Sampling/sample handling

Cali JP, and Reed WP (1976) The role of the National Bureau of Standards standard reference materials in accurate trace analysis. In Lafleur PD, ed. Accuracy in Trace Analysis Sampling, Sample Handling, and Analysis, NBS Special Publication 422, Vol i pp 41-63. National Bureau of Standards, Washington, DC. 

The four main phases involved in a field soil dissipation study are (I) planning and design phase, (II) field-conduct phase, (III) sample processing/analysis phase, and (IV) data handling/reporting phase. Each phase is vitally linked to the next and each is critical to study success. Results from an otherwise perfectly executed study may be made useless by uneven test substance application or improper sampling, sample handling, and/or analytical techniques. Each of these phases is discussed below. 

Patterson CC, Settle M (1976) The reduction of orders of magnitude errors in lead analysis. In LaFleur PD (ed) Accuracy in trace analysis sampling, sample handling, analysis. NBS Special Publication 422, p. 321... 

Methods and procedures, including sampling, sample handling, analysis and the estimated uncertainty of the final result, must be appropriate for the work carried out. All of the methods used, standard and non-standard, must be fully validated and documented. The extent of validation has to be considered on a case-by-case basis. The integrity of all analytical data must be protected at all times so that raw data can be inspected at a later date if required. 

Call, J. Paul and Reed, William P. "The Role of the National Bureau of Standards Standard Reference Materials in Accurate Trace Analysis." pp41-63 in. Accuracy in Trace Analysis Sampling. Sample Handling. Analysis., Proceedings of the 7th Materials Research Symposium NBS Special Publ. 422, yol. 1 2 Ed. by Philip D, LaFleur., U.S. Department of Commerce, National Bureau of Standards August, 1976. 

Sampling, Sample Handling and Storage of Medical Samples... 

The RPD calculated for pairs of identical environmental samples (field duplicates) is the measure of total sampling and analysis precision, which combines the precision of sampling, sample handling, and the precision of sample preparation and analysis. Precision of field duplicates may be significantly affected by matrix interferences and by inherent sample variability. That is why the SAP should make a distinction between analytical precision determined from LCS/LCSD pairs and total sampling and analysis precision determined from field duplicate pairs and adopt separate acceptance criteria for each. 

The chemist interprets the results of trip and equipment blank analyses to identify sample management errors during sampling, sample handling, and decontamination procedures and to determine whether these errors may have affected the collected sample representativeness. The chemist qualifies the data according to the severity of the identified variances from the SAP specifications and may even reject some data points as unusable. Example 5.8 shows a logical approach to the interpretation of the trip and equipment blank data. 

The analytical process consists of a series of steps sampling, sample handling, laboratory sample preparation, separation and quantitation, and statistical evaluation. Each one of these steps is important if accurate results are to be obtained, but the key component of the analytical process is sample preparation. It is important to bear in mind that these analytical steps are consecutive the next step cannot begin until the preceding one has been completed. If any one of these steps is not carried out properly, the overall performance of the procedure will be poor, errors will be introduced, and inconsistency in the results can be expected. 

The practice in many industrial analytical service laboratories is to present the analytical chemist with samples and some form of written request for analysis. Often discrepancies occur between expected values and those obtained by analysis and the blame for this is often placed on the analytical chemist. In many cases little or no thought is given to the sampling or handling of the material prior to submission for analysis. The analytical chemist is well advised to enquire into the history of samples and where possible to maintain some form of control over sampling, sample handling and storage. 

Study of the recent publication by the National Bureau of Standards on sampling, sample handling, and analysis (24) suggests that the best method of handling the oil and water is to filter, bubble with N2, and not acidify. Storage in acid-washed, conventional polyethylene bottles in a freezer is recommended. 

Murphy, T. E. in "Accuracy in Trace Analysis Sampling, Sample Handling, Analysis" (NBS Spec. Pub. 422) LaFleur, P. D., Ed U. S. Government Printing Office, Washington, 1976, p. 509. 

There are numerous biosensors described in the literature. However, only a relatively small number of them have been tested under realistic conditions. To apply a biosensor in an analytical system involves integration of biosensor technology with sampling, sample handling, and data processing. The lack of this integration may to a large extent explain the so far limited success that biosensors have had on the market. 

The above outlined measurements of the solution property change to determine the induction period may be complemented by the count of the number of nuclei formed within unit solution volume to assess nucleation rates. The simplest but somewhat tedious method of nuclei count is that via a hematocytometer (Burker cell) (Nielsen and Sohnel 1971). Sampling, sample handling, and sample quenching are critical in order to obtain a reliable count. A particle counter with a well-defined optical volume (sensing zone) can also be used. A less accurate procedure is based on determination of the number of nuclei from the mean size of a known mass of precipitate. In such experiments, size can be determined either from optical or electron photomicrographs or measured by an appropriate partiele sizer. 

Anand, V.D. and Ducharme, D.M. (1976). Stability of chromium ions at low concentrations in aqueous and biological matrices stored in glass, polyethylene, and polycarbonate containers. Natl. Bur. Standards Spec. Publ. 422. Accuracy in trace analysis Sampling, sample handling and analysis, pp. 611-619. 

Staff usually the chain of custody for a sample starts with the receipt of the sample in the laboratory. Once the laboratory acquires the sample, however, it is the laboratory s responsibility to have a system for unique identification of each sample, sample handling, storage and retention procedures, as well as safe disposal procedures. Identification of the population from which the sample is to be obtained, selection and withdrawal of valid gross samples of this population, and reduction of each gross sample to a laboratory sample suitable for the analytical technique to be used are some of the key steps to be considered in obtaining a representative sample for analysis [2]. Equally important is documented chain of custody procedures to authenticate and maintain the sample integrity. Several ASTM standards deal with sampling aspects for the analysis of petroleum products and lubricants ... 

A broad range of technical requirements is important in a laboratory quality system. These include aspects such as the selection of appropriately qualified and experienced personnel sampling, sample handling and preparation laboratory accommodation and environmental conditions equipment and reagents calibration reference standards and reference materials traceability (of standards and of samples) the selection or development, validation, and control of methods estimation of the uncertainty of measurements reporting of results and quality control and proficiency testing. 

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