Low Blank Preconcentration Technique for the Determination of Lead, Copper, and Cadmium in Small-Volume Seawater Samples by Isotope Dilution ICPMS

A simple low-blank method is described for the analysis of Pb, Cu, and Cd in seawater using Mg(OH)(2) coprecipitation and isotope dilution inductively coupled plasma mass spectrometry (ICPMS). Here, 20-40 μL of 9 M aqueous NH(3) is mixed into a 1.3 mL seawater sample spiked with enriched isotopes of Pb, Cu, and Cd. After centrifugation, the supernatant is discarded and the Mg(OH)(2) precipitate dissolved in 100 μL of 5% HNO(3) for ICPMS analysis. This method is simple, accurate, and precise, with detection limits of Pb = 1.3 pM, Cu = 39 pM, and Cd = 5.0 pM and blanks of Pb = 0.62 pM, Cu = 27 pM, and Cd = 6.0 pM. The method is demonstrated by oceanographically consistent profiles of these trace metals at an ocean station in the eastern North Atlantic.     

Radio Isotope Method for Rapid Determination of Proppant Concentration in Working Mixtures Used in Hydraulic Fracturing of Oil and Gas Containing Strata

A radio isotope method for rapid determination of proppant concentration and a test measurement unit RIKP-01 constructed on the basis of it provides a relative error in determining proppant concentration of not more than ± 3.5% with a measurement time of 15 sec that is four times better than for the world leader, i.e., the firm Halliburton (USA).Translated from Izmeritel’naya Tekhnika, No. 3, pp. 68–70, March, 2005.     

微波消化-原子吸收光谱法测定中成药中Cu、Pb、Hg、As

本文建立了微波消化-原子吸收光谱法测定中成药中Cu、Pb、Hg、As的方法。四种元素方法的相对标准偏差RSD％为2-4.8％,回收率在90～110％之间,定量检出限分别为6.8μgCu/g(干态)、0.41μg Pb/g(干态)、0.13μg As/g(干态)、0.1μg Hg/g(干态)。     

Fast Marching Method for Microseismic Source Location in Cavern-Containing Rockmass: Performance Analysis and Engineering Application

Microseismic (MS) event locations are vital aspect of MS monitoring technology used to delineate the damage zone inside the surrounding rock mass. However, complex geological conditions can impose significantly adverse effects on the final location results. To achieve a high-accuracy location in a complex cavern-containing structure, this study develops an MS location method using the fast marching method (FMM) with a second-order difference approach (FMM2). Based on the established velocity model with three-dimensional (3D) discrete grids, the realization of the MS location can be achieved by searching the minimum residual between the theoretical and actual first arrival times. Moreover, based on the calculation results of FMM2, the propagation paths from the MS sources to MS sensors can be obtained using the linear interpolation approach and the Runge–Kutta method. These methods were validated through a series of numerical experiments. In addition, our proposed method was applied to locate the recorded blasting and MS events that occurred during the excavation period of the underground caverns at the Houziyan hydropower station. The location results of the blasting activities show that our method can effectively reduce the location error compared with the results based on the uniform velocity model. Furthermore, the obtained MS location was verified through the occurrence of shotcrete fractures and spalling, and the monitoring results of the in-situ multipoint extensometer. Our proposed method can offer a more accurate rock fracture location and facilitate the delineation of damage zones inside the surrounding rock mass.     

一种新型萃取装置及其在水样挥发酚测定中的应用

本文介绍一种新型萃取装置,由磁力搅拌器、三角烧瓶和经改造的活塞组成。此装置已用于挥发酚的测定中。大量实验数据表明,该装置优于常规分液漏斗,克服了使用分液漏斗中常见的易漏、重现性差、工作强度大等缺点。其准确度,重现性,工作曲线相关性均较好,是一种可以取代分液漏斗,用于各类常规分析的理想玻璃仪器。     

Precise Three-Dimensional Deformation Retrieval in Large and Complex Deformation Areas via Integration of Offset-Based Unwrapping and Improved Multiple-Aperture SAR Interferometry: Application to the 2016 Kumamoto Earthquake

Conventional synthetic aperture radar (SAR) interferometry (InSAR) has been successfully used to precisely measure surface deformation in the line-of-sight (LOS) direction, while multiple-aperture SAR interferometry (MAI) has provided precise surface deformation in the along-track (AT) direction. Integration of the InSAR and MAI methods enables precise measurement of the two-dimensional (2D) deformation from an interferometric pair; recently, the integration of ascending and descending pairs has allowed the observation of precise three-dimensional (3D) deformation. Precise 3D deformation measurement has been applied to better understand geological events such as earthquakes and volcanic eruptions. The surface deformation related to the 2016 Kumamoto earthquake was large and complex near the fault line; hence, precise 3D deformation retrieval had not yet been attempted. The objectives of this study were to ① perform a feasibility test of precise 3D deformation retrieval in large and complex deformation areas through the integration of offset-based unwrapped and improved multiple-aperture SAR interferograms and ② observe the 3D deformation field related to the 2016 Kumamoto earthquake, even near the fault lines. Two ascending pairs and one descending the Advanced Land Observing Satellite-2 (ALOS-2) Phased Array-type L-band Synthetic Aperture Radar-2 (PALSAR-2) pair were used for the 3D deformation retrieval. Eleven in situ Global Positioning System (GPS) measurements were used to validate the 3D deformation measurement accuracy. The achieved accuracy was approximately 2.96, 3.75, and 2.86 cm in the east, north, and up directions, respectively. The results show the feasibility of precise 3D deformation measured through the integration of the improved methods, even in a case of large and complex deformation.     

Determination of Pentachlorophenol and Its Oil Solvent in Wood Pole Samples by SFE and GC with Postcolumn Flow Splitting for Simultaneous Detection of the Species

An alternative approach is described for the measurement of pentachlorophenol (PCP) and its oil solvent in wood samples by supercritical fluid extraction (SFE) and gas chromatography (GC). The determination is achieved over a single chromatographic run using postcolumn flow splitting for simultaneous ECD/FID detection of the SFE extracted species. First, PCP and oil components are quantitatively extracted from a 0.3-g wood sample using 10% MeOH/CO(2) supercritical fluid at 0.65 g/mL and 120 °C. An aliquot of the SFE solution is then mixed with 10 mL of a buffered aqueous phase at pH 9.4. After PCP is acetylated by the addition of 500 μL of acetic anhydride, it is followed by its extraction with 2.00 mL of hexane along with oil. Then, 0.5 μL of supernatant organic phase is injected into the GC for a selective and simultaneous determination of the species. The method has a linear response over 3 orders of magnitude for both species with a linear regression correlation coefficient higher than 0.98 (95% confidence limit) and an absolute detection limit of 60 ng of PCP and 80 μg of oil per 0.1-g wood sample. The precision (relative standard deviation) is 4% for PCP and 1% for oil as established for a typical average concentration sample. The accuracy of the SFE GC-ECD/FID combined technique for PCP and oil was assessed by analyzing wood samples collected from newly and in-service PCP/oil-impregnated red pine poles.     

Experimental Setup and Standardization of a Continuous Flow Stable Isotope Mass Spectrometer for Measuring Stable Isotopes of Carbon,Nitrogen and Sulfur in Environmental Samples

We present here the experimental setup and standardization of a newly acquired stable isotope ratio mass-spectrometer (Isoprime 100, Isoprime^® UK) coupled with elemental analyzer (Pyrocube, Elementar^®-Germany) in a continuous flow mode, for the measurements of C, N and S isotopes in a variety of natural as well as synthetic organics and sulfur containing solid samples. We have calibrated our instrument using a suite of certified international standards supplied by International Atomic Energy Agency Vienna and cross-checked against several in-house laboratory standards used by other institutions of international repute. A synthetic organic compound Sulfanilamide was continuously used along with international standards to develop an in-house internal laboratory standard for the accurate and precise isotopic measurements. Important components contributing to the overall uncertainty of the isotopic measurements such as blank contributions, amount effect and response of mass-spectrometric current against thermal conductivity detector were performed using several aliquots of ε-Amino-n-caproic acid and sulfanilamide (in-house) standards. Both short and long term variabilities in the measure isotopic data were assessed using our in-house laboratory standard Sulfanilamide. Overall estimated uncertainties of C, N and S isotopic measurements are better than 0.2, 0.2 and 0.3 ‰, respectively; which are well within the recommended limits of aforementioned isotopic data.     

Validation of a Capillary Zone Electrophoresis Method for Determination of Rimantadine Hydrochloride in Rimantadin100 Tablets and the Method Application to Dissolution Test Monitoring

A capillary zone electrophoretic method with indirect UV‐detection for determination of rimantadine, an antiviral drug against influenza A, in tablets was validated. Instrumental precision, the method precision, accuracy, calibration curve linearity, selectivity, robustness, and time stability of the sample and the standard were tested. The method was also applied to monitor dissolution tests of the tablets. The possibility of addition of an internal standard for improvement of the method precision was discussed.     

High Temperature Superconductivity Due to a Long-Range Electron–Phonon Interaction, Application to Isotope Effects, Thermomagnetic Transport and Nanoscale Heterogeneity in Cuprates

Strong electron–phonon (e–ph) interaction in cuprates and other high-temperature superconductors has gathered support over the last decade in a large number of experiments. I briefly review the “Fröhlich–Coulomb” multi-polaron model of high-temperature superconductivity, which includes strong onsite repulsive correlations and the long-range Coulomb and e–ph interactions. The extension of the BCS theory to the strong-coupling regime with a long-range unscreened e–ph interaction naturally explains the isotope effects, unconventional thermomagnetic transport, and checkerboard modulations of the tunnelling density of states (DOS) in cuprates.     

A Non-destructive FTIR Method for the Determination of Ammonium and Sulfate in Urban PM<Subscript>2.5</Subscript> Samples

Traditionally, the atmospheric particle composition is analyzed using destructive methods. In general, the destructive methods lead to the destruction of the samples, higher cost of the analysis and larger analysis time. In view of aforesaid, in current work, we present a method for the non-destructive analysis of atmospheric particles using open path-Fourier transform infrared spectroscopy (OP-FTIR). The developed method has been used for the measurement of ammonium and sulfate in atmospheric particles without destroying the samples. Here, we targeted the said species because of their relative importance for air pollution episode formation. Particulate sulfate plays a major role in formation of haze. However; particulate acidity is an important factor in this process, which is governed by particulate ammonium concentration. Therefore, both SO₄^2? and NH₄⁺ are important as far as atmospheric chemistry of haze formation is concerned. In the present study, the qualitative and quantitative estimation of ammonium and sulfate ions in PM_2.5 (particulate matter with aerodynamic diameter less than 2.5 µm) was carried out using OP-FTIR with the developed method. The seasonal average concentration of NH₄⁺ and SO₄^2? were measured to be 12.00 ± 5.80, 31.71 ± 12.71 µg/m³ respectively for winters, 3.00 ± 0.85 and 8.00 ± 2.28 µg/m³ respectively for summers and 2.60 ± 1.90 and 7.00 ± 5.21 µg/m³ respectively for monsoon season. The observed results are found to be in good agreement with that of other studies using destructive methods.     

A Method for Determining the Isotope Composition of U, Pu, Am, and Cm in "Hot" Particles and Spent Nuclear Fuel

A method was proposed for determining the content of ^234-238U, ^238-242Pu, ^241-243Am, and ^242-244Cm in "hot" fuel particles and spent nuclear fuel. The method is based on high-precision measurement of the -activity in the sample and calculation of the relative contributions of individual nuclides or radionuclide groups to the total activity. Partitioning of U, Pu, Am, and Cm was carried out by ion-exchange chromatography. The contents of ²³⁴U, ²³⁶U, ²³⁸U, ²³⁸Pu, ^239+240Pu, ²⁴²Pu, ²⁴¹Am, ^242mAm, ²⁴³Am, ²⁴²Cm, and ²⁴⁴Cm in "hot" particles sampled in the Chernobyl area were reported. The applicability of the method proposed to determining the radionuclide composition of spent nuclear fuel was discussed.     

Development of a Solid Phase Carbon Trap for Simultaneous Determination of PCDDs, PCDFs, PCBs, and Pesticides in Environmental Samples Using SFE-LC

The purpose of this study was to find materials that can be used as a solid phase trap in a commercial supercritical fluid extraction instrument. PX-21 active carbon mixed with ODS proved to yield the best results. After SFE of the target compounds, the planar fraction containing the environmental pollutants PCDDs, PCDFs, and planar PCBs was successfully separated on a PX-21 solid phase trap from the nonplanar fraction containing the other PCBs and pesticides. Direct injection of the concentrated fractions on GC/MS was possible without further cleanup. SFE followed by on-line carbon column chromatography was tested using standard solutions (applied on filter paper) as well as biological samples (human adipose tissue).     

High Performance Liquid Chromatographic Method for the Determination of Diphenhydramine in Liquid and Solid Drug Dosage Forms and Its Application to Stability Testing

Abstract

A simple, precise, rugged, stability-indicating method for diphenhydramine in liquid and solid drug preparations based on reversed phase ion-pair HPLC is described. The eluent used with the C8-bonded phase column, was acetonitrile/0.005 M aq. hexanesulfonic acid/acetic acid (70/30/1,v/v). The liquid product was simply dissolved in acetonitrile/water/acetic acid (70/30/1,v/v) and filtered; the solid product was briefly ground, dissolved in the same solvent, and filtered. The precision (rsd) of the method for diphenhydramine in the liquid sample is 0.52%, and 0.50% for the solid sample. The method is linear up to 200 μg/mL. Based on spiking studies, the recoveries are 100.1% for the liquid sample, and 99.2% for the solid sample. The method was applied to the study of the thermal stability of the drug by following the degradation of diphenhydramine in the two products at temperatures in the 42°C to 62°C range for up to 16 weeks. Shelf lives of the products were determined assuming zero and first order kinetics of decomposition, and are at least 163 days for the liquid product, and at least 255 days for the solid product.     

Time-efficient method for the determination of 210Pb, 210Bi, and 210Po activities in seawater using liquid scintillation spectrometry

A novel method has been developed for determining the natural decay series radionuclides (NDS), 210Pb, 210Bi, and 210Po, in seawater by way of state-of-the-art liquid scintillation spectrometry. For 210Pb analysis, the method makes use of a 212Pb yield tracer, prepared by ion exchange separation from aged Th(NO3)4. 210Bi recovery is determined using 207Bi as the yield tracer, and 210Po is determined using the conventional 208Po yield tracer. The limits of detection for this method are 0.32, 0.34, and 0.004 mBq 1-1 for 210Pb, 210Bi, and 210Po, respectively. The analysis can be completed within 10 days, as compared with up to one year for traditional methods. Results are presented for a preliminary study of 210Pb, 210Bi, and 210Po in the dissolved and particle-bound phases of Irish Sea water.     

Critical thicknesses for the transition from intermediate- to mixed-state behavior in superconducting thin films of Pb,Sn, and In

Recent direct observations of the magnetic structure in thin films of Pb, Sn, and In are discussed relative to resistance measurements on the same films and to earlier experimental and theoretical work on thin films. Comparison to the theoretical results of Maki and Lasher is made and it is found that these results predict reasonably accurately the critical thickness separating intermediate-and mixed-state behavior in the thin films studied. This implies that the critical thickness has been overestimated in earlier work on similar films. It is suggested that this accounts, in part, for the high values obtained for the pure, bulk Ginzburg-Landau parameter in those experiments.Work supported by the National Science Foundation under Grant No. GN34125 and also under Grant No. GH33637 through the facilities of the Material Science Center, Cornell University.The work reported here represents part of a Ph.D. thesis submitted to the Graduate School Faculty of Cornell University, Ithaca, New York.     

Method for characterizing sulfated glycoproteins in a glycosylation site-specific fashion, using ion pairing and tandem mass spectrometry

Structural analysis of sulfated glycans is essential in understanding their biological significance. Here, we present a new approach to characterize sulfated glycans present on glycoproteins. The analysis is performed on glycopeptides, so information about the sulfated species is obtained in a glycosylation site-specific manner. This method employs an ion-pairing reagent to stabilize the SO3 group of the glycopeptide, allowing useful information to be obtained during MS/MS experiments. The amount of structural information obtained from (+)ESI-MS/MS of the ion-pair complexes for sulfated glycopeptides of equine thyroid stimulating hormone is compared with information obtained by (-)ESI-MS/MS of the underivatized, sulfated glycopeptides. The results indicate that this new method provides detailed insights into the sequence, branching, and type of N-glycans present, compared to analysis via (-)ESI-MS/MS.     

Application of maize tassel for the removal of Pb, Se, Sr, U and V from borehole water contaminated with mine wastewater in the presence of alkaline metals

In this study, the removal of Pb(II) from aqueous solutions by tassel powder was studied and optimised. Batch experiments were conducted on simulated solutions using tassel powder adsorbent and the effects of contact time, pH and concentration on the extent of Pb (II) removal was studied. Equilibrium and kinetic models for Pb(II) sorption were developed by considering the effect of contact time and concentration at optimum pH 4 and fixed temperature(25 degrees C). The Freundlich model was found to describe the sorption energetics of Pb(II) on tassel more fully than the Langmuir. A maximum Pb(II) loading capacity of 333.3mg/g on tassel was obtained. The adsorption process could be well described by both the Langmuir and Freundlich isotherms with R(2) values of 0.957 and 0.972, respectively. The kinetic parameters were obtained by fitting data from the effect of contact time on adsorption capacity into the pseudo-first, pseudo-second-order and intra-particle diffusion equations. The kinetics of Pb(II) on tassel surface was well defined using linearity coefficients (R(2)) by pseudo-second-order (0.999), followed by pseudo-first-order (0.795) and lastly intra-particle diffusion (0.6056), respectively. The developed method was then applied to environmental samples taken from borehole waters contaminated with mine wastewater. The removal of Pb (ND-100%), Se (100%), Sr (5.41-59.0%), U (100%) and V (46.1-100%) was attained using tassel. The uptake of the metals from environmental samples was dependent on pH, ionic strength and levels of other competing species.