Mariusz Ślachciński

Recent Achievements in Sample Introduction Systems for Use in Chemical Vapor Generation Plasma Optical Emission and Mass Spectrometry: From Macro- to Microanalytics

Abstract Chemical vapor generation (CVG) offers several significant advantages for analyses, including efficient matrix separation, which often leads to a reduction of interferences and better detection limits; high transport efficiency of analyte into the atomic spectroscopic detector; in some cases, high selectivity to permit differentiation of chemical species of a particular element and enable use of gas-phase separation methods for speciation of some elements. The development of CVG techniques from a Marsh test (arsine generation) to a recent device combining vapor generation with multichannel sample introduction systems and separation or preconcentration techniques at the macro- and microscale for use in optical emission and mass spectrometry is reviewed.

Method development for simultaneous multi-element determination of transition (Au, Ag) and noble (Pd, Pt, Rh) metal volatile species by microwave induced plasma spectrometry using a triple-mode microflow ultrasonic nebulizer and in situ chemical vapor generation

The analytical potential of a coupled continuous-microflow ultrasonic nebulizer triple-mode micro capillary system (μ-USN/TCS)-Ar/He mixed gas microwave induced plasma-optical emission spectrometry (MIP-OES) has been evaluated for the purpose of determination of metal volatile species (Au, Ag, Pd, Pt, Rh). An extremely short reaction time between sample, acid and reductant and a rapid separation of the reaction products is obtained by mixing the sample, acid and the sodium borohydride reductant solution at the quartz oscillator, converting liquids into aerosol at the entrance to the spray chamber. A univariate approach and simplex optimization procedure was used to achieve optimized conditions and derive analytical figures of merit. Results showed that the analytical performance of the new system was superior to that of ultrasonic nebulizer dual-mode capillary system. Analytical performance of the ultrasonic nebulization system was characterized by determination of the limits of detection (LODs) and precision (RSDs) with the μ-USN/TCS observed at a 15 μL min−1 flow rate. The experimental concentration detection limits for simultaneous determination, calculated as the concentration giving a signal equal to three times of the standard deviation of the blank (LOD, 3σblank criterion, peak height) were 1.2, 1.5, 1.1, 2.9 and 1.8 ng mL−1 for Au, Ag, Pd, Pt and Rh, respectively. The method offers relatively good precision (RSD ranged from 7 to 8%) for liquid analysis and microsampling capability. The accuracy of the method was verified using certified reference materials (TORT-1, NIST 2710, NIST 1643e, IAEA-336) and by the aqueous standard calibration technique. The measured contents of elements in reference materials were in satisfactory agreement with the certified value (Ag) and added amounts (Au, Pd, Pt, Rh).

Method Development for Simultaneous Determination of Transition (Au, Ag, Cd, Cu, Mn, Ni, Pb, Zn) and Noble (Pd, Pt, Rh) Metal Volatile Species by Microwave-Induced Plasma Spectrometry Using Ultrasonic Micronebulizer Dual Capillary Sample Introduction System

ABSTRACT The commercial ultrasonic nebulizer NOVA-DUO (Optolab, Warsaw, Poland) has been evaluated for the simultaneous determination of transition (Au, Ag, Cd, Cu, Mn, Ni, Pb, Zn) and noble (Pd, Pt, Rh) volatile metal species by microwave induced plasma–optical emission spectrometry (MIP-OES). Simultaneous mixing and nebulization of the two solutions (acidified sample and reductant) on the piezoelectric transducer, with the possibility of flow rate adjustment, permits a wide variation of sensitivity. The vapor-phase species were rapidly transported via a stream of Ar carrier to an MIP–OES for simultaneous multi-element determination. A univariate approach and simplex optimization procedure was used to achieve optimized conditions and derive analytical figures of merit. Analytical performance of the ultrasonic nebulization system was characterized by determination of the limits of detection (LODs) and precision (RSDs) with the ultrasonic nebulizer/dual capillary system (USN/DCS) observed at 15 µL min−1 flow rate. An improvement in detection limits was achieved compared with pneumatic nebulization. Detection limits are superior to conventional pneumatic nebulization of elements. The experimental concentration detection limits for simultaneous determination, calculated as the concentration giving a signal equal to three times of standard deviation of the blank (LOD, 3σblank criterion, peak height), were 2.49, 1.75, 3.39, 2.13, 4.80, 6.21, 4.26, 2.01, 7.65, 3.92, and 4.65 ng mL−1 for Au, Ag, Cd, Cu, Mn, Ni, Pb, Pd, Pt, Rh, and Zn, respectively. The method offers relatively good precision (RSD ranged from 8 to 12%) for liquid analysis and microsampling capability. The accuracy of the method was verified by the use of digested certified reference materials (NRCC TORT-1, NIES CRM-13, NIST SRM 2710, INCT SBF-4) and by aqueous standard calibration technique. The measured elements content in reference materials was in satisfactory agreement with the certified values.

Analytical Evaluation of an Integrated Ultrasonic Nebulizer-hydride Generator System for Simultaneous Determination of Hydride and Non-hydride Forming Elements by Microwave Induced Plasma Spectrometry

ABSTRACT The commercial ultrasonic nebulizer NOVA-DUO (ultrasonic nebulizer dual capillary system USN/DCS) has been evaluated for the simultaneous determination of classical hydride forming (As, Bi, Ge, Sb, Se, Sn) and conventional non-hydride forming (Ba, Ca, Fe, Li, Mg, Sr) elements by microwave induced plasma-optical emission spectrometry (MIP-OES). Simultaneous mixing and nebulization of the two solutions (acidified sample and reductant) on the piezoelectric transducer, with the possibility of flow rate adjustment, permits a wide variation of sensitivity. The hydrides and aerosols were rapidly transported via a stream of Ar carrier to a MIP for simultaneous multi-element determination by OES. A univariate approach and simplex optimization procedure was used to achieve optimized conditions and derive analytical figures of merit. Analytical performance of the ultrasonic nebulization system was characterized by determination of the limits of detection (LODs) and precision (RSDs) with the USN/DCS observed at 11 µL min−1 flow rate. The experimental concentration detection limits for simultaneous determination, calculated as the concentration giving a signal equal to three times of standard deviation of the blank (LOD, 3σblank criterion, peak height) were 1.3, 5.9, 6.6, 1.8, 3.6, 2.6, 41, 8.1, 11, 7.5, 9.2, and 12 ng mL−1 for As, Bi, Ge, Sb, Se Sn, Ba, Ca, Fe, Li, Mg, and Sr, respectively. The method offers relatively good precision (RSD ranged from 9 to 13%) for liquid analysis and microsampling capability. Interference effects by transition metals have been shown to be corrected by the addition of thiourea, as a pre-reducing agent and masking agent. The accuracy of the method was verified by the use of certified reference materials (NRCC DOLT-2, NRC GBW 07302, NIST SRM 2710, NIST SRM 1643e) and by aqueous standard calibration technique. All results obtained for reference materials were in agreement with certified values at 95% confidence level by Student t-test.

Interfacing a microchip-based capillary electrophoresis system with a microwave induced plasma spectrometry for copper speciation

AbstractA microchip-based capillary electrophoresis (µCE) system was interfaced with a microwave induced plasma optical emission spectrometry (MIP-OES) to provide copper species separation capabilities. This system uses an extremely low flow demountable direct injection high efficiency nebulizer (D-DIHEN) sited directly at the liquid exit of the chip. A supplementary flow of buffer solution at the channel exit was used to improve nebulization efficiency. A small evaporation chamber has been incorporated into the interface in order to prevent the losses associated with traditional spray chambers, allowing the entire aerosol sample to enter the plasma. Syringe pumps were used to manipulate the flow rate and flow direction of the sample, buffer, and supplementary buffer solution. Sample volumes of 25 nL can be analyzed. With application of an electric field up to 500 V cm−1, species such as Cu(II) and Cu(EDTA)2− were separated in acidic solution within 90 s using a 26 mm long separation channel etched in a glass base. Resolution of the Cu(II) and Cu(EDTA)2− peaks was 1.1 using the chip-based µCE-MIP-OES system.

In situ vapor generation inductively coupled plasma spectrometry for determination of iodine using a triple-mode microflow ultrasonic nebulizer after alkaline solubilization

The analytical potential of a coupled continuous-microflow ultrasonic nebulizer triple-mode micro-capillary system (µ-USN/TCS) for the determination of iodine in biological samples by direct iodine vapor generation inductively coupled plasma optical emission spectrometry (VG-ICP-OES) has been investigated. The iodine atomic emission line at 183.038 nm was selected as the analytical line of interest. An extremely short oxidation reaction time between sample, acid and oxidant and a rapid separation of the reaction products is obtained by mixing the sample, sulfuric acid, hydrogen peroxide, and the sodium nitrite solution at the quartz oscillator, converting liquids into aerosol at the entrance to the spray chamber. A univariate approach and simplex optimization procedures were used to achieve optimized conditions and derive analytical figures of merit. Results showed that the analytical performance of the new system was superior to that of pneumatic nebulizer. Analytical performance of the ultrasonic nebulization system was characterized by determination of the limits of detection (LODs) and precision (RSDs) with the µ-USN/TCS-VG-ICP-OES observed at a 15 µL min−1 flow rate. The experimental concentration detection limits for iodine determination, calculated as the concentration giving a signal equal to three times of the standard deviation of the blank (LOD, 3σblank criterion, peak height), were 1.6 ng mL−1 for iodine. The method offers relatively good precision (RSD ranged from 2 to 4%) for liquid analysis and microsampling capability. Samples were prepared by solubilization with tetramethylammonium hydroxide (TMAH), permits complete sample solubilization and significantly reduces the risk of iodine evaporation, before iodine was quantified by USN-VG-ICP-OES. The accuracy of the method was verified using certified reference materials (NIST 1549 and NIST 1566b) and using a simple external calibration technique. The measured contents of elements in reference materials were in satisfactory agreement with the certified value (I). The method was applied to the determination of total iodine in different samples with satisfactory results.

Evaluation of various nebulizers for use in microwave induced plasma optical emission spectrometry

Three different micronebulizers, the micro3 (M3), the flow focusing pneumatic nebulizer (FFPN) and the microcapillary array nebulizer (NAR-1), were compared with a conventional Meinhard pneumatic concentric nebulizer (PN) working at low liquid flow rates for the elemental analysis of liquid samples by microwave induced plasma optical emission spectrometry (MIP-OES). Three nebulizers (M3, FFPN, PN) were operated in conjunction with the same cyclonic spray chamber. A critical evaluation has been carried out of the nebulization stages, such as the formation of the primary and tertiary aerosol, separation of large droplets (drop size distribution) in the spray chamber (also evaluated for the NAR-1 nebulizer) and aerosol transport to the plasma torch. Atomic emission was measured for Ba, Ca, Cd, Cu, Fe, I, Mg, Mn, Pb, Sr and Zn. Analytical performance of the nebulization systems were characterized by determination of the limits of detection (LODs), the precision (RSDs) and the memory effects (wash-out time) for these elements, and ranged between 0.004–0.099 μg mL−1, 4–8%, and 5–7 minutes, respectively. Analysis of certified reference materials (TORT-1, Human Hair No. 13, Lichen IAEA-336, Soya Bean Flour INCT-SBF-4) were performed to determine the accuracy and precision available with the presented nebulization systems. These materials were microwave/nitric acid digested and analyzed by calibration with synthetic solutions of the analytes. In general, the results indicated that the FFPN nebulizer gave rise to higher emission signals and slightly lower LOD values than the other three nebulizers. The nebulizers exhibited no clogging problems.

Ultrasonic Nebulization, Multimode Sample Introduction System for Simultaneous Determination of Hydride-Forming, Cold Vapor, and Non-Hydride-Forming Elements by Microwave-Induced Plasma Spectrometry

ABSTRACT A novel synergic effect of ultrasonic nebulization (USN) and a multimode sample introduction system (MSIS) when used in combination has been exploited for efficient generation of conventional hydride-forming (As, Bi, Ge, Sb, Se, Sn), Hg vapor, and non-hydride-forming (Ba, Ca, Li, Mg, Sr) elements. The ultrasonic nebulizer supplied a microliter sample to a quartz oscillator, converting liquid into aerosol at the entrance of the MSIS spray chamber. The argon carrier gas is passed to remove and transport the generated vapor species (from the MSIS) and aerosol (from the USN) to a microwave-induced plasma (MIP) for simultaneous element determination by optical emission spectrometry (OES). The experimental concentration detection limits for simultaneous determination, calculated as the concentration giving a signal equal to three times the standard deviation of the blank (LOD, 3σblank criterion, peak height) were 0.3, 1.5, 1.9, 0.5, 1.7, 0.6, 0.8, 9, 1.6, 1.9, 2.2, and 2.9 ng mL−1 for As, Bi, Ge, Sb, Se, Sn, Hg, Ba, Ca, Li, Mg, and Sr, respectively. The method offers relatively good precision (RSD ranged from 5% to 9%) for liquid analysis and microsampling capability. The methodology was validated through determination of elements in four certified reference materials (NIST 2710, NRC GBW 07302, NRCC DOLT-2, NIST 1643e) and by the aqueous standard calibration technique. Good agreement with certified values was obtained when this approach was applied to the determination of hydride-forming, cold vapor, and other elements in biological and environmental certified reference materials.

Pressurized Flow Solubilization System Using Electromagnetic Induction Heating Technique for Simultaneous Determination of Inorganic Elements (Ba, Ca, Cd, Cu, Fe, Mg, Mn, Na, Pb, Sr, Zn) in Sonicate Slurries of Biological Materials by Microwave Induced Plasma Optical Emission Spectrometry (MIP-OES)

A pressurized continuous flow system using electromagnetic induction heating technique has been developed for the determination of trace and minor element content in biological samples by microwave induced plasma-optical emission spectrometry (MIP-OES). The system allows the continuous solubilization of samples at an optimized temperature of 120 °C and pressure of 3.5 bar in 40 min. A system was used to perform off-line solubilization of slurried samples of biological tissues, non-fat milk powder and lichen (3% m/v). Recovery of trace and minor elements averaged 99.2 ± 0.1% was performed by MIP-OES using external calibration technique. The accuracy of the method was proved using certified reference materials from the National Research Council Canada (NRCC, Dogfish Liver, DOLT-2), National Institute of Standards and Technology (NIST, (Non-Fat Milk Powder, NIST 1549) and International Atomic Energy Agency (IAEA, Lichen, IAEA-336). Satisfied analytical results were also obtained in real sample analysis of milk powder, barley and cinnamon.

Analytical Evaluation of a Reduced-Pressure Microwave-Induced Plasma Studied by Optical Emission Spectrometry Method

ABSTRACT The authors describe a system that utilizes a reduced-pressure (RP) air-cooled microwave-induced plasma (MIP) torch to interface an ultrasonic nebulizer (USN) with an optical emission spectrometer (OES). Argon was investigated as plasma gas. The analytical potential of such techniques was illustrated for the determination of elements. A univariate approach and simplex optimization procedure was used to achieve optimized conditions and derive analytical figures of merit. Analytical performance of the RP-MIP was characterized by determination of the limits of detection (LODs) and precision (RSDs) with the RP-MIP-OES observed at flow rate of 10 µL min−1 without removal of any matrix. The experimental concentration detection limits for simultaneous determination, calculated as the concentration giving a signal equal to three times the standard deviation of the blank (LOD, 3σblank criterion, peak height), were 15, 4.5, 6.2, 2.9, 31, 6.3, 3.1, 13, 5.4, and 33 n g mL−1 for Ba, Ca, Cd, Cu, Fe, Mg, Mn, Ni, Sr, and Zn, respectively. Absolute limits of detection were 167, 50, 68, 32, 350, 69, 34, 143, 59, and 363 pg for Ba, Ca, Cd, Cu, Fe, Mg, Mn, Ni, Sr, and Zn, respectively. The method offers relatively good precision (RSD ranged from 7 to 12%) for liquid analysis and microsampling capability. The accuracy of the method was verified by the use of digested certified reference materials (SRM 1648 (Urban Particulate Matter), IAEA 336 (Lichen), SRM 2710 (Montand Soil), INCT-SBF-4 (Soya Bean Flour)) and by aqueous standard calibration technique. The analyte concentrations in reference materials were in satisfactory agreement with the certified values. The method requires small amounts of reagents and reduces contamination and losses. In general, low-pressure argon discharges proved to be superior, in terms of detection limits (DLs), to atmospheric pressure MIPs for the excitation of the analyte atomic or ionic emission.