Current Plasma Atomic Emission Spectrometry Research Articles

Study on effect of introduced gas bubbles for the low channel damage in direct and alternating current liquid electrode plasma atomic emission spectrometry

Liquid electrode plasma (LEP) is used as an excitation source for compact and sensitive elemental analysis, where the channel damage by plasma causes the severe tradeoff between sensitivity and lifetime. In alternative current (AC)-LEP, significantly less channel damage (1/3000) was reported compared to direct current LEP (DC-LEP). However, the mechanism has not been clear. In this paper, the effects of external gas introduction into AC-LEP and DC-LEP were studied. The results showed that the external gas bubbles facilitated stable and highly sensitive plasma generation with lower power, reducing channel damage and increasing the lifetime of the analysis chip. These effects are significant in Ar introduction and AC-LEP cases. The facts suggest that the lower damage in conventional AC-LEP without gas introduction is attributed to H2/O2 bubbles generated by hydrolysis at electrodes and consequently introduced into the LEP from outside of narrow channel.

Long-term evaluation of blood silicon and ostecalcin in operatively treated patients with benign bone tumors using bioactive glass and autogenous bone

In a study on 25 patients with verified benign bone tumors, bioactive glass (BG) and autogenous bone (AB) were used as bone-graft substitutes. The patients were randomized into two groups according to the filling material. Blood samples were taken both preoperatively, at 2 weeks, and 3, 8, 12, 24, and 36 months postoperatively, for evaluation of silicon concentration in blood. In the determination, direct current plasma atomic emission spectroscopy was used. No significant difference in blood silicon concentration between the BG group or the AB group could statistically be observed (p = 0.5400), and neither did the size of the bone tumor (p = 0.4259) nor the follow-up time affect the results (p = 0.2094). Concentration of osteocalcin in blood was significantly higher for large cysts (p < 0.0001). The filler material (BG or AB) did not affect the osteocalcin concentration level in blood.

Reactions of hydroxymatairesinol over supported palladium catalysts

In this work, hydroxymatairesinol (extracted from Norway spruce knots) was hydrogenolyzed to matairesinol over palladium impregnated H-Beta-300, H-Beta-150, H-Beta-25, H-Beta-11, H-Y, H-Mordenite, H-MCM-41, H-ZSM-5, SiO 2, and Al 2O 3. H-Beta-25 without palladium was also investigated. The hydrogenolysis was performed in 2-propanol at 70 °C under hydrogen and nitrogen atmospheres in a stirred glass reactor. The catalysts were characterized by nitrogen physisorption, direct current plasma atomic emission spectrometry, X-ray powder diffraction, CO pulse chemisorption, transmission electron microscopy, and Fourier transform infrared spectroscopy (pyridine adsorption). Palladium on H-Beta with different acidities was tested; the results showed that the reaction rate was inversely proportional to the acidity. However, Brønsted acid sites are needed for the reaction, because palladium on SiO 2 and Al 2O 3 is not active. In addition to the acidity, a metal is needed; the H-Beta-25 support without palladium displays no activity.

Phase Properties of Carbon-Supported Gold−Platinum Nanoparticles with Different Bimetallic Compositions

The ability to control the composition and phase properties of bimetallic nanoparticles is critical in exploring catalytic properties. In this paper we present results from a study aimed at determining those properties for carbon-supported gold−platinum (AuPt) catalysts with different bimetallic compositions. The bimetallic nanoparticle catalysts are prepared by a two-phase synthesis protocol employing organic monolayer encapsulation on bimetallic AuPt cores (∼2 nm). The size-controlled nanoparticles are assembled on carbon black support materials with controllable dispersion and metal loading and are further treated by calcination under controlled temperature and atmosphere. The core composition of the bimetallic nanoparticles is determined by direct current plasma-atomic emission spectroscopy. Structural characterization is carried out by X-ray diffraction. The bimetallic nanoparticles were shown to display alloy properties, which is in sharp contrast to the bimetallic miscibility gap known for the bulk...

Platinum-Catalyzed Synthesis of Water-Soluble Gold−Platinum Nanoparticles

The ability to control composition and size in the synthesis of bimetallic nanoparticles is important for the exploitation of the bimetallic catalytic properties. This paper reports findings of an investigation of a new approach to the synthesis of gold-platinum (AuPt) bimetallic nanoparticles in aqueous solution via one-phase reduction of AuCl(4-) and PtCl(4)(2-) using a combination of reducing and capping agents. Hydrogen served as a reducing agent for the reduction of Pt(II), whereas acrylate was used as a reducing agent for the reduction of Au(III). The latter reaction was found to be catalyzed by the formation of Pt as a result of the reduction of Pt(II). Acrylate also functioned as capping agent on the resulting nanocrystals. By controlling the feed ratios of AuCl(4-) and PtCl(4)(2-) and the relative concentrations of acrylate, an effective route for the preparation of AuPt nanoparticles with bimetallic compositions ranging from approximately 4 to 90% Au and particle sizes ranging from 2 to 8 nm has been demonstrated. The composition, size, and shell properties were characterized using transmission electron microscopy, direct current plasma-atomic emission spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. Implications of the results to the exploration of bifunctional catalysts are also briefly discussed.

Preparation, Characterization, and Activity of Silica Supported Metallocene Catalysts

Silica supported metallocene catalysts were prepared for ethylene polymerization by immobilizing bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2) onto both calcined silica, and silica treated with γ-aminopropyltrimethoxysilane or γ-mercaptopropyltrimethoxy-silane. Bis(cyclopentadienyl)zirconium chloride hydride (Cp2ZrClH) was also immobilized onto both calcined silica and vinyltrimethoxysilane treated silica. The catalysts were characterized by using direct current plasma atomic emission spectroscopy (DCP-AES), diffuse reflectance infrared spectroscopy (DRIFT), and X-ray photoelecton spectroscopy (XPS). It was found that both Cp2ZrCl2 and Cp2ZrClH were adsorbed on both calcined silica and silane treated silica, respectively. When γ-aminopropyltrimethoxysilane (APTMS) was used as the spacer molecule, some of the amine became protonated upon adsorption of Cp2ZrCl2. Initial catalytic tests showed that all of the complexes were catalytically active (methylaluminoxane as a cocatalyst), with the Cp2ZrClH supported complexes giving the highest activities, but still lower than the homogeneous catalyst, Cp2ZrCl2. The supported complexes produced polymer with higher molecular weight than the homogeneous catalyst. These observations, together with presented spectral evidence, support the view that the catalyst remained adsorbed in the presence of MAO.

Physico-chemical and catalytic properties of Zr- and Cu–Zr ion-exchanged H-MCM-41

H-MCM-41 catalyst ion-exchanged by Zr and/or Cu-cations were synthesized and characterized by XPS, 27Al- and 29Si-MAS-NMR, FTIR of pyridine adsorption, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and direct current plasma atomic emission spectrometry. The catalysts were evaluated towards 1-butene skeletal isomerization after pre-treatment with hydrogen or synthetic air. The dispersion of metals after ion-exchange was reasonably good, as revealed by LA-ICP-MS. Binding energies observed by XPS indicated that after reduction or oxidation pre-treatments copper is mainly present as Cu2+, except in case of reduced Cu-H-MCM-41. Pre-treatment had no influence on the oxidation state of Zr4+ species. Zr ion-exchange decreased the concentrations of Bronsted and Lewis acid sites. As a result, the initial conversion of 1-butene was decreased, but the selectivity and stability of the catalyst were increased. As reported before, the copper introduction decreased the Bronsted acid site density, but increased the conversion. The enhancement in the catalytic activity has been connected to the presence of copper with oxidation state +1, which is formed under reaction conditions due to the hydrogen formation. This led to a peculiar effect over oxidized bimetallic Cu–Zr-H-MCM-41 at a low temperature and high weight hourly space velocity (523 K and 15 h−1, respectively): The initial conversion of 1-butene was almost zero but increased during the time-on-stream reaching the value of about 13 mol%. These observations are related to the reduction of Cu2+ species to Cu+ during the reaction. The catalyst evaluation and characterization results led to a conclusion that the presence of Zr stabilizes copper’s oxidation state of Cu+2 under reductive conditions in the bimetallic Cu–Zr-H-MCM-41 catalyst.

Active copper species in 1-butene skeletal isomerization: comparison between copper-modified MCM-41 and beta catalysts

The role of copper was studied in the skeletal isomerization of 1-butene over copper-modified mesoporous MCM-41 molecular sieve and Beta zeolite. The Cu–H-MCM-41 and Cu–H-Beta catalysts were synthesized in our laboratory and characterized by XRD, nitrogen adsorption, X-ray fluorescence, FTIR of adsorbed pyridine and direct current plasma atomic emission spectrometry. The oxidation state of copper after oxidation and reduction in Cu–H-MCM-41 was evaluated by FTIR with probe molecules. Copper ion-exchanged and the proton forms of MCM-41 and Beta catalysts were tested towards 1-butene skeletal isomerization by varying the weight hourly space velocity and temperature. Quantum chemical calculations at the B3LYP/6-31 + G ** level were performed in order to understand the role of copper at the molecular level. Copper in Cu–H-MCM-41 pretreated in synthetic air was mostly in the form of Cu 2+ but reduced during the catalytic experiment to the metallic form Cu 0 via Cu +. Even if the copper exchange decreased the amount of Brønsted acid sites, Cu–H-MCM-41 pretreated in synthetic air was more active than H-MCM-41 towards 1-butene skeletal isomerization. The enhanced catalytic activity is due to copper Cu +, which was formed during the reaction. Introduction of copper into H-Beta, however, did not have any effect at all on the performance of the catalyst. The probable reason for this is the high initial activity of copper-modified H-Beta causing a very fast reduction of copper to the inactive metallic form Cu 0.

Pharmacokinetics of sodium borocaptate: a critical assessment of dosing paradigms for boron neutron capture therapy.

The pharmacokinetics of sodium borocaptate (BSH), a drug that has been used clinically for boron neutron capture therapy (BNCT) of malignant brain tumors, have been characterized by measuring boron concentrations by direct current plasma-atomic emission spectroscopy (DCP-AES) in a group of 23 patients with high-grade gliomas. The disposition of BSH following intravenous (i.v.) infusion, which was determined by measuring plasma boron concentrations by DCP-AES, was consistent with a three-compartment open model with zero-order input and first-order elimination from the central compartment. Boron disposition was linear over the dose range of 26.5-88.2 mg BSH/kg body weight (b.w.), corresponding to 15-50 mg boron/kg b.w. Mean total body boron plasma clearance was 14.4 +/- 3.5 ml/min and the harmonic mean half-lives (range) were 0.6 (0.3-3.7), 6.5 (4.8-10.1) and 77.8 (49.6-172.0) h for the alpha, beta, and gamma disposition phases, respectively. Using an empirically determined plasma: blood boron concentration ratio of 1.3 +/- 0.2, the calculated total body boron blood clearance was 18.5 +/- 4.5 ml/min. In order to develop a model for selecting the optimum dosing paradigm, a pharmacokinetic correlation was established between the boron content of normal brain, solid tumor, and infiltrating tumor to the shallow tissue pharmacokinetic compartment (C2). Based on our model, it was concluded that although multiple i.v. infusions of BSH might increase absolute tumor boron concentrations, they will not improve the tumor: plasma boron concentration ratios over those attainable by a single i.v. infusion. The results from our study are confirmatory of those previously reported by others when blood sampling has been carried out for a sufficient period of time to adequately characterize the pharmacokinetics.

A New Heterogeneously Catalytic Pathway for Isomerization of Linoleic Acid over Ru/C and Ni/H–MCM-41 Catalysts

The isomerization reaction of linoleic acid ( cis-9, cis-12-octadecadienoic acid) to conjugated linoleic acids (CLA) was studied. A new heterogeneously catalytic pathway was developed for synthesis of CLA at mild reaction conditions (80–120°C) over Ru/C and Ni/H–MCM-41 catalysts in a diluted system. The isomerization reaction was tested in 1-octanol and n-decane. Solvents with low polarity were selected to afford good reactant adsorption on the catalyst surface and a high solvent-to-reactant ratio was used to prevent potential side reactions. Catalyst characterization was done by X-ray powder diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy, hydrogen temperature-programmed desorption, direct current plasma atomic emission spectrometry, and BET techniques. The reactions taking place were isomerization of linoleic acid C 18:2, hydrogenation of C 18:2 acids to C 18:1 monounsaturated octadecenoic acids (oleic acid, elaidic acid, cis-vaccenic acid and trans-vaccenic acid), and further hydrogenation of C 18:1 acids to C 18:0 stearic acid ( n-octadecanoic acid) where isomerization and hydrogenation were two competing parallel reactions. The isomerization reaction was enhanced by preactivation of the catalysts under hydrogen, but such a treatment also increased the side reaction double-bond hydrogenation.

Linkage of boronated polylysine to glycoside moieties of polyclonal antibody; boronated antibodies as potential delivery agents for neutron capture therapy

Among the ways to deliver comparatively large amounts of boron to cells in vitro for boron neutron capture studies is the linkage of a boronated macromolecule such as polylysine to an antibody. In order to reduce interference with immunoreactivity, boronated polylysine (BPL) was linked to oligosaccharide moieties on the IgG molecule distant from the antibody combining sites. The resultant bioconjugate was chromatographically separated from free BPL and unconjugated antibody using a Sephacryl S300 column. The total measured boron per BPL-IgG conjugate, determined by direct current plasma atomic emission spectroscopy, was estimated to be ∼6 × 103 atoms. This, together with molecular weight estimations, indicated conjugation of about 3 polylysines to each IgG molecule. Immunoreactivity of the conjugate was found to be the same as that of the unconjugated polyclonal antibody. This was based on its concentration dependent interference with immunometric reactions for an antigen (TSH), whereas heat inactivated or non-specific antibody had no such inhibitory effects. The results support the hypothesis that the binding affinity of the conjugate for antigen was preserved after its linkage to BPL under the conditions described. The methodology described in this report may have applicability for the preparation of boronated antibodies as delivery agents for BNCT.

Boron Neutron Capture Therapy of Brain Tumors: Biodistribution, Pharmacokinetics, and Radiation Dosimetry of Sodium Borocaptate in Patients with Gliomas

The purpose of this study was to obtain tumor and normal brain tissue biodistribution data and pharmacokinetic profiles for sodium borocaptate (Na2B12H11SH) (BSH), a drug that has been used clinically in Europe and Japan for boron neutron capture therapy of brain tumors. The study was performed with a group of 25 patients who had preoperative diagnoses of either glioblastoma multiforme (GBM) or anaplastic astrocytoma (AA) and were candidates for debulking surgery. Nineteen of these patients were subsequently shown to have histopathologically confirmed diagnoses of GBM or AA, and they constituted the study population. BSH (non-10B-enriched) was infused intravenously, in a 1-hour period, at doses of 15, 25, and 50 mg boron/kg body weight (corresponding to 26.5, 44.1, and 88.2 mg BSH/kg body weight, respectively) to groups of 3, 3, and 13 patients, respectively. Multiple samples of tumor tissue, brain tissue around the tumors, and normal brain tissue were obtained at either 3 to 7 or 13 to 15 hours after infusion. Blood samples for pharmacokinetic studies were obtained at times up to 120 hours after termination of the infusion. Sixteen of the patients underwent surgery at the Beijing Neurosurgical Institute and three at The Ohio State University, where all tissue samples were subsequently analyzed for boron content by direct current plasma-atomic emission spectroscopy. Blood boron values peaked at the end of the infusion and then decreased triexponentially during the 120-hour sampling period. At 6 hours after termination of the infusion, these values had decreased to 20.8, 29.1, and 62.6 microg/ml for boron doses of 15, 25, and 50 mg/kg body weight, respectively. For a boron dose of 50 mg/kg body weight, the maximum (mean +/- standard deviation) solid tumor boron values at 3 to 7 hours after infusion were 17.1+/-5.8 and 17.3+/-10.1 microg/g for GBMs and AAs, respectively, and the mean tumor value averaged across all samples was 11.9 microg/g for both GBMs and AAs. In contrast, the mean normal brain tissue values, averaged across all samples, were 4.6+/-5.1 and 5.5+/-3.9 microg/g and the tumor/normal brain tissue ratios were3.8 and 3.2 for patients with GBMs and AAs, respectively. The large standard deviations indicated significant heterogeneity in uptake in both tumor and normal brain tissue. Regions histopathologically classified either as a mixture of tumor and normal brain tissue or as infiltrating tumor exhibited slightly lower boron concentrations than those designated as solid tumor. After a dose of 50 mg/kg body weight, boron concentrations in blood decreased from 104 microg/ml at 2 hours to 63 microg/ml at 6 hours and concentrations in skin and muscle were 43.1 and 39.2 microg/g, respectively, during the 3- to 7-hour sampling period. When tumor, blood, and normal tissue boron concentrations were taken into account, the most favorable tumor uptake data were obtained with a boron dose of 25 mg/kg body weight, 3 to 7 hours after termination of the infusion. Although blood boron levels were high, normal brain tissue boron levels were almost always lower than tumor levels. However, tumor boron concentrations were less than those necessary for boron neutron capture therapy, and there was significant intratumoral and interpatient variability in the uptake of BSH, which would make estimation of the radiation dose delivered to the tumor very difficult. It is unlikely that intravenous administration of a single dose of BSH would result in therapeutically useful levels of boron. However, combining BSH with boronophenylalanine, the other compound that has been used clinically, and optimizing their delivery could increase tumor boron uptake and potentially improve the efficacy of boron neutron capture therapy.

Atomic emission spectrometric determination of ephedrine, cinchonine, chlorpheniramine, atropine and diphenhydramine based on formation of ion associates with ammonium reineckate

Ion–associate complexes of ephedrine HCl (I), cinchonine HCl (II), chlorpheniramine maleate (III), atropine sulphate (IV) and diphenhydramine HCl (V) with ammonium reineckate were precipitated and their solubilities were studied as a function of pH, ionic strength and temperature. Saturated solutions of each ion–associate under the optimum precipitation conditions were prepared and the Cr ion content in the supernatant was determined. The solubility products were thus elucidated at different temperatures. A new accurate and precise method using direct current plasma–atomic emission spectrometry for the determination of the investigated drugs in pure solutions and in pharmaceutical preparations is described. The drugs can determined by the present method in the ranges 1.6–52,2.64–85.8,3.12–101.4,5.52–180.4 and 2.72–75.85 μg/ml solutions of I, II, III, IV and V, respectively.

Enhanced delivery of boronophenylalanine for neutron capture therapy of brain tumors using the bradykinin analog Cereport (Receptor-Mediated Permeabilizer-7).

Using the well-characterized F98 rat glioma model, the purpose of the present study was to determine whether the delivery of boronophenylalanine (BPA) could be enhanced by prior administration of the bradykinin analog Cereport (Alkermes, Inc., Cambridge, MA) (previously known as Receptor-Mediated Permeabilizer-7), which produces a transient, pharmacologically mediated opening of the blood-brain barrier. Two series of experiments were performed in F98 glioma-bearing rats that had received either intracarotid (i.c.) or intravenous infusions of Cereport (at doses ranging from 1.5 to 7.5 microg/kg of body weight), followed by i.c. (or intravenous) injection of BPA (300 mg/kg of body weight). Animals were killed 0.5, 2.5, or 4 hours later, samples of blood, skin, muscle, and eye were obtained, brains were removed, and tumors were excised for boron determination by direct current plasma-atomic emission spectroscopy. Averaged over all time points, i.c. infusion of Cereport significantly enhanced tumor boron uptake (P = 0.0001), compared with the excipient (saline) control values. Tumor boron values were equivalent at 0.5 (36.0 microg/g) and 2.5 hours (38.5 microg/g) after i.c. administration of Cereport and BPA and then decreased by 33% (to 25.7 microg/g) at 4 hours. These tumor boron uptake values were significantly different (alpha = 0.05), compared with values measured at the corresponding times after i.c. administration of BPA without Cereport (22.6, 21.8, and 15.3 microg/g, respectively). Although no time-related effects were observed, i.c. administration of Cereport followed by intravenous administration of BPA also significantly enhanced (alpha = 0.05) tumor boron uptake at 0.5, 2.5, and 4 hours (27.4, 30.3, and 28.0 microg/g, respectively), compared with values obtained without Cereport (11.3, 13.4, and 15.2 microg/g, respectively). Boron levels in normal brain tissue from tumor-bearing and non-tumor-bearing cerebral hemispheres and in blood were not significantly different from those measured in saline-treated control animals. This study established that i.c. infusion of Cereport significantly increased delivery of BPA to F98 rat gliomas, and this could enhance the efficacy of boron neutron capture therapy of this tumor.

Multivariate data analysis as a tool for evaluating emission intensity, background equivalent concentration and detection limit obtained for different plasma positions in direct current plasma-atomic emission spectrometry

Relative emission intensity, background emission concentration (BEC) and detection limit (DL) obtained for different analytes and different plasma positions are examples of multivariate data sets. The observations can be related to the emission distribution in the plasma for the different elements (the spatial profiles). Principal component analysis (PCA) as a tool for modelling, interpretation and visualisation of such data sets was applied (i) to elucidate the data structure caused by the profiles, (ii) to enhance structural information using replicate or similar data sets, (iii) to predict model results that are less prone to errors and random variations, and (iv) to compare data sets of different origin (e.g. directly observed results with those calculated from the profiles). The selection of a suitable optimisation element can be guided by visual procedures or rather simple calculations based on the PCA model.

Investigations into mild conditions for reduction of Se(VI) to Se(IV) and for hydride generation in determination of selenium by direct current plasma atomic emission spectrometry

Alternatives to hydrochloric acid for the reduction of Se(VI) to Se(IV) (prereduction) were explored. Prereduction of Se(VI) in 0.1–1 M HCl and 0.1–3 M HBr as a function of NaBr concentration and time of boiling was investigated and conditions for mild prereduction of Se(VI) have been found. Minimum concentrations of sodium tetrahydroborate(III) and HCl for reduction of Se(IV) to Se(- II) in selenium hydride were found and minimum acid concentrations were determined. Prereduction of Se(VI) by the method involving optimum concentrations of 0.48 M HCl plus 1.4 M KBr was verified by comparison with the 5 M HCl reference method for determination of Se(VI) in Niagara River waters.

Anion-exchange resin modified with pyrocatechol violet as a functional resin for retention of Sn(IV)

A selective chelating resin was prepared by loading pyrocatechol violet (PV) on a conventional anion-exchange resin, Dowex 2x4. PV loaded Dowex 2x4 was mixed with Sn(IV) solution and the pH was adjusted to 4 with acetate buffer. After equilibration for 6–7 h on a mechanical shaker, the mixture was set aside for 12 h, the resin was filtered off and Sn(IV) was desorbed with 1 M HNO 3 (25 ml). The Sn(IV) was determined in the acidic solution by direct current plasma atomic emission spectrometry at 283.999 nm. The loaded resin was also used for the separation of Sn(IV) from several metal ions.

Potentiometric Investigations of Nickel, Iron and Cobalt Interferences in the Generation of Selenium Hydride by Sodium Tetrahydroborate(III)

The products of the reactions of FeII, NiII and CoII with sodium tetrahydroborate(III), which interfere with the determination of selenium by hydride generation, were precipitated by different methods and investigated by potentiometric titration accompanied by monitoring of hydrogen evolution, direct current plasma atomic emission spectrometry and positive ion FAB mass spectrometry. Boron was found in the precipitates of NiII and CoII but not FeII obtained from the acid solutions under the conditions of hydride generation. Several sections on the potentiometric titration curves were found, which indicated the formation of several boride-like compounds with different compositions depending on the sequence of mixing reagents, pH, reactant concentrations and ratios, speed of mixing and the presence of oxygen. A hypothesis was formulated about the reduction of boronIII from sodium tetrahydroborate(III) to lower oxidation states of boron in boride-like species which is used to explain the properties of the potentiometric titration curves and the suppression of the selenium hydride signal in hydride generation.

Laboratory and analytical method performance of lead measurements in paint chips, soils, and dusts.

The National Lead Laboratory Accreditation Program (NLLAP) recognizes laboratories capable of analyzing lead in paints, soils, and dusts. NLLAP requires successful participation in the Environmental Lead Proficiency Analytical Testing (ELPAT) program. For paint chip analyses, laboratory-to-laboratory variability is about 10% relative standard deviation (RSD) for lead levels near 0.5%, the HUD definition of lead-based paint. For soil analyses, RSDs are about 9 to 10% near relevant federal soil standards and 16% near the lowest state bare soil standard that currently exists. For dust wipe analyses, RSDs range from 10 to 16% for lead levels near relevant HUD standards. Of participating laboratories, 92 to 93% consistently meet ELPAT performance limits. A variety of analytical methods gives similar results. No conclusive significant differences were found among most frequently used hotplate and microwave sample preparation techniques. In addition, several participating laboratories have successfully used ultrasonic extraction methods, a method suitable for use at abatement sites. The three most frequently used instrumental techniques, flame atomic absorption (FAA), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and graphite furnace atomic absorption show no statistically significant differences in ability to meet ELPAT performance limits. However, small statistically significant biases between these methods sometimes occur. The magnitude of biases is less than 5% of the corresponding laboratory mean near relevant federal standards except for lead levels near the lowest HUD lead wipe standard, where biases can be as high as 8%. Other instrumental methods that have been used successfully include ICP-mass spectroscopy, direct current plasma-atomic emission spectroscopy, dithizone spectrophotometry, and anodic stripping voltametry.

Laboratory and Analytical Method Performance of Lead Measurements in Paint Chips, Soils, and Dusts

The National Lead Laboratory Accreditation Program (NLLAP) recognizes laboratories capable of analyzing lead in paints, soils, and dusts. NLLAP requires successful participation in the Environmental Lead Proficiency Analytical Testing (ELPAT) program. For paint chip analyses, laboratory-to-laboratory variability is about 10% relative standard deviation (RSD) for lead levels near 0.5%, the HUD definition of lead-based paint. For soil analyses, RSDs are about 9 to 10% near relevant federal soil standards and 16% near the lowest state bare soil standard that currently exists. For dust wipe analyses, RSDs range from 10 to 16% for lead levels near relevant HUD standards. Of participating laboratories, 92 to 93% consistently meet ELPAT performance limits. A variety of analytical methods gives similar results. No conclusive significant differences were found among most frequently used hotplate and microwave sample preparation techniques. In addition, several participating laboratories have successfully used ultrasonic extraction methods, a method suitable for use at abatement sites. The three most frequently used instrumental techniques, flame atomic absorption (FAA), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and graphite furnace atomic absorption show no statistically significant differences in ability to meet ELPAT performance limits. However, small statistically significant biases between these methods sometimes occur. The magnitude of biases is less than 5% of the corresponding laboratory mean near relevant federal standards except for lead levels near the lowest HUD lead wipe standard, where biases can be as high as 8%. Other instrumental methods that have been used successfully include ICP-mass spectroscopy, direct current plasma-atomic emission spectroscopy, dithizone spectrophotometry, and anodic stripping voltametry.