HD Samples Research Articles

Simultaneous determination of thirteen organophosphate esters in settled indoor house dust and a comparison between two sampling techniques

An analytical method for the simultaneous determination of 13 organophosphate esters (OPEs) in house dust was developed. The method is based on solvent extraction by sonication, sample cleanup by solid phase extraction (SPE), and analysis by gas chromatography–positive chemical ionization–tandem mass spectrometry (GC/PCI–MS/MS). Method detection limits (MDLs) ranged from 0.03 to 0.43μg/g and recoveries from 60% to 118%. The inter- and intra-day variations ranged from 3% to 23%. The method was applied to dust samples collected using two vacuum sampling techniques from 134 urban Canadian homes: a sample of fresh or “active” dust (FD) collected by technicians and a composite sample taken from the household vacuum cleaner (HD). Results show that the two sampling methods (i.e., FD vs HD) provided comparable results. Tributoxyethyl phosphate (TBEP), triphenyl phosphate (TPhP), tris(chloropropyl) phosphate (TCPP), tri(2-chloroethyl) phosphate (TCEP), tris(dichloro-isopropyl) phosphate (TDCPP), tricresyl phosphate (TCrP), and tri-n-butyl phosphate (TnBP) were detected in the majority of samples. The most predominant OPE was TBEP, with median concentrations of 31.9μg/g and 22.8μg/g in FD and HD samples, respectively, 1 to 2 orders of magnitude higher than other OPEs. The method was also applied to the analysis of OPEs in the National Institute of Standards and Technology (NIST) standard reference material (NIST SRM 2585, organic contaminants in house dust). The results from SRM 2585 may contribute to the certification of OPE concentration values in this SRM.

The value of serum FGF-23 as a cardiovascular marker in HD patients

Fibroblast growth factor 23 (FGF-23) is a recently discovered regulator of phosphate and mineral metabolism and has been associated with both progression of CKD and mortality in dialysis patients. To evaluate the association between serum FGF-23 levels and echocardiographic measurements in long-term HD (HD) patients without cardiac symptoms, we studied 90 consecutive patients treated in a single HD center (51 males, 39 females; mean age 41.5 ± 14.2 years, mean HD duration 71.2 ± 14.2 months). Comprehensive echocardiography was performed after HD and blood samples were obtained before HD. The serum FGF-23 level in dialysis patients was 95.7 ± 88.4 pg/mL. In univariate analysis, serum calcium levels (r = 0.33, P <0.05), serum creatinine (r = 0.34, P <0.05), serum albumin (r = 0.35, P <0.05) and left ventricular mass index (LVMI) (r = 0.33, P <0.001) were correlated weakly with the FGF-23 levels. Neither s. phosphorus nor calcium x phosphorus product correlated with FGF-23. In univariate regression analysis, only LVMI [β = 0.42, P <0.05, confidence interval (CI) 0.3-4.3], serum calcium (β= 0.87, P <0.001, CI 0.8-7.3), serum albumin (β= 0.87, P < 0.001, CI 0.8-7.3) and serum creatinine (β= 0.67, P <0.05, CI 0.5-6.5) significantly correlated with FGF-23. FGF-23 was identified as a factor that is weakly associated with LVMI. Thus, FGF-23 alone may not be a parameter that can be used for evaluation of the cardiac status in HD patients.

Analysis of selected phthalates in Canadian indoor dust collected using household vacuum and standardized sampling techniques

Phthalates have been used extensively as plasticizers to improve the flexibility of polymers, and they also have found many industrial applications. They are ubiquitous in the environment and have been detected in a variety of environmental and biological matrices. The goal of this study was to develop a method for the determination of 17 phthalate esters in house dust. This method involved sonication extraction, sample cleanup using solid phase extraction, and isotope dilution GC/MS/MS analysis. Method detection limits (MDLs) and recoveries ranged from 0.04 to 2.93μg/g and from 84 to 117%, respectively. The method was applied to the analysis of phthalates in 38 paired household vacuum samples (HD) and fresh dust (FD) samples. HD and FD samples compared well for the majority of phthalates detected in house dust. Data obtained from 126 household dust samples confirmed the historical widespread use of bis(2-ethylhexyl) phthalate (DEHP), with a concentration range of 36μg/g to 3840μg/g. Dibutyl phthalate (DBP), benzyl butyl phthalate (BzBP), diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP) were also found in most samples at relatively high concentrations. Another important phthalate, diisobutyl phthalate (DIBP), was detected at a frequency of 98.4% with concentrations ranging from below its MDL of 0.51μg/g to 69μg/g.

γ-Diketone Axonopathy: Analyses of Cytoskeletal Motors and Highways in CNS Myelinated Axons

2,5-Hexanedione (HD) intoxication is associated with axon atrophy that might be responsible for the characteristic gait abnormalities, hindlimb skeletal muscle weakness and other neurological deficits that accompany neurotoxicity. Although previous mechanistic research focused on neurofilament triplet proteins (NFL, NFM, NFH), other cytoskeletal targets are possible. Therefore, to identify potential non-NF protein targets, we characterized the effects of HD on protein-protein interactions in cosedimentation assays using microtubules and NFs prepared from spinal cord of rats intoxicated at different daily dose rates (175 and 400 mg/kg/day). Results indicate that HD did not alter the presence of alpha- or beta-tubulins in these preparations, nor were changes noted in the distribution of either anterograde (KIF1A, KIF3, KIF5) or retrograde (dynein) molecular motors. The cosedimentation of dynactin, a dynein-associated protein, also was not affected. Immunoblot analysis of microtubule-associated proteins (MAPs) in microtubule preparations revealed substantial reductions (45-80%) in MAP1A, MAP1B heavy chain, MAP2, and tau regardless of HD dose rate. MAP1B light chain content was not altered. Finally, HD intoxication did not influence native NF protein content in either preparation. As per previous research, microtubule and NF preparations were enriched in high-molecular weight NF species. However, these NF derivatives were common to both HD and control samples, suggesting a lack of pathognomonic relevance. These data indicate that, although motor proteins were not affected, HD selectively impaired MAP-microtubule binding, presumably through adduction of lysine residues that mediate such interactions. Given their critical role in cytoskeletal physiology, MAPs could represent a relevant target for the induction of gamma-diketone axonopathy.

Simultaneous quantitation of parabens, triclosan, and methyl triclosan in indoor house dust using solid phase extraction and gas chromatography-mass spectrometry

An integrated analytical method for the simultaneous determination of five parabens (methyl-, ethyl-, propyl-, butyl-, and benzyl-), triclosan, and methyl triclosan in indoor house dust was developed based on gas chromatographic-mass spectrometric technique (GC/MS). Analytes were extracted from dust samples by sonication. After sample cleanup by solid-phase extraction (SPE), the extracts were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) and then analyzed by gas chromatography coupled with ion trap mass spectrometry operated in multiple reaction monitoring (MRM) mode. For quantitation, isotope-labelled internal standards were used for each corresponding target analyte. Only 0.05 g of dust sample was needed for the analysis. Method detection limits ranged from 6.5 to 10 ng/g, and absolute recoveries from 74% to 92%. The developed method demonstrated good repeatability and reproducibility, with relative standard deviations (RSDs) less than 16% for all the analytes. The analytes were determined in dust samples collected using two vacuum sampling methods from 63 Canadian homes: a sample of fresh or "active" dust (FD) collected using a Pullman-Holt vacuum sampler, and a composite sample taken from the household vacuum cleaner (HD). Methyl paraben, propyl paraben, and triclosan were detected in all HD and FD samples. HD samples yielded median values for methyl paraben, propyl paraben, and triclosan of 1080, 463, and 378 ng/g, respectively, which were comparable to the FD sample medians of 1120, 618 and 571 ng/g. Ethyl paraben was detected at frequencies of 89% in FD and 73% in HD samples, with median values of 52 and 25 ng/g, respectively. Butyl paraben was detected at frequencies of 44% in FD and 75% in HD samples, with median values of <10 and 59 ng/g, respectively. Benzyl paraben and methyl triclosan were not detected in any of the samples collected by either method. Samples collected according to the fresh dust protocol agreed with the household vacuum samples 90% of the time. Widely scattered concentration levels were observed for target analytes from this preliminary set of 63 Canadian samples, which suggests a wide variability in Canadian household exposures to these chemicals.

Distillation of [formula omitted] gas and measurement of spin–lattice relaxation times

The polarization (static or dynamic) of HD material requires very pure HD samples, with H 2 and D 2 impurities concentrations smaller than 0.1%. A new distillation apparatus equipped with a mass spectrometer has been built. It allows reaching such a level of purity and also measurement of the H 2 and D 2 residual concentrations down to 0.05%. The NMR spin–lattice relaxation times T 1 H and T 1 D have also been measured. The apparatus is described as well as the distillation method. T 1 H and T 1 D data as a function of [ H 2 ] and [ D 2 ] concentrations are given, at 0.85 T and 1.8 K.

Towards the polarization of DT molecules

The polarization of D and T nuclei should increase the reactivity of DT molecules in HIIF processes. At IPN Orsay, we have developed the static polarization of HD samples using “brute force” (BF). It has been demonstrated, that the ageing technique or the double distillation allow to get nuclear relaxation times larger than 1 h, even at 1.5 K and 1 T. It is advocated that it is possible to achieve by RF the conventional Dynamic Nuclear Polarization (DNP) of the proton and the deuteron contained in the HD molecule, using HD samples distilled at Orsay and suitably irradiated. The persistence after irradiation of the long nuclear relaxation times resulting from the double distillation has already been demonstrated. If feasible, the DNP of HD would open the possibility to polarize DT, which has the same magnetic structure as HD and is the ideal fuel for HIIF.

Progress in the polarization of HD

The static polarization of HD samples has been achieved using “brute force”, for HD samples purified by double distillation. Proton polarization in excess of 60% and deuteron vector polarization higher than 14% have been reached. It has been demonstrated that the ageing technique allows to get relaxation times at 1.5 K and 1 T larger than a week. It is advocated that the conventional dynamic polarization of HD should be feasible for the proton and the deuteron contained in the HD molecule. This would create the possibility of polarizing DT molecules, increasing their reactivity when used as fuel in HIIF processes.

A discharge investigation of hydrogen and deuterium atom formation, and parahydrogen and orthodeuterium reconversion.

Hydrogen is flowed through a mild tesla-coil discharge and trapped at 3.8 K: New infrared absorptions of H2 are induced by interaction with trapped H atoms and H- anions. High purity parahydrogen and orthodeuterium samples are 1%-9% reconverted depending on the discharge pressure and recombination of atoms. Annealing the solid samples to 7 K reveals growth in p-H2 induced by o-H2, which shows that H atom recombination produces thermal nuclear spin populations. Similar results are found in discharge experiments with HD and on annealing solid HD. The observed increase in induced HD absorption by J = 1, H2 and D2 molecules formed on recombination gives approximately 1% for the H[D] atom concentration in our solid HD samples.

Static and dynamic polarization of HD

The static polarization of HD samples has been achieved using “brute force”, for HD samples purified by double distillation. Proton polarization in excess of 60% and deuteron vector polarization higher than 14% have been reached. It has been demonstrated that the ageing technique allows to get relaxation times at 1.5 K and 1 T larger than a week. It is advocated that the conventional dynamic polarization of HD should be feasible for the proton and the deuteron contained in the HD molecule. This would simplify considerably the machinery presently necessary to perform nuclear physics experiments with HD targets polarized by the static method.

A polarized HD target factory in Europe

Highly polarized hydrogen molecules in the solid phase are of primary interest as “polarized targets” for Nuclear Physics experiments and polarized fuel for Inertial Confinement Fusion (ICF). Within the French–Italian GRAAL collaboration, we are constructing a new Polarized HD Target Factory, implanted at IPN Orsay. It consists of a powerful Dilution Refrigerator (12 μW at 10 mK) equipped with a 16.5 T superconducting magnet and several ancillary cryostats for condensation, storage, transfer and transport of polarized HD samples. The primary objective is to produce polarized HD targets (HYDILE project) for the photoproduction experiments with the GRAAL polarized high energy real photon beams, obtained from backscattering of laser light against the electron stored in the ESRF ring at Grenoble. Production of targets for other sites is forseen. The system will be described and the results already obtained for the static polarization of a HD sample will be given. The possibility to investigate dynamic polarization methods for HD and apply them to DT in order to produce polarized DT fuel for fusion will be discussed.

Abnormal Gene Product Identified in Huntington′s Disease Lymphocytes and Brain

Huntington′s disease(HD) is associated with expansion of an unstable CAG repeat. Using antibodies against the synthetic peptide corresponding to the sequence of HD gene IT15, we have identified the HD gene product in normal lymphocytes as a ≍350kDa protein by immunoblot analysis. Moreover, when a modified SDS-PAGE using a low concentration of methylenbisacrylamide was run longer, abnormal immunoreactive bands larger than normal ones were found exclusively in HD samples. These results demonstrate the existence of the expanded CAG repeat gene product and open a possibility that the expanded polyglutamine stretch may really participate in the pathological process of the CAG repeat diseases.

Interference effects in the spectrum of HD: II. The fundamental band for HD–rare gas mixtures

The absorption spectrum of the fundamental band of HD (λ ≈ 2.7 μm) has been studied at high resolution in mixtures with the rare gases He, Ne, and Ar at low temperatures (77 and 145 K) and moderate densities (&lt;205 amagat). Interference effects that occur between the collision-induced transitions and the dipole-allowed transitions of free HD were analyzed as a function of density and collision-partner. The R(0) and R(1)dipole transitions exhibited large changes in shape and intensity at high densities, but their behaviours were quite different from each other. Like the pure HD samples, the line shapes were well represented by series of Fano profiles, and the density dependences of the lines were well explained by the theory of Herman, Tipping, and Poll. These results should greatly improve the understanding of the physical processes underlying the interference effects.

Temperature-dependent relaxation of CO(v=1) by HD, D2, and He and of D2(v=1) by D2

Rate constants for the vibrational deactivation of CO in collisions with HD, D2, and He have been measured as a function of temperature using the laser excited vibrational fluorescence technique. Throughout the 109–630 °K range, CO–He and CO–HD samples exhibit a single exponential decay, dominated by V–T,R transfer, with rates increasing rapidly with temperature. Typical collision deactivation rate constants at 630 °K are 22.7 sec−1 torr−1 for He and 82.5 sec−1 torr−1 for HD, and, at 109 °K, 0.067 sec−1 torr−1 for He and 0.27 sec−1 torr−1 for HD. At low temperatures, diffusion and radiative decay become important contributions to the observed rates. In CO–D2 mixtures, double exponential decay of CO fluorescence at large D2 mole fractions is obtained, corresponding to rapid V–V transfer between the (v=1) vibrational levels of CO and D2, followed by coupled V–T,R deactivation. The V–V transfer rate (ΔE=−850 cm−1) increases from 0.26 sec−1 torr−1 at 202 °K to 69.4 sec−1 torr−1 at 633 °K. The V–T,R deactivation rate constant for excited CO by D2 is significantly slower than that by HD and H2, going from 0.089 sec−1 torr−1 at 156 °K to 3.7 sec−1 torr−1 at 450 °K, indicating the decreased importance of the rotational states of D2 in the deactivation of CO than hypothesized for H2 and HD. The deactivation of excited D2 by collisions with D2 also increases with temperature, ranging from 0.080 sec−1 torr−1 at 202 °K to 6.9 sec−1 torr−1 at 450 °K.

Resistance of solid HD polarized-proton targets to damage from high-energy proton and electron beams

Solid HD samples, suitable for use as polarized proton targets by virtue of their low ortho-H 2 and para-D 2 impurity concentrations and consequently long proton spin-lattice relaxation times, T 1 H, were irradiated in the 10.4 GeV external beam of the Cornell electron synchrotron and in the 28 GeV extracted proton beam of the AGS synchrotron at Brookhaven National Laboratory. No direct beam-induced depolarization of the protons in HD was observed for integrated particle fluxes up to 10 13/cm 2. The proton beam exposure resulted in a spin-lattice relaxation rate, (T 1 H) rad −1, of 0.9 × 10 −16 s −1 per unit integrated flux (i.e. per particle/cm 2), and the electron beam exposure led to a value about 30% higher, due mostly to the production of secondaries. The T 1 H recovers nearly to its original long value when the sample is melted and refrozen after irradiation, indicating that the principal contribution to (T 1 H) rad − comes from radicals such as atomic H or D and not from symmetry species conversion induced by the beams. After irradiation, annealing of the damage centers was observed at 4.2 K and 4.7 K by monitoring (T 1 H) rad −1 as a function of time. These experiments support the proposed usage, at temperatures between 1 and 4 K, of pure solid HD with long T 1 H as a metastably highly polarized proton target for high energy physics experiments at particle fluxes up to about 10 7 particles/cm 2 s.