Analytical method field test results

Repeatability is defined as precision under conditions where independent test results are obtained with the same method on identical test material in the same laboratory by the same operator using the same equipment within short intervals of time. The replicate analytical portion for testing can be prepared from a common field sample containing incurred residues. This approach is used extremely rarely. Normally, repeatability is estimated by the relative standard deviation ofrecoveries, which should be lower than 20% per commodity and fortification levels according to SANCO/825/00. In justified cases, higher variability can be accepted. 

For petroleum and petroleum product releases in a nonsensitive area (if there is such an area), the analytical methods preferred to determine the concentration of total petroleum hydrocarbons in environmental media is the standard EPA test method (EPA 418.1). For initial delineation of the area, test field kits may be used in nonsensitive areas, provided that the results are comparable to laboratory data. Final confirmatory sampling and analyses should be carried out using laboratory analyses. 

Field tests are analytical tests that are normally carried out outside the laboratory (in the field ). Field tests for explosives are usually performed when a rapid, on-site diagnostic detection of explosive materials is required. Thus, they are often carried out on suspects hands and belongings, in post-explosion sites, or in border stations, seaports, and airports. It should be emphasized that they constitute only prehminary examinations, and positive results should not be presented to court unless confirmed by reliable laboratory methods. Because field tests are usually carried out by individuals with no scientific background, their application must be easy, involving simple equipment and methodology. 

It used to be true that material balance analytical results obtained in the field were of limited reliability, as field test methods had poorer detection limits and a lower degree of accuracy and reproducibility than those methods employed in laboratories. This is now not always the case, as more and more operators and field service personnel use colorimetric, spectrophotometric, or other sophisticated (yet easy to use) test apparatus. The fact is, however, that it is not always necessary to use particularly elaborate instrumentation for field use, and there is a risk that the equipment will perhaps be selected more for its marketing appeal to customers rather than for being the most appropriate for the circumstances. 

Prior to a field study, enough untreated control material should be provided to allow the lab to develop and validate adequate analytical methods. The control material should match the test samples as closely as possible to minimize the matrix variations which might affect the performance of the method. Development and validation of a method using a matrix which does not closely resemble the actual test matrix frequently results in a method which is not adequate for the actual study samples. The method revisions required in such a case represent a clear waste of... 

Eurolab is the European Federation of National Associations of Measurement, Testing, and Analytical Laboratories. The function of EUROLAB is to provide an interface between the testing community and other concerned parties, to accelerate development and harmonization of test methods, to promote mutual acceptance of test results, and to provide expertise in the field of testing, www.eurolab.org... 

The selection of analytical methods for determining soil properties may vary depending on several factors including the objectives of soil testing the speed at which the soil analysis must be done where the soil analysis will occur (i.e., in the field or laboratory) the native properties of the soil whether the soil can be disturbed the cost and speed of the analysis the accuracy and precision of the method any imposed requirements for standard testing and quality control procedures the availability of information to interpret the analytical results the... 

ABSTRACT The aim of this study was to test portable infrared spectroscopy for non-destructive analysis of ancient construction mortar. Mortar samples from the House of the Vestals, in Pompeii, Italy, were initially examined with traditional analytical techniques, including X-ray fluorescence, X-ray diffraction and thin section analysis. These techniques were used to establish mineralogical and chemical profiles of the samples and to verify the results of experimental field methods. Results showed the lime-based binder was composed of calcite, and the volcanic sand aggregate contained clinopyroxene, plagioclase, sanidine and olivine crystals. 

Another result of the requirements to distribute homogeneous test material is that some pretreatment steps usually performed on routine samples are not done on the interlaboratory sample. For example, in interlaboratory rounds for the determination of metals by inductively coupled plasma, the test material is often a solution of the metals in water. Often a method requires extraction of the metals by acid digestion of the field sample, a procedure that will have significant uncertainty in terms of recovery of analyte. 

If there is any doubt about whether 100% of the analyte is presented to the measuring system or that the response of the calibrated system leads to no bias, then the assumptions must be tested during method validation and appropriate actions taken. If a series of measurements of a CRM (not used for calibration) leads to the conclusion that there is significant bias in the observed measurement result, the result should be corrected, and the measurement uncertainty should include the uncertainty of the measurement of the bias. If the bias is considered insignificant, no correction need be made, but measuring the bias and concluding that it is zero adds uncertainty (perhaps the bias was not really zero but is less than the uncertainty of its measurement). One approach to measurement uncertainty is therefore to include CRMs in the batch to be used to correct for bias, and then the uncertainty of estimation of bias, which includes the uncertainty of the quantity value of the CRM, is combined with the within-laboratory reproducibility. In some fields of analysis it is held that routine measurement and correction for bias... 

Below, sample preparation methods of various types of samples will be briefly discussed. The description is based on sample matrices and is not intended to be comprehensive. Sample preparation techniques originally developed for a specific sample type may, however, also be successfully used for another sample matrix. As a result of international round-robin exercises in the field of verification analysis, a number of recommended operating procedures (ROPs) has been published and tested (34). Further testing of these procedures has taken place since 1995 during proficiency testing under the auspices of the Technical Secretariat of the OPCW. These procedures were developed for the analysis of samples with unknown analytes, in order to allow the identification of as many different chemicals of CWC interest as possible. This approach implies that these procedures can be further optimized in cases... 

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