Atmospheric pressure ionization mass spectrometry techniques for the analysis of alkyl ethoxysulfate mixtures (original) (raw)
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Atmospheric Pressure Ionization Mass Spectrometry
Analytical Chemistry, 1983
This paper compares two liquid introduction atmospheric pressure ionization techniques for the analysis of alkyl ethoxysulfate (AES) anionic surfactant mixtures by mass spectrometry, i.e., electrospray ionization (ESI) in both positive and negative ion modes and atmospheric pressure chemical ionization (APCI) in positive ion mode, using a triple quadrupole mass spectrometer. Two ions are observed in ESI(ϩ) for each individual AES component, [M ϩ Na] ϩ and a "desulfated" ion [M Ϫ SO 3 ϩ H] ϩ , whereas only one ion, [M Ϫ Na] Ϫ is observed for each AES component in ESI(Ϫ). APCI(ϩ) produces a protonated, "desulfated" ion of the form [M Ϫ NaSO 3 ϩ 2H] ϩ for each AES species in the mixture under low cone voltage (10 V) conditions. The mass spectral ion intensities of the individual AES components in either the series from ESI(ϩ) or APCI(ϩ) can be used to obtain an estimate of their relative concentrations in the mixture and of the average ethoxylate (EO) number of the sample. The precursor ions produced by either ESI(ϩ) or ESI(Ϫ), when subjected to low-energy (50 eV) collision-induced dissociation, do not fragment to give ions that provide much structural information. The protonated, desulfated ions produced by APCI(ϩ) form fragment ions which reveal structural information about the precursor ions, including alkyl chain length and EO number, under similar conditions. APCI(ϩ) is less susceptible to matrix effects for quantitative work than ESI(ϩ). Thus APCI(ϩ) provides an additional tool for the analysis of anionic surfactants such as AES, especially in complex mixtures where tandem mass spectrometry is required for the identification of the individual components. (J Am Soc Mass Spectrom 1999, 10, 529 -536)
Negative ion field desorption mass spectrometry of anionic surfactants
Fresenius Journal of Analytical Chemistry, 1982
Die Felddesorptions-Massenspektrometrie negativer Ionen wurde zur direkten Mischungsanalyse von Detergentien, die anionaktive Tenside enthalten, angewendet. Die Massenspektren zeigen eine hohe Selektivität der Methode für den Nachweis der Sulfonate (Konzentrationsgrenze 10−5 mol/l). Die Spektren enthalten weder Fragmentionen noch Ionisierungsprodukte nichtionischer Komponenten der Mischung. Negative ion field desorption mass spectrometry has been applied to detergents containing anionic surfactants. The mass spectra demonstrate a high selectivity for the detection of the sulphonates (concentration limit 10−5 mol/l). The spectra do not contain fragment ions nor ionization products from non-ionic components of the mixture.
2012
Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) is used to investigate the reaction of non-ionic ethylene oxide based surfactants, with divalent metal ions. The effect of capillary-skimmer potential difference and the ion residence time in the hexapole ion trap in the external ion optic of the FT mass spectrometer were systematically investigated for the single oligomer systems, hexaethylene glycol monodecyl ether (HEGMDE) interacting with the nitrate salts of Cd(II) in methanol. It is observed that these variables impact significantly on the type of ions observed in the ESI experiment and hence the mass spectra and so it is essential to identify their contribution prior to undertaking any binding efficiency experiments. Collision induced dissociation in the capillary skimmer region and by on resonance irradiation is used to investigate structures and fragmentation pathways. In particular the loss of HNO3 in the nitrate salts is a f...
Talanta, 2015
A new paired ion electrospray ionization tandem mass spectrometry method for determination of anionic surfactants in water samples was developed. In this method, dicationic ion-pairing reagents were complexed with monoanionic analytes to facilitate analyte detection in positive mode electrospray ionizationmass spectrometry. Single ion monitoring and selected reaction monitoring on a triple quadrupole instrument were performed and compared. Four dicationic reagents were tested for the determination of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), sodium dodecyl sulphate (SDS), dodecylbenzene sulfonic acid (DBS), and stearic acid (SA), among other common anions. The obtained limits of detection were compared with those from previous literature. Solid phase extraction using a C18 cartridge was performed in order to eliminate matrix interferences. A literature review was compiled for the methods published between 2010 and 2015 for determination of anionic surfactants. The optimized method was more sensitive than previously developed methods with LOD values of 2.35, 35.4, 37.0, 1.68, and 0.675 pg for SDS, SA, DBS, PFOS, and PFOA, respectively. The developed method was effectively applied for the determination of anionic surfactants in different water samples such as bottled drinking water, cooking water, tap water, and wastewater.
Journal of Chromatography A, 2008
Non-derivatized Brij 58 oligomers were analyzed by using non-aqueous capillary electrophoresis (NACE) hyphenated to mass spectrometry (ion trap). The separation of this neutral polyethylene oxide surfactant was based on its complexation with ammonium cation in methanolic medium. Cationic complexes were formed within the capillary and migrated against the anodic electroosmotic flow. The latter was obtained by using a pre-treatment of the capillary with hexadimethrine bromide. By optimizing mass detection and the separation conditions separately, it was demonstrated that two different salts had to be used. Ammonium acetate was used in the sheath liquid to optimize detection sensitivity whereas ammonium iodide was used in the running electrolyte in order to obtain the more appropriate electroosmotic flow for the separation. Despite an aspiration effect due to the hyphenation with MS. that did not allow us to obtain a baseline resolution for the entire mixture, we were able to visualize and characterize more than 25 oligomers of Brij 58. As regards detection sensitivity, the limits of detection (LOD) were estimated at about 7.5 ng for the entire distribution of Brij 58 and 15 pg for C 16 E 5 or C 16 E 6 used as standards.
HPLC Analysis of Aliphatic Sulfonate Surfactants using Ion-Pair Detection
Molecules, 2005
A method was developed for the analysis of a number of surfactants which contained no UV-chromophores, using RP-HPLC with Indirect Photometric Detection, IPD. Pyridinium salts such as N-methylpyridinium iodide, N-methyl-2,2'-dipyridinium iodide and N,N'-dimethyl-2,2'-dipyridinium diiodide, were used as the visualization reagents, forming ion-pair complexes with the sulfonate surfactants. This allowed ordinary UV-detection. N-methylpyridinium iodide proved to be a suitable reagent, both with respect to ease of preparation and response. The eluents consisted of mixtures of acetonitrile and water, being 0.1 -0.25 mM with respect to pyridinium salt. The method was sensitive and exhibited good signal to noise ratios, as well as linear responses over a wide concentration range. All of the analyzed surfactants were separated, including the diastereomeric forms of some of the surfactants.
Capillary Electrochromatography−Mass Spectrometry of Nonionic Surfactants
Analytical Chemistry, 2007
The Triton X (TX)-series are alkylphenol polyethoxylates -type nonionic surfactants of varying numbers of ethylene oxide units. Applications include industrial and household detergent formulations as well as emulsifying agents. For analysis of these surfactants, capillary electrochromatography-electrospray ionization-mass spectrometry (CEC-ESI-MS) offers several unique advantages over the traditional hyphenation methods based on HPLC-MS. These include higher plate numbers attainable in CEC-MS, as well as more compatible flow rate (submicroliter) when coupled to ESI-MS and, perhaps most importantly, less consumption of toxic and costly organic solvents. In this work, different CEC-ESI-MS parameters such as mobile-phase composition, sheath liquid, and spray chamber parameters were optimized to provide suitable and sensitive analysis of short-, medium-, and long-chain length (e.g., n ) 1-16) TX-series nonionic surfactants. The optimized CEC-ESI-MS conditions were mobile phase containing 90/10 ACN/2.5 mM Tris, pH 8, sheath liquid containing 50/50 MeOH/10 mM HCO 2 NH 4 delivered at 5 µL/min, spray chamber set to drying gas flow of 6 mL/ min, nebulizer pressure of 5 psi, and drying gas temperature set to 200°C. This optimization is followed by the more challenging separation of very long chain TX-series with a large number (n ) 30-70) of ethoxy units, which were initially found to exhibit extreme retention using the developed method. It was observed that through the addition of small volume fraction of polar-aprotic tetrahydrofuran solvent to the running buffer, the retention time could be significantly reduced thus enhancing the feasibility for CEC-ESI-MS analysis of these very long chain nonionic surfactants for the first time. The detection limit was ∼37 µg/mL total octylphenol ethoxylate for TX-45; acceptable precision of migration time (<1% RSD, n ) 3) and peak area (∼4% RSD, n ) 3) were achieved.
Selective enhancement of ion signal of charged surfactant in fast atom bombardment mass spectrometry
Journal of Mass Spectrometry, 1995
The addition of sodium dodecylsulfate (SDS) to a glycerol solution containing equal concentrations of a series of quaternary amines has been found to have a significant effect on the relative fast atom bombardment (FAB) response factors for each analyte. The relative FAB signals of quaternary amines with different alkyl chain length were found to be either enhanced or degraded under different SDS concentrations. The effect observed can be correlated with the difference in the rate of ion-pair precipitate formation between negatively charged dodecylsulfate and positively charged quaternary amine. It is also demonstrated that, in much the same way, SDS can be used to enhance the response of the less surface-active component in an industrial dye by FAB analysis.
Analytical Chemistry, 2002
An amphoteric (cocamidopropylbetaine, CAPB) and a nonionic (alcohol polyethoxylate, AE) surfactant were characterized by electrospray ionization quadrupole ion trap mass spectrometry (ESI-MS) as to their homologue distribution and ionization/fragmentation chemistry. Quantitative methods involving reversed-phase gradient HPLC and (+)ESI-MS n were developed to directly determine these surfactants in hydroponic plant growth medium that received simulated graywater. The predominant homologues, 12 C alkyl CAPB and 9 EO AE, were monitored to represent the total amount of the respective surfactants. The methods demonstrated dynamic linear ranges of 0.5-250 ng (r 2 > 0.996) for CAPB and 8-560 ng (r 2 > 0.998) for AE homologue mixture, corresponding to minimum quantification limits of 25 ppb CAPB and 0.4 ppm AE with 20-µL injections. This translated into an even lower limit for individual components due to the polydispersive nature of the surfactants. The procedure was successfully employed for the assessment of CAPB and AE biodegradation in a hydroponic plant growth system used as a graywater bioreactor.