Micro-scaled high-throughput digestion of plant tissue samples for multi-elemental analysis

BackgroundQuantitative multi-elemental analysis by inductively coupled plasma (ICP) spectrometry depends on a complete digestion of solid samples. However, fast and thorough sample digestion is a challenging analytical task which constitutes a bottleneck in modern multi-elemental analysis. Additional obstacles may be that sample quantities are limited and elemental concentrations low. In such cases, digestion in small volumes with minimum dilution and contamination is required in order to obtain high accuracy data.ResultsWe have developed a micro-scaled microwave digestion procedure and optimized it for accurate elemental profiling of plant materials (1-20 mg dry weight). A commercially available 64-position rotor with 5 ml disposable glass vials, originally designed for microwave-based parallel organic synthesis, was used as a platform for the digestion. The novel micro-scaled method was successfully validated by the use of various certified reference materials (CRM) with matrices rich in starch, lipid or protein. When the micro-scaled digestion procedure was applied on single rice grains or small batches of Arabidopsis seeds (1 mg, corresponding to approximately 50 seeds), the obtained elemental profiles closely matched those obtained by conventional analysis using digestion in large volume vessels. Accumulated elemental contents derived from separate analyses of rice grain fractions (aleurone, embryo and endosperm) closely matched the total content obtained by analysis of the whole rice grain.ConclusionA high-throughput micro-scaled method has been developed which enables digestion of small quantities of plant samples for subsequent elemental profiling by ICP-spectrometry. The method constitutes a valuable tool for screening of mutants and transformants. In addition, the method facilitates studies of the distribution of essential trace elements between and within plant organs which is relevant for, e.g., breeding programmes aiming at improvement of the micronutrient density in edible plant parts. Compared to existing vial-in-vial systems, the new method developed here represents a significant methodological advancement in terms of higher capacity, reduced labour consumption, lower material costs, less contamination and, as a consequence, improved analytical accuracy following micro-scaled digestion of plant samples.

[1]  P. White,et al.  Biofortification of crops with seven mineral elements often lacking in human diets--iron, zinc, copper, calcium, magnesium, selenium and iodine. , 2009, The New phytologist.

[2]  J. Becker,et al.  Multielemental analysis in small amounts of environmental reference materials with inductively coupled plasma mass spectrometry , 2000, Fresenius' journal of analytical chemistry.

[3]  Ivan Baxter,et al.  Ionomics and the study of the plant ionome. , 2008, Annual review of plant biology.

[4]  I. Rodushkin,et al.  Multi-elemental characterization of soft biological tissues by inductively coupled plasma–sector field mass spectrometry , 2004 .

[5]  T. E. Edmonds,et al.  Investigation of decomposition products of microwave digestion of food samples. , 1995, The Analyst.

[6]  M. Suchanek,et al.  Trace element analysis in CRM of plant origin by inductively coupled plasma mass spectrometry , 1998 .

[7]  E. Jackwerth,et al.  Probenvorbehandlungsstudien mit biologischen und Umweltmaterialien , 1987 .

[8]  Kristian Holst Laursen,et al.  Multi-elemental fingerprinting of plant tissue by semi-quantitative ICP-MS and chemometrics , 2009 .

[9]  W. Goessler,et al.  Efficiency of oxidation in wet digestion procedures and influence from the residual organic carbon content on selected techniques for determination of trace elementsPresented at the 2002 Winter Conference on Plasma Spectrochemistry, Scottsdale, AZ, USA, January 6???12, 2002. , 2002 .

[10]  I. Lavilla,et al.  Multielemental determination in breast cancerous and non-cancerous biopsies by inductively coupled plasma-mass spectrometry following small volume microwave-assisted digestion. , 2008, Analytica chimica acta.

[11]  I. Saito,et al.  Microwave digestion with HNO3/H2O2 mixture at high temperatures for determination of trace elements in coal by ICP-OES and ICP-MS , 2004 .

[12]  Ute Krämer,et al.  Zinc biofortification of cereals: problems and solutions. , 2008, Trends in plant science.

[13]  A. Hulanicki,et al.  Atomic absorption spectrometric determination of mercury in soil standard reference material following microwave sample pretreatment , 1995 .

[14]  Lauren McIntyre,et al.  Genomic scale profiling of nutrient and trace elements in Arabidopsis thaliana , 2003, Nature Biotechnology.

[15]  M. Azizi,et al.  Genetic and dietary control of plasma tissue kallikrein secretion and urinary kinins exretion in man , 2008, Journal of hypertension.

[16]  I. Lavilla,et al.  Multiple small volume microwave-assisted digestions using conventional equipment for multielemental analysis of human breast biopsies by inductively coupled plasma optical emission spectrometry. , 2009, Talanta.

[17]  I. Cakmak.  Enrichment of cereal grains with zinc: Agronomic or genetic biofortification? , 2007, Plant and Soil.

[18]  D. Salt,et al.  A high-throughput method for Saccharomyces cerevisiae (yeast) ionomics , 2009 .

[19]  Shaole Wu,et al.  Microwave Digestion of Plant and Grain Reference Materials inNitric Acid or a Mixture of Nitric Acid or a Mixture of Nitric Acid andHydrogen Peroxide for the Determination of Multi-elements by InductivelyCoupled Plasma Mass Spectrometry , 1997 .

[20]  B. Bocca,et al.  Determination of 30 elements in colorectal biopsies by sector field inductively coupled plasma mass spectrometry: method development and preliminary baseline levels. , 2007, Rapid communications in mass spectrometry : RCM.

[21]  Olga Vitek,et al.  The leaf ionome as a multivariable system to detect a plant's physiological status , 2008, Proceedings of the National Academy of Sciences.

[22]  E. Flores,et al.  Sample preparation techniques based on combustion reactions in closed vessels — A brief overview and recent applications , 2007 .

[23]  B. Bocca,et al.  Simple, fast, and low-contamination microwave-assisted digestion procedures for the determination of chemical elements in biological and environmental matrices by sector field ICP-MS , 2007 .

[24]  A. Bohlen,et al.  Development and application of a micro-digestion device for elemental analysis of biological samples , 2002 .

[25]  H. Longerich,et al.  Analysis of biological reference materials, prepared by microwave dissolution, using inductively coupled plasma mass spectrometry. , 1990, The Analyst.

[26]  S. Husted,et al.  Pollen development and fertilization in Arabidopsis is dependent on the MALE GAMETOGENESIS IMPAIRED ANTHERS gene encoding a type V P-type ATPase. , 2005, Genes & development.

[27]  Ross M. Welch,et al.  A new paradigm for world agriculture: meeting human needs: Productive, sustainable, nutritious , 1999 .

[28]  B. Bocca,et al.  High-throughput microwave-digestion procedures to monitor neurotoxic elements in body fluids by means of inductively coupled plasma mass spectrometry , 2003, Analytical and bioanalytical chemistry.

[29]  Carlo Vandecasteele,et al.  Modern Methods for Trace Element Determination , 1993 .

[30]  J. Dombovári,et al.  Comparison of Sample Preparation Methods for Elemental Analysis of Human Hair , 1998 .

[31]  T. Karner,et al.  Microwave-assisted parallel synthesis of fused heterocycles in a novel parallel multimode reactor. , 2008, Journal of combinatorial chemistry.

[32]  G. H. Vickers,et al.  Reduction of Mass-Dependent Interferences in Inductively Coupled Plasma-Mass Spectrometry by using Flow-Injection Analysis , 1989 .

[33]  K. H. Laursen,et al.  Simultaneous iron, zinc, sulfur and phosphorus speciation analysis of barley grain tissues using SEC-ICP-MS and IP-ICP-MS. , 2009, Metallomics : integrated biometal science.