Samples biological reference material

Zeisler R, Wise SA (1985) Quality assurance and protocols in sampling and sample preparation of biological samples. In Wolf WR, ed. Biological Reference Materials Availability, Uses and Need for Validation of Nutrient Measurement, pp. 257-279. John Wiley and Sons, New York. 

Within collaborative work on element concentrations in a number of biological reference materials using solid sampling and other analytical methods, calibration of Cd, Cu, Pb and Zn in BCR CRM 185 Bovine liver with solid CRMs was performed for each element with a reference material of the same matrix, NIST SRM 1577... 

Discontinuity between the physical form of the sample and reference material used can lead to error. This is another manifestation of the matrix effect, but one which has to be considered when analyzing biological and environmental samples. There is no easy answer to the relationship between partide size and homogeneity. It is a popular assumption that the smaller the partide size the less the degree of heterogeneity. In some cases this may be true but there are a number of considerations. 

Figure 4.19. Determination of Pb in biological reference materials in the vicinity of the 217.001 nm line pyrolysis temperature 700°C, atomization temperature 1700°C Ru permanent modifier direct solid sampling analysis (a) wavelength integrated over time for the NIST 8414 Bovine Muscle SRM (b) wavelength integrated over time for NIST 8415 Whole Egg Powder (c) absorbance over time for Whole Egg Powder, recorded at selected pixels in the vicinity of the analytical line.

No aqueous reference material was available in the laboratory during the validation tests. This test was thus performed on biological reference materials milk powder (IAEA-152) and dried clover (IAEA-156). These samples had to undergo a thermal mineralization at 500 °C. The salts were recovered in 1 M hydrochloric acid. Then alcalino-terrous elements were preconcentrated by coprecipitation in the form of calcium phosphate in basic medium to get rid of some undesirable elements. In order to eliminate a possible presence of Ra an Empore Radium Rad Disk was superposed on the usual Sr Rad Disk. 

The results of the two biological reference materials indicate that this type of samples can be eventually analysed with the Rad Disk membranes. 

It is worth mentioning that certified reference data were not available for the elements aluminum, titanium, vanadium, boron, nickel, and phosphorus at the time of analysis. This is a frequent problem in multielement analyses. It is diflBcult to obtain standard biological reference materials similar to the samples being analyzed with more than but a few certified analytical results. The lack of standard reference material limits quality assurance review of the data and diagnosis of analytical problems. The recent issue of new standards such as spinach leaves and brewers yeast will improve the material variety. Certification of more elements in the existing standards will also greatly assist the analyst. 

Satake, K. and Uehiro, T. (1985). Carbonisation technique for pretreatment of biological materials in x-ray fluorescence spectrometry. Analyst 110,1165-1168 Schauenburg, H. and Weigert, P. (1992). Determination of element concentrations in biological reference materials by solid sampling and other analytical methods, Fres. Z. Anal. Chem. 342, 950-956... 

Silver. Silver has a variety of applications, e.g., in photographic industry, electronics, and jewelry. It can be released to the environment where it can accumulate in biological organisms, including human beings. A postirradiation RNAA procedure has been developed for the determination of Ag in biological reference materials in ng/g mass fractions at the Nuclear Physics Institute, Rez, Czech Republic (Mizera et al. 2008). Samples were irradiated in a Cd... 

NAA is a quantitative method. Quantification can be performed by comparison to standards or by computation from basic principles (parametric analysis). A certified reference material specifically for trace impurities in silicon is not currently available. Since neutron and y rays are penetrating radiations (free from absorption problems, such as those found in X-ray fluorescence), matrix matching between the sample and the comparator standard is not critical. Biological trace impurities standards (e.g., the National Institute of Standards and Technology Standard Rference Material, SRM 1572 Citrus Leaves) can be used as reference materials. For the parametric analysis many instrumental fiictors, such as the neutron flux density and the efficiency of the detector, must be well known. The activation equation can be used to determine concentrations ... 

KuRFiiRST U, Grobecker KH, Stoeppler M (1984) Homogeneity studies in biological reference and control materials with solid sampling and direct Zeeman-AAS. In Schramel P, Bratter P, eds. Trace Element Analytical Chemistry in Medicine and Biology, Vol. 3, pp 591-601. de Gruyter, Berlin. 

Taylor A (1996) Reference materials and analytical standards to stimulate improved laboratory performance Experience from the external quality assessment scheme for trace elements in biological samples. Mikrochim Acta 123 251-260. 

A selected list of reference materials (sediments as well as biological tissues) distributed by several Canadian, U.S., and E.U. sources shows a wide range of solid samples that could be used for comparative analysis of major organic elements (Table 4.2). These materials are widely available and have been analyzed for at least some constituents. In addition, these materials are homogeneous and can be expected to exhibit stable compositions over time. All of the thirty or so listed reference materials,... 

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