The Analysis of Water

The typical water analysis certificate includes the concentration of inorganic salts, dissolved gases, matter in suspension, and organic matter that is in suspension or dissolved. 

Inorganic salts are dissociated in cations (M ) and anions (X ). The results are generally expressed in  

The ionic equilibrium of water requires the number of milliequivalents of anions to be equal to that of cations. Otherwise, the water analysis is incomplete or improperly done. There is no rule which defines the concentration ratios of the various anions and cations. Potassium and nitrates are not abundant in surface waters. The distribution of other elements varies greatly from one water to another. It depends on the geological layers that have been crossed by water, which explains why a very wide range of water compositions can be found. 

Water can also contain ammonium (NH4), nitrates (NOJ), phosphates (PO ), dissolved metals such as copper as (Cu ) and iron as (Fe ), generally as traces (a few milligrams per litre). 

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Examine a procedure from Standard Methods for the Analysis of Waters and Wastewaters (or another manual of standard analytical methods), and identify the steps taken to compensate for interferences, to calibrate equipment and instruments, to standardize the method, and to acquire a representative sample. 

Two examples from the analysis of water samples illustrate how a separation and preconcentration can be accomplished simultaneously. In the gas chromatographic analysis for organophosphorous pesticides in environmental waters, the analytes in a 1000-mL sample may be separated from their aqueous matrix by a solid-phase extraction using 15 mb of ethyl acetate. After the extraction, the analytes are present in the ethyl acetate at a concentration that is 67 times greater than that in... 

With a few exceptions, most quantitative applications of complexation titrimetry have been replaced by other analytical methods. In this section we review the general application of complexation titrimetry with an emphasis on selected applications from the analysis of water and wastewater. We begin, however, with a discussion of the selection and standardization of complexation titrants. 

Selected Examples of the Application of UV/Vis Molecular Absorption to the Analysis of Waters and Wastewaters... 

Environmental Applications Methods for the analysis of waters and wastewaters relying on the absorption of UV/Vis radiation are among some of the most frequently employed analytical methods. Many of these methods are outlined in Table 10.6, and a few are described later in more detail. 

Method 417B in Standard Methods for the Analysis of Water and Wastewater, American Public Health Association Washington, D.C. 15 ed., 1981, pp. 356-360. 

Spike recoveries for samples are used to detect systematic errors due to the sample matrix or the stability of the sample after its collection. Ideally, samples should be spiked in the field at a concentration between 1 and 10 times the expected concentration of the analyte or 5 to 50 times the method s detection limit, whichever is larger. If the recovery for a field spike is unacceptable, then a sample is spiked in the laboratory and analyzed immediately. If the recovery for the laboratory spike is acceptable, then the poor recovery for the field spike may be due to the sample s deterioration during storage. When the recovery for the laboratory spike also is unacceptable, the most probable cause is a matrix-dependent relationship between the analytical signal and the concentration of the analyte. In this case the samples should be analyzed by the method of standard additions. Typical limits for acceptable spike recoveries for the analysis of waters and wastewaters are shown in Table 15.1. ... 

The packed columns of Shodex OHpak SB-800HQ series are packed with polyhydroxymethacrylate gels and are designed for use with high-resolution, high-speed aqueous size exclusion chromatography. The packed columns are best suited for the analysis of water-soluble polymers and proteins (Table 6.8). 

We have defined above a way of quantifying the structure of water based on the profile of fx values that encode the number of each possible joined state of a molecule. It is now possible to use this profile as a measure of the structure of water at different temperatures. As an application of this metric it is possible to relate this to physical properties. We have shown the results of our earlier work in Table 3.3. The reader is encouraged to repeat these and to explore other structure-property relationships using the fx as single or multiple variables. A unified parameter derived from the five fx values expressed as a fraction of 1.0, might be the Shannon information content. This could be calculated from all the data created in the above studies and used as a single variable in the analysis of water and other liquid properties. 

The required volume for the analysis of water samples from a drainage flow, stream, or river is collected from a depth of up to 50 cm at the center of a flow using an appropriate sampling bottle. A sample size of 1000 mL should be sufficient for the usual type of determination. The sampling bottle and bottles for storage and shipment should be well washed with an appropriate organic solvent and distilled water so that the sample is not contaminated, and keeping those bottles in a clean container is recommended. It is recommended that samples taken are kept below 5 °C and shipped to the laboratory as soon as possible. 

Other extraction methods use an SPE disk and SPME. The analysis of water samples using SPE disks (SPE-Cig disk) was performed according to the methodology described by Albanis and Hela. Generally, the SPME method is a more reliable technique than SPE for trace analysis that can shorten the analytical procedure. 

In the analysis of water, the use of ethanol to remove more than traces of nitrate or nitrite ion may lead to formation of fulminic acid, and if mercury(II) is used as a catalyst, explosive mercury fulminate may be formed. 

C97001 Methods and Guidance for the Analysis of Water (Includes EPA Series 500, 600, 1600 Methods) Single User (on CDROM)... 

Ion-pairing reagents are detergent-like molecules added to the mobile phase to provide additional retention or selectivity for the analytes with opposite charge. Long-chain alkyl sulfonates are commonly used for the separation of water-soluble basic analytes as shown in Figure 16 in the analysis of water-soluble vitamins (WSV). Hexanesulfonate binds with... 

Miller, J. W. Garrison, A. W. Rogers, L. B. A General Approach to the Analysis of Water for Nonvolatile Organics by Precolumn Trace Enrichment High Performance Liquid Chromatography to be published. 

This chapter does not constitute a comprehensive review of all recently published HPLC methods for the analysis of water-soluble vitamins. It is a summary of selected methods and is intended to serve as a tool for the analyst in search of a method for quantitating one or more of the water-soluble vitamins in foods. The selected methods must ... 

Spliid and Kpppen described a method using LLE and LC-APCI-MS for the analysis of water. The method proposed was then used to investigate the contamination of Danish ground-water with pesticides. More than 200 samples of groundwater collected from various areas of the country were analyzed. Metramitron was detected one or more times in concentrations ranging from the detection limit level to 19 /rg/L (32). 

A number of different approaches, all of which have both advantages and shortcomings, have been proposed for the analysis of water-soluble dyes. The separation of colours has been carried out using ion-exchange resins, reverse-phase HPLC coupled with ion-pair reagents and reverse-phase HPLC at low pH where the ionisation of the dyes is suppressed. The last of these is the technique used at RSSL and is also the method recommended by Wadds (1984). It offers the simplest approach to this type of analysis and a typical HPLC profile of... 

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