Magdalena Krawczyk

Determination of total antimony and inorganic antimony species by hydride generation in situ trapping flame atomic absorption spectrometry: a new way to (ultra)trace speciation analysis

The analytical performance of non-chromatographic coupled hydride generation, integrated atom trap (HG-IAT) atomizer flame absorption spectrometry (FAAS) systems were evaluated for the speciation analysis of antimony in environmental samples. Antimony, using formation of stibine (SbH3) vapors were atomized in an air–acetylene flame-heated IAT. A new design of HG-IAT-FAAS hyphenated technique that would exceed the operational capabilities of existing arrangements (a water-cooled single silica tube, double-slotted quartz tube or an “integrated trap”) was investigated. For the estimation of Sb(III) and Sb(V) concentrations in samples, the difference between the analytical sensitivities of the absorbance signals obtained for antimony hydride without and with previous treatment of samples with L-cysteine can be used. The concentration of Sb(V) was calculated by the difference between total Sbtot and Sb(III). A dramatic improvement in detection limit was achieved compared with that obtained using either of the atom trapping techniques, presented above, separately. This novel approach decreases the detection limit down to low pg mL–1 levels. The concentration detection limit, defined as 3 times the blank standard deviation (3sigma), was 0.2 ng mL–1. For a 120 s in situ pre-concentration time (sample volume of 2 mL), sensitivity enhancement compared to flame AAS, was 550 fold for Sb, using hydride generation-atom trapping technique. The sensitivity can be further improved by increasing the collection time. The precision, expressed by RSD, was 8.0% (n = 6) for Sb. The designs studied include slotted tube, water-cooled single silica tube and integrated atom traps. Reference and real sample materials were analyzed. The accuracy of the method was verified by the use of certified reference materials (NIST SRM 2704 Buffalo River Sediment, SRM 2710 Montana Soil, SRM 1633a Coal Fly Ash, SRM 1575 Pine Needles, SRM 1643e Trace Elements in Water) and by aqueous standard calibration technique (solutions). The measured Sb content, in reference materials, were in satisfactory agreement with the certified values. The hyphenated technique was applied for antimony determinations in soil, sediment, coal fly ash, sewage and river water.

Kraft lignin/silica-AgNPs as a functional material with antibacterial activity.

Advanced functional silica/lignin hybrid materials, modified with nanosilver, were obtained. The commercial silica Syloid 244 was used, modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane to increase its chemical affinity to lignin. Similarly, kraft lignin was oxidized using a solution of sodium periodate to activate appropriate functional groups on its surface. Silver nanoparticles were grafted onto the resulting silica/lignin hybrids. The systems obtained were comprehensively tested using available techniques and methods, including transmission electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, elemental analysis and atomic absorption spectroscopy. An evaluation was also made of the electrokinetic stability of the systems with and without silver nanoparticles. Conclusions were drawn concerning the chemical nature of the bonds between the precursors and the effectiveness of the method of binding nanosilver to the hybrid materials. The antimicrobial activity of the studied materials was tested against five species of Gram-positive and Gram-negative bacteria. The addition of silver nanoparticles to the silica/lignin hybrids led to inhibition of the growth of the analyzed bacteria. The best results were obtained against Pseudomonas aeruginosa, a dangerous human pathogen.

Ultrasound-assisted dispersive micro solid-phase extraction with nano-TiO2 as adsorbent for the determination of mercury species.

The combination of ultrasound-assisted dispersive micro solid-phase extraction (USA DMSPE), with the use of TiO2 nanoparticles (NPs) as adsorbent, with cold vapor atomic absorption spectrometry (CV AAS) is proposed for preconcentration and determination of mercury species (Hgtotal, Hg2+ and CH3Hg+) in biological, geological and water samples. The experimental parameters including the amount of TiO2 NPs, pH of sample solution, ultrasonication and centrifugation time, TiO2 slurry solution preparation before injection to CV AAS were investigated. Effective preconcentration of trace mercury with 10mg of TiO2 was achieved in pH 7.5. After extraction, adsorbent with analytes was mixed with 500μL of 1molL-1 HNO3 to prepare slurry solution. The concentration limit of detection was 0.004ngmL-1 for Hg2+. The achieved preconcentration factor was 35. The relative standard deviations (RSDs, %) for mercury species in real samples were 4-20%. The accuracy of this method was evaluated by analyses of certified reference materials: DOLT-2 (Dogfish Liver), IAEA-085 (Human hair), SRM 2709 (San Joaquin Soil), SRM 2711 (Montana Soil) and SRM 2704 (Buffalo River Sediment). The measured mercury species contents in reference materials were in satisfactory agreement with the added amounts (according to the t-test for a 95% confidence level). The presented method has been successfully applied for the determination of mercury species in real water samples (lake and river water).

Silver nanoparticles as a solid sorbent in ultrasound-assisted dispersive micro solid-phase extraction for the atomic absorption spectrometric determination of mercury in water samples

The combination of ultrasound-assisted dispersive micro solid-phase extraction (USA DMSPE), with the use of silver nanoparticles (AgNPs) as a solid sorbent, with high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ETAAS) is proposed for the preconcentration and determination of Hg2+ ions in water samples. The main extraction and detection parameters were investigated. Effective preconcentration of trace mercury was achieved at pH 3.5 with 10 mg of AgNPs. Amalgamated mercury was dissolved in 200 μL of 7 mol L−1 HNO3 before atomic absorption spectrometry (AAS) detection. The concentration limit of detection was 0.005 ng mL−1. The achieved preconcentration factor was 15 and the relative standard deviations (RSDs, %) for real water samples were 6–11%. The accuracy of this method was evaluated by analyses of CRMs. The method has been successfully applied to the determination of mercury in three different real water samples.

Determination of macro and trace elements in multivitamin dietary supplements by high-resolution continuum source graphite furnace atomic absorption spectrometry with slurry sampling

In this research, three different commercially available multivitamin dietary supplements were analyzed by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) with slurry sampling. The concentrations of Cr, Cu, Fe, Mn, and Se were determined and compared to the amounts stated by producers. The safety of multivitamin dietary supplements depends on various factors including the manufacturing process and the purity and origins of the raw ingredients. For this reason, this research determined concentrations of several toxic elements (As, Cd, and Pb). Microwave-assisted high pressure Teflon bomb digestion was used to determine total amounts of elements in samples. Samples were prepared as slurries at a concentration of 0.1% (m/v) for macro elements (Cr, Cu, Fe, Mn, and Se) and at a concentration of % (m/v) for trace elements (As, Cd, and Pb) in acidic media (3M HNO3). The influence of acid concentration, Triton X-100 addition, sonication time, and sonication power on absorbance was investigated. The accuracy of this method was validated by analyses of NRCC LUTS-1 (Lobster hepatopancreas), NRCC DORM-1 (Dogfish Muscle), NRCC DOLT-2 (Dogfish Liver), NBS SRM 1570 (Spinach Leaves) and NBS SRM 1573 (Tomato Leaves) certified reference materials. The measured elements contents in these reference materials (except NRCC DOLT-2) were in satisfactory agreement with the certified values according to the t-test for a 95% confidence level.

Determination of nickel by chemical vapor generation in situ trapping flame AAS

AbstractThe analytical performances of coupled chemical vapor generation, integrated atom trap (CVG-IAT) atomizer flame atomic absorption spectrometry (FAAS) system were evaluated for determination of nickel in environmental samples. Nickel chemical vapors are atomized in an air-acetylene flame-heated IAT. A new design of CVG-IAT-FAAS hyphenated technique that would exceed the operational capabilities of existing arrangements (a water-cooled single silica tube, double-slotted quartz tube) permitting construction of an “integrated trap” was investigated. An improvement in limit of detection was achieved compared with that obtained using any of the above atom trapping techniques separately. The concentration limit of detection was 1 ng mL−1 for Ni. The overall efficiencies of the vapor generation process was estimated to be ca. 50%. For a 2 min in situ pre-concentration time, sensitivity enhancement, compared to FAAS, was 200 folds for Ni, using vapor generation atom trapping technique. The sensitivity can be further improved by increasing the collection time. The precision of the measurements for 25 ng mL−1 of Ni was 9% RSD. The accuracy of this method was tested by analyses of NIST SRM 2704 (Buffalo River Sediment), NIST SRM 1648 (Urban Particulate Matter), NIST SRM 2710 (Montana Soil), NBS SRM 1633a (Coal Fly Ash) and NIST SRM 1643e (Trace Element in Water) certified reference materials. The measured Ni content in five reference materials was in satisfactory agreement with the certified values (in the range of 14.3–98 μg g−1). The hyphenated technique was applied for nickel determination in coal fly ash, soil, sediment, sewage and river water.

Application of dendrimer modified halloysite nanotubes as a new sorbent for ultrasound-assisted dispersive micro-solid phase extraction and sequential determination of cadmium and lead in water samples

The combination of ultrasound-assisted dispersive micro-solid phase extraction (USA DMSPE) and high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) was developed for the sequential determination of cadmium and lead in water samples. During the preconcentration step, dendrimer modified halloysite nanotubes (HNTs-G3) were used as a solid sorbent. Fourier transform infrared (FTIR) spectroscopy was used to characterize HNTs during the modification steps. HNTs-G3 were dispersed in water samples containing trace elements to be determined. After the sorption, the aqueous samples were separated by centrifugation. Then, the metal loaded HNTs-G3 were suspended using a small volume of deionized water and introduced into an atomizer. The main extraction and detection parameters were investigated. The concentration limits of detection were 0.5 and 10 ng L−1 for Cd and Pb, respectively. The preconcentration factors achieved for Cd and Pb were 46 and 41, respectively. The relative standard deviations (RSDs) were 4% and 5% for Cd and Pb, respectively. The accuracy of this method was validated by analyses of NIST SRM 1643e (Trace Elements in Water), TMRAIN-04 (Rainwater) and ERM – CA011b (Hard Drinking Water). The measured element contents in these reference materials were in satisfactory agreement with the certified values according to the t-test for a 95% confidence level. The proposed method has been successfully applied to the determination of cadmium and lead in six different water samples (seawater, lake water, river water, stream water, mine water and tap water).

Determination of gold by high-resolution continuum source atomic absorption spectrometry with chemical vapor generation

The analytical potential of chemical vapor generation and high-resolution continuum source atomic absorption spectrometry (CVG HR-CS AAS) with quartz tube atomization in determination of gold was evaluated. The volatile species of gold were formed by reaction with sodium tetrahydroborate(III) in the presence of hydrochloric acid. The influence of didodecyldimethylammonium bromide (DDAB) and sodium diethyldithiocarbamate (DDTC) on the absorbance was investigated. The concentration limit of detection was 2.6 ng mL-1 for Au. The precision of measurement at 20 ng mL-1 of Au was 10% of the relative standard deviation (RSD). The accuracy of this method was validated by analyses of NRCC PCT-1a (Copper-Nickel Sulfide Concentrate with Noble Metals), NIST SRM 2710 (Montana Soil) and NIST SRM 1643e (Trace Element in Water) certified reference materials. The measured Au contents in these three reference materials were in satisfactory agreement with the certified values. This method was also applied for gold determination in coal fly ash, sediment and nickel alloy.

Solid-phase extraction with multiwalled carbon nanotubes prior to photochemical generation of cadmium coupled to high-resolution continuum source atomic absorption spectrometry

Multiwalled carbon nanotubes (MWCNTs) were used as sorbent for solid phase extraction (SPE) of cadmium ions from water samples. After extraction, volatile cadmium species were generated in the presence of propionic acid under ultraviolet radiation (photochemical generation, UV CVG) and determined by high-resolution continuum source atomic absorption spectrometry (HR-CS AAS) with quartz tube atomization (QTA). The experimental parameters including pH of the solutions, amount of MWCNTs, flow rate of sample, eluent concentration, maximum sample volume and coexisting ions, as well as main parameters of UV CVG HR-CS QTA AAS were investigated. The effective preconcentration of trace cadmium was achieved in pH 7 and the retained cadmium was efficiently eluted with 0.5 mol L−1 HNO3. The limit of detection was 25 μg L−1 and the achieved preconcentration factor was 8.8. The relative standard deviation (RSDs) was 15%. The accuracy of this method was validated by the analyses of NIST SRM 1643e (trace elements in water) and ERM-CA011b (hard drinking water) certified reference materials. The element contents measured in these reference materials were in satisfactory agreement with the certified values according to the t-test for a 95% confidence level. The presented method was successfully applied for the determination of cadmium in four different water samples (seawater, lake water, mine water and tap water).

Determination of Silver by Chemical Vapor Generation with In Situ Trapping Flame Atomic Absorption Spectrometry

ABSTRACT The hyphenation of chemical vapor generation with an integrated atom trap system for flame atomic absorption spectrometry (CVG-IAT-FAAS) was evaluated for determination of silver in real samples (coal fly ash, sediment, and nickel alloy). The volatile species of silver were formed by reaction with sodium tetrahydroborate(III) in the presence of nitric acid. A new CVG-IAT-FAAS design (versus a water-cooled single silica tube, double-slotted quartz tube) significantly improved the sensitivity and detection limits compared with conventional flame atomic absorption spectrometry (FAAS) for determination of silver. The concentration limit of detection was 0.7 ng mL−1 for Ag. The overall efficiency of the vapor generation process was estimated to be ca. 12%. For a 2 min in situ preconcentration time, sensitivity was enhanced 143-fold for Ag using the vapor generation atom trapping technique, compared to conventional FAAS. Sensitivity can be further improved by increasing the collection time. The precision of measurement at 10 ng mL−1 of Ag was 10% RSD. The accuracy of this method was validated by analyses of NRC GBW 07302 (Stream Sediment), BCS CRM No. 346 (Nickel Alloy), NIST SRM 2710 (Montana Soil), NRCC LUTS-1 (Lobster Hepatopancreas), and NIST SRM 1643e (Trace Element in Water) certified reference materials. The measured Ag contents in these five reference materials were in satisfactory agreement with the certified values (spanning the range of 0.066–35 µg g−1).