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Katzenmeyer B.C.,University of Akron | Katzenmeyer B.C.,Valspar Corporation | Cool L.R.,University of Akron | Williams J.P.,Waters Corporation | And 3 more authors.
International Journal of Mass Spectrometry | Year: 2015

Abstract The electron transfer dissociation (ETD) characteristics of doubly sodiated polylactide were investigated at varying ion-ion reaction times, ranging from 20 to 220 ms. ETD product ion yields and signal-to-noise ratio maximized at the shortest reaction time. At longer times, the extent of Na/H or H/Na exchange reactions rose, causing spectral crowding; in addition, the sensitivity decreased significantly due to ion losses from neutralization and scattering. ETD in quadrupole ion trap (QIT) and quadrupole/time-of-flight (Q/ToF) mass spectrometers using fluoranthene and p-nitrotoluene reagent anions, respectively, led to similar product ions. The Q/ToF configuration allowed for collisionally activated dissociation (CAD) of the ETD total ion current under mild activation conditions, which gave rise to new and more abundant fragment distributions by mainly depleting residual reduced precursor ions. The ETD and ETD/CAD fragmentation patterns were markedly different from the fragments generated by simple CAD, thereby providing complementary structural information about the analyzed polyester. The collision cross-sections of the major ETD fragment series, determined by ion mobility mass spectrometry (IM-MS) experiments on the Q/ToF instrument, agreed well with the linear architectures expected from radical-induced cleavages at the (CO)-O-alkyl bonds promoted by the electron added in the ETD event. © 2014 Elsevier B.V. All rights reserved. Source

Oldring P.K.T.,Valspar Corporation | O'Mahony C.,Trinity Technology and Enterprise Campus | Dixon J.,FIG Consultant | Vints M.,Amcor Flexibles Europe and Americas | And 3 more authors.
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2014

The approach used to obtain European Union-wide data on the usage and concentration of substances in different food packaging materials is described. Statistics were collected on pack sizes and market shares for the different materials used to package different food groups. The packaging materials covered were plastics (both flexible and rigid), metal containers, light metal packaging, paper and board, as well as the adhesives and inks used on them. An explanation as to how these data are linked in various ways in the FACET exposure modelling tool is given as well as an overview of the software along with examples of the intermediate tables of data. The example of bisphenol A (BPA), used in resins that may be incorporated into some coatings for canned foodstuffs, is used to illustrate how the data in FACET are combined to produce concentration distributions. Such concentration distributions are then linked probabilistically to the amounts of each food item consumed, as recorded in national food consumption survey diaries, in order to estimate exposure to packaging migrants. Estimates of exposure are at the level of the individual consumer and thus can be expressed for various percentiles of different populations and subpopulations covered by the national dietary surveys. © 2014 Taylor & Francis. Source

Magami S.M.,University of Leeds | Oldring P.K.T.,Valspar Corporation | Castle L.,UK Environment Agency | Guthrie J.T.,University of Leeds
Progress in Organic Coatings | Year: 2015

In this study, the suitability of four chemically different melamino cross-linkers for use in formulating epoxy coatings was investigated on the basis of the composition and of the tendency of cured coatings to hydrolyse to melamine and to formaldehyde when they were retorted in aqueous food simulants. The four cross-linkers were characterised for their composition identity, flow behaviour, thermal stability and for the presence of residual species. The different cross-linkers were used individually to cross-link selected epoxy coatings. The effects of the cross-linker chemistry, the curing conditions and the kinetics of the hydrolysis and subsequent migration processes, leading to melamine and formaldehyde were investigated following thermal treatments that were designed to represent the conditions of food sterilisation. The results show that each cross-linker type is different in its rheological characteristics, its solids content, its thermal behaviour and its physical properties. The chemistry of each cross-linker plays a major role in the manner in which the epoxy coatings undergo hydrolysis to release melamine and formaldehyde. The greatest migration of melamine (from an unpigmented epoxy anhydride coating, cured with the hexamethoxymethyl melamine cross-linker) into the 10% (v/v) aqueous ethanol food stimulant, after retorting at 131 °C, for 1 h was 525 μg/6 dm2. The greatest migration of formaldehyde into the simulant was also from this coating at 11 μg/6 dm2, when retorted at 131 °C for 1 h. The curing conditions affected the extent of the cross-linker hydrolysis. The influence of varying the curing time and the curing temperature was used to control the hydrolysis of the cross-linked, epoxy-based coatings. A decrease in the extent of cross-linker hydrolysis by 50-80% was achieved in all cases as the temperature of the curing was increased, in stages, from 160 °C to 200 °C. © 2014 Elsevier B.V. Source

Fowler J.N.,Syngenta | Kirkwood J.,Valspar Corporation | Wagner N.J.,Syngenta
Applied Rheology | Year: 2014

A novel shear thickening suspoemulsion is formulated and studied with a new rheo-microscope instrument. The experimental fluid system is comprised of a immiscible blend of Newtonian, low molecular weight poly(dimethylsiloxane) and a shear thickening suspension of colloidal silica in poly(ethylene glycol). The blend is studied as a function of composition where phase inversion is evident at low shear rates and is found to be shear rate dependent. A shear thickening viscosity curve is observed when blends comprised of shear thickening fluid dispersed as droplets are subjected to high shear rates. Dispersing a continuously shear thickening fluid, Φsilica = 0.42, results in continuously shear thickening response from the blend. Dispersing a discontinuously shear thickening fluid, Φsilica = 0.51, results in bulk shear thickening that can also be discontinuous. Shear thickening in the final suspoemulsion is consistently first detected at ΦSTF = 0.2, with the magnitude of shear thickening being dependent on the particle concentration in the STF phase. The onset of shear thickening also corresponds with the formation of extended droplet structures in the fluid. The complex properties of these suspoemulsions and the ability to formulate dispersed droplet morphologies in this mixture are shown to result from the underlying shear thickening rheology of the dispersed phase. © Appl. Rheol. Source

Katzenmeyer B.C.,University of Akron | Katzenmeyer B.C.,Valspar Corporation | Hague S.F.,University of Akron | Hague S.F.,University of South Florida | Wesdemiotis C.,University of Akron
Analytical Chemistry | Year: 2016

Mass spectrometry (MS) and tandem mass spectrometry (MS/MS) were interfaced with ultra-performance liquid chromatography (UPLC) and ion mobility (IM) separation to characterize a complex nonionic surfactant, consisting of a methylated glucose core (glucam) conjugated with poly(ethylene oxide) (PEOn) branches that were partially esterified with stearic acid to form ethoxylated glucam (PEOn-glucam) stearates. Reverse-phase LC-MS afforded fast separation according to polarity into five major fractions. Accurate mass measurements of the ions in the mass spectra extracted from these fractions enabled conclusive identification of six components in the surfactant, including PEOn-glucam mono-, di-, and tristearates as well as free and esterified PEOn as byproducts. MS/MS experiments provided corroborating evidence for the fatty acid content in each fraction based on the number of stearic acid losses observed. With IM-MS, the total surfactant ions were separated according to charge and shape into four distinct bands. Extracted mass spectra confirmed the presence of two disaccharide stearates in the surfactant, which were undetectable by LC-MS. PEOn-glucam tristearates were, however, not observed upon IM-MS. Hence, LC-MS and IM-MS unveiled complementary compositional insight. With each method, certain components were particularly well separated from other ingredients (by either polarity or shape), to be detected with confidence. Consequently, combined LC-MS and IM-MS offer a superior approach for the characterization of surfactants and other amphiphilic polymers and for the differentiation of similarly composed amphiphilic blends. It is finally noteworthy that NH4 + charges minimized chemical noise in MS mode and Li+ charges maximized the fragmentation efficiency in MS/MS mode. © 2015 American Chemical Society. Source

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