Samples certified

You purchased a Standard Reference Material (Box 3-1) coal sample certified by the National Institute of Standards and Technology to contain 3.19 wt% sulfur. You are testing a new analytical method to see whether it can reproduce the known value. The measured values are 3.29, 3.22, 3.30, and 3.23 wt% sulfur, giving a mean of 3r = 3.260 and a standard deviation of, v = 0.04,. Does your answer agree with the known answer To find out, compute the 95% confidence interval for your answer and see if that range includes the known answer. If the known answer is not within your 95% confidence interval, then the results do not agree. 

The data user may assess laboratory performance through analysis of singleblind and double-blind PE samples for project-specific analytes. Single-blind samples are clearly identified as PE samples, whereas double-blind samples are disguised as field samples. Certified blind PE samples may be obtained from several manufacturers in the USA. They are prepared as water and soil samples spiked with a variety of common contaminants. The manufacturer collects the interlaboratory recovery data for these samples and calculates acceptance criteria that are available to the PE sample purchaser. 

Sample Certified concentration Concentration Recovery, % Concentration Recovery, % Concentration Recovery, %... 

In order to demonstrate the application of the PSII sub-membrane fractions immobilized in PVA-SbQ for detection of metal pollutants in environmental samples, certified residential sewage sludge have been analyzed. Most of the sewjge sludge samples had the metal concenaations higher than the limits of detection obtained with the metals in solution (Table 4). 

Developments of quality assurance of the analytical speciation procedures and results are of prime importance at this point. Validation of new methodologies should be carried out if possible with certified reference materials (CRMs) (with a matrix as similar as possible to the real sample certified for the sought species). Unfortunately, very few CRMs are commercially available today for chemical speciation. Thus, alternative approaches for validation using complementary methods based on different mechanisms of separation and complementary detectors are now in order. 

Typical samples analyzed with CMCPEs and biosensors For practically oriented electroanalysts, it is useful to overview the spectrum of samples, certified specimens, and other materials that have already been analyzed some... 

Sample Certified value Mean Standard deviation... 

A standard sample provided by an external agency as part of certifying the quality of a laboratory s work. 

There are no estabHshed specifications for the standard reference samples used in general chemical analysis. Many such substances, however, are analyzed and certified by the National Institute of Standards and Technology (NIST), formerly the National Bureau of Standards (NBS). Specific reference standards are required for many of the analyses included in the USP and NE standards for dmgs. 

Colorants. According to U.S. regulations, colorants are divided into two classes certified and exempt (see Colorants for foods, drugs, COSMETICS, AND MEDICAL DEVICES). Batch samples of certified colors must be sent to the FDA for analysis and confirmation that the colorants comply with estabhshed specifications. Color manufacturers pay a small fee for each batch of color that is analy2ed. The number of certified colors available to food technologists has declined. Several of the historical colorants were found to have carcinogenic effects. Table 1 shows the certified colors that are permissible for food use in the United States as of 1993. 

It is known that the reliability of analytical information obtained depends particularly on the range of reference materials (RM) used. The most of RMs developed by the Institute of Geochemistry, SB RAS are included in the State Register of certified types of National Certified Reference Materials of Russian Federation. The reference materials are routinely analyzed for the stability and their life durations are timely prolonged. Developed RMs (27 samples) characterize mainly mineral substances. 

The X-ray determination of REE in geological samples is normally complicated by the relatively low concentrations of the REE, their complex X-ray spectra, the high concentration of matrix elements and the lack of reference standards with certified values for REE. A rapid and sensitive ion exchange and X-ray fluorescence procedure for the determination of trace quantities of rare earths is described. The REE in two U.S.G.S. standards, two inhouse synthetic mixtures and three new Japanese standards have been determined and corrections for inter-rare earth element interferences are made. 

Comparing results obtained by concerned decomposition techniques with the data certified (recommended), the two-stage microwave sample preparation procedure is preferable. 

The analysis was performed by SRXRF at the XRF beam-line of VEPP-3, Institute of Nuclear Physics, Novosibirsk, Russia. For the accuracy control the different types of the International Certified Reference Materials were used. There were obtained all metrological characteristics, namely precision, accuracy and lower limits of detections. This is the SRXRF method, that allow to analyze the sample mass of 0.5 mg directly without the destruction. The puncture from patient may be picked out more than once. 

Unit checkout Check that required mechanical work has been completed, tags and blinds pulled, and temporary piping disconnected. Plant supervision must certify completion of work. Cancel all entry and work permits. Utility system has been commissioned. Check blind list and inspect lines close bleed, drain and sample valves. 

NAA is a quantitative method. Quantification can be performed by comparison to standards or by computation from basic principles (parametric analysis). A certified reference material specifically for trace impurities in silicon is not currently available. Since neutron and y rays are penetrating radiations (free from absorption problems, such as those found in X-ray fluorescence), matrix matching between the sample and the comparator standard is not critical. Biological trace impurities standards (e.g., the National Institute of Standards and Technology Standard Rference Material, SRM 1572 Citrus Leaves) can be used as reference materials. For the parametric analysis many instrumental fiictors, such as the neutron flux density and the efficiency of the detector, must be well known. The activation equation can be used to determine concentrations ... 

Many of these are also available as BCS Certified Reference Materials (CRM) supplied by the Bureau of Analysed Samples Ltd, Newham Hall, Middles borough, UK, who also supply EURONORM Certified Reference Materials (ERCM), the composition of which is specified on the basis of results obtained by a number of laboratories within the EEC. BCS Reference Materials are obtainable from the Community Bureau of Reference, Brussels, Belgium. In the USA similar reference materials are supplied by the National Bureau of Standards. 

The EC type-examination is the process that the manufacturer may use to obtain independent verification that a design conforms to essential requirements, when a certified QA system has not been applied to the design process. The manufacturer must submit an application to the notified body, accompanied by documentation on the device design and physical samples of the device. The Notified Body examines the... 

EC verification provides an alternative to the model of establishing a certified production QA system. Independent testing of either all devices, or a statistically representative sample of each batch, is conducted by or on behalf of the Notified Body, which then issues a certificate of conformity for the tests conducted. This is not a popular option due to the costs involved. The procedure is not capable of providing adequate assurance as to the sterility of devices. Instead, an assurance of sterility must be based on the application of a production QA system to the sterilisation process. 

If the sample and standard have essentially the same matrices (e.g., air particulates or river sediments), one can go through the total measurement process with both the sample and the standard in order to (a) check the accuracy of the measurement process used (compare the concentration values obtained for the standard with the certified values) and (b) obtain some confidence about the accuracy of the concentration measurements on the unknown sample since both have gone through the same chemical measurement process (except sample collection). It is not recommended, however, that pure standards be used to standardize the total chemical measurement process for natural matrix type samples chemical concentrations in the natural matrices could be seriously misread, especially since the pure PAH probably would be totally extracted in a given solvent, whereas the PAH in the matrix material probably would not be. All the parameters and matrix effects. Including extraction efficiencies, are carefully checked in the certification process leading to SRM s. 

NIST s first four certified reference materials were steel samples, and these were followed by many others. The program supplied analytically well characterized homogeneous materials. This program included, from the beginning, homogeneity... 

The most important document, accompanying a CRM is its certificate. ISO Guide 31 (1981) provides guidance for the establishment of certificates, labeling of CRMs, and certification reports. The certificate contains among other information the certified values and their respective uncertainties. As important as this information is the traceability statement, which defines to what references the CRM is traceable. Ideally, a CRM is traceable to a suitable (combination) of SI units. This is not always possible, so other stated references may appear here. Especially when certifying matrix reference materials, making the measurements traceable to SI does not imply that the CRM is traceable to SI as well. The steps necessary to transform the sample into a state that can be measured may have a serious impact on the traceability of the values, and thus on the traceability statement. 

The number of samples of reference material needed is a commercial issue in the first place. An important variable is the number of samples likely to be sold during the lifetime ( shelf life ) of the reference material. As the lifetime is a function of the intrinsic stability of the material, this variable also affects the amount of raw material is needed. For instance, microbiological materials have limited intrinsic stability, and therefore their lifetime is expected to be shorter than for a dry sediment certified for trace elements. So, under the assumption of an equal number of sam-... 

Definition of the reference material, i.e. the matrix, the properties to be certified, and their desired levels Design of a sampling procedure Design of a sample preparation procedure... 

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