DESIGN AND USE OF BACKGROUND-REDUCED AL-27 NMR PROBES FOR THE STUDY OF DILUTE SAMPLES FROM THE ENVIRONMENT

Development of methods for the detection and measurement of aluminum ( Al) is crucial for our understanding of Al(III) chemistry and toxicity in natural waters, soil solutions, and environmental samples. Traditi onal colorimetric assays; by their very nature, alter solution Al(III) chemistry, potentially biasing measurements. Methods based on Al-27 N MR spectroscopy have the advantage of being nondestructive and of not altering the chemistry of the solution. Standard commercial NMR probes and sample tubes, unfortunately, are constructed from aluminum-contai ning components. These materials give substantial background signal, w hich is detected as a large, broad hump, overwhelming signals from dil ute samples. We describe here the construction of two novel NMR probes and a sample container built from a variety of materials with low Al content. The designs feature the nse of transversely mounted solenoid coils with aluminum-free sample holders, The sample container features a second chamber which can be filled with an external reference solut ion. These novel Al-27 NMR probes me being used for the NMR spectrosco pic investigation and quantitation of natural, dilute (10(-6) M) Al(II I) samples from the environment.