Determination of technology-critical elements in seafood reference materials by inductively coupled plasma-tandem mass spectrometry.

The certified reference materials (CRMs) BCR-668 (mussel tissue), NCS ZC73034 (prawn), NIST SRM 1566a (oyster tissue) and NIST SRM 2976 (mussel tissue) were analyzed for their mass fractions of 23 elements using inductively coupled plasma tandem-mass spectrometry (ICP-MS/MS). This study focused on the quantification of selected technology-critical elements (TCEs), specifically rare earth elements (REE) and the less studied TCEs Ga, Ge, Nb, In and Ta. Microwave assisted closed vessel digestion using an acid mixture of HNO3, HCl and H2O2 was applied to varying sample masses and two different microwave systems. Recoveries of 76% (Gd, NCS ZC73034) to 129% (Lu, BCR-668) were obtained for the REE and 83% (Ge, NCS ZC73034) to 127% (Nb, NCS ZC73034) for the less studied TCEs across all analyzed CRMs (compared to certified values) using the best-performing parameters. Mass fractions for all analyzed, non-certified elements are suggested and given with a combined uncertainty U (k = 2), including mass fractions for Ga (11 µg kg-1 ± 9 µg kg-1 to 67 µg kg-1 ± 8 µg kg-1) and In (0.4 µg kg-1 ± 0.3 µg kg-1 to 0.8 µg kg-1 ± 0.7 µg kg-1). This study provides mass fractions of possible new emerging contaminants and addresses the relevant challenges in quantification of less studied TCEs, thus allowing the application of existing CRMs for method validation in studies dealing with the determination of TCEs in seafood or other biota.

[Determination of toxic element concentrations in flour and cereal products by mass spectrometry with inductively coupled plasma].

Systemic control and monitoring in the sphere of providing sanitary epidemiological welfare of population require routine procedures for determining toxic elements in variable foodstuffs. Their development is a pressing issue. Our research goal was to develop a procedure for determining concentrations of arsenic, cadmium, lead, mercury, aluminum and strontium in flour and cereal products by mass spectrometry with inductively coupled plasma. Material and methods. The most relevant calibration parameters for an Agilent 7900 mass spectrometer with octopole collision/ reaction cell and conditions for sample preparation by microwave digestion have been established; calibration characteristics and a range of determined concentrations have been identified. The limits of detections (LOD) and limits of quantification (LOQ) for 6 analyzed elements have been calculated. Results. Our procedure for determining mass concentrations of arsenic, cadmium, lead, mercury, aluminum and strontium in flour and cereal products by mass spectrometry with inductively coupled plasma has yielded the following results: when analyzing a sample weighing 0.5 g, we determine cadmium concentration within a range from 0.0008 to 70.0 mg/kg with inaccuracy from 14 to 25%; arsenic concentration within a range from 0.002 to 70 mg/kg with inaccuracy varying from 11 to 26%; mercury concentration from 0.003 to 7.0 mg/kg with inaccuracy from 15 to 25%; lead concentration from 0.01 to 70.0 mg/kg with inaccuracy from 12 to 26%; aluminum concentration from 0.2 to 70.0 mg/kg with inaccuracy from 13 to 20%; strontium concentration from 0.02 to 70 mg/kg with inaccuracy from 12 to 20%. The procedure was tested on samples of rice groats with the focus on the most popular brands. Thus, arsenic was detected in a concentration equal to 0.163 mg/kg in round-grain rice and 0.098 mg/kg in parboiled rice, which does not exceed the permissible level fixed for the element at 0.2 mg/kg. In all the analyzed samples, content of cadmium, lead and mercury did not exceed maximum permissible levels established by the Technical regulation of the Customs Union TR CU 021/2011 for flour and cereal products. These levels are 0.1 mg/kg for cadmium, 0.5 mg/kg for lead and 0.03 mg/kg for mercury. Conclusion. The developed procedure for determining toxic elements in flour, cereals and bakery products by using mass spectrometry with inductively coupled plasma gives an opportunity to determine such elements in quantities lower than permissible levels fixed for them in technical regulations and sanitary rules. The procedure expands the existing methodical instruments for control of food quality in the Russian Federation.

Determination of 48 elements in 7 plant CRMs by ICP-MS/MS with a focus on technology-critical elements.

Seven plant certified reference materials (NIST SRM1515 Apple Leaves, NIST SRM1547 Peach Leaves, BCR-129 Hay Powder, BCR-670 Aquatic Plant, GBW07603 Bush Twigs and Leaves, GBW10015 Spinach Leaves and NCS ZC73036a Green Tea) were analysed for their mass fractions of 48 elements by inductively coupled plasma tandem-mass spectrometry (ICP-MS/MS): Li, Be, Na, Mg, Al, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Y, Nb, Mo, Ag, Cd, Sb, Te, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ta, Tl, Pb, Bi, Th, U. Special focus was put on the determination of technology-critical elements (TCEs), to which, e.g. Li, Be, Ga, Ge, Nb, Sb, Ta, Tl, Bi, and the rare-earth elements (REEs, lanthanides and Y) are counted. Closed-vessel microwave digestion was performed using HNO3, H2O2 and HBF4. The average bias for certified values is - 1% ± 13% (SD). Limits of detection (xL) in the measured solutions lie between 13 fg g-1 (Tb) and 52 ng g-1 (Ca). This article seeks to provide an optimised measurement procedure for the determination of element mass fractions of emerging importance in environmental samples, which are challenging to analyse with more traditional techniques such as single-quad ICP-MS. In addition, it aims to improve the characterisation of commonly used plant reference materials by providing mass fraction data for rarely studied elements.

Evaluation of collision/reaction gases in single-particle ICP-MS for sizing selenium nanoparticles and assessment of their antibacterial activity.

Selenium nanoparticles (SeNPs) have recently attracted attention because they combine the benefits of Se and lower toxicity compared to other chemical forms of this element. In this study, SeNPs were synthesized by a green method using ascorbic acid as the reducing agent and polyvinyl alcohol as stabilizer. The nanoparticles were widely characterized. To determine the total concentration of Se by ICP-MS, several isotopes and the use of He as collision gas were evaluated, which was effective in minimizing interferences. A method for sizing SeNPs by single particle ICP-MS (SP-ICP-MS) was developed. For this purpose, He and H2were evaluated as collision/reaction gases, and the second one showed promising results, providing an average diameter of 48 nm for the SeNPs. These results agree with those obtained by TEM (50.1 nm). Therefore, the SP-ICP-MS can be implemented for characterizing SeNPs in terms of size and size distribution, being an important analytical tool for Se and other widely studied nanoparticles (e.g. Ag, Au, Ce, Cu, Fe, Zn). Finally, the antibacterial activity of SeNPs was assessed. The SeNPs showed bacteriostatic activity against three strains of Gram-positive bacteria and were particularly efficient in inhibiting the growthE. faecaliseven at very low concentrations (MIC < 1.4 mg l-1). In addition, a bactericidal activity of SeNPs againstS. aureuswas observed. These nanoparticles may have potential application in pharmaceutical industry, biomedicine and agriculture.

Determination of ultra-trace level plutonium isotopes in soil samples by triple-quadrupole inductively coupled plasma-mass spectrometry with mass-shift mode combined with UTEVA chromatographic separation.

Although triple-quadrupole inductively coupled plasma-mass spectrometry (ICP-MS/MS) has become an attractive technique for the measurement of long-lived radionuclides, the abundance sensitivity, isobaric and polyatomic ions interferences seriously restrict the application. The spectral peak tailing and uranium hydrides (UH+, UH2+) from 238U have a serious influence on the accurate measurement of 239Pu and 240Pu, especially for the ultra-trace level plutonium isotopes in the higher uranium sample. A new method was developed using ICP-MS/MS measurement in mass-shift mode with collision-reaction gas combined with a chemical separation procedure. As O2 readily converted Pu+ ion to PuO2+, while disassociated the interfering diatomic ions of interfering elements (U, Pb, Hg, Tl, etc.), the interferences from these elements were completely eliminated if plutonium was detected as PuO2+ at the m/z more than 270. By the mass filter in MS/MS mode combined with O2 as reaction gas the lower peak tailing of 238U+ (<5 × 10-12) was significantly suppressed. By this way, the 238UO2H+/238UO2+ atomic ratio was reduced to 4.82 × 10-9, which is significantly lower than that of other collision-reaction gas modes. Interferences from Pb, Hg and Tl polyatomic ions were also completely eliminated. Thus, accurate measurement of ultra-trace level 239Pu in high uranium sample solutions with the 239Pu/238U concentration ratio of 10-10 was achieved by the mass-shift mode with 0.15 mL/min O2/He + 12.0 mL/min He as collision-reaction gas, and high elimination efficiency of uranium interferences up to 1014 can be obtained by combination with the chemical separation using a single UTEVA resin column. The developed method can be applied to accurately determine the fg level 239Pu in high uranium samples, such as large-size deep seawater, deep soil and sediment, uranium debris of nuclear fuel.

Method development for determination of trace amounts of palladium in environmental water samples by ICP-MS/MS after pre-concentration on thiol-functionalized MCM-41 materials.

The anthropogenic cycle of Pd in the environment, its fate and impact is still unknown due to limitations of measurement techniques. For separation and pre-concentration of Pd(II) ions, mesoporous silica materials MCM-41 were synthesized and functionalized with different amounts of 3-mercaptopropyltrimethoxysilane (MPTMS) by co-condensation and grafting methods. The structural and textural properties of materials were characterized using XRD, TEM, SEM and BET techniques. The results proved that functionalization with thiol groups did not significantly affect structural and textural parameters of synthesized sorbents. The Pd(II) ions were quantitatively retained on sorbents functionalized by grafting in acidic solutions (pH 2), efficiently eluted with 0.1 mol L-1 thiourea solution in 1 mol L-1 HCl and determined by electrothermal atomic absorption spectrometry (ETAAS). The limit of detection (LOD) of the developed SPE ETAAS method was 0.06 ng mL-1, and the pre-concentration factor was 30. For analysis of Pd in environmental water samples inductively coupled plasma mass spectrometry (ICP-MS) in MS/MS mode was used. Spectral interferences on 105Pd caused by the presence of Sr in water samples were eliminated using helium (5 mL min-1) or ammonia (7 mL min-1) gas in collision/reaction cell. The developed SPE ICP-MS method is characterized by good selectivity in the presence of interfering elements and chloride ions and detection limit of 0.0002 ng mL-1. Its accuracy was confirmed by analysis of spiked water samples. The application of ICP-MS together with efficient separation/pre-concentration of analyte on thiol-functionalized MCM-41 sorbents allows to determine Pd in environmental water samples at pg mL-1 level.

On the effect of using collision/reaction cell (CRC) technology in single-particle ICP-mass spectrometry (SP-ICP-MS).

In this work, the effects of using collision/reaction cell (CRC) technology in quadrupole-based ICP-MS (ICP-QMS) instrumentation operated in single-particle (SP) mode have been assessed. The influence of (i) various CRC gases, (ii) gas flow rates, (iii) nanoparticle (NP) sizes and (iv) NP types was evaluated using Ag, Au and Pt NPs with both a traditional ICP-QMS instrument and a tandem ICP-mass spectrometer. It has been shown that using CRC technology brings about a significant increase in the NP signal peak width (from 0.5 up to 6 ms). This effect is more prominent for a heavier gas (e.g., NH3) than for a lighter one (e.g., H2 or He). At a higher gas flow rate and/or for larger particle sizes >100 nm), the NP signal duration was prolonged to a larger extent. This effect of using CRC technology has been further demonstrated by characterizing custom-made 50 and 200 nm Fe3O4 NPs (originally strongly affected by the occurrence of spectral overlap) using different CRC approaches (H2 on-mass and NH3 mass-shift). The use of NH3 (monitoring of Fe as the Fe(NH3)2+ reaction product ion at m/z = 90 amu) induces a significant peak broadening compared to that observed when using H2 (6.10 ±â€¯1.60 vs. 0.94 ±â€¯0.49 ms). This extension of transit time can most likely be attributed to the collisions/interactions of the ion cloud generated by a single NP event with the CRC gas and it even precludes 50 nm Fe3O4 NPs to be detected when using the NH3 mass-shift approach. Based on these results, the influence of a longer peak width on the accuracy of SP-ICP-MS measurement data (NP size, particle number density and mass concentration) must be taken into account when using CRC technology as a means to overcome spectral overlap. To mitigate the potential detrimental effect of using CRC technology in the characterization of NPs via SP-ICP-MS(/MS), the use of light gases and low gas flow rates is recommended.

Determination of ultra-low level plutonium isotopes (239Pu, 240Pu) in environmental samples with high uranium.

In order to measure trace plutonium and its isotopes ratio (240Pu/239Pu) in environmental samples with a high uranium, an analytical method was developed using radiochemical separation for separation of plutonium from matrix and interfering elements including most of uranium and ICP-MS for measurement of plutonium isotopes. A novel measurement method was established for extensively removing the isobaric interference from uranium (238U1H and 238UH2+) and tailing of 238U, but significantly improving the measurement sensitivity of plutonium isotopes by employing NH3/He as collision/reaction cell gases and MS/MS system in the triple quadrupole ICP-MS instrument. The results show that removal efficiency of uranium interference was improved by more than 15 times, and the sensitivity of plutonium isotopes was increased by a factor of more than 3 compared to the conventional ICP-MS. The mechanism on the effective suppress of 238U interference for 239Pu measurement using NH3-He reaction gases was explored to be the formation of UNH+ and UNH2+ in the reactions of UH+ and U+ with NH3, while no reaction between NH3 and Pu+. The detection limits of this method were estimated to be 0.55 fg mL-1 for 239Pu, 0.09 fg mL-1 for 240Pu. The analytical precision and accuracy of the method for Pu isotopes concentration and 240Pu/239Pu atomic ratio were evaluated by analysis of sediment reference materials (IAEA-385 and IAEA-412) with different levels of plutonium and uranium. The developed method were successfully applied to determine 239Pu and 240Pu concentrations and 240Pu/239Pu atomic ratios in soil samples collected in coastal areas of eastern China.

Evaluation of the multi-element capabilities of collision/reaction cell inductively coupled plasma-mass spectrometry in wine analysis.

This work explores the multi-element capabilities of inductively coupled plasma-mass spectrometry with collision/reaction cell technology (CCT-ICP-MS) for the simultaneous determination of both spectrally interfered and non-interfered nuclides in wine samples using a single set of experimental conditions. The influence of the cell gas type (i.e. He, He+H2 and He+NH3), cell gas flow rate and sample pre-treatment (i.e. water dilution or acid digestion) on the background-equivalent concentration (BEC) of several nuclides covering the mass range from 7 to 238u has been studied. Results obtained in this work show that, operating the collision/reaction cell with a compromise cell gas flow rate (i.e. 4 mL min(-1)) improves BEC values for interfered nuclides without a significant effect on the BECs for non-interfered nuclides, with the exception of the light elements Li and Be. Among the different cell gas mixtures tested, the use of He or He+H2 is preferred over He+NH3 because NH3 generates new spectral interferences. No significant influence of the sample pre-treatment methodology (i.e. dilution or digestion) on the multi-element capabilities of CCT-ICP-MS in the context of simultaneous analysis of interfered and non-interfered nuclides was observed. Nonetheless, sample dilution should be kept at minimum to ensure that light nuclides could be quantified in wine. Finally, a direct 5-fold aqueous dilution is recommended for the simultaneous trace and ultra-trace determination of spectrally interfered and non-interfered elements in wine by means of CCT-ICP-MS. The use of the CCT is mandatory for interference-free ultra-trace determination of Ti and Cr. Only Be could not be determined when using the CCT due to a deteriorated limit of detection when compared to conventional ICP-MS.