Sampling and storage

Samples for the determination of thiosulphate are taken in the same way as for oxygen. It is, however, only necessary to rinse the 100 mL bottle by allowing about 50 mL to overflow so that sample water is not wasted, as it might be needed for the determination of other constituents. The analysis must be performed within about 60 min after sampling, but the sulphide should be precipitated immediately (see Section 6.2.4.2). 

---

Batley, G. E. Gardner, D. Sampling and Storage of Natural Waters for Trace Metal Analysis , Wat Res. 1977,11, 745-756. 

Although the DL 40 was capable of performing Karl Fischer water titrations and Mettler developed a separate microprocessor-controlled push-button operated DL 18 KF titrator, they also introduced as an all-purpose apparatus the improved DL 40 RC (see Fig. 5.11) with a dual titration head and with a modified software program to handle the new two-component titrants for Karl Fischer titration (see pp. 204-205). The instrument can also be expanded into an automatic series titrator by connecting the RT 40 sample transport for 16 samples and storage of 50 sample weights from a connected balance this series routine can be interrupted at any time after completion of the titration in progress. 

Field spikes with laboratory standards as well as spraying solutions were taken at a wide range of concentrations to determine the stability of the samples during both sampling and storage and possible contamination during the sampling procedure. Field blanks were also taken. 

Spencer and Brewer [112] have reviewed the determination of radionucleides in seawater and discuss sampling and storage methods together with tables of radionucleides that have been determined in the oceans. 

The problem of species changes during sampling and storage can be ameliorated in two ways. First, the soil component of interest can be measured in situ,... 

The effect of storage of water samples before determination of nitrogen and carbon associated with particulate matter was investigated. Freezing of the samples, and storage at 5°C, both affected the results obtained, but changes were minimized if the samples were filtered immediately after collection and the particulate matter stored on the filter paper. It is recommended that samples for determination of particulate carbon and nitrogen should be filtered immediately, and analysed as soon as possible. 

If a water sample is to be analyzed for trace levels of metals, why is a glass container for sampling and storage inappropriate ... 

Receipt, handling, sampling and storage of test and reference items should be clearly defined activities, with well-defined procedures. Also procedures must be provided for the records that are to be kept as evidence of good practice and the identification information on storage containers. 

Handling, sampling and storage procedures to ensure homogeneity and stability and avoid contamination or mix-up... 

Storage at 4 °C or less is recommended for all samples, and storage at —20 °C or less is recommended for crude and processed extracts. The recommended containers are amber glass bottles with Teflon tops, but Teflon containers may be used for particularly corrosive samples. Stainless steel containers are not considered acceptable because of the potential for sample contamination. Additional research to address optimum storage conditions (temperature, time, and storage containers) that preserve sample integrity is recommended. This study should include research on the storage of raw samples, crude extracts, and processed extracts. 

Sampling. Monthly samplings were performed at the deepest point of the water column (depth = 31 m) over a period of 2 years. Because a number of labile reduced species occur in anoxic water samples, special attention has to be given to the sampling and sample pretreatment methods to obtain reliable results. Several approaches have been used to circumvent sampling and storage problems. Rapid field analysis of labile species has been recommended (e.g., ref. 9). This rapid analysis is particularly important in measuring the very labile species of Fe(II) and S(-II). 

Sampling and Storage of the Sample.—.Before analysis, the sample should be well mixed, either by pouring it repeatedly from one vessel to another, but avoiding the formation of froth, or by stirring it vertically, slowly and without beating it, with a rod fitted at the end with either a perforated disc or a metal bucket. 

Batley, G.E. and Gardner, D., 1977. Sampling and storage of natural waters for trace metal analysis. Water Res., 11 745-756. 

CEN/ISO EN/ISO 16000-11 Indoor Air-Part 11 Procedure for sampling and storage of samples and preparation of test specimens Will supercede 13419-3... 

It is highly preferable to use standard methods for sampling and storage (Lapa et al., 2002b) and conditioning (EN 12457-1 to 4, 2002) of solid wastes. It is also important to know, before any leaching experiments are conducted, relevant properties of the waste, such as ... 

Sampling of subsurface soil into core barrel liners has been widely used until EPA Method 5035 came into effect. In this sampling method, after a core barrel liner has been filled with soil, it is capped with PTFE sheets or aluminum foil and plastic caps. These types of closure do not prevent the VOC loss from soil, which for some compounds may exceed 97 percent after only 6 days of cold storage (Hewitt, 1999). If sampling and storage in glass jars or core barrel liners cannot be avoided, samples must be delivered to the laboratory and analyzed within the shortest time after collection. 

The uncertainty for the determination of e.g. atrazine in water consists of the calibration of several components of uncertainty, such as the uncertainty of the true content of the atrazine standard, uncertainty from dilution of this standard, uncertainty regarding the loss of atrazine in sampling and storage prior to analysis, as well as that associated with the preconcentration step after correction for recovery. 

The receipt, identification, labeling, handling, sampling, and storage of the test and reference items. 

Once the material has been chosen for sampling and storage, it is important to establish a protocol for the collection of milk samples. The extraction will be achieved manually or by means of a plastic milk extractor, a new one for each sampling. The nipple and the skin around it should be cleaned with soap and distilled water before collection. The milk thus collected should then be stored in plastic containers previously decontaminated, as explained above. The containers should be labeled and kept at — 20°C until analysis. 

Keenan, T., Patton, S. 1995. The structure of milk implications for sampling and storage A. The milk lipid globular membrane. In Handbook of Milk Composition (R.G. Jensen, ed.), pp. 5 44, Academic Press, Inc., San Diego. 

---