Recommended Reference Materials

TABLE 4.5 Distribution of Mineral, Trace Metal, and Organic Analytes in the Target Biological Matrices Recommended as Reference Maferials (+ = presenf and - = absenf). 

TABLE 4.6. Examples of Locations Where the Recommended Sedimentary Reference Materials Could be Obtained 

Matrix Types Open-Ocean Locations Coastal Locations 

Clastic detrital North Pacific Gyre Gulf of Mexico 

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Head A J and Sabbah R 1987 Enthalpy Recommended Reference Materials for the Realization of Physicochemical Properties ed K N Marsh (Oxford Blackwell)... 

Tardajos, G. Diaz Pena, M. Lainez, A. Aicart, E. J. Chem. Eng. Data 31 (1986) 492. Marsh, K. N. Recommended Reference Materials for the Realization of Physicochemical Properties, Blackwell Sci. Pub. Oxford, Relative Mol. Mass (1987). Shiohama, Y. Ogawa, H. Murakami, S. Fluid Phase Equilib. 32 (1987) 249. 

The calibration of DTA systems is dependent on the use of appropriate reference materials, rather than on the application of electrical heating methods. The temperature calibration is normally accomplished with the thermogram being obtained at the heating rate normally used for analysis [20], and the temperatures known for the thermal events used to set temperatures for the empirically observed features. Recommended reference materials that span melting ranges of pharmaceutical interest include benzoic acid (melting point 122.4°C), indium (156.4°C), and tin (231.9°C). 

The rationale for choosing particular reference materials (and, in some cases, for recommending certification of reference materials) was discussed in Chapters 3 and 4. In this section, the committee proposes specifications for such reference materials, as well as some further suggestions specific to the preparation of the recommended reference materials. 

Recommended reference materials for achievement of specific physicochemical properties. 

Versieck J (1989) Sample analysis — including current status of trace element analysis, recommended reference materials, and considerations of quality control. J Micronutr Anal 6 261-304. Wellbeloved DB, Craven PM and Waudby JW... 

Recommended Reference Materials for the Realization of Physicochemical Properties — This lUPAC book emphasizes highly accurate data on substances and materials that can be used as calibration standards. It covers physical, thermal, optical, and electrical properties. (K. N. Marsh, ed., Blackwell Scientific Publications, Oxford, 1987)... 

Reference materials for combustion calorimetry have been recommended by the lUPAC Commission Physicochemical Measurements and Standards [130-132] and by the ICTAC Thermochemistry Working Group [133]. They are classified as primary, secondary and tertiary reference materials and when their properties are certified by a national or international organization, agency or laboratory authorized they are called certified reference materials . For combustion calorimetry, the recommended reference materials must be selected according to the atoms in the molecule and its physical state [133] benzoic acid (C,H,0, cr, primary), succinic acid (C,H,0, cr, secondary), hippuric acid (C,H,0,N, cr, tertiary), acetanilide (C,H,0,N, cr, secondary), nicotinic acid (C,H,0,N, cr, tertiary), 1,2,4-triazole (C,H,0,N, cr, secondary)[134], urea (C,H,0,N, cr, tertiary), thiantrene (C,H,0,S, cr, secodary), 4-fluorobenzoic acid (C,H,0,F, cr, secondary), pentafluorobenzoic acid (C,H,0,F1, cr, tertiary), 4-chorobenzoic acid (C,H,0,C1, cr, secondary), 4-bromobenzoic acid (C,H,0,Br, cr, tertiary), 4-iodobenzoic acid (C,H,0,I, cr, tertiary), triphenylphosphine oxide... 

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