Ultrasonic Slurry Sampling Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry Research Articles

Multi-element analysis of sunscreens using slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

The determination of Cu, As, Cd, Sb, Hg, Pb and Bi in titanium based sunscreens by ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) is described. Thioacetamide (TAC) was used as the modifier to enhance the volatility of the elements studied. The influence of the instrument operating conditions and slurry preparation on the ion signals were studied. A relatively low vaporization temperature of 1500 °C was used, which separated the analytes from the major matrix component, titanium, thus improved the ion signals. The method has been applied to determine Cu, As, Cd, Sb, Hg, Pb and Bi in a reference material GBW09305 cosmetic (cream), and three brands of titanium based sunscreens using isotope dilution and standard addition calibration methods. The concentrations obtained are in good agreement between the different calibration methods. The results of As and Pb in the reference material agreed with the certified values. The precision between the sample replicates was better than 9%, when the USS-ETV-ICP-MS technique was used. The method detection limits estimated from standard addition curves were 0.8, 0.4, 0.2, 0.4, 0.8, 0.5 and 0.1 ng g−1 for Cu, As, Cd, Sb, Hg, Pb and Bi, respectively, in real titanium based sunscreens.

Determination of trace elements in medicinal activated charcoal using slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry with low vaporization temperature

The determination of Cd, Sb, Te, Hg, Tl and Pb in medicinal activated charcoal by ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) was described. EDTA was used as the modifier to enhance the volatility of elements studied. The influences of instrument operating conditions and slurry preparation on the ion signals were studied. A relatively low vaporization temperature of 1000°C was used, which separated the analyte from the major matrix components that improved ion signals. The method has been applied to determine Cd, Sb, Te, Hg, Tl and Pb in an NIST SRM 1633b Coal Fly Ash reference material and three brands of medicinal activated charcoal capsules using isotope dilution and standard addition calibration methods. The concentrations that are in ngg−1 levels were in good agreement between different calibration methods. The precision between sample replicates was better than 7% with USS-ETV-ICP-MS technique. The method detection limit estimated from standard addition curves was 0.4, 0.3, 0.3, 0.3, 0.04 and 0.9ngg−1 for Cd, Sb, Te, Hg, Tl and Pb, respectively, in original medicinal activated charcoal.

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of Cr, Fe, Cu, Zn and Se in cereals

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to determine Cr, Fe, Cu, Zn and Se in several cereal samples. Thioacetamide was used as the modifier to enhance the ion signals. The background ions at the masses of interest were reduced in intensity significantly by using 1.0mLmin−1 methane (CH4) as reaction cell gas in the dynamic reaction cell (DRC). Since the sensitivities of Cr, Fe, Cu, Zn and Se in different matrices were quite different, standard addition and isotope dilution methods were used for the determination of Cr, Fe, Cu, Zn and Se in these cereal samples. The method detection limits estimated from standard addition curves were about 1, 10, 4, 12 and 2ngg−1 for Cr, Fe, Cu, Zn and Se, respectively, in original cereal samples. This procedure has been applied to the determination of Cr, Fe, Cu, Zn and Se whose concentrations are in μgg−1 (except Cr and Se) in standard reference materials (SRM) of National institute of standards and technology (NIST), NIST SRM 1568a Rice Flour and NIST SRM 1567a Wheat Flour and two cereal samples purchased from a local market. The analysis results of reference materials agreed with certified values at 95% confidence level according to Student's T-test. The results for the real world cereal samples were also found to be in good agreement with the pneumatic nebulization DRC ICP-MS results of the sample solutions.

Palladium nanoparticles as the modifier for the determination of Zn, As, Cd, Sb, Hg and Pb in biological samples by ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

Palladium nanoparticles (Pd-NPs) were used as the modifier for the determination of Zn, As, Cd, Sb, Hg and Pb in biological samples by ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS). The preparation and characterization of palladium nanoparticles (Pd-NPs) is described. Compared to traditional Pd aqueous solution, better ion signals were obtained when Pd-NPs was used as modifier. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. The introduction of dry aerosol with ETV sampling device alleviated the spectral interferences effectively. This method has been applied for the determination of Zn, As, Cd, Sb, Hg and Pb in NIST SRM 1568a Rice Flour and SRM 1573a Tomato Leaves reference materials and two biological samples obtained locally. The analysis results of the reference material agree with the certified values. The results for the real world samples were also found to be in good agreement with the pneumatic nebulization ICP-MS results of the sample solutions. The method detection limits estimated from standard addition curves are in the range 1.9–3.6, 0.2–0.4, 0.5–0.8, 0.1–0.2, 0.4–0.8 and 0.4–0.6 ng g−1 for Zn, As, Cd, Sb, Hg and Pb, respectively, in original samples.

Determination of trace elements in silicon powder using slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

The determination of B, Al, P, Fe, Ni, Cu, Zn, Cd and Pb in silicon powder by ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) using citric acid as the modifier was investigated. The influences of instrument operating conditions and slurry preparation on the ion signals were studied. A relatively low vaporization temperature of 1900 °C was used, which separated the analyte from the major matrix components that not only improved ion signals significantly but also alleviated the spectral interferences caused by 28Si29Si+, 28Si16O16O+, 28Si17O18O+ and 38Ar28Si+ on 57Fe+, 60Ni+, 63Cu+ and 66Zn+ determinations. The method has been applied to determine B, Al, P, Fe, Ni, Cu, Zn, Cd and Pb in a 99.999% pure silicon powder sample and four solar grade silicon powder samples using standard addition calibration methods. The concentrations that are in μg g−1 to sub μg g−1 levels were in good agreement with those of digested samples analyzed by pneumatic nebulization membrane desolvation ICP-MS. The precision between sample replicates was better than 9% with USS-ETV-ICP-MS technique. The method detection limit estimated from standard addition curves was about 8, 7, 9, 50, 9, 3, 7, 1 and 0.4 ng g−1 for B, Al, P, Fe, Ni, Cu, Zn, Cd and Pb, respectively, in original silicon samples.

Determination of trace Cr, Mo, Pd, Cd, Pt and Pb in drug tablets by ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to determine Cr, Mo, Pd, Cd, Pt and Pb in drug tablets. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. A mixture of ammonium pyrrolidine dithiocarbamate (APDC) and 8-hydroxyquinoline (8-HQ) was used as the modifier to enhance the ion signals. The background ions at the Cr masses m/z 52 and 53 were significantly reduced in intensity by using NH3 as reaction cell gas in the dynamic reaction cell (DRC). The introduction of dry aerosol with ETV sampling device and DRC effectively alleviated the spectral interferences. This procedure has been applied to determine Cr, Mo, Pd, Cd, Pt and Pb in antihypertensive tablets purchased locally. The values obtained by ETV-ICP-MS were in good agreement with reference values obtained by pneumatic nebulization ICP-MS of completely dissolved samples. The precision between sample replicates was better than 5% (25% for Pt) for all determinations. The method detection limits estimated from standard addition curves were in the range 0.1–0.5, 0.5–0.9, 0.2–0.3, 0.1–0.3, 0.1 and 0.2–0.3 ng g−1 for Cr, Mo, Pd, Cd, Pt and Pb, respectively, in original tablets.

8-Hydroxyquinoline-5-sulfonic acid as the modifier for the determination of trace elements in cereals by slurry sampling electrothermal vaporization ICP-MS

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to determine V, Cr, Co, Ni, Cu, Zn, Se, Cd, Hg and Pb in cereal samples. 8-hydroxyquinoline-5-sulfonic acid (8-HQ-5-SA) was used as the modifier to increase the volatility of the elements studied which makes the quantification possible using external calibration. The influences of instrument operating conditions and slurry preparation on the ion signals were studied to get better sensitivity of the elements studied and also similar sensitivity between slurry and aqueous solution. In this study, Cr, Cu, Zn and Se were determined under dynamic reaction cell (DRC) mode, while V, Co, Ni, Cd, Hg and Pb were determined under standard mode separately. The background ions at the masses m/z 52 and 80 were reduced in intensity significantly by using 1.0 mL min−1 CH4 as reaction cell gas in the DRC. This method has been applied to the determination of V, Cr, Co, Ni, Cu, Zn, Se, Cd, Hg and Pb in NIST SRM 1568a Rice Flour and SRM 1567a Wheat Flour reference materials and two cereal samples purchased from the local market. Analysis of the reference material agreed with the certified values. The results for the real world cereal samples were also found to be in good agreement with the pneumatic nebulization ICP-MS results of the sample solutions. The method detection limit was 1.3, 2.1, 3.6, 4.3, 6.8, 16, 1.7, 0.6, 0.8 and 2.6 ng g−1 for V, Cr, Co, Ni, Cu, Zn, Se, Cd, Hg and Pb, respectively, in original cereal samples.

Determination of Ga, Ge, As, Se and Sb in fly ash samples by ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to determine Ga, Ge, As, Se and Sb in fly ash samples. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. Pd and ascorbic acid were used as the mixed modifiers to enhance the ion signals. This method has been applied to determine Ga, Ge, As, Se and Sb in NIST SRM 1633a and 1633b coal fly ash reference materials and a fly ash sample collected locally. Since the sensitivities of the elements studied in slurry solution and aqueous solution were different slightly, analyte addition technique was used for the determination of Ga, Ge, As, Se and Sb in these samples. The As and Se analysis results of the reference materials agreed with the certified values. The results for which no certified value was available were also found to be in good agreement between the ETV-ICP-MS results and the reference values. The reference value was obtained by digesting the samples and analyzing the digested sample solutions by pneumatic nebulization Dynamic Reaction Cell™ (DRC) ICP-MS. The method detection limits estimated from analyte addition curves were about 0.23, 0.13, 0.17, 0.25 and 0.11 μg g −1 for Ga, Ge, As, Se and Sb, respectively, in original fly ash samples.

Microhomogeneity assessments using ultrasonic slurry sampling coupled with electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) is a very powerful technique for the direct analysis of solid materials prepared as slurries. The use of isotope dilution USS-ETV-ICP-MS (USS-ETV-ID-ICP-MS) for micro-homogeneity characterization studies of powdered reference materials based on elemental analyses, was investigated. Slurry analysis conditions were optimized taking into consideration density, particle size, analyte extraction, slurry mixing, analyte transport and sampling depth. Slurries were prepared using 1–20 mg of material and adding 1.0 ml of 5% nitric acid diluent containing 0.005% Triton X-100®. Three reference materials were analyzed (RM 8431a Mixed Diet, SRM 1548a Typical Diet and SRM 2709 San Joaquin Soil). Cu and Ni were determined in each material and Fe was also determined in RM 8431a Mixed Diet. ETV conditions were optimized and the benefit of using Pd as a carrier to enhance transport, combined with oxygen ashing was demonstrated. The accuracy of the method was verified by comparing analytical results with certified values. The precision of the method was demonstrated by comparing R.S.D.'s for slurry samples and aqueous standards and elemental ‘homogeneity’ was quantified based on the slurry sampling variability. The representative sample mass analyzed was calculated taking into consideration extraction of analyte into the liquid phase of the slurry. Representative sample masses of approximately 4 mg of RM 8431a provided slurry sampling variabilities of 10% or less for Cu, Fe and Ni. Representative sample masses of approximately 10 mg of SRM 1548a provided slurry sampling variabilities of approximately 10% for Cu and Ni. Representative sample masses of approximately 0.3 mg of SRM 2709 resulted in total analytical variabilities of less than 7%, highlighting the fact that the San Joaquin Soil is clearly the most homogeneous of the materials characterized.

Organic acids as the modifier to determine Zn, Cd, Tl and Pb in soil by slurry sampling electrothermal vaporization inductively-coupled plasma mass spectrometry

Ultrasonic slurry sampling electrothermal vaporization inductively-coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to the determination of Zn, Cd, Tl and Pb in several soil samples. A mixture of 1% m/v EDTA and 1.5% m/v of ascorbic acid was used as the modifier to enhance the ion signals. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. In this study, a relatively low vaporization temperature was used which separated the analyte from the major matrix components and improved the ion signals significantly. With ETV sample introduction device, spectroscopic and nonspectroscopic interferences were alleviated significantly. Since the sensitivities of Zn, Cd, Tl and Pb in various soil slurries and aqueous solution were different, standard addition method and isotope dilution method were used for the determination of Zn, Cd, Tl and Pb in these soil samples. This method has been applied to the determination of Zn, Cd, Tl and Pb in NIST SRM 2711 Montana soil reference material and several soil samples collected from Kaohsiung area. The analysis results were agreed with the certified values. The precision between sample replicates was better than 9% with USS-ETV-ICP-MS method. Detection limits estimated from standard addition curves were about 260–620, 3–5, 0.3–1 and 9–20 ng g −1 for Zn, Cd, Tl and Pb, respectively, in different samples.

EDTA as the modifier for the determination of Cd, Hg and Pb in fish by slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to the determination of Cd, Hg and Pb in several fish samples. The influences of the instrument operating conditions and slurry preparation on the ion signals were reported. In this study, a relatively low vaporization temperature was used which separated the analyte from the major matrix components and improved the ion signals significantly. EDTA was used as the modifier to enhance the ion signals. Since the sensitivities of Cd, Hg and Pb in various fish slurries and aqueous solution were quite different, the standard addition method and isotope dilution method were used for the determination of Cd, Hg and Pb in these fish samples. This method has been applied to the determination of Cd, Hg and Pb in dogfish muscle reference material (DORM-2) and a swordfish sample purchased from the market. The analysis results agreed with the certified values. The precision between sample replicates was better than 14% with the USS-ETV-ICP-MS method. Detection limits estimated from standard addition curves were about 3-6, 3-9 and 6-7 ng g –1 for Cd, Hg and Pb, respectively, in different samples.

Determination of mercury in fish samples by slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to the determination of mercury in several fish samples. The effects of instrument operating conditions and slurry preparation on the ion signals are reported. Palladium was used as modifier to delay the vaporization of mercury in this study. As the vaporization behavior of mercury in fish slurry and aqueous solution is quite different, the standard addition method was used for the determination of mercury in reference materials. The detection limit of mercury estimated from the standard addition curve was in the range 0.002–0.004 μg g −1 for different samples. This method has been applied to the determination of mercury in dogfish muscle reference material (DORM-1 and DORM-2) and dogfish liver reference material (DOLT-1). Accuracy was better than 4% and precision was better than 7% with the USS-ETV-ICP-MS method.

Determination of mercury in fish samples by slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to the determination of mercury in several fish samples. The effects of instrument operating conditions and slurry preparation on the ion signals are reported. Palladium was used as modifier to delay the vaporization of mercury in this study. As the vaporization behavior of mercury in fish slurry and aqueous solution is quite different, the standard addition method was used for the determination of mercury in reference materials. The detection limit of mercury estimated from the standard addition curve was in the range 0.002–0.004 μg g −1 for different samples. This method has been applied to the determination of mercury in dogfish muscle reference material (DORM-1 and DORM-2) and dogfish liver reference material (DOLT-1). Accuracy was better than 4% and precision was better than 7% with the USS-ETV-ICP-MS method.

Analyte Transport Studies of Aqueous Solutions and Slurry Samples Using Electrothermal Vaporization ICP-MS

Analyte transport of both aqueous solutions and slurry samples was studied with the use of ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS). The elements studied included V, Mn, Ni, Cu, and Pb, and the materials analyzed included NIST SRM 1548 Total Diet, SRM 1632a Coal, SRM 1566a Oyster Tissue, and NRCC LUTS-1 Lobster Hepatopancreas. The effect of microgram amounts of Pd as well as the effect of oxygen ashing on analyte transport were studied. Slurry samples were found to have better analyte transport in comparison to aqueous solutions when no physical carriers were added. Under these experimental conditions, the determined slurry concentrations were apparently high when quantified with the use of external calibration. Microgram amounts of Pd were used to investigate whether it was possible to reduce the difference in analyte transport between slurry samples and aqueous standards. The use of microgram amounts of Pd resulted in signal intensity suppression. Such a signal reduction could be related to the presence of space charge effects or losses of analyte due to condensation of the physical carrier together with the analyte on different parts of the ETV cell or the transfer line. On the other hand, quantitation for slurry samples was improved by the use of Pd as a physical carrier. Pd by itself was not completely effective for samples with high carbon content; therefore the effect of oxygen ashing combined with Pd was studied. An enhancement of signal intensities was observed when oxygen ashing was used, as well as a shift in the carbon signal to earlier times. In this case, signal enhancement was associated with an improvement in analyte transport caused by an increased number of carbon particles leaving the furnace at the same time as the analytes studied. With oxygen ashing, slurry samples behaved more similarly to aqueous solutions, facilitating quantitation with aqueous standards.