Sampling recommended storage

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. 

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). 

Statements on which regulatory guidelines, such as 21 CFR 58 for FDA GLP compliance, will be followed and on Animal Care Committee protocol review Information on the drug substance, which commonly includes the test article name or number, identification criteria, physical description, who is responsible for test article characterization, the concentration(s) to be used, recommended storage conditions, inventory maintenance, formulation procedures, reserve samples, retention samples, analyses for content and homogeneity (if necessary), disposition, and safety precautions Information on the animal species to be studied, animal husbandry procedures, such as housing, food, water, contaminants, environment conditions, acclimation, and justification of selection... 

A stability schedule is a series of stability test intervals at which time all or some of the stability tests will be run on a sample in the study. There is also a group of stability environments that are used to study the product. The combination of results obtained for the various test intervals and environmental conditions creates a stability profile. Data from this profile are used to define the recommended storage conditions for the product and the expiration date that can be supported by the data. A typical ICH stability schedule is found in Table 3. 

Recommended storage condition Proposed retest period Special precautions Sampling plan/frequency Commercial stability protocol... 

One laboratory reported results obtained after storing the reconstituted samples in the dark under a CO2 blanket for a few weeks. The Cr(VI) results were much lower while the Cr(III) results were much higher than the ones obtained directly after reconstitution and they did not agree with the rest of the laboratories. Clearly a reduction of Cr(VI) has occurred in the reconstituted sample during storage. It is therefore recommended to start the separation of the species as soon as possible after reconstitution. 

Blessing et al. [119] provide a useful review and discussion on potential limitations associated with CSIA of environmental samples, particularly with respect to contaminated site remediation. The authors provide specific recommendations in relation to groundwater sampling, sample preservation, storage, and sample preparation. Potential fractionation effects and considerations during data interpretation are also addressed. 

Even if the above-mentioned conservation methods are used, the storage period for water samples is limited. Table 1.2, derived from the current (2003 edition) international ISO standard [14], gives an overview of recommended sampling and storage bottles as well as conservation methods and maximum storage periods for different determinants in the sample. 

Recommended Storage Containers for Water Samples, with Preservation Options and Maximum Recommended Periods for Storage Prior to Analysis. Consistent with Ref. [14]... 

Figure 1 FAST index in 9 non-hydrolyzed infant formidas and changes during storage. Solid bars starting formulas (n=7) hatched bars follow-on formulas (n-2) first bar sample taken immediately after purchase second bar sample taken at the end of recommended storage period FAST/ref fluorescence of advanced Maillard products/fiuorescence of soluble tryptophan...

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