Soils, bone, and the Baltic shoulder - archaeological applications of vibrational spectroscopy

4 Soils, bone, and the Baltic shoulder - archaeological applications of vibrational spectroscopy 

A modified single solution method for the determination of phosphate in natural waters , pp. 31-6, copyright 1962, with permission from Elsevier. 

The simple colorimetric method is based on that originally published by Murphy and Riley (1962). Phosphates are colorless or pale in solution, so the phosphorus in the test solution is quantitatively converted to a colored compound, firstly using an acidic molybdate solution (ammonium molybdate in nitric acid)  

This ammonium phosphomolybdate complex is yellow, but if mildly reduced by ascorbic acid in the presence of potassium antimonyl tartrate a solution of stable bluish-purple color ( molybdenum blue ) develops after about ten minutes, which has its strongest absorption at 882 pm (Fig. 4.6). Other mild reducing agents have also been used, including tin(II) chloride, or hydrazine sulfate, which give maximum absorbances at slightly different wavelengths. The intensity of the color which develops is linearly proportional to the 

In chemistry, infrared spectroscopy is usually the first method of choice for the identification of organic functional groups and inorganic species such as CO32 in a wide range of materials. Because it can easily identify the OH- group in many materials (a broad absorption band at 3700-2700 cm ), it has proved useful for the study of corroded glass and weathered obsidian, where the corrosion 

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