Sampling handling protocols

At ambient pH, the unpreserved water exhibited over 50% loss of Cr(III) within 1.5 h due to precipitation. With nitric acid preservation, both chromium species were preserved in solution for a week. Care must be taken when spiking standards into any natural water sample. Organisms and suspended solids present in the water are easily oxidized by Cr(VI). All possible sample matrices cannot be anticipated, so acid (or other) preservation cannot be recommended as a general strategy. The best sample handling protocol for specific needs and specific matrices must be determined during method development Prompt analysis of the sample is often the best approach for accurate determinations. 

Similar to most Hg sampling methods, sampling sediments and soils require care in avoiding contamination artifacts due to improper sample handling. However, because Hg concentratiorrs are much higher in soUd matrices than in water, if corrrmonly accepted trace-metal protocols are used, substantial contamination artifacts should be exceedingly rare. Also, because sediment Hg concentration profiles... 

These are relatively simple and robust procedures. Some of the factors to keep in mind when working with anthocyanins are excessive heat, light, oxidation, and sample handling, as these factors can alter or destroy these labile compounds. The preparation and HPLC separation of anthocyanins on silica C]8 columns (see Basic Protocol 1) is the easiest and most robust of the procedures. Typical care in filtering samples and solvents prior to HPLC analysis is about all that is necessary. 

In sum, EMPs have emerged as a preferred direct method for assessing EC injury in different disorders. EMP analysis could provide insight into the actual status of the endothelium in vivo by a simple blood analysis. However, there is a need for refinement and standardization of the assay method. Overall, most groups have relied on flow cytometry for the measurement of EMPs nevertheless, other methods such as ELISA are available and may be an option in the future. The main challenge remains in the selection of specific and sensitive monoclonal antibodies that may yield consistent results between different laboratories. In addition, the protocols for sample handling and storage need to be clearly delineated. The assay is still a... 

Since the aim of the protocol is to ensure the mitigation of problems, the essential elements of the protocol consists of sections that include (a) an Introduction, (b) treatment and disposition of data, (c) types of methods being transferred, (d) materials, reference standards, and reagents being used, (e) recommended type of equipment, (f) sample handling, (g) predetermined acceptance criteria, and (h) an Acknowledgment section. An example of a typical table of contents (TOC) of an analytical methods transfer protocol is discussed in Table 16-2. 

Ahlers W. W., Reid R. M., Kim P. J., and Hunter K. A. (1990) Contamination-free sample collection and handling protocols for trace elements in natural fresh waters. Austral. J. Mar. Freshwater Res. 41, 713-720. 

Chapter 8 provides practical guidance on the use of widely used extraction and isolation techniques from the sample preparation perspective. The first two sections, solid-phase extraction and liquid-liquid extraction deal with liquid samples. The sections on supercritical fluid extraction and accelerated solvent extraction focus mainly on solid samples while the centrifugation and filtration sections handle suspensions. A successful sample preparation protocol accounts for specificity and homogeneity as well as recovery and final physical state of the targeted material. The ultimate aim is to produce a sample that is compatible with the desired analytical technique to assure generation of maximum information. 

Different laboratories have different routine protocols to overcome this problem but whatever the processes employed, initial sample handling must minimise the loss or chemical alteration of important analytical parameters (e.g. reduction of sulfates, biological breakdown of nitrates, volatilisation of As, Sb, Hg and volatile organic parameters). 

The systems audit should consist of a review of the total data production process, which includes on-site reviews of the field s operational systems, the physical facilities for sampling, sample handling, storage, transportation, and the measurement protocols. 

It is important to use proper safety precautions in TLRC experiments, such as working in a weU-ventilated area (preferably a fume hood) and frequent monitoring of analysts for exposure. Both the half lives and energies of the isotopes used should be considered in designing safety protocols for sample handling and analytical procedures. 

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