Preservation of water samples

The best method of preserving the water samples taken is to provide for analysis as soon as possible. The water samples taken should be stored in 

Attempts should be made to ensure that samples taken arrive at the laboratory for analysis on the following day, or at the latest the day after that. If immediate analysis of the water samples in the analytical laboratory is not possible, these should be kept in cold storage at around k °C 

Cooling or preservation of samples is particularly important when taking 

Some general information is included below for selected inorganic or 

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Preservation methods for water samples are diverse and depend on the chemical nature of the contaminants. Several analytical methods require chemical preservation of water samples with acid, base or other chemicals as shown in Appendix 13. Typical chemical preservation techniques for water samples and the underlying chemical reasons are as follows ... 

Preservation of Water Samples for the Determination of Inorganic Compounds. .. 19... 

PRESERVATION OF WATER SAMPLES FOR THE DETERMINATION OF INORGANIC COMPOUNDS... 

Numerous approaches, both physical and chemical, are recommended in the literature for the preservation of water samples for inorganic chemicals analysis. In particular, the significance of freezing, pasteurization, as well as the use of chemical preservatives such as acids, sodium hydroxide, chloroform, formaldehyde, or mercuric chloride as alternative techniques has been emphasized.810 Table 2.1 describes some recommended stabilization methods. 

PRESERVATION OF WATER SAMPLES FOR TH E SPECIATION ANALYSIS OF METALS... 

Henriksen, A. 1969. Preservation of water samples for phosphorus and nitrogen determination. Vatten 25 247-254. 

Szymanski, A., Z. Swit, and Z. Lukaszewski. 1995. Studies of preservation of water samples for the determination of non-ionic surfactants. Anal. Chim. Acta 311 31-36. 

Table 2 Procedures used for the preservation of water samples collected for toxic chemical analyses ...

Ideally samples should be analyzed in situ or at the site of sampling in the field. If direct measurements are not possible or are too expensive, samples should be analyzed as soon as possible to avoid the need for preservation. However, samples cannot always be analyzed directly and they may have to be stored for so long that preservation is necessary. The preservation of water samples is covered in ISO standard 5667/3 (1985). The preservation methods described in this standard include time limits for sample storage and analysis specifications for container material prevention of exposure to light temperature control (2-5°C) pH control (addition of sulfuric, nitric, or phosphoric acid, or sodium hydroxide) addition of special reagents (e.g., ethylenediaminetetraacetic acid (EDTA), copper sulfate, zinc acetate, formaldehyde) to retard biological activity, hydrolysis of compounds and complexes and measures for reducing volatility of compounds and sorption effects. 

Fishman, M.J., Schroder, L.J., and Shockley, M.W., Evaluation of methods for preservation of water samples for nutrients analysis, International Journal of Environmental Studies 26,231,1986. 

R.B. McCleskey, D.K. Nordstrom, and A.S. Maest. Preservation of water samples for arsenic (III/V) determinations an evaluation of the literature and new analytical results. Applied Geochemistry 19 995-1009, 2004. 

Once the water samples are collected, they should be stored at 4°C until extraction, which is usually performed within 48 h. Storage of water samples for longer periods may lead to degradation of target compoimds in water samples [50]. For longer preservation of water samples, chemical agents such as formaldehyde (1% v/v) and sulfuric acid (pH < 3) can be added to the water samples to prevent bacterial activity. 

The chemical preservation of a sample is dependent on the chemistry of the ground-water (e.g., pH) and on the chemical characteristics of the pesticide being studied. Preservatives can be added to the sample containers in the field or prepared in advance at the laboratory. To determine the need for a chemical preservative in the field (i.e., pH analyses), test the groundwater collected during the purging process and not the sample collected for analysis. 

These results should be taken into account in the laboratory and field routines for characterizing AMD samples for instance they demonstrate the need to filtrate samples in the field, since refrigeration does not necessarily preserve this kind of water samples during transport to the lab. 

ISO (2003) Standard 5667-3 Water quality sampling, part 3 guidance on the preservation and handling of water samples... 

Methods for the Preservation of Water and Wastewater Samples for the Determination of Organic Compounds... 

Sliwka-Kaszynska, M., A. Kot-Wasik, and J. Namiesnik. 2003. Preservation and storage of water samples. Crit. Rev. Environ. Sci. Technol. 33 31—14. 

ISO. 1995. Quality of water. Sampling Principles rules at preservation storage of samples. EN ISO... 

Kotlash, A.R. and B.C. Chessman. 1998. Effects of water sample preservation and storage on nitrogen and phosphorus determinations Implications for the use of automated sampling equipment. Water Res. 32 3731-3737. 

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