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RECENT DEVELOPMENTS IN ICPMS APPLIED TO STUDIES IN NUTRITION & HEALTH Steven F. Durrant 1 and Neil. I Ward 2 1 Laboratório de Plasmas Tecnológicos, Campus Experimental de Sorocaba, UNESP , Sorocaba, SP, Brazil 2 ICPMS Facility, University of Surrey, Guildford, Surrey, UK.
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RECENT DEVELOPMENTS IN ICPMS APPLIED TO STUDIES IN NUTRITION & HEALTH Steven F. Durrant1 and Neil. I Ward2 1Laboratório de Plasmas Tecnológicos, Campus Experimental de Sorocaba, UNESP, Sorocaba, SP, Brazil 2 ICPMS Facility, University of Surrey, Guildford, Surrey, UK
Inductively coupled plasma mass spectrometry (ICPMS) Advantages Multielemental analysis Isotope ratio analysis Solution-based calibration High throughput Wide linear dynamic range Detection limits down to a few fgg-1 Low background count rates Flexible magnetic sector instruments
ICPMS Disadvantages Interferences Matrix effects Hazardous & time-consuming sample preparation Limited precision for isotope ratio analysis (Quadrupole) (Only) bulk analyses
Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) Advantages Direct analysis of solids (conductors or insulators); Little or no sample preparation; High sample throughput; Reduced water-related interferences; Lower blank responses; Reduced memory effects; Spot, line, area or bulk analysis.
Laser ablation inductively coupled plasma mass spectrometry Disadvantages ● Difficulty in obtaining fully quantitative analysis ● Poor precisions for isotope ratio measurements
● Pickhardt, C, Izmer, AV, Zoriy, MV, Schumlöffel, D, Becker, JS (2006) Int J Mass Spectrom 248:136-141. ● Online isotope dilution was employed with LA-ICPMS. ● A microflow total consumption nebuliser DS-5 (CETAC Technologies, Omaha, NE, USA) was mounted in the ablation chamber.
● A nebuliser solution uptake rate of 7 μlmin-1 was provided by a high precision syringe pump. ● To determine a doped uranium concentration in NIST SRM 1515 Apple leaves using a CETAC LSX 200 systemλ = 266 nm, 10 Hz, φ = 300 μm. ●A quadrupole ICPMS fitted with a collision cell was used for detection.
Procedure (1) LA and SN to determine 235U:238U in the samples (S);(2) Nebulisation of isotopically-enriched tracer solution and simultaneous LA for the determination of 235U:238U in the mixture (X);(3) Nebulisation of isotope-enriched tracer (without LA) and measurement of the 235U:238U ratio in this solution (T). The elemental concentration was then obtained using QS = QT(T – X)/[(X – S)mS/mT] where Q is concentration, and m is atomic mass.
An internal standardization procedure was employed to compensate for differences in sensitivity between LA- and SN-ICPMS. Results ● A concentration of 11.19 ± 1.11 μgg-1 was determined in Apple Leaves (Doped uranium concentration of 10 μgg-1). Advantages ● Low flow rate of the isotope-enriched tracer ● Easy and rapid analysis in any concentration range; the possibility to perform single-shot analysis.
Cizdziel, JV (2007) Anal Bioanal Chem 388:603-611. Determination of Pb in whole blood Application: Suspected pediatric lead poisoning Traditional collection by finger of heel stick onto specially designed filter paper. LA-ICP-TOF-MS with ablation using a CETAC LSX-213 system, λ = 213 nm, at 20 Hz, scan rate of 100 μms-1, φ = 200 μm. Detection was with an Optimass 8000 ICP-TOF-MS (GBS Scientific Equipment Ltd, Australia).
●Results: A linear calibration curve was obtained (r2 = 0.996) but the analysis of Seronorm Whole Blood Reference Material yielded 5.6 ± 0.3 μgdl-1 compared to the 3.3 μgdl-1 reference value, i.e. the analysis was semi-quantitative. ● Reproducibility for individual blood spot scan data was typically about 7% RSD. ● A difficulty encountered was the different spreading characteristics of reconstituted freeze-dried CRMs compared to those of fresh blood.
H. Sela, Z. Karpas, M. Zoriy, C. Pickhardt, J.S. Becker (2007) Biomonitoring of hair samples by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) International Journal of Mass Spectrometry 261 (2007) 199–207
Krause-Bucholz, U, Becker, JS, Zoriy, M, Pickhardt, C, Przybylski, M, Rödel, G, Becker, JS (2006) Int J Mass Spectrom 248:56-60. Analytes 31P+, 32S+, 28Si+, 27Al+, 63Cu+, 64Zn+ Identification of phosphorylated subunits of yeast mitochondrial ATPase.
The complexes were separated in their native state in the 1st dimension (BN-PAGE) and their subunit composition resolved by SDS-PAGE in the 2nd dimension under denaturing conditions. LA-ICPMS was then used to screen for P in the subunits. CETAC LSX 200, ELEMENT HR-ICPMS. S was used for internal standardization. P was determined in subunits Atp1p and Atp2p of the ATPase by MALDI-FTICR-MS
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) in elemental imaging of biological tissues and in proteomics J. Sabine Becker, Miroslav Zoriy, J. Susanne Becker, Justina Dobrowolska and Andreas Matusch J Anal Atom Spectrom, 2007, 22, 736-744
Applications ● Matrices: Teeth, hair, blood, nails, brain tissue, etc. Elemental mapping Proteomics Single-cell analysis or analysis of organelles
Performance (Resolution) ● Theoretical depth resolutions of 5 nm are possible: 1mJ pulses at 266 nm. ● Barnes, JH, Schilling GD, Hieftje, GM, Sperline, RP, Bonner Denton, M, Barinaga, CJ, Koppenaal, DW, (2004) J Am Mass Spectrom, 15, 769-776.
Lateral resolutions of 5 μm (zircon using a MicroLas GeoLas 102 ArF excimer laser, λ = 193 nm. Paquette, JL, Tiepolo, M (2007) Chem. Geol. 240:222-237. Improved lateral resolution down to the hundred nm scale using the near-field effect induced by a silver needle positioned extremely close to the sample surface. Becker, JS, Gorbunoff, A, Zoriy, M, Izmer, A, Kayser, M (2006) J Anal At Spectrom 21:19-25.
Acknowledgements ● SFD thanks the Brazilian agency FUNDUNESP for financial support