This report documents work at the U.S. Geological Sur- vey (USGS) National Water Quality Laboratory (NWQL) to validate enzymatic reduction, colorimetric determinative meth- ods for nitrate + nitrite in filtered water by automated discrete analysis. In these standard- and low-level methods (USGS I-2547-11 and I-2548-11), nitrate is reduced to nitrite with nontoxic, soluble nitrate reductase rather than toxic, granular, copperized cadmium used in the longstanding USGS auto- mated continuous-flow analyzer methods I-2545-90 (NWQL laboratory code 1975) and I-2546-91 (NWQL laboratory code 1979). Colorimetric reagents used to determine resulting nitrite in aforementioned enzymatic- and cadmium-reduction meth- ods are identical. The enzyme used in these discrete analyzer methods, designated AtNaR2 by its manufacturer, is produced by recombinant expression of the nitrate reductase gene from wall cress (Arabidopsis thaliana) in the yeast Pichia pastoris. Unlike other commercially available nitrate reductases we evaluated, AtNaR2 maintains high activity at 37°C and is not inhibited by high-phenolic-content humic acids at reaction temperatures in the range of 20°C to 37°C. These previously unrecognized AtNaR2 characteristics are essential for success- ful performance of discrete analyzer nitrate + nitrite assays (henceforth, DA-AtNaR2) described here.

A thorough presentation of analytical methods for characterizing soil chemical properties and processes, Methods, Part 3 includes chapters on Fourier transform infrared, Raman, electron spin resonance, x-ray photoelectron, and x-ray absorption fine structure spectroscopies, and more.

Methods for Analysis of Carbohydrate Metabolism in Photosynthetic Organisms: Plants, Green Algae and Cyanobacteria examines both general and detailed aspects of carbohydrate metabolism in photosynthetic organisms, along with the four main oligosaccharides and each enzymatic reaction that gives birth to them. Chapters include information on how biological active protein is extracted for different cells, determination of enzymatic activity, separation of proteins by different available methods, and descriptions of analytical methods for the determination of various types of carbohydrates in photosynthetic organisms. The book contains useful protocols for researchers working on the determination of carbohydrate metabolism. The book provides foundational content as well as step-by-step guidance on how to design and conduct an experiment, including what other methodologies could be used if advanced instruments are not readily available. - Includes a variety of analytical methods and how to apply the methods using examples from specific case studies - Discusses technical information on how to characterize plant carbohydrates and sugar nucleosides - Contains easy-to-follow protocols with detailed explanations for self-guidance - Provides foundational content as well as step-by-step guidance on how to design and conduct an experiment

Thoroughly updated and revised, this second edition of the bestselling Soil Sampling and Methods of Analysis presents several new chapters in the areas of biological and physical analysis and soil sampling. Reflecting the burgeoning interest in soil ecology, new contributions describe the growing number and assortment of new microbiological

The study of the environment requires the reliable and accurate measurement of extremely small quantities of chemicals and the ability to determine if they are pollutants or naturally occurring species. Historically, a "dilute and disperse" method of waste disposal has been accepted; yet as we learn the long-term consequences of such an approach, it is clear that more rigorous waste management techniques are necessary to understand the sources and fates of contaminants and to regulate their discharge. This volume presents the details of the basic analytical science involved in making these measurements. It concentrates on the basic principles of sampling and sample preparation, followed by the chemical principles of the major instrumental methods used in chemical analysis, and detailed discussions of the major environmental matrices. This book also provides coverage of topics usually only partially discussed in textbooks, such as quality assurance plans and statistical data handling. Students majoring in environmental sciences need a foundation in measurement techniques used in the field. Environmental Chemical Analysis gives students a thorough grounding in this field and enough information to judge the quality and interpret the information produced in the analytical laboratory.