The Mahalanobis distance

Assessment of seasonal and polluting effects on the quality of river water by exploratory data analysis

Headspace solid-phase microextraction is a solvent-free sample preparation technique in which a fused silica fiber coated with polymeric organic liquid is introduced into the headspace above the sample. The volatilized organic analytes are extracted and concentrated in the coating and then transferred to the analytical instrument for desorption and analysis. This modification of the solid-phase microextraction method (SPME) shortens the time of extraction and facilitates the application of this method to analysis of solid samples. The detection limits of the headspace SPME technique are at ppt level when ion trap mass spectrometry is used as the detector and are very similar to that of the direct SPME technique

Headspace solid-phase microextraction

Effect of organoclay structure on nylon 6 nanocomposite morphology and properties

A compilation of 68 studies from throughout many of the world9s mountain belts reveals an empirically consistent and linear relationship between change in elevation and change in the isotopic composition of precipitation along altitudinal transects. The isotopic composition of precipitation decreases linearly with increasing elevation in most regions of the world except in the Himalayas and at elevations >5000 m. There are no significant differences in isotopic lapse rates from most regions of the world (∼0.28 permil/100 m) except at the extreme latitudes where isotopic lapse rates are higher. Given information on past changes in the isotopic composition of precipitation preserved in pedogenic or authigenic minerals, this global isotopic lapse rate can be used to place numerical constraints on the topographic development of some ancient mountain belts or plateaus. There are many complicating factors that can confound interpretation of paleoelevation change based on stable isotopes, and many of these are unique to specific mountain belts or time periods. Relevant to all stable isotope based paleoelevation change studies is the temperature dependent isotope fractionation between a pedogenic or authigenic mineral and the water from which it forms. In cases where isotopic proxy minerals are sampled from localities where temperature will change simultaneously with elevation change, the apparent change in the isotopic composition of precipitation may be dampened by several permil. This suggests that samples taken from the rainshadow side of an emerging orographic barrier may be more likely to preserve isotopic changes resulting from mountain uplift than samples taken from atop a rising mountain range or plateau.

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Empirical Relationships Between Elevation and the Stable Isotope Composition of Precipitation and Surface Waters: Considerations for Studies of Paleoelevation Change

Introduction. Errors in Classical Analysis - Statistics of Repeated Measurements. Significance Tests. Quality Control and Sampling. Errors in Instrumental Analysis. Regression and Correlation. Non-parametric and Robust Methods. Experimental Design. Optimization and Pattern Recognition. Solutions to Exercises. Appendix 1: Summary of Statistical Tests. Appendix 2: Statistical Tests.

J.N. Miller

Papers

Statistics for Analytical Chemistry