Recent Advances in Speciation Analyses of Tobacco and Other Important Economic Crops

Background: Speciation analysis is defined as the analytical activities of identifying and/or measuring the quantities of one or more individual chemical species in a sample. The knowledge of elemental species provides more complete information about mobility, bioavailability and the impact of elements on ecological systems or biological organisms. It is no longer sufficient to quantitate the total elemental content of samples to define toxicity or essentiality. Thus speciation analysis is of vital importance and generally offers a better understanding of a specific element. Discussion: Thorough speciation scheme consisting of sampling, sample preparation, species analysis and evaluation were described. Special emphasis is placed on recent speciation analysis approaches including both direct and coupling methods. A current summary of advantages and limitations of the various methods as well as an illustrative method comparison are presented. Certain elements and species of interest are briefly mentioned and practical examples of speciation applications in tobacco and other important economic crops are also discussed. Aim/Conclusion: This review aims to offer comprehensive knowledge about elemental speciation and provide readers with valuable information. Many strategies have been developed for the determination of multiple elemental species in tobacco and other important economic crops. Nevertheless, it is an eternal pursuit to establish speciation methods which can balance accuracy, agility as well as universality.

Quick Analysis of Organic Amendments via Portable X-ray Fluorescence Spectrometry

The determination of heavy metals in soils and organic amendments, such as compost, manure, biofertilizer, and sludge, generally involves the digestion of samples with aqua regia, and the determination of those in the solution using various techniques. Portable X-ray fluorescence (PXRF) has many advantages in relation to traditional analytical techniques. However, PXRF determines the total elemental content and, until now, its use for the analysis of organic amendments has been limited. The objective of this work is the calibration of a PXRF instrument to determine the aqua regia-soluble elemental contents directly in solid samples of organic amendments. Our proposal will avoid the digestion step and the use of other laboratory techniques. Using a training set of samples, calibration functions were obtained that allow the determination of the aqua regia-soluble contents from the PXRF readings of total contents. The calibration functions (obtained by multiple linear regression) allowed the quantitative determination of the aqua regia-soluble contents of Fe, K, P, S, Zn, Cu, Pb, Sr, Cr, and Mn, as well as the organic matter content and a semi-quantitative assessment of Al, Ca, V, Ba, Ni, and As contents. The readings of Si, Fe, Al, Ca, K, or S were used as correction factors, indicating that the calibrations functions found are truly based on the chemical composition of the sample matrix. This study will allow a fast, cheap, and reliable field analysis of organic amendments and of other biomass-based materials.

Correlation of Intracellular Calcium Measurements Using X-Ray Microanalysis and Fluorescence Microscopy Techniques

It is my thought that calcium plays a major role in the development of irreversible cellular injury in the myocardium.There are two basic forms of calcium within the cell, the active, ionized calcium and the inactive form which may be bound to cell proteins or held in storage sites within the cells.The use of energy dispersive x-ray microanalysis in an analytical electron microscope permits the localization and measurement of the total elemental content of subcellular regions of cells. These measurements generally require that the cells be cryofixed , cryosectioned, cryotransfered and freeze dried in the electron microscope. The Hall method of continuum normalization is then used to convert the x-ray intensity measurements into dry weight concentrations.Because the cells have to be cryofixed, it is not possible to follow the development of elemental changes within a single cell over time, thus many cells have to be frozen at different time intervals to measure time dependent changes of irreversible injury and cell death. Thus, selected time points are identified and sampled for x-ray microanalysis.

Biomass and nutrient distribution patterns in a young Pseudotsugamenziesii ecosystem

Calculations are presented giving biomass and quantities of nitrogen, phosphorus, potassium, calcium, and magnesium contained in soil, understory vegetation, and standing arboreal components of a low-site, immature Pseudotsugamenziesii (Mirb.) Franco ecosystem on southern Vancouver Island. For the standing arboreal crop, biomass and elemental content of the foliage, live and dead branches, wood, bark, and total tree were estimated, using the formula logeY = a + b logeD2H, where D = diameter breast height and H = total tree height.The soil component contained over 70% each of the total organic matter biomass and nitrogen, calcium, and magnesium content in the ecosystem. Although the soil also contained large quantities of potassium and phosphorus, the vegetative component significantly increased in importance with regard to these two elements. Biomass and nutrient distribution patterns within the standing arboreal crop are discussed in terms of elemental concentrations and distribution between components over the diameter range encountered. The distribution of biomass and the total elemental content among the various ecosystem components are discussed and comparisons are made with related studies.