Calibration of instruments for

These reference materials are also suitable for calibration of instruments for isotopic measurements, calibration and evaluation of isotopic measurement procedures, development of isotopic measurement methods, and nuclear material accountability measurements. Many of these IRMM materials are, in fact, concerned with the last of these applications, i.e. in the area of nuclear material accountability. Some of them have been examined by a nuclear experts committee and certified as EC-NRMs (European Community - Nuclear Reference Materials). 

Methods of measuring the components of photochemical smog are reviewed in Chapter 6. There have been significant advances in the calibration of instruments for monitoring ozone in ambient air. A method based on the absorption of ultraviolet radiation at 254 nm has been adopted by California for the calibration of air monitoring instruments. The method is based on the use of a commercially available instrument that measures ultraviolet absorption as a transfer standard in the calibration process. 

The applications of isokinetic sampling cover but are not limited to the sampling of aerosols such as flu gas in chimney, soots (unbumed carbons) from diesel engine exhaust, dusts suspended in the atmosphere, and fumes from various sprayers measurements of particulate mass fluxes in pneumatic transport pipelines and other particulate pipe flows solid fuel (also some liquid fuels) distributions in furnaces, engines, and other types of combustors and calibrations of instruments for the measurements of particle mass concentrations. Isokinetic sampling can also be applied to flows with liquid droplets. In this case, the droplet sample is usually collected by an immiscible liquid (Koo et al., 1992 Zhang and Ishii, 1995). 

Saturated aqueous solutions of inorganic salts are convenient secondary standards for calibration of instruments for measurement of relative humidity. The International Union of Pure and Applied Chemistry has recommended salt solutions for calibrations in the range of 10% to 90% relative humidity, and the American Society for Testing and Materials has published similar standards. The data in this table are taken from the lUPAC recommendations, except for K CO and K SO, which are ASTM recommendations. 

Niizawa, A. Yamaguchi, M. Standard dye solutions for calibration of instruments for measurement of ASTM color of petroleum products. Ger. Offen. DE 4310597, 1993 Chem. Abstr. 1994, 120, 34368. 

Requirements for standards used In macro- and microspectrofluorometry differ, depending on whether they are used for Instrument calibration, standardization, or assessment of method accuracy. Specific examples are given of standards for quantum yield, number of quanta, and decay time, and for calibration of Instrument parameters. Including wavelength, spectral responslvlty (determining correction factors for luminescence spectra), stability, and linearity. Differences In requirements for macro- and micro-standards are considered, and specific materials used for each are compared. Pure compounds and matrix-matched standards are listed for standardization and assessment of method accuracy, and existing Standard Reference Materials are discussed. 

Enzyme Reference Serums. Several companies sell lyophilized or stabilized reference serums for the calibration of instruments and for quality control. The label values given for the enzymatic activity of these serums should never be taken at face value, as at times they may be quite erroneous (19,33). Also, these values should only be used for the assay with which they were standardized, as interconversion of activity from one method to another for the same enzyme may often lead to marked errors. For instance, it is not recommended that alkaline phosphatase expressed in Bodansky units be multiplied by a factor to convert it to the units of the Ring-Armstrong method, or any other method for that matter. 

BCR Analytical Approach for the Certification of PAHs in Natural Matrix CRMs Prior to the certification analyses for the CRM, each participating laboratory has to prepare standard solutions of the analytes to be determined from certified reference compounds (purity >99.0 %) to calibrate their instruments for response and response linearity (multiple point calibration), detection limit, and reproducibility. In the case of PAH measurements, reference compounds of certified purity are used as internal standards, which are not present at a detectable concentration in the matrix to be analyzed (e.g. indeno[i,2,3-cd]fluoranthene (CRM 267), 5-methylchrysene (CRM 081R), benzo[f ]chry-sene (CRM 046), picene (CRM 168), and/or phenanthrene-dio). 

Errors in density result from errors in temperature measurement or control calibration of instruments transfer, handling and weighing of samples and impurities in the samples. At temperatures well below the critical temperature and near room temperature, standard techniques easily achieve accuracies of +0.05%. For the compounds in this compilation, that level corresponds to about +0.4 kg m"3. Under these conditions, errors in temperature are not very significant. This level of accuracy only requires... 

Cindy Wiebeck of the Nebraska State Agriculture Laboratory aspirates calcium standards into the atomic absorption flame in order to calibrate the instrument for the analysis of fertilizer for calcium. In the background, note the hollow cathode lamps held in a rotating turret in the instrument. 

For the most reliable results, chamber environment should be monitored continuously with instruments and techniques equivalent to those used in ambient-air monitoring networks (see Chapter 6). Calibration of instruments should follow recommendations by appropriate agencies and be checked by cross comparisons with those in other analytic laboratories. 

The reference standards used for calibration of instruments should be checked for accuracy annually by an authorized measuring institution (e.g.. Office of Weights and Measures or Bureau of Standards). The reference standard employed should have an uncertainty of measurement which is 1/10 to 1/5 the uncertainty required in the measurement equipment. 

In the United States GMP regulations [7] issues related to laboratory controls are covered in Subpart I, which consists of regulations 211.160,211.165,211.166,211.167, 211.170, 211.173, and 211.176. The contents of Subpart I is presented in Table 24. Regulation 211.160 states the requirements for the establishment of laboratory controls such as specifications, standards, sampling plans, and test procedures. Furthermore, it covers the requirements stated for the calibration of instruments, apparatus, gauges, and recording devices. Regulation 211.165 states the require-... 

The calibration of instruments, apparatus, gauges, and recording devices at suitable intervals in accordance with an established written program containing specific directions, schedules, limits for accuracy and precision, and provisions for remedial action in the event accuracy and/or precision limits are not met. Instruments, apparatus, gauges, and recording devices not meeting established specifications shall not be used. 

In addition to inspection and calibration of instrumentation carried out as part of an SAT, the need for recalibration of critical instruments prior to IQ, OQ, and PQ should be reviewed and the decision documented in the respective qualification report. All site calibration activity should be conducted in accordance with quality standards and the respective engineering procedures. Any remedial work should be undertaken under document control, and where necessary, evaluated under change control. 

Coal analysis has, by convention, involved the use of wet analysis or the use of typical laboratory bench-scale apparatus. This trend continues and may continue for another decade or two. But the introduction of microprocessors and microcomputers in recent years has led to the development of a new generation of instruments for coal analysis as well as the necessary calibration of such instruments (ASTM D-5373). In particular, automated instrumentation has been introduced that can determine moisture, ash, volatile matter, carbon, hydrogen, nitrogen, sulfur, oxygen, and ash fusion temperatures in a fraction of the time required to complete most standard laboratory bench procedures. 

The calibration of instruments used for organic compound analyses is a particularly lengthy procedure due to the large number of target analytes that are analyzed simultaneously. For example, laboratories analyze a minimum of 55 chemicals in EPA Method 8260 and a minimum of 75 chemicals in EPA Method 8270. (These numbers may be as high as 100 for either method). Even with the help of modern computers, a calibration procedure of this enormous scope may easily take 6-8 hours or even longer in some circumstances. Fortunately for the laboratories, once... 

RMs Considering the limitations of available primary methods, emphasis is placed by the CCQM on the elaboration of synthetic RMs derived from pure materials. These would then be used for calibration of instruments and hence, could help in the metrological step of analytical procedures. As appears from the cited examples, such RMs are hardly suitable as reference samples in many applications of analytical chemistry. 

Multi-component hydrocarbon standards to provide accurate calibration of instruments (generally gas chromatographs) used to monitor the concentrations of a wide range of volatile organic hydrocarbon compounds (VOCs) in ambient air. These standards currently contain 30 different hydrocarbon species that are important to photochemical ozone formation, with concentrations ranging down to a few parts per billion by molar value. They are disseminated widely in the United Kingdom and the rest of Europe as calibration standards, and as test mixtures for assessment of the quality of international ambient hydrocarbon measurements (often under the auspices of the European Commission - EC). 

In their regular day to day practice, field laboratories use commercial reagents or prepare in-house solutions for the calibration of instruments, and they rely on purity assessment of producers. For method validation and even measurement uncertainty, field labs regularly participate in proficiency testing schemes. In such inter-laboratory comparisons, the reference value is usually obtained as the arithmetic mean of results of participants. 

Procedures—An underutilized practice in validation is the SOP, whereby repetitive activities can be defined. The use of SOPs increases reproducibility of execution and allows for further brevity in both protocols and reports. Procedures make everyone who is involved with the project substantially more efficient, and should be employed wherever possible. Practices such as calibration of instrumentation, biological indicator placement, sampling of validation batches, and microbial testing are clear candidates for inclusion in SOPs. Among the more innovative uses is the inclusion of standardized validation acceptance criteria for similar products. 

Note Species name, phylum or division, common name, and concentration of total MAAs ([MAA], in nmol mg-1 protein) are indicated. Notes describe whether samples are from a whole organism or specific tissues, and value indicates if data are from a single measurement, a maximum value from several samples (max), or a maximum mean value (mean) reported. See text Section II.A.6 for an explanation of how rankings were determined. The comparison of values from different research laboratories may be somewhat problematic as there are currently no commercial standards available for MAAs and calibration of instruments is achieved by a variety of means. 

Step 5. Calibrate the instrument for mass response by feeding a multielement standard solution into the system. This is necessary to calibrate the mass response of the detector and introduction system (magnetic sector or quadrupole) to insure that the appropriate mass-window reading is being recorded. Record data in Data Table 19.1 and examine especially the region for masses 234, 235, and 238. 

Step 8. Calibrate the instrument for analyte concentration response with uranium standards. If the response is near linear over the range of interest, use at least four uranium standard concentrations per sample concentration range, with one each at the upper and lower extreme. Repeat for the two other uranium isotopes in their own concentration ranges. Record the concentration calibration data in Data Table 19.2. Plot and examine calibration curves to assure their linearity. 

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