Dissolution Procedure Research Articles

The development of a digestion procedure for the determination of metals in gum obtained from deposits in internal combustion engines by ICP–OES

The accurate determination of metals in gum (deposits found in internal combustion engines) is strongly influenced by a selection of the right sample digestion method. The difficult and heterogeneous nature of this kind of sample, and its unpredictable reaction behavior are the major obstacles in getting correct analytical results. The studies were implemented with one sample called “reference sample”. Two digestion procedures were tested in this work. The dry ashing procedure was followed by another dissolution procedure with HF and heating, in order to complete the dissolution of the ash in the samples. The process was performed in 36 h. The second digestion procedure was implemented in closed system (pressurized) with 2 mL of HNO 3 and 2 mL of H 2SO 4. This last one presented a reduction of 80.5% time-consuming in relation to the first one (dry ashing). Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Na, Ni, Pb, Si, and Zn were determined in 14 samples of gum by ICP –OES. The wet closed system digestion procedure showed efficiency in the Cr, Cu, Fe, K, Ni, Pb, Si, and Zn determination. The correlation matrix results contribute to the characterization studies of the gum formation process, as well as the corrosion of the motor parts and fuel quality control.

Effect of organic matter and iron oxides on quaternary herbicide sorption–desorption in vineyard-devoted soils

Herbicide soil/solution distribution coefficients ( K d ) are used in mathematical models to predict the movement of herbicides in soil and groundwater. Herbicides bind to various soil constituents to differing degrees. The universal soil colloid that binds most herbicides is organic matter; however metallic hydrous oxides might also have some influence. The adsorption–desorption of three quaternary ammonium herbicides on soils with different chemical–physical characteristics was determined using a batch equilibration method before and after the following sequential selective dissolution procedures: removal of organic matter, and removal of organic matter plus free iron oxides. The experimentation involved paraquat (PQ), diquat (DQ) and difenzoquat (DFQ) herbicides. The distribution coefficients ( K d ) of the molecules and their correlation to the soil components were determined and a significant negative correlation with organic carbon was highlighted ( r < − 0.610 , p < 0.035 , n = 12 ). All quats cations experiment high adsorption in the control soils with a Zeta potential at about −21 mV. The order of adsorption on soils (based on K d ) was the following: PQ > DQ ≫ DFQ. The adsorption isotherms of these three herbicides on the natural and processed soils were satisfactorily fitted with the Freundlich equation, and a significant correlation with organic carbon was highlighted for quats K F ( r < − 0.696 , p < 0.012 , n = 12 ). The removal of organic matter from soils seems to leave free new adsorption sites for quats on the clay surface, which is no longer occluded by organic matter. This work shows that the amount and nature of the surface that remains available after the removal of single soil constituents is a critical parameter in determining the sorptive behavior of cationic contaminants.

Change in Criteria for USP Dissolution Performance Verification Tests

The US Pharmacopeial Convention has been evaluating its performance verification tests (PVT) for several years. These tests help ensure the integrity of the US Pharmacopeia performance test when a dissolution procedure, as described in General Chapter Dissolution <711>, is relied upon to test a nonsolution orally administered dosage form. One result of the evaluation is a change in the PVT criterion from one based on individual tablet results to one based on the mean and variability of a set of tablets. This paper describes the new PVT and its criterion and how its acceptance limits are derived from results of a collaborative study, explains a two-stage option for the test, and presents operating characteristics.

Uncertainty in dissolution test of drug release

The uncertainty estimation of measurements in pharmaceutical manufacturing is often neglected in process optimization. For instance, tablet manufacturing consists of several process steps called unit operations where many measurements on the process conditions and quality are carried out. These measurements are assumed to be error-free and the possibility of the cumulative error throughout the process stages that only goes up has been ignored. Good manufacturing practices (GMP) guidelines provide regulations for the pharmaceutical industry on how to establish high quality production. However, they do not provide any instructions on pre-optimizing the process using a proper sampling scheme at each step. The uncertainty tests of measurements, for example in the tableting process, accounts for all significant sources of uncertainty in the production. In this study, the total error of the dissolution test according to the uncertainties described in the Pierre Gy's sampling theory has been studied. The present study shows that the overall uncertainty of the dissolution procedure could be clearly improved with optimization of the sampling chain.

Pb–Pb dating of chondrules from CV chondrites by progressive dissolution

To refine absolute Pb–Pb ages of chondrules, we have experimented with progressive dissolution procedures of chondrules in the CV chondrite Allende in an attempt to effectively remove terrestrial contamination and generate Pb fractions of sufficient size and spread in 207Pb– 206Pb space to adequately define meaningful isochrons. Samples are extricated from the matrix, ultrasonicated, abraded and repeatedly pre-cleaned by ultrasonicating in distilled ethanol, water and acetone. Subsequent steps of weak HCl and HBr acids combined with ultrasonic agitation and modest heating effectively removes terrestrial contamination in most samples we analyzed. Subsequent exposure to warm 4 M HNO 3 typically isolates the least-radiogenic component of the stepwise dissolution series. Continuing the dissolution steps with HCl of increasing molarity with longer and higher temperature heating steps returns more radiogenic Pb fractions. The most radiogenic Pb fraction typically corresponds to the first warm 1 M HF step with subsequent steps in stronger HF yielding progressively less radiogenic signatures. Importantly, the Pb components extracted in the dissolution of the final residues with 28 M HF + 14 M HNO 3 typically lie slightly below the isochron defined by previous steps, corresponding to a slightly younger 207Pb /206Pb model age than the inferred real age. The wide range of total Pb contents (20–> 2000 pg) in different fractions returned by this method requires analyses by TIMS using a high-efficiency Pb emitter, 202Pb/ 205Pb double spike and diligent monitoring of laboratory Pb blank. As expected, U and Pb are highly and variably fractionated during the procedure such that no U/Pb age information is recovered. A multi-chondrule fraction from the CV chondrite Allende yields an age of 4565.32 ± 0.81 Ma, which is statistically younger than calcium–aluminum inclusions from the CV chondrite Efremovka.

Characterization of solids originating from the Fenton's process

Fenton's process has proven to be a viable alternative for the oxidation of organic pollutants in mixed waste chemicals, with a high efficiency in the removal of heavy metals from the effluent as a side effect. However, a solid residue loaded with metals is obtained as a by-product. In this paper, the solids originating from the Fenton's oxidation of mixed waste chemicals from an academic laboratory were studied. The process was applied to different wastewater cases (two composite samples generated in different periods) in order to study the effect of their characteristics on the residues composition. Residues were evaluated and classified according to their leaching properties. In addition, a most comprehensive assessment of metal mobility in the residues was obtained by chemical speciation. The Fenton's residues were classified as hazardous according to Brazilian waste regulations. The application of the sequential dissolution procedure indicated that the metals in the Fenton's residues are mainly constituted of amorphous material (over 80%). Furthermore, the reactive fractions of the residues (exchangeable and amorphous iron oxide fractions) retain most of remaining metals. Therefore, the Fenton's residues present great potential for environmental contamination, and require an administration system and control of their final disposal.

Relevance of NH 4F in acid digestion before ICP-MS analysis

In order to implement a simpler, less expensive and more safe sample dissolution procedure, we have substituted the HF–HClO 4 mixture by NH 4F. By testing three certified reference materials, lichen 336, basalt BE-N, soil 7, it was found that the three-reagents digestion without HF and HClO 4 (HNO 3 + H 2O 2 + NH 4F was used) was very effective for the pretreatment of ICP-MS measurement. The comparison was based on the measurement results and their uncertainties. All are reference material for amount contents of different trace elements. The accuracy and precision of the developed method were tested by replicate analyses of reference samples of established element contents. The accuracy of the data as well as detection limits (LODs) vary among elements but are usually very good (accuracy better than 8%, LODs usually below 1 μg/g in solids). ICP-MS capabilities enable us to determine routinely 13 and 16 minor and trace elements in basalt and soil.

The Pb–Pb age of Angrite SAH99555 revisited

Representing a suite of well-preserved basaltic meteorites with reported ages from 4566.18 ± 0.14 Ma to 4557.65 ± 0.13 Ma, angrites have been recurring targets for cross-calibrating extinct and absolute chronometers. However, inconsistencies exist in the available chronological data set, including a 4566.18 ± 0.14 Ma Pb–Pb age reported by Baker et al. [Baker J., Bizzarro M., Wittig N., Connelly J. and Haack H. (2005) Early planetesimal melting from an age of 4.5662 Gyr for differentiated meteorites. Nature 436, 1127–1131] for Sahara 99555 (herein SAH99555) that is significantly older than a Pb–Pb age for D’Orbigny, despite the two meteorites yielding indistinguishable Hf–W and Mn–Cr ages. We re-evaluate the Pb–Pb age of SAH99555 using a stepwise dissolution procedure on a whole rock fragment and a pyroxene separate. The combined data set yields a linear array that reflects a mixture of radiogenic Pb and terrestrial contamination and corresponds to an age of 4564.58 ± 0.14 Ma, which is 1.60 ± 0.20 Ma younger than that reported by Baker et al. [Baker J., Bizzarro M., Wittig N., Connelly J. and Haack H. (2005) Early planetesimal melting from an age of 4.5662 Gyr for differentiated meteorites. Nature 436, 1127–1131]. Our conclusion that SAH99555 crystallized at 4564.58 ± 0.14 Ma requires that all initial Pb was removed in the first progressive dissolution steps, an assertion supported by linearity of data generated by stepwise dissolution of a single fragment and the removal of an obvious highly-radiogenic component early in the dissolution process. We infer that the linear array defined by Baker et al. [Baker J., Bizzarro M., Wittig N., Connelly J. and Haack H. (2005) Early planetesimal melting from an age of 4.5662 Gyr for differentiated meteorites. Nature 436, 1127–1131] and their older age reflects a ternary mixture of Pb with constant relative proportions of highly-radiogenic initial Pb and radiogenic Pb with varying amounts of a terrestrial contamination. This requires that the phase harboring the initial Pb is insoluble in 2 M HCl, the only acid applied to the samples by Baker et al. [Baker J., Bizzarro M., Wittig N., Connelly J. and Haack H. (2005) Early planetesimal melting from an age of 4.5662 Gyr for differentiated meteorites. Nature 436, 1127–1131] prior to dissolution.

Desenvolvimento e validação do ensaio de dissolução para captopril em cápsulas magistrais por CLAE

O captopril é um fármaco anti-hipertensivo e vasodilatador utilizado na insuficiência cardíaca congestiva e encontra-se disponível, no mercado brasileiro, sob as formas de comprimidos e cápsulas, sendo estas manipuladas em farmácias. O objetivo deste estudo foi validar o procedimento de dissolução e o método de análise. A avaliação do perfil de dissolução do captopril na forma farmacêutica cápsulas magistrais quando submetidas a diferentes condições de pH, aparatos, velocidades de agitação do meio de dissolução e métodos para quantificação foram alvo deste estudo. As concentrações do fármaco no meio foram determinadas por cromatografia líquida e espectrofotometria. Os resultados mostraram que o método cromatográfico foi o mais adequado para avaliação de captopril na forma farmacêutica cápsulas, enquanto o método espectrofotométrico (recomendado pelas Farmacopéias Brasileira e Americana) apresentou baixa especificidade. O procedimento de dissolução nas condições estabelecidas foi preciso, exato e seletivo. O método foi linear. Com base nos resultados obtidos as condições do teste de dissolução para cápsulas foram o uso de HCl 0,01 M (900 mL, 37 ºC ± 0,5 ºC), aparato cesta, 50 rpm, tempo de coleta (20 minutos) e quantificação pelo método cromatográfico. Todas as cápsulas apresentaram resultados satisfatórios nos testes de qualidade a que foram submetidas.

The shotgun clause

PurposeThis paper aims to examine the economic rationale for the shotgun clause, a legally specified protocol for the dissolution of a partnership or a private corporation that empowers one investor to acquire ownership of all the venture's assets.Design/methodology/approachEmploying simple mathematics, the behavior of the initiating party or offeror is modeled in a situation of informational asymmetry and then optimized. The implications of offeror optimal behavior are then examined.FindingsThe paper finds that the introduction of a shotgun clause lowers the offeror's optimal offer price. Whereas in the absence of the clause, the offer price must exceed the offeror's private valuation of the business, in the presence of said clause the offeror's price may not exceed the offeror's private valuation. Situations where the shotgun clause improves versus impairs economic efficiency are delineated. For high (low) offeror private valuations of the business, the shotgun clause induces a greater (lower) discrepancy between said valuation and the offer price. Offerors with high private valuations of the business are shown to prefer the inclusion of the shotgun clause.Practical implicationsThe behavioral ramifications of the shotgun clause are presented, thus providing potential partners and private corporation shareholders a guide for the clause's inclusion or exclusion when the small business is structured.Originality/valueThis is the first paper to provide an analysis of the shotgun clause in the context of informational asymmetry, employing refinements and simplifications of extant models that address other small business dissolution procedures.

The USP Performance Verification Test, Part I: USP Lot P Prednisone Tablets—Quality Attributes and Experimental Variables Contributing to Dissolution Variance

Beyond instrumental qualification, proficiency testing is not usually a prerequisite for many analytical procedures, given reliance on a manufacturer's assay validation coupled with regulatory review and inspection. Given the special features of the dissolution procedure, proficiency testing was put in place initially by pharmaceutical manufacturers and carried on by USP. Proficiency testing is designed to help ensure that execution of a dissolution procedure for solid oral dosage forms adequately supports administrative and legal decisions so that measurements made at different times, by different analysts, or with different methods can be confidently compared. USP has applied metrological principles to aid practitioners in carrying out the dissolution procedure alone and in collaborative studies to facilitate understanding potential sources of variability. The present study aimed to identify key dissolution variables associated with USP Lot P Prednisone Tablets in conjunction with the USP Performance Verification Test (PVT). Using five dissolution test assemblies from different manufacturers, at least four of six analysts determined percents prednisone dissolved on dissolution Apparatus 1 (basket) and Apparatus 2 (paddle) on each assembly. Six replicate experiments were performed on each analyst-assembly combination with a set of six to eight tablets in each experiment. Statistical analysis demonstrated that dissolution test assemblies were the largest factor contributing to dissolution variability. Inherent tablet variability was low, and USP Lot P Prednisone Tablets did not contribute importantly to dissolution variability. Contributions from analyst and analytical procedure also were estimated to be low.

Analysis of Metallic Glass Sample Including Niobium, Boron and Silicon by Microwave-Assisted Dissolution/Inductively Coupled Plasma- Optical Emission Spectrometry Using Hydrofluoric and Nitric Acids Mixture

Metallic glasses containing iron, cobalt, niobium, boron and silicon were analyzed. The samples could be dissolved only with a mixture of hydrofluoric acid and nitric acid. After a sample dissolved, metallic elements were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). Conventional ICP-OES instruments were not employed because hydrofluoric acid attacked the plasma torch, chamber and nebulizer, which were made of quartz or glass. When a sample solution contained hydrofluoric acid, hydrofluoric acid was removed by heating with sulfuric acid. However, this removal technique led to a loss of boron and silicon. By a microwave-assisted dissolution procedure with a mixture of hydrofluoric acid and nitric acid, boron and silicon were not vaporized. A hydrofluoric acid resisting ICP-OES instrument was employed for elemental determination. The total values of all the elements determined were almost 100%.

Development of Discriminating Method for Dissolution of Aceclofenac Marketed Formulations

The development of a meaningful dissolution procedure for drug products with limited water solubility has been a challenge to the pharmaceutical industry. Aceclofenac (BCS Class II drug) is a nonsteroidal anti-inflammatory drug. There is no official dissolution medium available in the literature. In the present study, parameters such as solubility, medium pH, surfactant type, dissolution behavior of formulations, influence of sink conditions, stability, and discriminatory effect of dissolution testing were studied for the selection of a proper dissolution medium. Results of solubility data revealed that solubility increased with an increase in pH. Sink conditions were exhibited in all media except double-distilled water and 0.1 N HCl. The drug and marketed formulations were stable in the dissolution media used. An agitation speed of 50 rpm showed a more discriminating drug release profile than 75 rpm. The discriminating dissolution method for aceclofenac formulation is paddle at 50 rpm, 900 mL pH 6.8 phosphate buffer, greater than 80% of the label amount is released over 60 minutes.

Novel strategies for rapid trace element analysis of polyamide by graphite furnace atomic absorption spectrometry and inductively coupled plasma mass spectrometry. Dissolution in an organic solvent versus direct solid sampling approaches.

Titanium dioxide is added to polyamide since it efficiently scatters visible light and imparts whiteness, brightness and high opacity. TiO2, however, can degrade easily and to counteract this, it is coated with a layer of inorganic material, containing Al, Mn and Si. For quality control, it is important to develop fast and reliable methods for the determination of these elements. Due to the fact that acid digestion techniques are labor-intensive, time-consuming and bring about the risk of contamination, an alternative dissolution procedure has been developed using formic acid to dissolve polyamide. The solutions thus obtained were measured by means of graphite furnace atomic absorption spectrometry (GFAAS) and inductively coupled plasma mass spectrometry (ICPMS). For the latter technique, sample introduction was performed using a pneumatic nebulization system, containing a membrane desolvating unit to remove the organic solvent. This approach provided satisfactory results in terms of precision (6–10% RSD) and limits of detection (0.1–0.6 μg g−1, except for Si when using ICPMS). Addition of formic acid to the calibration standards was demonstrated to be required. To enhance the sensitivity, increase the sample throughput and reduce the risk of contamination and/or analyte losses, the direct solid sampling methods solid sampling GFAAS and electrothermal vaporization (ETV)-ICPMS were also evaluated. Both techniques provided accurate results using calibration versus aqueous standards, with RSD values of ∼10%. Limits of detection were improved considerably compared to those attainable after dissolution. In contrast to GFAAS, ETV-ICPMS allows the simultaneous determination of all of the analytes.

Optimization and validation of a dissolution test for selegiline hydrochloride tablets by a novel rapid HPLC assay using a monolithic stationary phase

The present study reports the optimization and validation of a dissolution test for selegiline·HCl tablets using a new high-performance liquid chromatographic (HPLC) method. Rapid separation of the analyte from sample matrix was achieved in less than 60 s using a Cromolith ® RP-18e monolithic column using UV detection at 220 nm. Thorough validation of the assay based on pre-defined criteria included linearity, LOD/LOQ, accuracy, precision, selectivity and ruggedness. The dissolution test was optimized in terms of dissolution medium, basket (type I)/paddle (type II) agitation and rotation speed. Its ruggedness was also validated. The presented analytical and dissolution procedures are currently being applied in the quality and stability control of Cosmopril ® tablets (5 mg/tablet selegiline·HCl, Cosmopharm Ltd., Korinthos, Greece).

Contribuição dos constituintes da fração argila de solos subtropicais à área superficial específica e à capacidade de troca catiônica

A área superficial específica (ASE) está relacionada com diversas propriedades que definem o comportamento físico-químico dos solos. Neste trabalho, foi estudada a fração argila de 23 amostras de solos desenvolvidos a partir de diferentes materiais de origem, encontrados na região Sul do Brasil, a fim de estabelecer a contribuição dos principais constituintes para a ASE e a capacidade de troca de cátions efetiva (CTCe). Foram identificados os minerais por difratometria de raios X (DRX); quantificados por análise termogravimétrica (ATG); determinados os valores de CTCe e de ASEt (total), pelo método do etilenoglicol mono-etil éter (EGME); de ASEe (externa), pelo método BET-N2; e de ASEi, pela diferença dos valores obtidos entre os dois métodos. Essas determinações foram feitas antes e após os procedimentos seqüenciais de dissolução seletiva, que visavam remover: a matéria orgânica (argila-NaOCl); a matéria orgânica e os óxidos de Fe livres (argila NaOCl + DCB); e a matéria orgânica, os óxidos de Fe livres, a caulinita, a gibbsita e os minerais aluminossilicatados de baixa cristalinidade (argila-NaOCl+DCB+NaOH 5 mol L-1). Os solos estudados apresentaram grande variação na mineralogia da fração argila; para a maioria deles, a caulinita foi o mineral predominante, seguido dos argilominerais do tipo 2:1 expansíveis ou dos óxidos e hidróxidos de Fe e Al. Entre a ASEe e a CTCe da fração argila-natural não se constatou relação de dependência, devido ao recobrimento da superfície da amostra pela matéria orgânica. O efeito agregante dos óxidos de Fe promoveu diminuição de 21 % da ASEe. Os argilominerais do tipo 2:1 encontram-se em concentrações variando de 3 a 65 % da fração silicatada, contribuindo com valores médios de 1.054 mmol c kg-1 e de 202 m² g-1 para CTCe e ASEt, respectivamente. A ASEi contribui com 58 % da ASEt na fração argila com remanescentes de argilominerais do tipo 2:1.

239, 240, 241Pu fingerprinting of plutonium in western US soils using ICPMS: solution and laser ablation measurements

Sector field inductively coupled plasma mass spectrometry (SF-ICPMS) has been used with analysis of solution samples and laser ablation (LA) of electrodeposited alpha sources to characterize plutonium activities and atom ratios prevalent in the western USA. A large set of surface soils and attic dusts were previously collected from many locations in the states of Nevada, Utah, Arizona, and Colorado; specific samples were analyzed herein to characterize the relative contributions of stratospheric fallout vs. Nevada Test Site (NTS) plutonium. This study illustrates two different ICPMS-based analytical strategies that are successful in fingerprinting Pu in environmental soils and dusts. Two specific datasets have been generated: (1) soils are leached with HNO3-HCl, converted into electrodeposited alpha sources, counted by alpha spectrometry, then re-analyzed using laser ablation SF-ICPMS; (2) samples are completely dissolved by treatment with HNO3-HF-H3BO3, Pu fractions are prepared by extraction chromatography, and analyzed by SF-ICPMS. Optimal laser ablation and ICPMS conditions were determined for the re-analysis of archived alpha spectrometry "planchette" sources. The best ablation results were obtained using a large spot size (200 microm), a defocused beam, full repetition rate (20 Hz) and scan rate (200 microm s(-1)); LA-ICPMS data were collected with a rapid electrostatic sector scanning experiment. Less than 10% of the electroplated surface area is consumed in the LA-ICPMS analysis, which would allow for multiple re-analyses. Excellent agreement was found between (239+240)Pu activities determined by LA-ICPMS vs. activity results obtained by alpha spectrometry for the same samples ten years earlier. LA-ICPMS atom ratios for 240Pu/239Pu and 241Pu/239Pu range from 0.038-0.132 and 0.00034-0.00168, respectively, and plot along a two-component mixing line (241Pu/239Pu = 0.013 [240Pu/239Pu] - 0.0001; r2 = 0.971) with NTS and global fallout end-members. A rapid total dissolution procedure, followed by extraction chromatography and SF-ICPMS solution Pu analysis, generates excellent agreement with certified (239+240)Pu activities for standard reference materials NIST 4350b, NIST 4353, NIST 4357, and IAEA 385. (239+240)Pu activities and atom ratios determined by total dissolution reveal isotopic information in agreement with the LA-ICPMS dataset regarding the ubiquitous mixing of NTS and stratospheric fallout Pu sources in the regional environment. For several specific samples, the total dissolution method reveals that Pu is incompletely recovered by simpler HNO3-HCl leaching procedures, since some of the Pu originating from the NTS is contained in refractory siliceous particles.

Microwave assisted volatilization of silicon as fluoride for the trace impurity determination in silicon nitride by dynamic reaction cell inductively coupled plasma-mass spectrometry

A low pressure microwave assisted vapor phase dissolution procedure for silicon nitride and volatilization of in situ generated SiF 4 has been developed using H 2SO 4, HF and HNO 3 for the determination of trace impurities present in silicon nitride. Sample was taken in minimum amount (0.5 mL for 100 mg) of H 2SO 4 and treated with vapors generated from HF and HNO 3 mixture in presence of microwaves in a closed container. An 80 psi pressure with ramp and hold times of 30 min and 60 min respectively, operated twice, resulted in 99.9% volatilization of Si. Matrix free solutions were analyzed for impurities using DRC-ICP-MS. The recoveries of Cr, Mn, Fe, Ni, Co, Cu, Zn, Sr, Y, Cd, Ba and Pb were between 80 and 100% after volatilization of Si. The blanks were in lower ng g −1 with method detection limits in lower ng g −1 to sub ng g −1 range. The method was applied for the analysis of two silicon nitride samples.

Comparison of atomic absorption, mass and X-ray spectrometry techniques using dissolution-based and solid sampling methods for the determination of silver in polymeric samples

In this work, the capabilities and limitations of solid sampling techniques – laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), wavelength dispersive X-ray fluorescence spectrometry (WD-XRFS) and solid sampling electrothermal atomic absorption spectrometry (SS-ETAAS) – for the determination of silver in polymers have been evaluated and compared to those of acid digestion and subsequent Ag determination using pneumatic nebulization ICPMS (PN-ICPMS) or flame AAS (FAAS). In a first stage, two dissolution procedures were examined: conventional acid digestion in a Kjeldahl flask and the combination of dry ashing and microwave-assisted digestion. Accurate results for Ag could be obtained, although occasionally, problems of analyte losses and/or incomplete dissolution were observed. LA-ICPMS shows potential for direct analysis of solid materials, but calibration was found to be difficult. A polypropylene sample was used as standard. This approach provided satisfactory results for other polypropylene samples and even for other types of plastics, provided that the 13C + signal was used as internal reference, correcting for variations in ablation efficiency. However, the results for polyoxymethylene were overestimated. Similar calibration problems appeared with WD-XRFS, due to differences in absorption efficiency of X-rays. In this case, the accuracy could be improved by using a matrix correction procedure, which however required the matrix composition to be known into sufficient detail. SS-ETAAS, proved to be a fast approach that allowed accurate determination of Ag in polymers using aqueous standard solutions for calibration. Due to the high Ag content and the excellent sensitivity, the use of a 3-field mode Zeeman-effect background correction system was essential for the extension of the working range.

Analysis of pure copper – a comparison of analytical methods

The reliability and performance of various analytical methods for the determination of 22 trace elements in pure copper is compared and discussed. The work was performed in the framework of an interlaboratory comparison for the preparation of four pure copper reference materials with graded element mass fractions of Ag, Al, As, Bi, Cd, Co, Cr, Fe, Mg, Mn, Ni, P, Pb, S, Sb, Se, Si, Sn, Te, Ti, Zn, and Zr. Special analytical results (ET-AAS, ICP-MS) obtained by the authors were described in more detail and were compared to the certified values. Special regard was paid to the influence of the copper matrix on performance and sensitivity of each analytical method and to the dissolution procedure of copper matrix and interferences from insoluble residues. For a generalized evaluation of the figures of merit for each applied elemental analytical method results from several independent laboratories were included in the discussion.