1、 Reference number ISO 16107:2007(E) ISO 2007INTERNATIONAL STANDARD ISO 16107 Second edition 2007-10-15 Workplace atmospheres Protocol for evaluating the performance of diffusive samplers Air des lieux de travail Protocole pour lvaluation de la performance des dispositifs de prlvement par diffusion I
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6、e address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2007 All rights reservedISO 16107:2007(E) ISO 2007 All righ
7、ts reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 2 4 Symbols and abbreviated terms . 2 5 Summary of test protocol 3 5.1 Factors affecting performance 3 5.2 “Accuracy” as providing a single performance value linking to measuremen
8、t uncertainty 4 5.3 Bias, intersampler variability and the effects of environmental uncertainty 4 5.4 Reverse diffusion 5 5.5 Capacity Control of effects from interfering compounds 6 5.6 Capacity overload detection 6 5.7 Desorption efficiency . 7 5.8 Atmospheric pressure 7 5.9 Wind direction . 7 5.1
9、0 Simplifications 7 6 Apparatus 7 6.1 Exposure chamber specifications 7 6.2 Controlled environmental conditions. 8 6.3 Inter-run variability . 8 7 Reagents and materials . 9 8 Procedure 9 9 Sampler performance classification. 9 10 Accuracy 10 10.1 General. 10 10.2 Accuracy range confidence limit 10
10、10.3 Expanded uncertainty 11 11 Test report . 11 Annex A (informative) Worked example Program for diffusive sampler accuracy range calculation . 13 Annex B (informative) Calculation of variances 15 Bibliography . 16 ISO 16107:2007(E) iv ISO 2007 All rights reservedForeword ISO (the International Org
11、anization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been establi
12、shed has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardizatio
13、n. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
14、Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such pat
15、ent rights. ISO 16107 was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 2, Workplace atmospheres. This second edition cancels and replaces the first edition (ISO 16107:1999), which has been technically revised. ISO 16107:2007(E) ISO 2007 All rights reserved v Introduction
16、Gas or vapor sampling is often accomplished by actively pumping air through a collection medium such as activated charcoal. Problems associated with a pump, such as inconvenience, inaccuracy and expense, are inextricable from this type of sampling. The alternative covered by this International Stand
17、ard is to use diffusion for moving the compound of interest onto the collection medium. This approach to sampling is attractive because of the convenience of use and low total monitoring cost. However, previous studies have found significant problems with the accuracy of some samplers. Therefore, al
18、though diffusive samplers may provide a plethora of data, inaccuracies and misuse of diffusive samplers may yet affect research studies. Furthermore, worker protection may be based on faulty assumptions. The aim of this International Standard is to counter the uncertainties in diffusive sampling thr
19、ough achieving a broadly accepted set of performance tests and acceptance criteria for proving the efficacy of any given diffusive sampler intended for use. This International Standard is intended specifically for the large-scale evaluation of many diffusive sampler/analyte pairs of practical applic
20、ation and is complementary to EN 838. An affordable, experimental evaluation determines a single performance value indicating how a sampler performs in a typical situation. A sampler can thereby be quickly judged as to acceptability. Additionally, sufficient data are obtained to predict performance
21、in many atypical situations. For example, although sampling may normally be done at room temperature, a particular need may call for use in extreme cold. In such a case, the single performance value would be superseded by the particular needs. INTERNATIONAL STANDARD ISO 16107:2007(E) ISO 2007 All ri
22、ghts reserved 1 Workplace atmospheres Protocol for evaluating the performance of diffusive samplers 1 Scope This International Standard specifies methods for evaluation of sampler performance in terms of workplace conditions: wind speed, humidity, temperature, atmospheric pressure, and analyte varia
23、tion. The concise set of experiments specified aims to minimize cost to the user. The evaluation is limited to conditions commonly encountered in personal sampling in the indoor workplace setting, namely wind speeds of up to 0,5 m/s and for sampling periods typically from 2 h to 8 h. Static or area
24、sampling, unlike personal sampling where movement of the subject is significant, may sometimes be subject to sampling-rate reduction due to stagnation at very low wind speeds. This International Standard therefore does not apply to wind speeds of less than 0,1 m/s relative to static samplers. Sample
25、rs are also tested for compliance with the manufacturers stated limits on capacity, possibly in the presence of interfering compounds. Given a suitable exposure chamber, the sampler evaluation protocol can be extended to cover sampler use for other sampling periods and conditions. This International
26、 Standard indicates how to measure diffusive sampler uncertainty for characterizing concentration estimates obtained subsequent to the evaluation. It is impractical continually to re-evaluate diffusive sampler performance under various environmental conditions prevailing during application. NOTE 1 I
27、n this International Standard, the confidence level for the initial method evaluation becomes an integral part of the measurement uncertainty. This approach slightly broadens the statistical protocols given in ISO Guide 98:1995. Furthermore, the possibility of sampler errors related to correctible s
28、ampler bias is addressed. NOTE 2 This International Standard is an extension of previous research on diffusive samplers (References 1 to 17 inclusive and EN 838). 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, o
29、nly the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 838, Workplace atmospheres Diffusive samplers for the determination of gases and vapours Requirements and test methods ISO Guide 98:1995, Guide to the expressio
30、n of uncertainty in measurement. BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OIML ISO 16107:2007(E) 2 ISO 2007 All rights reserved3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 838 and ISO Guide 98:1995 and the following apply. 3.1 symmetric accuracy range A
31、 fractional range about the measurand concentration, c, within which 95 % of sampler measurements are found NOTE See References 18 to 21 inclusive. If the modulus of the bias is small, i.e. R/1,645, the symmetric accuracy range, A, can be shown to be closely approximated (Reference 21) by Equation (
32、1): 221,960 AR =+ (1) where is the bias, expressed relative to true concentrations; R is the overall true relative standard deviation, expressed relative to true concentrations. Otherwise | | 1,645 AR =+ (2) If the bias is corrected, the expected value of 2in Equation (1) becomes equal to the varian
33、ce of the bias correction, reflecting an uncorrectable residual bias due to uncertainty in the correction. Then if the bias uncertainty is under control, the low bias modulus model of Equation (1) indicates the proportionality of A to the root mean squared combined uncertainty components. 4 Symbols
34、and abbreviated terms A symmetric accuracy range (3.1) in terms of bias and precision A estestimated symmetric accuracy range, A A 95 %95 % confidence level on the symmetric accuracy range, A c true or reference analyte concentration, in milligrams per cubic metre, or parts per million as a ratio of
35、 analyte to air molecules, per instructions of the sampler manufacturer c estmean of (four) concentration estimates (including pressure and temperature corrections), in milligrams per cubic metre or parts per million as a ratio of analyte to air molecules, per instructions of the sampler manufacture
36、r h humidity, partial pressure of water vapor, in kilopascals n number of diffusive samplers tested for measuring sampler capacity p (atmospheric) pressure R overall true relative standard deviation of concentration estimates (dependent on assumed environmental variability), expressed as a percentag
37、e relative to a “true” concentration as estimated by reference sampling ISO 16107:2007(E) ISO 2007 All rights reserved 3 R estestimated true relative standard deviation, expressed as a percentage R runtrue relative standard deviation characterizing inter-run chamber variability, expressed as a perce
38、ntage R sintersampler component of the true relative standard deviation, expressed as a percentage R s estestimated intersampler true relative standard deviation, R s , expressed as a percentage R tpulse-induced true relative standard deviation, expressed as a percentage R 95 %95 % confidence limit
39、on the true relative standard deviation, expressed as a percentage s estimated standard deviation characterizing intersampler variation t 0,95 ( ) value which, at the 95 % probability level, exceeds random variables distributed according to the Student t-distribution with degrees of freedom T temper
40、ature, in degrees Celsius u ambient wind speed, in metres per second xconcentration estimate dependence on environmental variable, x (T, h, u, or c) bias relative to concentration, c estestimated bias, tbias associated with concentration pulse 95 %95 % confidence limit on the bias, degrees of freedo
41、m in determining R s effeffective number of degrees of freedom in determining R cassumed concentration variability hassumed humidity variability Tassumed temperature variability uassumed ambient wind speed variability 5 Summary of test protocol 5.1 Factors affecting performance 5.1.1 Diffusive sampl
42、ing may first of all suffer from error in the sampling rate as stated by the manufacturer of the sampler. As diffusive samplers are usually used without recalibration, this error implies a bias or systematic error in all concentration estimates made. As the bias may be in one direction, such error c
43、annot be minimized by averaging several measurements. If the error is correctible it is not strictly part of the sampler uncertainty. ISO 16107:2007(E) 4 ISO 2007 All rights reserved5.1.2 Aside from bias, several sources of random error exist. Some of these errors are associated with the sampler its
44、elf. For example, the samplers dimensional tolerance may be low, leading to variation in the sampling rate, sampler to sampler. The sampler may become overloaded or may not follow concentration changes adequately. 5.1.3 Other errors relate to a non-constant environment which may affect the sampling
45、rate. Potentially significant environmental influence quantities include temperature, humidity, wind speed, and atmospheric pressure. To predict the effect of any such parameter, an experiment on the sampler type may be carried out. Moreover, the variation expected of the parameter requires estimati
46、on. So as to result in a single performance measure, typical ranges of these environmental parameters are specified in this International Standard. 5.2 “Accuracy” as providing a single performance value linking to measurement uncertainty 5.2.1 A sampler presented by a manufacturer for evaluation may
47、 be found to exhibit both imprecision and bias. In the language of ISO Guide 98:1995, imprecision and bias together relate to the “accuracy” of a sampler, rather than “uncertainty”. Accuracy refers to the closeness between measured values and measurand (in this case the concentration to be measured)
48、, whereas uncertainty refers to what is known about the measurand on the basis of the measurement. In other words, the manufacturer could recommend use of information about the bias for correction of the measured values. This International Standard provides means of judging a sampler as recommended
49、for use by a manufacturer. 5.2.2 A useful statistical measure exists which summarizes the overall effect of both random variation and bias. This function has come to be known as the symmetric accuracy range, A (3.1). 5.2.3 The definition directly implies that A increases with both random error and bias magnitude. Therefore A is one particular quantification of accuracy as defined in ISO Guide 98:1995. The greater the disparity between measured values and measurand, the larger the
