Automated Online Preconcentration System for the Determination of Trace Amounts of Lead Using Pb‐Selective Resin and Inductively Coupled Plasma–Atomic Emission Spectrometry

Abstract

An automated sequential‐injection online preconcentration system was developed for the determination of lead by inductively coupled plasma–atomic emission spectrometry (ICP‐AES). The preconcentration of lead was performed with a minicolumn containing a lead‐selective resin, Analig Pb‐01, which was installed between a selection and a switching valve. In an acidic condition (pH 1), lead could be adsorbed on the resin. The concentrated lead was afterward eluted with 25 µL of 0.06 M nitrilotriacetic acid (NTA) solution (pH 9) and was subsequently transported into the nebulizer of ICP‐AES for quantification. The selectivity of the resin toward lead was examined using a solution containing a mixture of 61 elements. When a sample volume of 5 mL was used, the quantitative collection of lead (≥97%) was achieved, along with an enrichment factor of 19, a sampling frequency of 12 samples hr^?1, a detection limit of 70 pg mL^?1, and a lowest quantification limit of 100 pg mL^?1. The linear dynamic range was 0.1 to 5 ng mL^?1, and the relative standard deviation (n=9) was 0.5% at a 5 ng mL^?1 Pb level. The detection limit of 30 pg mL^?1 and lowest quantification limit of 50 pg mL^?1 could be achieved when 10 mL of sample volume was used. The accuracy of the proposed method was validated by determining lead in the standard reference material of river water (SLRS‐4), and its applicability to the determination of lead in environmental river water samples was demonstrated.     

Online Copper Removal for Selenium Determination by Hydride Generation–Inductively Coupled Plasma Optical Emission Spectrometry

Abstract

Selenium determination in samples with a high copper content by hydride generation–inductively coupled plasma optical emission spectrometry (HG‐ICP‐OES) after online copper removal and selenium (VI) reduction is described. An activated carbon minicolumn was used for the retention of copper and its subsequent separation of Se. Se(VI) was then online reduced by heating into a PTFE coiled reactor with 12 M HCl. The analyte was introduced into a water stream containing sodium tetrahydroborate (NaBH₄) in order to generate selenium hydride (H₂Se). The detection limit (DL) obtained was 0.8 µg L^?1, and the precision, expressed by the relative standard deviation (RSD), was 2.5% (n=10; 10 µg L^?1 selenium level). The current method was applied to the Se determination in two copper reference materials, MBH‐39DK 3601 (with a Se content of 90 mg kg^?1) and MBH‐39 DK 3604 (with a Se content of 15 mg kg^?1).     

Trace Metal Determination in ‘Marsh’ Grapefruit Peel by Automated Fast Sequential Inductively Coupled Plasma Atomic Emission Spectrometry

Major trace elements (K, Ca, Mg, P, Na), minor trace minerals (B, Sr, Mo, Fe, Cu, Ni, Ba, Zn, Mn, Al, Cr, Sn, Rb), and ultra trace metals (Ti, V, Co, Li) in fresh ‘Marsh’ grapefruit peel samples collected during two consecutive seasons (1981–82 and 1982–83) were determined by an automated fast sequential multielement spectrometer using Inductively Coupled Plasma (ICP) as an excitation source for Atomic Emission Spectrometry (AES). Among the major elements K showed a range of 2000–3200 ppm with a significant difference of concentration fluctuations in both seasons. Within the ultra trace metal group, concentrations were found at constant levels for both periods. In the minor trace group, elements such as Sr, Mo, Fe, Cu, Ni, Ba, Al, and Cr showed slight concentration differences during the 1981–82 season when compared to the 1982–83 period.     

Determination of Copper,Iron, and Zinc in Crayfish (Procambrus clarkii) by Inductively Coupled Plasma–Optical Emission Spectrometry

Inductively coupled plasma–optical emission spectrometry was used to determine copper, iron, and zinc in both whole Crayfish and tail meat of crayfish from selected areas in southwestern Louisiana. Also included was a comparison between male and female crayfish. Results showed no significant difference between male and female crayfish and individuals from different sites. Iron was approximately four times greater in concentration for whole crayfish compared with tail meat.     

Determination of Trace Elements in High‐Purity Palladium by Inductively Coupled Plasma Mass Spectrometry Using an Internal Standard Method

Method validation of inductively coupled plasma mass spectrometry analyses for trace impurities in high‐purity materials is often limited not only by the lack of suitable reference materials with the same matrix composition but also by the lack of a significant number of certified trace element concentrations in the available reference materials. This paper demonstrates a new and simple method for the direct determination of 44 trace elements in high‐purity palladium using inductively coupled plasma mass spectrometry and an internal standard method. Sc and In were employed as internal standards to effectively eliminate nonspectral interferences from the Pd matrix. The detection limits of the 44 trace impurities were from 0.00078 to 0.46 µg/mL and the relative standard deviations (n=6) were below 3.5%. The method was further validated using a palladium standard material (Aldrich palladium standard material, CAS no. 7440053). The analytical results are in good agreement with the certified values.     

Ultratrace Determination of Selenium by Hydride Generation–Inductively Coupled Plasma Mass Spectrometry Operated Under Nonrobust Plasma Conditions

A hydride generation–inductively coupled plasma mass spectrometer (HG‐ICPMS) operated at low RF power (720 W) was demonstrated to be suitable for ultra trace determination of Se, which is an element with high ionization potential (IP). ⁷⁸Se analysis free from ³⁸Ar⁴⁰Ar spectral interference was achieved by operating the plasma under a so‐called warm plasma condition (as opposed to traditionally defined hot and cool plasmas). In this warm plasma, there is a sufficient population of energetic Ar⁺ to ensure ionization of Se, while the number of ³⁸Ar⁴⁰Ar ions is at the minimum, due to the dimer's bimodal profile. A detection limit of 1 ng/L was achieved for ⁷⁸Se. Background spectra of warm and hot plasmas were compared. Two types of HG gas–liquid separators were compared. The technique was applied to measure trace amounts of Se in atmospheric samples; namely, cloud water and aerosol particulate. Good agreement was found between HG warm plasma ICPMS and pneumatic micronebulization hot plasma ICPMS for the cloud water samples. The water extract of aerosol particulate typically contained 50–100 ng/L of Se, equivalent to 0.25–0.5 ng/m³ in the atmosphere. Ours appears to be the first report of the use of nonrobust plasma ICPMS for a high‐IP element; the superb accuracy and sensitivity of this technique rival those of other powerful trace analytical methodologies such as HG‐LIF, HG‐LEI, or DRC‐ICPMS. It is conceivable that warm plasma ICPMS is applicable to other elements with high IP.     

Recent Advances in Microwave Induced Plasma Atomic Emission Spectrometry with Okamoto‐Cavity

Abstract

Microwave induced plasmas with an Okamoto‐cavity (Okamoto‐cavity MIP) are noted as a new excitation source in atomic emission spectrometry. The Okamoto‐cavity MIP can be sustained with various plasma gases, and can produce each stable plasma with a high robustness against loading of various types of samples. For example, the oxygen‐containing MIP becomes an effective atomization and excitation source for direct injection of organic solvents analysis because they are completely burned in the plasma. In this review, the fundamental structure of the microwave cavity, the spectrochemical characteristics, and the analytical applications are summarized from reference papers.     

Tuning Effect on the Electron Energy Distribution Function of an Inert Gas Mixture in nitrogen Inductively Coupled Plasma Discharges

By using a Langmuir probe, the electron energy distribution function (EEDF) is measured in inductively coupled plasma discharges in N2/Ar mixtures at 200W rf powers. In pure N2 discharges a Maxwellian EEDF is observed.When the mixing ratio of Ar increases, the distribution of high-energy electrons evolves with a different trend from that of low-energy electrons, resulting in an apparent “two temperature structure” of the EEDF. We discuss this non-Maxwellian EEDF and its effect on the measurement and the interpretation of “electron temperature”by both the probe and line ratio technique.     

Process Analytical Chemistry—Application of Mass Spectrometry in Environmental Analysis: An Overview

Abstract

Considering the cost and effectiveness, spectroscopic techniques have an increasing importance within the chemical industry. This review concentrates on the use of mass spectrometry with particular emphasis on technological advances, historical evolution, and applications in chemical processes and environmental chemistry.     

Application of Gas Chromatography–Atomic Fluorescence Spectrometry Hyphenated System for Speciation of Butyltin Compounds in Water Samples

ABSTRACT

A laboratory-established capillary gas chromatography (GC)–atomic fluorescence spectrometry (AFS) hyphenated system was applied to butyltin speciation in water samples. Monobutyltin (MBT), dibutyltin (DBT), and tributyltin (TBT) were extracted and preconcentrated with headspace solid-phase microextraction (SPME) technique after derivatization using KBH₄, and then determined by GC-AFS directly. The experimental conditions—including the flow rates of carrier gas, argon and hydrogen–and the lamp current—were optimized in detail. Under the optimum conditions, the detection limits for MBT, DBT, and TBT, calculated as three times the baseline noise, were 10, 0.2, and 0.1 ng mL^?1 Sn, respectively. Good linear relationships were obtained when the concentrations of MBT, DBT, and TBT increased to 3000, 100, and 200 ng mL^?1 Sn. The relative standard deviations (RSDs) of five replicates were 5.2%, 7.4%, and 7.1% for MBT, DBT, and TBT, respectively. The recoveries of MBT, DBT, and TBT in three different types of water samples (seawater, tap water, and wastewater) were between 72.1% and 97.9%, indicating that the proposed method was accurate and feasible for speciation analysis of butyltin compounds in water samples.     

Comparative Study on Excitation Mechanism of Chromium Emission Lines in Argon Radio‐Frequency Inductively‐Coupled Plasma,Nitrogen Microwave Induced Plasma,and Argon or Nitrogen Glow Discharge Plasmas

Boltzmann plots of both atomic and ionic chromium emission lines are investigated to compare the excitation mechanisms in four different plasmas: an argon inductively‐coupled plasma (Ar‐ICP), a nitrogen high‐power microwave induced plasma (N₂‐MIP), an argon glow discharge plasma (Ar‐GDP), and a nitrogen glow discharge plasma (N₂‐GDP). The plots of the atomic lines and the ionic lines give both linear relationships as well as similar excitation temperatures in the case of the Ar‐ICP, the N₂‐MIP, and the N₂‐GDP. It implies that a thermodynamic process such as electron collision would control their excitations. However, only in the case of the ionic‐line plot in the Ar‐GDP, a departure from linear relationship is observed and the estimated excitation temperature is rather higher than that with the atomic lines, meaning that a specific excitation mechanism exists in the Ar‐GDP. A possible explanation for these results is that a charge‐transfer collision between chromium atom and argon ion plays a dominant role in exciting highly‐lying energy levels of chromium ion, especially in the Ar‐GDP.     

Ultrasonic Extraction–Ozonation Sequential Sample Treatment for the Determination of Arsenic in Environmental Certified Reference Materials by Hydride Generation–Atomic Fluorescence Spectrometry

Abstract

A sample pretreatment method based on ultrasound‐assisted extraction followed by ozonation is developed for sensitive determination of total As in biological and environmental certified reference materials and an unknown plant sample (Acacia dealbata) by flow injection and continuous‐flow hydride generation–atomic fluorescence spectrometry. The method is meant to minimize the use of corrosive and oxidizing acids for sample decomposition and common errors in trace analysis. Problems derived from introduction of sonicated extracts in continuous flow and flow injection manifolds in combination with an atomic fluorescence detector, such as excessive foaming and flame instability, are addressed. The following certified reference materials (CRMs) were employed for method assessment: BCR CRM 482 lichen; BCR CRM 60 and 61 aquatic plants; BCR CRM 279 sea lettuce; NIST 1633b fly ash; BCR 320 river sediment; RTC CRM 024‐050 soil. Effect of variables such as extraction time, ultrasound amplitude, concentration of extractant acid, sample mass, drying mode, and particle size was investigated. Leaves of Acacia dealbata were also employed for method development. Limits of detection ranged from 0.03 to 0.15 µg/g As depending on the sample. Between‐batch precision values ranged from 2% to 11%. Sample throughput was 40 hr^?1 with flow injection.     

Measurement of the Stark Broadening of Atomic Emission Lines in Non–Optically Thin Plasmas by Laser‐Induced Breakdown Spectroscopy

We propose a new method for determining the Stark broadening of atomic emission lines using laser‐induced breakdown spectroscopy. The method allows the determination of the Stark broadening in non–optically thin plasmas, through the introduction of a correction for self‐absorption. Couples of lines of the same species are considered. If one of the Stark broadenings is known, the determination of the other does not require the measurement of the electron density of the plasma. Examples are given for the application of the proposed method to the measurement of the Stark broadening of several aluminum emission lines (Al I at 308.2 nm, Al I at 394.4 nm, and Al I at 396.2 nm).     

Optimization of Pretreatment Method for Alkylmercuries Speciation in Coal by High‐Performance Liquid Chromatography Coupled with UV‐Digestion Cold Vapor Atomic Fluorescence Spectrometry

Abstract

Exhaustive extraction of analytes in their original chemical forms from samples with complex matrices is a pivotal step for speciation analysis. Herein we propose a pretreatment method for extracting and preconcentrating methylmercury and ethylmercury from coal samples by using KBr–H₂SO₄/CuSO₄–C₆H₅CH₃–Na₂S₂O₃ system. The extraction conditions, including the volume of the organic phase and the extraction time, were optimized in detail. Speciation analysis of alkylmercuries was carried out by high‐performance liquid chromatography online coupled with UV‐digestion and cold vapor atomic fluorescence spectrometry. The detection limits were 0.6 ng mL^?1 for methylmercury and 1 ng mL^?1 for ethylmercury, respectively. The recoveries of methylmercury and ethylmercury spiked in a sample were 84% and 82%, respectively. The method was applied successfully to analysis of alkylmercuries in four coal samples collected from northeast China.     

Features of the Coupled Nuclear–Electron Spin Precession in the Bose–Einstein Condensate of Magnons

JETP Letters - The experimental detection of the Bose-Einstein condensate of magnons in coupled nuclear-electron spin precession in antiferromagnets brings the prospect of its use for magnonics and...     

Amplification of Nonpotential Waves in a Magnetized Beam–Plasma System Taking into Account the Evolution of the Plasma

We have analyzed the beam instability taking into account nonpotential effects in a completely magnetized plasma with a density varying slowly with time. It is shown that a frequency shift appears in the amplified signal (during the propagation in such an electrodynamic system); analytic relations determining this shift have been obtained.     

Determination of Cd in Water Samples by Hollow-Fiber–Supported Liquid-Membrane Extraction Coupled with Thermospray-Flame–Furnace Atomic-Absorption Spectrometry

ABSTRACT

A new method of hollow-fiber–supported liquid-membrane extraction (HF-SLME) coupled with thermospray-flame–furnace atomic-absorption spectrometry (TS-FF-AAS) for the determination of cadmium in water samples was developed. 1-Octanol was immobilized in the pores of the polypropylene hollow fiber as liquid membrane and used as the acceptor solution. Cd was selectively extracted from water samples into 1-octanol that filled the inner part of hollow fiber as the acceptor solution. The authors evaluated in detail some parameters that influence extraction and determination, such as the concentration of sodium diethyldithiocarbamate (DDTC), pH of samples, stirring rate, extraction time, flow rate of the pump, and interferences. Under optimized conditions, an enrichment factor of 146 could be obtained. In combination with thermospray-flame–furnace atomic-absorption spectrometry, a very low limit of detection (LOD) (5 ng L^?1) was achieved. The relative standard deviation (RSD) was 4.3% for five determinations of 0.1 ng mL^?1 cadmium. The accuracy of this method was validated by determination of certified reference water samples (GBW(E) 08607 and GSBZ(E) 50009-88). The proposed method was also applied to the determination of cadmium in tap water and river water, with the recoveries in the range of 90–96% for spiked samples.     

On the Theory of the Mandelstam–Brillouin Scattering in a Plasma Layer

Optics and Spectroscopy - The evolution of a perturbation from a local source upon the Mandelstam–Brillouin scattering in a plasma layer of a finite thickness and infinite length is examined...     

An alternative method for the exact calculation of Wannier–Stark localization in superlattices

We present an alternative method for the exact calculations of the Wannier–Stark (WS) localization in a long periodic potential corresponding to a (50 Å/30 Å) GaAs/Ga_0.7Al_0.3As superlattice. We show that the electric field dependence of the electron wavefunction has unique localization dynamics. One interesting prediction is a small effect involving the change of the dipole field with increasing WS field. It is argued that this may give rise to parasitic effects in Bloch oscillations and, therefore, to noise in coherent terahertz emission.