon reaction with several dehydrating agents and the products from elimination of the C-8 acetoxy group in driman-8α,11-diol diacetate were investigated in detail. A new effective synthesis of drimenylacetate from driman-8α, 11-diol-11-monoacetate by its regioselective dehydration using methanesulfonic acid trimethylsilyl ether was developed.

Imidacloprid residues in fruits, vegetables and water samples from Palestine

The aim of this work was to report on imidacloprid [IUPAC name 1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] residues in some vegetables, fruits, and water samples collected from the West Bank, Palestine, in 1998 and 1999. Imidacloprid and its derivatives in the study samples were extracted by methanol/water and oxidized into 6-chloronicotinic acid and subsequently derivatized into 6-chloronicotinic acid trimethylsilyl ester before being determined by GC/MS. Imidacloprid residues were detected in more than half of the analyzed samples. The highest and lowest imidacloprid concentrations were found in eggplant (0.46 mg/kg) and green beans (0.08 mg/kg), respectively. An increase of 11-120% in imidacloprid concentration in the 1999 samples was observed when compared with those of 1998. This may suggest imidacloprid accumulation in the soil and/or increased use by local farmers. The imidacloprid residue concentrations in several crops were found to exceed the CODEX maximum residue limit.

Polyphosphoric Acid Trimethylsilyl Ester (PPSE) in the Synthesis of Heterocycles

AbstractFor Abstract see ChemInform Abstract in Full Text.

Determination of underivatised sterols and bile acid trimethyl silyl ether methyl esters by gas chromatography–mass spectrometry–single ion monitoring in faeces

A method for quantification of total faecal sterols and bile acids (BAs) in human stool by using gas chromatography–mass spectrometry–single ion monitoring (GC–MS–SIM) is described. Cholesterol, coprostanol, coprostanone, cholestanol, iso-lithocholic acid ( iso-LCA), lithocholic acid (LCA), iso-deoxycholic acid ( iso-DCA), deoxycholic acid (DCA), chenodeoxycholic acid (CDCA), cholic acid (CA), and 12-oxo-deoxycholic acid (12-oxo-DCA) in faeces of 86 healthy subjects were determined. The sample preparation for sterol analysis requires hydrolysis and liquid extraction from matrix, but no derivatisation. The GC-flame ionisation detection (FID) and total ion current (TIC) in GC–MS were not sufficient for sterol and BA determination, whereas selectivity and specificity of the GC–MS–SIM ensured the analysis of sterols and BAs in faeces.

Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry detection: analysis of amino acid and organic acid trimethylsilyl derivatives, with application to the analysis of metabolites in rye grass samples

First, standard mixtures of trimethylsilyl (TMS) derivatives of amino acid and organic acid are analyzed by comprehensive two-dimensional (2D) gas chromatography (GC) coupled to time-of-flight mass spectrometry (GC × GC/TOFMS) in order to illustrate important issues regarding application of the technique. Specifically of interest is the extent to which the peak capacity of the 2D separation space has been utilized and the procedure by which the derivative standards are identified in the 2D separations using the mass spectral information. The resulting 2D separation is found to make extensive use of the GC × GC separation space provided by the complementary stationary phases employed. Second, in order to demonstrate GC × GC/TOFMS on two real sample types, trimethylsilyl metabolite derivatives were analyzed from extracts of common lawn grass samples (i.e., perennial rye grass), as a means to provide insight into both the pre and post harvest physiology. Various chemical components in the two rye grass extract samples were found to either emerge or disappear in relation to the trauma response. For example, a significant difference in the peak for the TMS derivative of malic acid was found. The successful analysis of various components was readily facilitated by the 2D separation, while a 1D separation would have produced too much peak overlap, thus impeding the analysis. The importance of using a GC × GC separation approach for the analysis of complex samples, such as metabolite extracts, is therefore demonstrated. The real-time analysis capability of GC × GC/TOFMS for multidimensional metabolite analysis makes this technique well suited to the high-throughput analysis of metabolomic samples, especially compared to slower, stopped-flow type separation approaches.

Trimethylsilyl transfer during electron ionization mass spectral fragmentation of some omega-hydroxycarboxylic and omega-dicarboxylic acid trimethylsilyl derivatives and the effect of chain length.

The electron ionization (EI) mass spectral fragmentation of omega-hydroxycarboxylic and omega-dicarboxylic acid trimethylsilyl derivatives was investigated. The mass spectra of these compounds exhibited fragment ions resulting from classical fragmentation of the trimethylsilyl ether and ester groups, and others resulting from the interactions between the two functionalities (m/z 147, 204, 217, [M-31](+) and [M-105](+) in the case of omega-hydroxycarboxylic acid derivatives and m/z 147, 204, 217 and [M-131](+) in the case of omega-dicarboxylic acid derivatives). Several fragmentation pathways were proposed to explain the formation of these different fragment ions. It is proposed that the ions at m/z 204 and 217 are formed via an initial trimethylsilyl transfer between the ether and the ester group or between the two ester groups. This transfer appeared to be more favoured in the case of omega-dicarboxylic acid derivatives and to be dependent on the chain length. A more efficient transfer was in fact observed for compounds with a relatively long alkyl chain. In the case of shorter omega-hydroxycarboxylic and omega-dicarboxylic acid trimethylsilyl derivatives the formation of the ions at m/z 204 and 217 suffers strongly from competition from production of the ion at m/z 147.