Marvin J. Fishman

Evaluation of methods for preservation of water samples for nutrient analysis

Mercuric ion, sulfuric acid, and chloroform were examined as preservatives for nitrogen and phosphorus species in water samples containing biologically active microorganisms. Chilling at 4°C without addition of a chemical preservative also was examined. Chilling alone at 4°C was an adequate preservation technique for 8‐day storage for the water samples used in this study. However, for samples analyzed after 16‐day storage, the addition of 40 milligrams per liter of mercuric ion plus chilling at 4°C, appeared to be the preservation technique of choice. Neither chloroform nor sulfuric acid, coupled with chilling, were adequate as preservation techniques for all analytes determined during the 16‐day study period.

Validation of an automated fluorescein method for determining bromide in water

Abstract Surface, atmospheric precipitation and deionized water samples were spiked with μg l−1 concentrations of bromide, and the solutions stored in polyethylene and polytetrafluoroethylene bottles. Bromide was determined periodically for 30 days. Automated fluorescein and ion chromatography methods were used to determine bromide in these prepared samples. Analysis of the data by the paired t-test indicates that the two methods are not significantly different at a probability of 95% for samples containing from 0.015 to 0.5 mg l−1 of bromide. The correlation coefficient for the same sets of paired data is 0.9987. Recovery data, except for the surface water samples to which 0.005 mg l−1 of bromide was added, range from 89 to 112%. There appears to be no loss of bromide from solution in either type of container.

A standard-reference water-suspended sediment sample for total recoverable metals

The U.S. Geological Survey has been preparing and maintaining a library of standard-reference water samples for dissolved inorganic constituents for 19 years. Recently, the reference-sample program was expanded to include a water-suspended sediment mixture for the determination of total recoverable metals. An interlaboratory round-robin study was conducted. Digestion procedures used by the U.S. Geological Survey and the U.S. Environmental Protection Agency were used to solubilize the metals before their measurement. The data indicate the both digestion procedures for total recoverable metals are essentially equivalent. Precision data are comparable to those data obtained in standard-reference water samples for dissolved metals.

Pilot study for U.S. Geological Survey Standard Reference Water Samples for pesticides

The U.S. Geological Survey has been preparing and maintaining a library of standard reference water samples for inorganic constituents for 19 years. Recently, a pilot study was conducted to see if the reference-sample program could be expanded to include pesticides and other organic materials. Two samples containing organochlorine and organophosphorus insecticides, and chlorophenoxy acid herbicides were distributed to a number of laboratories in the United States. One of the samples also contained polychlorinated biphenyls. Interlaboratory data obtained from these round robin studies are presented with intralaboratory information on long-term stability.

Inorganic pollution in water—the analyst's viewpoint†

Abstract Inorganic pollution comprises both major and minor constituents, although only 12 chemical elements may be considered major components. Twenty‐eight elements constitute a group of common minor elements and an additional 13 elements comprise a group of less common minor constituents. Reliable quantitative data are required on the occurrence of these substances in a wide variety of water types, usually at extremely low concentrations. The analysis of standard reference water samples provides information on the overall reliability of water‐quality data. Although most major constituents may be determined with acceptable reliability, determinations of certain minor constituents lack comparable precision; for example, determinations of boron, nickel, and chromium. Few precision data are available on the determination of the less common trace elements. Several comparatively new analytical techniques, such as flameless atomic absorption spectrophotometry, voltammetry, and emission spectroscopy with plasm...