Matrix‐assisted laser desorption/ionization mass spectrometry of synthetic polymers. VI. Analysis of phenol–urea–formaldehyde cocondensates

Phenolic resoles can be regarded as copolymers of phenol and formaldehyde that are distributed in the chain length and the number of methylol groups per molecule. While other spectroscopic methods like FTIR and NMR only give average structures, MALDI–TOF mass spectrometry is able to resolve the oligomer distribution of phenolic resoles. Using 2,5‐dihydroxybenzoic acid or 2,4,6‐trihydroxyacetophenone as matrices, MALDI–TOF spectra are obtained where each oligomer peak can be assigned to a particular chemical structure. Thus, the degree of polymerization and the number of reactive methylol groups can be determined. For urea‐modified resoles, in addition to phenol–formaldehyde and urea–formaldehyde structures, for the first time, phenol–urea–formaldehyde cocondensate structures can be identified directly. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2540–2548, 2003     

Characterization of the polymer of a dipyrrolyl monomer by pyrolysis mass spectrometry

In this work, characterization of a homopolymer of succinic acid bis(4‐pyrrol‐1‐ylphenyl) ester prepared by galvonastatic polymerization was carried out by direct pyrolysis mass spectrometry. Although decomposition of the monomer yielding mainly butadionic acid and pyrrole occurred under the galvonastatic polymerization conditions, growth of the polymer through the pyrrole moieties was also achieved, yielding a ladder‐type polymer film. The polypyrrole chains contained both quinoid and aromatic units as in the case of polypyrrole, yet the extent of network structure was significantly diminished. A three‐step mechanism is proposed for the thermal decomposition process. The first step involves the cleavage of C₄H₄NC₆H₄O end groups. In the second step, decomposition of phenyl ester units and polypyrrole chains having quinoid structure takes place. The final stage of thermal degradation was attributed to decomposition of polypyrrole chains having aromatic structure. Copyright © 2004 Society of Chemical Industry     

Molar mass distributions of polymers from size exclusion chromatography and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry: Methods for comparison

Equations are presented for calculating molar mass averages and molar mass distributions from matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) data and from size exclusion chromatography (SEC) data. The utility of polydispersity is examined as an indicator of the expectation of MALDI‐TOF MS mass discrimination effects. Cumulative distributions are found to be rich in information for comparing the two techniques and are easily obtained from both SEC and MALDI‐TOF MS data. Analyses of a series of narrow molar mass distribution poly(methyl methacrylate) (PMMA) standards and one polydisperse sample have been performed with both methods. MALDI‐TOF MS did not detect dimer and trimer in the PMMA samples, and it often indicated lower amounts of high‐molar‐mass polymers than did SEC. The results showed that the distribution breadth, as evidenced by the standard deviation of the distribution (calculated from the polydispersity and number‐average molar mass), correlated well with the molar mass range observed in the MALDI‐TOF MS spectra, whereas the polydispersity alone did not. Ratioing the extremes in the molar mass concentrations measured with the SEC differential refractometer, which were necessary to adequately define molar mass distributions, showed that detector dynamic range values as high as approximately 370,000 were required for the polydisperse samples. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 627–639, 2005     

Study on the structure of mangrove polyflavonoid tannins with MALDI-TOF mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is a suitable method for examining polyflavonoid tannin oligomers as it is capable to determine aspects of their oligomeric structure and characteristics, which are otherwise too difficult to determine by other techniques. It has been possible to determine by MALDI-TOF for Rhizophora apiculata mangrove polyflvonoid tannins that: (i) procyanidins oligomers formed by catechin/epicatechin, epigallocatechin, and epicatechin gallate monomers are present in great proportions; (ii) oligomers, up to nonamers, in which the repeating unit at 528–529 Da is a catechin gallate dimer that has lost both the gallic acid residues and an hydroxy group which are the predominant species; (iii) oligomers of the two types covalently linked to each other also occur. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Characterization of polyisobutylene succinic anhydride chemistries using mass spectrometry

Representative Polyisobutylene succinic anhydride (PIBSA) samples have been studied by different MS techniques including Electrospray Ionization Fourier Transform Ion Cyclotron Resonance MS (ESI‐FTMS) (positive and negative modes), Atmospheric Pressure Chemical Ionization Fourier Transform Ion Cyclotron Resonance MS (negative mode), and Matrix‐Assisted Laser Desorption/Ionization Time‐of‐Flight (positive and negative modes). Negative ion ESI‐FTMS produces the best results. Differences between “mono‐succan” and “di‐succan” content can readily be observed. The source of the PIBSA (PIBSA‐I and PIBSA‐II processes) can be easily distinguished and the formation of methyl esters and amide derivatives can provide complementary data. The experiments have demonstrated the capabilities of mass spectrometry to detect and characterize such polymers samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

液相色谱-串联质谱法测定化妆品中多种激素

采用液相色谱-串联质谱法测定化妆品中糖皮质激素、雌激素、雄激素、孕激素等激素的含量。不同形态的化妆品样品以甲醇为提取剂进行超声提取,样品提取液离心后得到上清液经HLB固相萃取小柱净化,用Agilent ZORBAXEclipse XDB-C18柱(1.8μm,2.1 mm×50 mm),乙腈-水作为流动相,梯度洗脱,流速0.3 mL/min,柱温25℃,进样量2.0μL,糖皮质激素、雄激素、孕激素采用正离子扫描模式,雌激素采用负离子扫描模式,多反应监测测定。化妆品样品平均加标回收率为72.31%~97.89%,相对标准偏差为2.24%~11.34%,方法检出限为0.002 mg/kg~0.8 mg/kg。     

Structure of resorcinol,phenol, and furan resins by MALDI‐TOF mass spectrometry and 13C NMR

The structure of traditional, linear phenol–resorcinol–formaldehyde (PRF) resins, urea‐branched PRF resins, and phenol–resorcinol–furfural (PRFuran) resins has been investigated in depth by both matrix‐assisted laser desorption/ionization time of flight (MALDI‐TOF) mass spectroscopy and ¹³C NMR. The structure of a variety of oligomers has been obtained, and the structures present in each of the three types of resins related to the very different percentages of resorcinol needed for their equal performance as adhesives. The oligomers type and species distribution appeared very different for each case. PRF resins performance is improved by maximizing either the proportion of resorcinol‐containing oligomers or methylol‐groups containing oligomers, even without any resorcinol, or both. It is equally obtained by the minimization of the relative proportion of the low reactivity Phenol (CH₂ Phenol) species in which resorcinol is not present, this being the most important parameter. This can be obtained by more effective use of the resorcinol by just modifying the resin manufacturing procedure. This parameter instead does not appear to be determinant in PRFuran resins. In these, it is the higher molecular weight of furfural in relation to formaldehyde that engenders for the same manufacturing procedure a correspondingly lower proportion of resorcinol in the resin. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2665–2674, 2004     

Synthesis of G0 aminopolyol and aminosugar dendrimers,controlled by NMR and MALDI TOF mass spectrometry

Organic compounds designed to serve as stable dendrimer cores were developed. A series of aminosugar and amino polyol containing G0 dendrimers were synthesized. The reaction mixture composition was checked by MALDI TOF mass spectrometry, while that of purified products – by ¹H and ¹³C NMR combined with 2D NMR spectroscopy as well as MALDI TOF MSMS mass spectra. Mass spectrometric fragmentation experiments were performed in positive ion mode in order to determine common fragmentation patterns of [M+H]⁺ ions.     

Matrix-assisted laser desorption/ionization imaging mass spectrometry

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a powerful tool that enables the simultaneous detection and identification of biomolecules in analytes. MALDI-imaging mass spectrometry (MALDI-IMS) is a two-dimensional MALDI-mass spectrometric technique used to visualize the spatial distribution of biomolecules without extraction, purification, separation, or labeling of biological samples. MALDI-IMS has revealed the characteristic distribution of several biomolecules, including proteins, peptides, amino acids, lipids, carbohydrates, and nucleotides, in various tissues. The versatility of MALDI-IMS has opened a new frontier in several fields such as medicine, agriculture, biology, pharmacology, and pathology. MALDI-IMS has a great potential for discovery of unknown biomarkers. In this review, we describe the methodology and applications of MALDI-IMS for biological samples.     

Mass spectrometry/mass spectrometry: capabilities and applications to fuel-related materials

The expanding capabilities of mass spectrometry/mass spectrometry (m.s.-m.s.) in mixture analysis and its applications to fuel-related materials are illustrated. High and low collision energy m.s.-m.s. data obtained on reverse geometry and triple quadrupole spectrometers are given for coal-derived liquid (SRC II) and diesel particulate samples. The direct analysis capability of the m.s.-m.s. methodology and its limitations are illustrated for the identification of an aliphatic carboxylic acid in diesel paniculate. The selective ionization techniques of ammonia chemical ionization and negative chemical ionization are shown to be particularly useful in enhancing the specificity of m.s.-m.s. characterizations. Negative chemical ionization is used to confirm the presence of hydroxybenzoic acid in a diesel particulate sample. Combined laser desorption-chemical ionization is also demonstrated to be an effective ionization technique in m.s.-m.s. analysis. A variant of m.s.-m.s., in which selected anions fragment with charge inversion to give fragment cations, is also employed in the analysis of SRC II and used to identify thioaryl moieties. Functional group screening by an alternative m.s.—m.s. scan procedure, neutral loss scanning, is demonstrated for phenols in SRC II. A scan for all parent ions of a selected daughter ion provides a screening procedure for rapidly identifying all compounds of a given structural type in a complex mixture. The dependence of m.s.-m.s. spectra on collision energy and pressure is shown to add further detail to m.s.—m.s. analysis. The development of a library of m.s.—m.s. spectra of reference compounds to be used for the identification of individual constituents in fuel-related materials is described.     

Analysis of tocopherols by capillary supercritical fluid chromatography and mass spectrometry

Tocopherol-containing mixtures were analyzed by gas chromatography (GC) and capillary supercritical fluid chromatography (SFC). GC analysis of tocopherols required the formation of the silyl derivatives, while SFC analysis of the tocopherol-containing mixtures was accomplished on neat samples. SFC analysis conditions were optimized with respect to column type and density/pressure programming. Enhanced resolution of many components was achieved by using inverse temperature programming during the SFC analyses. Both SFC and GC analyses permitted the separation and quantitation of alpha-, beta-, gamma- and delta-tocopherols. In addition, SFC proved particularly applicable for characterizing the composition of a deodorizer distillate and commercial antioxidant formulation. Coupling of a quadrapole mass spectrometer with a supercritical fluid chromatograph was also achieved; the mass spectrometer provided electron impact mass spectra on the underivatized tocopherol and sterol moieties. Both SFC and SFC/mass spectrometry proved effective for the analysis of complex lipid-containing mixtures, requiring minimal sample preparation prior to analysis. Presented at the 82nd Annual Meeting of the American Oil Chemists’ Society, Chicago, IL, May 12–15, 1991.     

液相色谱-质谱联用法检测化妆品中添加的喹诺酮类药物

建立同时测定化妆品中的喹诺酮类抗生素(依诺沙星、氟罗沙星、氧氟沙星、诺氟沙星、培氟沙星、环丙沙星、恩诺沙星、沙拉沙星、双氟沙星、莫西沙星)的液相色谱-串联质谱法。方法样品以2%甲酸-乙腈(体积比15∶10)溶液超声提取,离心分离,以0.2%甲酸水-乙腈溶液为流动相,LCMS/MS测定喹诺酮类抗生素的含量。结果该方法的线性范围为1～50μg/g,相关系数>0.998,加标1～40μg/g时,回收率为84.3%～99.2%,RSD为0.5%～8.5%,检出限为0.1～0.2μg/kg。结论该方法灵敏、快速、准确,适用于化妆品中喹诺酮类抗生素的检测。     

Thermal characterisation of polymeric systems by mass spectrometry

The utility of mass spectrometry as a technique for the characterisation of polymeric formulations is discussed in general terms. The use of thermal techniques in which sufficient energy is given to the system to liberate volatile components of the formulation and, in some cases, to induce small amounts of polymer degradation, is described. Results obtained using this technique for a variety of polymer systems are discussed and the advantages of using this approach outlined. Recent developments in field desorption-mass spectrometry for the direct characterisation of modern polymer systems are discussed and some early results presented.     

Surfactant analysis by matrix-assisted laser desorption time-of-flight mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to characterize nonionic, anionic and cationic surfactants. Rapid mass analyses can be achieved with proper choice of matrix material. The technique is suitable for development as a routine analytical tool.     

Analysis of flame structure by molecular-beam mass spectrometry using electron-impact and synchrotron-photon ionization

Molecular-beam mass spectrometry (MBMS) has proven to be a powerful tool for the general analysis of flame structure, providing concentrations of radical and stable species for low-pressure flat flames since the work of Homann and Wagner in the 1960’s. In this paper, we will describe complementary measurements using electron-impact ionization with a high-mass-resolution quadrupole mass spectrometer and vacuum-ultraviolet photoionization in a time-of-flight mass spectrometer. Isomers are resolved that have not been separately detectable before in MBMS studies of flames, including C₃H₂, C₃H₄, C₄H₃, C₄H₄, C₄H₅, C₆H₆, and C₂H₄O. The qualitative and quantitative results of MBMS have led to advances in modeling and applying flame chemistry. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 6, pp. 58–63, November–December, 2006.     

Quantitation of alcohol ethoxylate surfactants in environmental samples by electrospray mass spectrometry

This report describes a method for obtaining the concentrations of the total and individual alcohol ethoxylate (AE) species in sewage treatment plant (STP) effluents by using electrospray liquid chromatography/mass spectrometry (LC/MS). This is a more advantageous method for quantitative analysis of AE in environmental matrices as compared with a previous thermospray LC/MS method. This new method is more sensitive, uses less solvents, utilizes a deuterated internal standard blend [C₁₃D₂₇O(CH₂CH₂O) _n H, where n varies from 0 to 21 with an average of n=9], which corresponds more closely to the AE, and it is a more robust instrumental technique. In this report, we document the results for validation of the electrospray LC/MS method by spike recovery of AE from STP effluent and influent samples.     

Deciphering the structure of itaconate‐based unsaturated polyester resins by high resolution mass spectrometry

Unsaturated polyester (UP) resins are widely used to manufacture composite materials and fulfil a wide panel of specification for industrial or domestic applications at low cost. These resins consist of a highly viscous polyester oligomer and a reactive diluent, which allow their processability and crosslinking. The oligomers are synthesized from diols and saturated or unsaturated diacids. Maleic anhydride is classically used as an unsaturated acid because of its reactivity for esterification and its competitive cost. However, maleic anhydride is petroleum based and classified as skin and respiratory sensitizing by the European Chemicals Agency. Itaconic acid which is recognized as one of the top 12 biobased molecules by the US Department of Energy is a biobased alternative with a reactive unsaturation. In this work, a UP based on propylene glycol, itaconic acid and dimethyl terephthalate was synthesized by polycondensation and characterized by high resolution mass spectroscopy, ¹H, ¹³C 1D and 2D NMR as well as ion mobility spectrometry mass spectrometry. The main structures were linear but cyclic species and a few branched chains due to the intermolecular Ordelt reaction were also detected by NMR and high resolution mass spectroscopy. Molecular modelling has indeed demonstrated that itaconate‐based UPs are more prone to cyclization than fumarate‐based UPs. Moreover, NMR analysis showed a significant consumption of itaconate unsaturation by the Ordelt reaction. Ion mobility spectrometry mass spectrometry allowed an additional structure to be distinguished for the same m/z peaks first attributed to a linear structure only. These results suggest the existence of cyclic species based on an intramolecular Ordelt reaction. © 2020 Society of Chemical Industry     

Considerations on the macromolecular structure of chestnut ellagitannins by matrix‐assisted laser desorption/ionization‐time‐of‐flight mass spectrometry

The rather novel picture of chestnut wood tannin, in situ in the wood, which emerges from matrix‐assisted laser desorption/ionization‐time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) is that of a pervasive and extended random tridimensional macromolecular network, formed by pentagalloylglucose clusters linked to each other, to form chains and encrust the wood constituents matrix. Up to pentagalloylglucose trimers were identified in the MALDI‐TOF analysis of the commercial chestnut tannin extract, which were clearly degradation products of more extensive chains likely to be present in situ in the wood before extraction, in the network through polygallic/polyellagic chains or flavogallonic acid bridges. The hydrolyzable chestnut tannin network is capable of being extracted, to yield the commercial chestnut tannin extract exclusively by its degradation, a degradation that is possible only because of the susceptibility to hydrolysis of the ester bridges holding the network together. Internal rearrangements of the fragments formed by the extraction appear to occur readily and with ease, to yield a variety of structures characterized by the presence of ellagic acid residues, flavogallonic acid residues, and also, but less readily, nonahydroxytriphnoic acid residues. The other main constituents of the commercial tannin extract, castalagin and vescalagin, are shown to be simply the more stable degradation plus internal rearrangement products derived from the hydrolysis of polypentagalloylglucose chains. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 429–437, 2002     

Quick identification of polyterephthalate in laundry detergents by simultaneous pyrolysis methylation-gas chromatography/mass spectrometry

This report summarizes method development for the identification of polyterephthalates using simultaneous pyrolysis methylation-gas chromatography with mass spectrometry. Ground detergent products are directly pyrolyzed together with the methylation reagent tetramethylammonium hydroxide. Key fragments separated via gas chromatography are detected by a mass selective detector. Trace levels of polyterephthalates in laundry detergent products were identified within 20 min without interference from surfactants or other organics. Detection limit was 0.05% by weight in product.     

The characterization of polyaniline and polypyrrole composites by pyrolysis mass spectrometry

In this work, direct insertion probe pyrolysis mass spectrometry technique was applied to investigate the thermal and structural characteristics of electrochemically prepared polyaniline (PANI), polypyrrole (PPy), and their composites/copolymers synthesized either by electrochemical polymerization of pyrrole on PANI‐coated electrode (PANI/PPy) or by coating PANI on PPy (PPy/PANI) in H₂SO₄ solutions. It has been determined that the polymer first coated on the electrode degraded to a certain extent during the polymerization of the second. The extent of degradation was greater for PPy and increased with the increase in acid concentration. On the other hand, the detection of mixed dimers confirmed copolymer formation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009