Conventional Sample Introduction System Research Articles

Characterisation of titanium dioxide (nano)particles in foodstuffs and E171 additives by single particle inductively coupled plasma-tandem mass spectrometry using a highly efficient sample introduction system

This study addressed primarily the characterisation and quantification of titanium dioxide (TiO2) (nano)particles (NPs) in a large variety of commercial foodstuffs. The samples were purchased from local markets in Spain before the ban of TiO2 food additive (E171) in the EU. The analyses were carried out by single particle inductively coupled plasma-tandem mass spectrometry (spICP-MS/MS) in mass shift mode (oxidation of 48Ti to 48Ti16O (m/z = 64)) and using a highly efficient sample introduction system (APEX™ Ω). This novel analytical approach allowed accurate characterisation of a large panel of TiO2 NPs sizes ranging from ∼12 to ∼800 nm without isobaric interferences from 48Ca isotope, which is highly abundant in most of the analysed foodstuffs. TiO2 NPs were extracted from foodstuffs using sodium dodecyl sulphate (0.1%, w/v) and diluted with ultra-pure water to reach ∼ 1000 particles signals per acquisition. All the analysed samples contained TiO2 NPs with concentrations ranging from 1010 to 1014 particles kg−1, but with significant low recoveries compared to the total Ti determination. A selection of samples was also analysed using a similar spICP-MS/MS approach with a conventional sample introduction system. The comparison of results highlighted the improvement of the limit of detection in size (12 nm) by the APEX™ Ω system, providing nanoparticulate fractions ranging from ∼4% (cheddar sauce) up to ∼87% (chewing gum), which is among the highest nanoparticulate fractions reported in literature using a spICP-MS approach. In addition, two commercially available E171 additives were analysed using the previous approaches and other techniques in different European laboratories with the aim of methods inter-comparison. This study provides occurrence data related to TiO2 NPs in common commercial foodstuffs but it also demonstrates the potential of the novel analytical approach based on APEX™-ICP-MS/MS to characterise nano-size TiO2 particles in complex matrices such as foodstuffs.

Novel method for chlorine determination in biofuel lipid feedstock by coupling a total sample introduction system (hTISIS) to an inductively coupled plasma tandem mass spectrometry (ICP-MS/MS)

BackgroundChlorine concentrations above 1 mg kg−1 in lipid feedstocks for biofuel production can generate corrosion issues in the different refining units as well as catalyst deactivation by clogging or fouling. To reach accurate analyses by inductively coupled plasma (ICP) techniques at low concentration levels, dilution in organic solvents rises as a simpler and more straightforward sample preparation methodology than conventional sample decomposition procedures (e.g., microwave-assisted acid digestion). However, matrix effects and the impact of the Cl chemical form on the signal must be overcome to obtain accurate results. ResultsIn this work, the high temperature torch integrated sample introduction system (hTISIS) operated at 350 °C is coupled to an inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) for the determination of Cl in lipid biofuel feedstock samples diluted in xylene and these results are compared with those reported by a conventional sample introduction system. Under optimal conditions of the hTISIS-ICP-MS/MS configuration, matrix effects are efficiently overcome (recovery values ranged from 101 to 104%) as well as the effect of the Cl chemical form on the signal for 6 organochloride compounds. Thus, an external calibration approach can be set to carry out the quantification of this element in real samples. The method is successfully validated, obtaining a good agreement in the Cl concentration reported in a standard reference material (SRM NIST 1634c) and also by comparing the concentration results obtained by external calibration and standard addition approaches in two biofuel feedstock samples. Significance and noveltyThe hTISIS coupled to an ICP-MS/MS system is used for the first time to overcome not only matrix effects but also the impact of the Cl chemical form in biofuel feedstock samples. This novel method, with a limit of quantification (LOQ) of 7.1 μg kg−1, give access to an accurate Cl determination in all kind of lipid feedstocks for clean fuel production.

Assessment of total sample consumption infrared-heated system for minimization of matrix effects in ICP-tandem mass spectrometry

A total sample consumption infrared-heated system (IR-TSC) has been coupled to ICP-tandem mass spectrometry (ICP-MS/MS) for the first time. The objective of this study was to assess the analytical performance of the IR-TSC system, in terms of analytical figures of merit and mitigation of matrix effects. Twenty-seven elements have been determined: Ag, Al, As, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, K, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, Tl, V and Zn. Different operating conditions, including nebulization flow rate and spray chamber temperature, were optimized to improve sensitivity, signal stability, and plasma thermal conditions. The results showed that the infrared-heated sample introduction system improved the signal intensity by a factor of 2 to 4 compared to a conventional sample introduction system, whereas the limits of detection (LODs) improved by a factor going from 1.2 (Ba) to 3.3 (Cr) for a sample containing 2% HNO3. Meanwhile, for a 10% ethanol sample the improvement factor ranged from 1.4 (Ti) to 3.8 (Cr). Matrix effects for solutions containing inorganic acids or high content of sodium (2% HNO3, 10% HNO3, 20% HNO3, 10% HCl; 500 mg kg−1 Na, 500 mg kg−1 Na + 10% HNO3) were mitigated under optimum conditions (IR-TSC at 125 °C). Meanwhile, for solutions containing organic solvents (10% ethanol, 10% acetic acid, and 10% formic acid) it was not possible to eliminate matrix effects, even when applying an internal standard. For Se and As, elements spectrally interfered, the combination of IR-TSC sample introduction system with oxygen as reaction/collision gas mode in ICP-MS/MS provided accurate results. For 10% HNO3 and 10% HCl relative intensities values, calculated taking the signal intensity obtained for 2% HNO3 as reference, were close to the unity. Environmental and clinical control and certified reference materials were analyzed by means of an external calibration approach, with most of the elements showing concentrations not significantly different from the certified values. Finally, the IR-TSC was tested on twelve real samples, including seawater, surface water, peritoneal fluid, seminal plasma, wine, and bioethanol samples, demonstrating the system potential in different application fields.

High temperature total consumption sample introduction system coupled to microwave plasma optical emission spectrometry (MIP-OES) for the analysis of aqueous samples

The high temperature torch integrated sample introduction system (hTISIS) is coupled to microwave plasma optical emission spectrometry (MIP-OES) for the first time. The goal of this work is to develop an accurate analysis of digested samples under continuous sample aspiration mode by coupling the hTISIS to a MIP-OES instrument. To achieve this, different operating conditions such as, nebulization flow rate, liquid flow rate and the spray chamber temperature were optimized in terms of sensitivity, limits of quantification (LOQs) and background equivalent concentration (BECs) for the determination of Ca, Cr, Cu Fe, K, Mg, Mn, Na, Pb and Zn, and these values were compared with those reported with a conventional sample introduction system. Under optimum conditions (0.8–1 L min−1, 100 μL min−1 and 400 ᵒC, respectively), the hTISIS improved MIP-OES analytical figures of merit and shortened 4-times wash out times with respect to a conventional cyclonic spray chamber, reporting an enhancement factor in the sensitivity among 2–47 times and LOQs from 0.9 to 360 μg kg−1. Once the best operating conditions were set, the magnitude of the interference caused by 15 different acid matrices (2, 5 and 10% w/w of HNO3, H2SO4, HCl and mixtures of HNO3 with H2SO4 and HNO3 with HCl) was significantly lower for the former device. Finally, 6 different digested oily samples (used cooking oil, animal fat, corn oil and the same samples after a filtration step) were analyzed by means of an external calibration approach based on the use of multielemental standards prepared in 3% (w/w) HCl solution. The obtained results were compared against those supplied by a conventional methodology employing an inductively coupled plasma optical emission spectrometry, ICP-OES, instrument. It was clearly concluded that the hTISIS coupled to MIP-OES afforded similar concentrations as compared to the conventional methodology.

Impact of Measurement Protocol on ICP-MS Data Quality Objectives: Part II

The first part of this article focused on the fundamental principles of a scanning quadrupole and how measurement protocol can be optimized based on the data quality objectives of the analysis and in particular the compromise between limit of detection and sample throughput. Part 2 looks at different ways to assess detection capability when processing continuous signals generated by a conventional sample introduction system, and also transient signals produced by different types of sampling methods such as chromatographic separation techniques and nanoparticle size studies.

Application of a lab-made ternary Fe-Cr-Al coil vaporizer coupled to ICP OES for boron determination in powdered food after the sample preparation in alkaline media

This work presents the development of a method for boron determination in food using a lab-made ternary Fe-Cr-Al coil vaporizer (composed of a glass chamber, a Fe-Cr-Al coil, and a power supply) after the sample dissolution in tetramethylammonium hydroxide. The sample preparation and the instrumental parameters were optimized using a central composite design. The chemical characterization and surface analysis of the Fe-Cr-Al coil were performed. The temperature of pyrolysis and vaporization, as well as the memory effect, and accuracy and analytical figures of merit were studied. After the proper optimization, the ternary Fe-Cr-Al coil applied as a vaporization system presented to solve the memory effect for boron determination in ICP OES. The comparison with a conventional sample introduction system presented good accuracy, as well as the analytical curve, showed good sensitivity with a good R-squared (0.992). The limit of detection obtained was 2 µg g−1.

An environmentally-friendly, highly efficient, gas pressure-assisted sample introduction system for ICP-MS and its application to detection of cadmium and lead in human plasma

An environmentally friendly and highly efficient gas pressure-assisted sample introduction system (GPASIS) was developed for inductively-coupled plasma mass spectrometry. A GPASIS consisting of a gas-pressure control device, a customized nebulizer, and a custom-made spray chamber was fabricated. The advantages of this GPASIS derive from its high nebulization efficiencies, small sample volume requirements, low memory effects, good precision, and zero waste emission. A GPASIS can continuously, and stably, nebulize 10% NaCl solution for more than an hour without clogging. Sensitivity, detection limits, precision, long-term stability, double charge and oxide ion levels, nebulization efficiencies, and matrix effects of the sample introduction system were evaluated. Experimental results indicated that the performance of this GPASIS, was equivalent to, or better than, those obtained by conventional sample introduction systems. This GPASIS was successfully used to determine Cd and Pb by ICP-MS in human plasma.

Bromine isotope ratio measurements in seawater by multi-collector inductively coupled plasma-mass spectrometry with a conventional sample introduction system.

A simple and accurate methodology for Br isotope ratio measurements in seawater by multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) with pneumatic nebulization for sample introduction was developed. The Br(+) signals could be measured interference-free at high mass resolution. Memory effects for Br were counteracted using 5 mmol L(-1) of NH4OH in sample, standard, and wash solutions. The major cation load of seawater was removed via cation exchange chromatography using Dowex 50WX8 resin. Subsequent Br preconcentration was accomplished via evaporation of the sample solution at 90 °C, which did not induce Br losses or isotope fractionation. Mass discrimination was corrected for by external correction using a Cl-matched standard measured in a sample-standard bracketing approach, although Sr, Ge, and Se were also tested as potential internal standards for internal correction for mass discrimination. The δ(81)Br (versus standard mean ocean bromide (SMOB)) values thus obtained for the NaBr isotopic reference material NIST SRM 977 and for IRMM BCR-403 seawater certified reference material are in agreement with literature values. For NIST SRM 977, the (81)Br/(79)Br ratio (0.97291) was determined with a precision ≤0.08‰ relative standard deviation (RSD).

Combination of a multimode sample introduction system with a pre-evaporation tube to improve multi-element analysis by ICP-OES

A pre-evaporation tube (heated to 400 °C) was inserted between a multi-mode sample introduction system (MSIS) and the plasma torch in inductively coupled plasma optical emission spectrometry (ICP-OES) to improve the simultaneous determination of hydride-forming and other elements. Multivariate optimisations were conducted to find operating conditions improving plasma robustness. Under these conditions and compared to conventional sample introduction with a pneumatic nebulizer and spray chamber, using MSIS with a pre-evaporation tube (PET) improved sensitivity and detection limits for hydride-forming elements (As, Sn, Hg, Sb and Bi) and other elements as well. In order to obtain a significant improvement for all elements, irrespective of hydride formation or not, the pneumatic nebulizer was replaced by an ultrasonic nebulizer (USN) and the same experimental conditions were used for the simultaneous introduction of aerosol and hydrides (from the MSIS) into a PET. With USN-MSIS-PET, the figures of merit of ICP-OES improved by over an order of magnitude for both hydride-forming elements and other elements compared to those with a conventional sample introduction system. Furthermore, using either PN-MSIS-PET or USN-MSIS-PET increased plasma robustness, likely as a result of the hydrogen gas by-product of hydride generation, which was reported to increase energy transfer within the plasma, and from the introduction of water vapor (with PET), which was reported to improve plasma stability as well as sensitivity. Good agreement with certified values was obtained when this approach was applied to the determination of hydride-forming and other elements in environmental certified reference materials.

Improvement of the capabilities of inductively coupled plasma optical emission spectrometry by replacing the desolvation system of an ultrasonic nebulization system with a pre-evaporation tube

The effect of replacing the desolvation system (i.e., heater/condenser (HC) and membrane desolvator (MD)) of an ultrasonic nebulizer (USN) system with a pre-evaporation tube (PET) that is heated to about 400 °C on the analytical capabilities of inductively coupled plasma optical emission spectrometry (ICP–OES) was investigated. A multivariate optimisation was conducted in each case to find operating conditions maximizing plasma robustness. Under optimum conditions, the analytical performance of ICP–OES was significantly improved (i.e., better sensitivity, detection limit and plasma robustness) with USN–PET compared to that achieved with both the commercially-available USN–HC–MD and a conventional pneumatic nebulizer/spray chamber sample introduction system. However, only the USN–PET approach allows the determination of Hg, which appears to otherwise be lost in the heater/condenser system. Using a simple external calibration, without any matrix matching, and using an argon emission line for internal standardization, the results obtained for the determination of trace elements in certified soil reference materials (SRM 2710 and 2711) by USN–PET were in good agreement with certified values. This is unlike with conventional sample introduction systems where internal standardization using an Ar line is unusual, as it does not compensate for physical interferences, and either internal standardization (with internal standards added to the sample and standard solutions) or matrix-matched calibration is required.

Evidence supporting the occurrence of Coulomb fission during conventional sample introduction in inductively coupled plasma mass spectrometry

Axial and radial profiles of ion (Al+, V+, Cr+, Mn+, Fe+, Ni+, Co+, Cu+, Zn+, As+, Mo+, Sb+, La+, LaO+, Ce+ and CeO+) distribution in inductively coupled plasma mass spectrometry were examined for solutions containing 1% v/v HNO3 (i.e. 0.16 M) with and without 0.02 M NaNO3, KNO3, CsNO3, HI or HCl. None of the latter matrices induced a significant change in sample introduction efficiency compared to 1% v/v HNO3 alone. Nonetheless, although analyte signal suppression was predominant in the presence of the K and Cs matrices, 0.02 M Na induced an enhancement by 1.6 ± 0.3 across the mass range, which was irrespective of the analyte ionization potential (i.e. even analytes that should be completely ionized were enhanced). This may be rationalized using a Coulomb fission mechanism within the spray chamber, which shifts the droplet size distribution towards smaller ones that are then more efficiently transported through the spray chamber and ultimately result in more analyte ions in the plasma. Furthermore, desolvation of these smaller droplets is completed sooner in the ICP, as axial profiles of the oxide fraction of La and Ce were shifted lower in the plasma in the presence of a non-volatile ionic matrix (0.02 M NaNO3, KNO3, CsNO3) but were unaffected by 0.02 M HCl or HI. The broadened analyte radial profile in the presence of 0.02 M Na, which was observed at the optimum sampling depth for a 1% v/v HNO3 matrix, also points to earlier desolvation. These results suggest that the Coulomb fission mechanism may be significant with a conventional sample introduction system.

Application of a microwave-based desolvation system for multi-elemental analysis of wine by inductively coupled plasma based techniques

Elemental wine analysis is often required from a nutritional, toxicological, origin and authenticity point of view. Inductively coupled plasma based techniques are usually employed for this analysis because of their multi-elemental capabilities and good limits of detection. However, the accurate analysis of wine samples strongly depends on their matrix composition (i.e. salts, ethanol, organic acids) since they lead to both spectral and non-spectral interferences. To mitigate ethanol (up to 10% w/w) related matrix effects in inductively coupled plasma atomic emission spectrometry (ICP-AES), a microwave-based desolvation system (MWDS) can be successfully employed. This finding suggests that the MWDS could be employed for elemental wine analysis. The goal of this work is to evaluate the applicability of the MWDS for elemental wine analysis in ICP-AES and inductively coupled plasma mass spectrometry (ICP-MS). For the sake of comparison a conventional sample introduction system (i.e. pneumatic nebulizer attached to a spray chamber) was employed. Matrix effects, precision, accuracy and analysis throughput have been selected as comparison criteria. For ICP-AES measurements, wine samples can be directly analyzed without any sample treatment (i.e. sample dilution or digestion) using pure aqueous standards although internal standardization (IS) (i.e. Sc) is required. The behaviour of the MWDS operating with organic solutions in ICP-MS has been characterized for the first time. In this technique the MWDS has shown its efficiency to mitigate ethanol related matrix effects up to concentrations of 1% (w/w). Therefore, wine samples must be diluted to reduce the ethanol concentration up to this value. The results obtained have shown that the MWDS is a powerful device for the elemental analysis of wine samples in both ICP-AES and ICP-MS. In general, the MWDS has some attractive advantages for elemental wine analysis when compared to a conventional sample introduction system such as: (i) higher detection capabilities; (ii) lower ethanol matrix effects; and (iii) lower spectral interferences (i.e. ArC +) in ICP-MS.

Characterization of a multimode sample introduction system (MSIS) for multielement analysis of trace elements in high alloy steels and nickel alloys using axially viewed hydride generation ICP-AES

A commercial multimode sample introduction system (MSIS) was characterized for simultaneous multielement hydride and nonhydride-forming elements (As, Bi, Co, Cr, Fe, Mn, Mo, Ni, Sb, Se, Sn, Ti, V, W) in high alloy steels and nickel alloys by axially viewed ICP-AES. Vapor formed by the NaBH4 reaction and aerosol from a specially designed dual conical spray chamber and pneumatic nebulizer were injected simultaneously into a robust plasma. Spectroscopic effects caused by major and minor elements and nonspectroscopic interferences induced by matrix concomitants were evaluated both for conventional nebulization and for hydride generation. The objective of the study was to establish optimized operating conditions whereby both nonhydride and hydride forming elements could be determined simultaneously. It was observed that the sensitivities of the ‘hydride generating’ elements using a MSIS, were similar to those observed using conventional hydride generation. In comparison to conventional pneumatic nebulization, hydride LODs, were enhanced significantly by factors varying from about 2–20. Limits of detection using the MSIS, for nonhydride elements (Co, Cr, Fe, Mn, Mo, Ni, Ti, V, W) were similar to those reported for the conventional sample introduction system. Several fundamental parameters such as Mg II 280.270/Mg I 285.213 nm ratios, excitation temperature (Tex) and the effect of hydrogen were also determined. The effect of hydrogen, formed during hydride generation, on intensities of nonhydride and hydride forming elements and excitation temperature was evaluated. This is important because hydrogen can modify the properties of the ICP. The effect of variable concentrations of tartaric acid, L-cystein, EDTA, and 1,1,3,3-tetramethy-2-thiourea as retarding agents for reducing deleterious effects of Ni was investigated. The accuracy of the procedure was verified by analyzing several certified reference metallurgical samples. An important conclusion of this multielement study is that the application of the MSIS for simultaneous determination of hydride forming and non-hydride forming elements in complex metallurgical samples by ICP-AES is constrained by matrix derived spectral line interferences.

Introduction of organic solvent solutions into inductively coupled plasma-atomic emission spectrometry using a microwave assisted sample introduction system

A microwave assisted sample introduction system based on the use of a TM010 cavity (MWDS2) has been employed for the introduction of 10% w/w organic solvent solutions in inductively coupled plasma atomic emission spectrometry (ICP-AES). Ethanol, propan-2-ol, formic and acetic acids have been used. Firstly, the effect of the incident microwave power and the sample uptake rate on the emission signal was evaluated. For all matrices tested, the higher emission signals were obtained when operating at the highest microwave power (i.e., 290 W) and sample uptake rate (400 μL min−1). Results with the MWDS2 were compared with those afforded by a desolvation system based on the use of a domestic microwave oven (MWDS) and by a conventional sample introduction system (CS). The MWDS2 provides the highest emission signals (up to 7 and 17 times higher than those with the MWDS and the CS, respectively). As regards the matrix effects originated by the organic solutions, results demonstrate that the use of a microwave-based sample introduction system, mainly the MWDS2, affords a noticeable reduction in the matrix effects originated by the use of organic solvent solutions in ICP-AES with a conventional sample introduction system. This behaviour can be explained by taking into account the solution transport rates afforded by the different sample introduction systems. For all the analytical lines and matrices tested and operating at 400 μL min−1, the MWDS2 gives rise to signal values that are, on average, 1.2 ± 0.2 times the signal obtained with water. For the MWDS and the CS, this factor takes values of 1.6 ± 0.2 and 2.0 ± 0.5, respectively. Transient matrix effects have been observed operating with the MWDS2 when switching between water and an organic matrix solution. These transient effects result in a drift time about 4.5 times higher than those with a CS.

An alternative interface for CE–ICP–MS cadmium speciation in metallothioneins based on volatile species generation

An alternative CE–ICP–MS interface based on volatile species generation (VSG) is here developed, evaluated and compared to the conventional sample introduction systems via nebulisation. For this purpose, the speciation of Cd–metallothioneins (MTs) in rabbit liver is taken as a model. Cd, bound to the different MT isoforms previously separated by CE, is transformed into volatile species at the exit of the capillary and on-line detected by ICP–MS. Optimum conditions for Cd VSG have been investigated in a flow injection device, using NaBH 4 as hydrogenation reagent in a HCl medium containing cobalt and thiourea as catalysts. Sample volume injected, CE separation voltage and reagents flows have been optimised. Analytical performance characteristics of the CE–VSG–ICP–(Q)MS coupling developed were evaluated, in terms of repeatability and linearity of response, using standard rabbit liver metallothionein isoforms (MT1 and MT2). Detection limits for Cd–MTs turned out to be almost one order of magnitude better than those derived from using a conventional Babington nebuliser-based interface. Compared to a MicroMist-based interface detection limits resulted to be similar, but the observed peak height was eight times higher using the VSG interface, indicating the enhanced analyte transport efficiency derived from VSG sample introduction systems.

A microwave assisted desolvation system based on the use of a TM010 cavity for inductively coupled plasma based analytical techniques

A new microwave assisted desolvation system based on the use of a TM010 cavity (MWDS2) has been developed and evaluated in plasma based analytical techniques: inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The new design overcomes the main experimental drawbacks shown by previous designs based on the use of domestic ovens: (i) lack of control on microwave generation and application; and (ii) inappropriate MW cavity characteristics. The evaluation has been performed in terms of the effect of the incident microwave power and the sample uptake rate and the results obtained has been compared with those afforded by a conventional sample introduction system (nebulizer and double pass spray chamber) and a desolvation system based on the use of a domestic microwave oven (MWDS). The new MWDS2 give rise to higher analytical signals and lower limits of detection and stabilization times (2–3 times) than those obtained with the MWDS in ICP-AES and ICP-MS.

Investigation of the direct injection high efficiency nebulizer for axially and radially viewed inductively coupled plasma atomic emission spectrometry

A direct injection high efficiency nebulizer (DIHEN) is explored for introduction of the sample aerosol into the central channel of the axially and radially viewed inductively coupled plasma (ICP) of a commercial ICP atomic emission spectrometer (ICPAES). The DIHEN is a micro-nebulizer that requires very low solution uptake rates (1–100 µL min−1) and nebulizer gas flow rates (<0.2 L min−1) compared to conventional nebulizer-spray chamber arrangements (∼1.0 mL min−1 and ∼1.0 L min−1, respectively). Signal-to-background ratios (SBRs), detection limits, and precision of the DIHEN are comparable or superior to those of the conventional sample introduction system, but the Mg II 280.270/Mg I 285.213 nm ratios are lower with the DIHEN, indicating that the DIHEN is more susceptible to matrix effects than the conventional nebulization system, for both the axial and radial ICPAES systems. Matrix effects are further investigated by comparing intensity ratios with and without 0.1% and 0.5% Na for several spectral lines having energy sum ranging from 7.93 to 14.79 eV. Replacement of Ar with Ar–O2 and Ar–N2 mixtures in the outer gas flow of the plasma improves SBRs and Mg II 280.270/Mg I 285.213 nm ratios of the DIHEN, and reduces matrix effects. By reducing solution uptake rate from 60 to 30 µL min−1, matrix effect is also reduced. Operation of the radial instrument at 1700 W reduces matrix effect compared to the effect noted for the axial instrument at 1500 W. Finally, the utility of the technique in practical ICPAES studies is demonstrated using a custom made organo-metallic standard for As, Hg, and Pb in xylene.

Determination of Memory-Prone Elements Using Direct Injection High Efficiency Nebulizer Inductively Coupled Plasma Mass Spectrometry

A direct injection high efficiency nebulizer (DIHEN) and a large-bore DIHEN (LB-DIHEN) are investigated for the determination of difficult-to-analyze and memory-prone elements (mercury, iodine, and boron). The determination of such elements is problematic using conventional sample introduction systems incorporating spray chambers and/or desolvation devices owing to their large surface area and hence long wash-out characteristics. With the DIHEN or LB-DIHEN, the spray chamber is eliminated and the dead volume is reduced to &lt;10 μL, thus reducing memory effects. In comparison with the crossflow-spray chamber combination, wash-in and wash-out times are reduced to less than 10 s when a DIHEN or LB-DIHEN is used for mercury, iodine, and boron at a concentration of 100 ng/mL. The accuracy of the DIHEN-ICPMS (inductively coupled plasma mass spectrometry) technique is evaluated in the analysis of the National Institute of Standards and Technology standard reference material (NIST SRM) 2670 (Toxic Metals in Freeze-Dried Urine) and NIST SRM 8414 (Bovine Muscle Powder). Further, the effectiveness of the DIHEN-ICPMS technique is examined in the determination of mercury and iodine in an alternative remedy medicine (seahorse genital tonic pills) and boron in rodent liver samples as part of a pharmacokinetic screening study for boron neutron capture therapy.

Recycling Nebulization-Sample Introduction System for Inductively Coupled Plasma Atomic Emission Spectrometry

A recycling nebulization-sample introduction system which exhibits the long-term stability of analyte emission signals while consuming small sample volumes was constructed for inductively coupled plasma atomic emission spectrometry. The present system is composed of five main parts: i.e., a spherical cyclone spray chamber, two commercial concentric nebulizers, two 3-way stopcocks, an aerosol transport tube with heater, and a commercial concentric three-tube plasma torch. It is based on the spray chamber where the two nebulizers are mounted (twin-nebulizer configuration): one is for introduction of a sample or a rinse solution into the spray chamber, and the other one is for recycling nebulization of the solution introduced. The nebulizers are easily demountable symmetrically and horizontally outside the spray chamber. Analytical performance and nebulization characteristics are described in comparison with a conventional sample introduction system. A stable signal of analyte emission intensity was extended to 20 min for 1 ml of sample under the ordinary condition of 0.6 l/min carrier gas flow rate

Indirect measuring method of aerosol transport efficiency in inductively coupled plasma spectrometry

An indirect method developed for measuring the aerosol transport efficiency in inductively coupled plasma spectrometry using a conventional sample introduction system composed of concentric nebulizer/spray chamber/torch is described. The precision of this simple method is within 5% in terms of the relative standard deviation for the 23 °C distilled water with argon carrier gas flow rates of 0.6 to 1.4 l/min.