SIST EN 16339:2013
(Main)Ambient air - Method for the determination of the concentration of nitrogen dioxide by diffusive sampling
Ambient air - Method for the determination of the concentration of nitrogen dioxide by diffusive sampling
This European Standard specifies a method for the sampling and analysis of NO2 in ambient air using diffusive sampling followed by extraction and analysis by colorimetry or ion chromatography (IC). It can be used for the NO2 measurement in a concentration range of approximately 3 μg/m³ to 130 μg/m3. A sample is typically collected for a period of 1 to 4 weeks [13], with exposure periods depending on the design of the samplers and the concentration levels of NO2. Several sorbents can be used for trapping NO2 in ambient air using a diffusive sampler. This standard specifies the application of triethanolamine as the reagent. Nitrous acid and peroxyacetyl nitrate are the major chemical interferences of sorption by triethanolamine. However, in ambient air monitoring over long sampling times, both contaminants are generally present at low concentrations relative to NO2. Moreover, these species can also interfere with the measurement of NO2 when applying the EU reference method for NO2 monitoring based on chemiluminescence (see [2]). This standard describes the application of a tube-type sampler with either a cylindrical or a slightly conical tube. Its typical uptake rate is about 1 cm3/min. Only for this sampler type sufficient evidence of validation has been found in a literature survey [12]. The relative expanded uncertainty of NO2 measurements performed using these tube-type diffusive samplers can potentially be lower than 25 % for individual measurements. When aggregating results to form annual average values, the relative expanded uncertainty can be further reduced to levels below 15 % due to the reduction of random effects on uncertainty [6].
Luftqualitãt - Methode zur Bestimmung der Konzentration von Stickstoffdioxid mittels Passivsammler
Diese Europäische Norm legt ein Verfahren zur Probenahme von NO2 in Außenluft mit Passivsammlern sowie der anschließenden Extraktion und Analyse mittels Kolorimetrie oder Ionenchromatographie (IC) fest. Sie kann für die Messung von NO2 in einem Konzentrationsbereich von etwa 3 µg/m3 bis 130 µg/m3 angewendet werden. Eine Probe wird üblicherweise über einen Zeitraum von 1 Woche bis 4 Wochen genommen [13], wobei der Expositionszeitraum von der Ausführung des Sammlers und dem NO2-Konzentrationsniveau abhängt.
Zur Bindung des in der Luft enthaltenen NO2 mit einem Passivsammler können verschiedene Sorptionsmittel verwendet werden. In dieser Norm ist Triethanolamin als Sorbens festgelegt.
Salpetrige Säure und Peroxyacetylnitrat sind bei der Sorption durch Triethanolamin die wesentlichen chemischen Störkomponenten. Über längere Zeiträume gesehen liegen diese beiden Substanzen im Vergleich zu NO2 im Allgemeinen jedoch in niedrigen Konzentrationen vor. Zudem können sie auch die Messung von NO2 mit dem auf Chemilumineszenz basierenden EU Referenzverfahren stören (siehe [2]).
Die vorliegende Norm beschreibt die Anwendung eines Sammlers des Röhrchentyps mit entweder zylindrischem oder konischem Röhrchen. Die übliche Aufnahmerate beträgt etwa 1 cm3/min. Nur für diesen Sammlertyp wurden in der Literaturübersicht angemessene Validierungsdaten gefunden [12].
Die relative erweiterte Unsicherheit von NO2 Messungen, die mit Passivsammlern des Röhrchentyps durchgeführt werden, kann bei Einzelmessungen unter 25 % liegen. Werden die Ergebnisse zu Jahres-mittelwerten zusammengefasst, kann die relative erweiterte Unsicherheit aufgrund der Verringerung der zufälligen Einflüsse auf die Unsicherheit auf unter 15 % gesenkt werden [6].
Air ambiant - Méthode pour la détermination de la concentration du dioxyde d’azote au moyen d’échantillonneurs par diffusion
La présente Norme européenne spécifie une méthode pour l'échantillonnage et l'analyse du NO2 dans l'air ambiant à l'aide d'échantillonneurs par diffusion, suivis de l'extraction et de l'analyse par colorimétrie ou chromatographie ionique (CI). Elle peut être utilisée pour le mesurage de NO2 dans une gamme de concentration allant de 3 µg/m³ à 130 µg/m3 environ. Un échantillon est habituellement collecté sur une période de 1 à 4 semaines [13], les durées d'exposition dépendant de la conception des échantillonneurs et des niveaux de concentration en NO2.
Plusieurs sorbants peuvent être utilisés pour piéger le NO2 contenu dans l'air ambiant à l'aide d'un échantillonneur par diffusion. La présente norme spécifie l'utilisation de la triéthanolamine comme réactif.
L'acide nitreux et le nitrate de péroxyacétyle sont les principaux interférents chimiques en cas de sorption par la triéthanolamine. Toutefois, lors de la surveillance de l'air ambiant sur de longues durées d'échantillonnage, ces deux polluants sont généralement présents à de faibles concentrations par rapport à NO2. De plus, ces espèces peuvent aussi interférer avec le mesurage de NO2 en cas d'application de la méthode de référence européenne pour la surveillance du NO2 basée sur la chimiluminescence (voir [2]).
La présente norme décrit la mise en œuvre d'un échantillonneur en forme de tube comportant un tube cylindrique ou légèrement conique. Son débit d'échantillonnage caractéristique est de l'ordre de 1 cm3/min. Lors d'une recherche bibliographique [12], des preuves de validation suffisantes n'ont été trouvées que pour ce type d'échantillonneur.
L'incertitude élargie relative des mesurages de NO2 réalisés à l'aide de ces échantillonneurs par diffusion en forme de tube peut potentiellement être inférieure à 25 % pour les mesurages individuels. Lors de l'agrégation des résultats pour obtenir les valeurs moyennes annuelles, l'incertitude élargie relative peut être encore réduite à des niveaux inférieurs à 15 % en raison de la réduction des effets aléatoires sur l'incertitude [6].
Zunanji zrak - Metoda za določevanje koncentracije dušikovega dioksida z difuzijskim vzorčenjem
Ta evropski standard določa metodo za vzorčenje in analizo NO2 v zunanjem zraku z difuznim vzorčenjem, ki mu sledi ekstrakcija in analiza s kolorimetrijo ali ionsko kromatografijo (IC). Lahko se uporabi za meritve NO2 v koncentraciji približno od 3 do 130 μg/m3. Vzorec se običajno zbere za obdobje od 1 do 4 tednov [13], obdobje izpostavljenosti pa je odvisno od zasnove vzorčevalnika in nivojev koncentracije NO2. Z uporabo difuzijskega vzorčevalnika se za lovljenje NO2 v zunanjem zraku lahko uporablja več različnih sorbentov. Ta standard za reagent določa uporabo trietanolamina. Dušikova kislina in peroksiacetil nitrat sta dve glavni kemijski motnji pri sorpciji s trietanolaminom. Toda pri spremljanju zunanjega zraka skozi daljša obdobja vzorčenja se oba kontaminanta v primerjavi z NO2 načeloma pojavljata v nizkih koncentracijah. Prav tako lahko te kemijske vrste vplivajo na meritev NO2 pri uporabi referenčne metode EU za spremljanje NO2, ki temelji na kemiluminiscenci (glej [2]). Ta standard opisuje uporabo cevastega vzorčevalnika s cilindrično ali rahlo konično cevjo. Njegova stopnja absorpcije je približno 1 cm3/min. V poročilih o raziskavah je bilo najdenih dovolj dokazov za validacijo samo za to vrsto vzorčevalnika[12]. Relativna razširjena negotovost za NO2 pri uporabi teh cevastih vzorčevalnikov je pri posameznih meritvah morda lahko nižja od 25 %. Pri združevanju rezultatov in ustvarjanju povprečnih vrednosti se zaradi zmanjšanja naključnih učinkov na negotovost relativna razširjena negotovost lahko zmanjša pod 15 % [6].
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Luftqualitãt - Methode zur Bestimmung der Konzentration von Stickstoffdioxid mittels PassivsammlerAir ambiant - Méthode pour la détermination de la concentration du dioxyde d’azote au moyen d’échantillonneurs par diffusionAmbient air - Method for the determination of the concentration of nitrogen dioxide by diffusive sampling13.040.20Kakovost okoljskega zrakaAmbient atmospheresICS:Ta slovenski standard je istoveten z:EN 16339:2013SIST EN 16339:2013en,fr,de01-december-2013SIST EN 16339:2013SLOVENSKI
STANDARD
SIST EN 16339:2013
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16339
July 2013 ICS 13.040.20 English Version
Ambient air - Method for the determination of the concentration of nitrogen dioxide by diffusive sampling
Air ambiant - Méthode pour la détermination de la concentration du dioxyde d'azote au moyen d'échantillonneurs par diffusion
Außenluft - Bestimmung der Konzentration von Stickstoffdioxid mittels Passivsammler This European Standard was approved by CEN on 15 June 2013.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16339:2013: ESIST EN 16339:2013
EN 16339:2013 (E) 2 Contents Page Foreword .3 Introduction .4 1 Scope .5 2 Normative references .5 3 Terms and definitions .5 4 Principle of the method .7 5 Materials .8 6 Sampling . 12 7 Analytical procedure . 13 8 Calculation of the concentration of nitrogen dioxide . 16 9 Quality control/quality assurance . 17 10 Report . 18 11 Performance requirements and measurement uncertainty . 18 Annex A (normative)
Description of samplers . 21 Annex B (informative)
Other samplers . 26 Annex C (informative)
Estimation of the uptake rate of the samplers . 34 Annex D (informative)
Measurement uncertainty . 39 Bibliography . 47
SIST EN 16339:2013
EN 16339:2013 (E) 3 Foreword This document (EN 16339:2013) has been prepared by Technical Committee CEN/TC 264 “Air quality”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by January 2014, and conflicting national standards shall be withdrawn at the latest by January 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 16339:2013
EN 16339:2013 (E) 4
Introduction Experience gained across the European Union (EU) in implementing EU ambient air quality legislation [1] has shown that, generally, for nitrogen dioxide (NO2), meeting the annual average limit value of 40 µg/m3 is more problematic than meeting the 1-h limit value of 200 µg/m³ [2]. EU Directive 2008/50/EC [1] stipulates that European Union Member States shall apply the reference measurement methods and criteria specified in the Directive. For NO2 monitoring in ambient air, the reference method being that described in EN 14211:2012 [3]. However, a Member State may use any other method that provides results equivalent to that of the reference method, to be demonstrated in accordance with the Guide for the demonstration of equivalence of ambient air monitoring methods [4]. The GDE devotes specific paragraphs to methods based on diffusive sampling. For the measurement of longer-term average concentrations of nitrogen dioxide for comparison with the annual average limit value diffusive sampling is an attractive alternative to fixed monitoring using the reference methodology described in EN 14211 because of small size of diffusive samplers; no requirement for electric power; potential for covering areas with a high spatial density; cost effectiveness. Consequently, diffusive samplers can partially substitute and supplement fixed monitoring as an instrument for the assessment of air quality, provided that they fulfil the specific Data Quality Objectives given in [1]. At the time of publication of this standard, no full demonstration of equivalence according to [4] has been performed. However, some studies have compared NO2 annual average concentrations measured by chemiluminescence and by diffusive samplers [5], [6], [7] and [8]. These have shown the potential of diffusive sampling to meet the data quality objective of 15 % expanded uncertainty for fixed measurements [1]. The methodology described in this standard can be applied to obtain air quality information with a relatively high spatial density that can be used to complement the appropriate siting of fixed monitoring stations, or in the validation of dispersion models.
Further, the methodology described can be used for simultaneously measuring sulphur dioxide (SO2) when using ion chromatography as the method of analysis. The analytical method is described in [9], [10] and [11]. This standard has been prepared based on the findings of reviews of implemented diffusive samplers in the European Union [12]. The methodology described in this standard may also be used to determine NO2 in indoor air. Appropriate strategies for NO2 measurement in indoor air are described in EN ISO 16000-15. SIST EN 16339:2013
EN 16339:2013 (E) 5
1 Scope This European Standard specifies a method for the sampling and analysis of NO2 in ambient air using diffusive sampling followed by extraction and analysis by colorimetry or ion chromatography (IC). It can be used for the NO2 measurement in a concentration range of approximately 3 µg/m³ to 130 µg/m3. A sample is typically collected for a period of 1 to 4 weeks [13], with exposure periods depending on the design of the samplers and the concentration levels of NO2. Several sorbents can be used for trapping NO2 in ambient air using a diffusive sampler. This standard specifies the application of triethanolamine as the reagent. Nitrous acid and peroxyacetyl nitrate are the major chemical interferences of sorption by triethanolamine. However, in ambient air monitoring over long sampling times, both contaminants are generally present at low concentrations relative to NO2. Moreover, these species can also interfere with the measurement of NO2 when applying the EU reference method for NO2 monitoring based on chemiluminescence (see [2]). This standard describes the application of a tube-type sampler with either a cylindrical or a slightly conical tube. Its typical uptake rate is about 1 cm3/min. Only for this sampler type sufficient evidence of validation has been found in a literature survey [12]. The relative expanded uncertainty of NO2 measurements performed using these tube-type diffusive samplers can potentially be lower than 25 % for individual measurements. When aggregating results to form annual average values, the relative expanded uncertainty can be further reduced to levels below 15 % due to the reduction of random effects on uncertainty [6]. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025) 3 Terms and definitions For the purpose of this document, the following terms and definitions apply. 3.1 certified reference material reference material [3.8], characterized by a metrologically valid procedure for one or more specified properties, accompanied by a certificate that provides the value of the specified property, its associated uncertainty, and a statement of metrological traceability [SOURCE: ISO Guide 35:2006] 3.2 combined standard uncertainty standard measurement uncertainty [3.10] that is obtained using the individual standard measurement uncertainties associated with the input quantities in a measurement model
[SOURCE: JGCM 200:2012]
3.3 desorption efficiency ratio of the mass of analyte desorbed from a sampling device to that applied
SIST EN 16339:2013
EN 16339:2013 (E) 6 [SOURCE: EN 13528-2:2002]
3.4 diffusive sampler
device which is capable of taking samples of gases or vapours from the atmosphere at a rate controlled by a physical process such as gaseous diffusion through a static air layer or a porous material and/or permeation through a membrane, but which does not involve the active movement of air through the device [SOURCE: EN 13528-1:2002] Note 1 to entry: Active normally refers to the pumped movement of air. 3.5 diffusive uptake rate rate at which the diffusive sampler collects a particular gas or vapour from the atmosphere. [SOURCE: EN 13528-1:2002] Note 1 to entry: The uptake rate is usually expressed in units of (pg/(nmol/mol)/min) or (cm3/min). Note 2 to entry: pg/(nmol/mol)/min is equivalent to ng/(µmol/mol)/min. 3.6 expanded (measurement) uncertainty product of a combined standard measurement uncertainty and a factor larger than the number one
[SOURCE: JCGM 200:2008]
Note 1 to entry:
The factor depends upon the type of probability distribution of the output quantity in a measurement model and on the selected coverage probability. Note 2 to entry:
The term “factor” in this definition refers to a coverage factor. 3.7
field blank sealed sampler drawn from the same batch as the samplers being used for NO2 monitoring. This sampler is taken unopened to the field and returned together with exposed samplers after the sampling is completed Note 1 to entry: This blank is only used for quality control purposes. Note 2 to entry: A transport blank is considered to be a special case of a field blank. A transport blank is taken to the exposure site, left unopened and returned to the laboratory immediately after placement or collection of the samplers. Transport blanks may be used when regular field blanks reveal an unacceptable level of nitrite to investigate the possibility of contamination of samplers during transport. 3.8 laboratory blank sealed sampler drawn from the same batch as the samplers being used for NO2 monitoring which is stored in a refrigerator during sampling of the exposed samplers. 3.9 repeatability condition condition of measurement, out of a set of conditions that includes the same measurement procedure, same operators, same measuring system, same operating conditions and same location, and replicate measurements on the same or similar objects over a short period of time
[SOURCE: JGCM 200:2012] SIST EN 16339:2013
EN 16339:2013 (E) 7 3.10 standard (measurement) uncertainty measurement uncertainty expressed as a standard deviation
[SOURCE: JGCM 200:2012] 3.11 uncertainty (of measurement) non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used Note 1 to entry: For footnotes to the definition the reader is referred to the parent document JGCM 200:2012. [SOURCE: JGCM 200:2012] 4 Principle of the method The diffusive sampler is exposed to air for a measured time period. NO2 migrates through the sampler diffusion path and is collected as nitrite by reaction with triethanolamine (TEA). TEA is coated onto a suitable support. Supports that have been demonstrated to be suitable in practice are (see Annex A): a series (2 or 3) of circular stainless steel grids with a fine mesh size; a cylindrical stainless steel grid with a fine mesh size; a cellulose-fibre filter. A number of pathways have been proposed for the reaction of nitrogen dioxide with triethanolamine. More details can be found in [14]. The diffusive uptake rate is determined either by numerical calculation based on Fick’s first law of diffusion (see EN 13528-3) or through calibration by exposure to standard atmospheres, and/or by field comparison of diffusive samplers measurements with measurements carried out using the EU reference method (EN 14211). This latter approach has been described in [5], [6], [7] and [18]. Values of and equations to calculate diffusive uptake rates associated with different diffusive samplers are given in Annex C.
NOTE 1 The theory of performance of diffusive samplers is given in EN 13528-3 together with information on possible saturation of the sorbent, the effect of transients and the effect of face velocity. This standard explains the dependence of diffusion uptake rates on the concentration level of pollutants and sampling time. The nitrite formed in the sampler is subsequently extracted. The resulting extract is analyzed by: colorimetry after derivatization of the nitrite, using the Griess-Saltzman method [15]; ion chromatography [16]. The Griess-Saltzman derivatization consists of reacting nitrite with a mixture of sulphanilamide and N-(naphthyl-1) ethylenediamine dihydrochloride in dilute orthophosphoric acid (see Table 1). The absorbance of the azo dye formed is measured at approximately 540 nm. NOTE 2 In practice, when applying colorimetry, the derivatization agent solution is directly used for desorption. NOTE 3 When using ion chromatography, sulphur dioxide can be determined simultaneously [9], [10] and [11]. The analytical system is calibrated by means of solutions of nitrite in water with accurately known concentrations. SIST EN 16339:2013
EN 16339:2013 (E) 8 NOTE 4
An example of commercially available European sampler based on a sorption media not containing triethanolamine is given in the informative Annex B.2 (badge-type A with typical uptake rate of about 12 cm³/min). 5 Materials 5.1 Sampling 5.1.1 Diffusive samplers 5.1.1.1 Description Descriptions of the tube-type sampler with cylindrical and with conical tube are given in Annex A. The descriptions hold for sampler designs that have a proven practical validity.
NOTE 1 A radial-type sampler, with typical uptake rate about 70 cm3/min, exists and is widely used in the EU. Limited validation data are available for this sampler; it is therefore described in the informative Annex B.1.
NOTE 2
A badge-type NO2 diffusive sampler exists that is based on the application of triethanolamine. Limited validation data is available for this sampler. The sampler is described in the informative Annex B.3 (badge-type B with typical uptake rate of about 12 cm³/min). The sampler may include a turbulence barrier or a protective device (5.1.2) in order to avoid effects of turbulence inside the diffusion path during sampling. When a turbulence barrier or a protective device is considered an integral part of the sampler, the performance of the sampler shall be validated including the turbulence barrier or protective device. 5.1.1.2 Preparation The preparation of the sampler consists of the coating of a support with triethanolamine from a solution in water, methanol or acetone. To this solution a wetting agent may be added to facilitate the coating. In principle, one of the procedures specified in Annex A shall be used for the coating. Preparation procedures are taken from references describing tube-type samplers with a cylindrical tube. Three preparation methods are given in Annex A. These preparation methods have proven to be effective in practice. Other methods may be used provided that their suitability has been satisfactorily demonstrated. 5.1.1.3 Triethanolamine (TEA) Purity ≥ 99 %.
TEA has a melting point of approximately 20 °C depending on its purity. When using volumetric techniques for measuring quantities of TEA, the TEA should be handled at temperatures well above its melting point. Alternatively, gravimetry may be used. 5.1.1.4 Acetone For the preparation of TEA coating solutions. Purity ≥ 99,9 %. 5.1.1.5 Ultrapure water For the preparation of TEA coating solutions. Its conductivity shall be equal or less than 0,1 µS/cm.
SIST EN 16339:2013
EN 16339:2013 (E) 9 5.1.1.6 Wetting agent compound A wetting agent, for example BRIJ 35®1 [15, 16], may be used for the preparation of TEA coating solutions. The wetting agent shall not contain significant nitrite impurities. 5.1.1.7 Storage and shelf-life of samplers After preparation, samplers shall be sealed and stored under cool conditions, for example at temperatures between 0 °C and 4 ºC, in the dark, in order to minimize any undesired reactions. Samplers are stable for up to one year [16] when prepared according to the preparation method described in A.1.3. and stored under the above conditions. Tube-type samplers shall be stored in a position that minimizes the probability of the absorbing solution moving onto the tube walls, for example in a vertical position with the TEA at the bottom of the tube. When storing samplers for periods ≥ 3 months, subsets shall be analyzed periodically to check that blank development does not occur. 5.1.2 Protective device Consisting of a protective cover or box to be used, where appropriate, to prevent: the entrance of coarse particles or water droplets into the sampler during sampling; exposure to direct sunlight; exposure to high wind velocities. NOTE 1 EN 13528-3 gives general recommendations for the design of protective devices.
NOTE 2 In Annex A protective devices are described in for the tube-type samplers; in Annex B protective devices are described for the other samplers. Protective devices should be used consistently over time when measuring at a specific site for a prolonged period, or over space when performing monitoring campaigns, in order to ensure the internal consistency of sampler behaviour. 5.1.3 Support A device capable of positioning the sampler at an appropriate height and distance from obstacles to warrant undisturbed sampling. 5.1.4 Instructions for use The manufacturer shall make available a manual or instruction sheet for the handling of the samplers. These shall be followed in order to ensure proper operation of the sampler. 5.2 Analysis 5.2.1 General During the analysis, use only reagents of known purity appropriate to the application. Use only volumetric glassware, pipettes and syringes that are calibrated to ensure traceability of volume to primary standards. Volumetric glassware shall be cleaned with ultra pure water (see 5.2.2.1).
1 BRIJ 35® is an example of a suitable product available commercially. This information is given for the convenience of users of this European Standard and does not constitute an endorsement by CEN of this product. SIST EN 16339:2013
EN 16339:2013 (E) 10 5.2.2 Reagents 5.2.2.1 Ultra pure water To be used for the preparation of reagents, calibration solutions and chromatography eluents. Its conductivity shall be equal or less than 0,1 µS/cm.
5.2.2.2 Sodium nitrite To be used for the preparation of calibration standards and check solutions (see 7.2 and 9.1).
The sodium nitrite shall be of a minimum established purity of 99,5 %. The sodium nitrite shall be dried before preparation of the solution by placing a small quantity of sodium nitrite on a container (for example a Petri-dish) placed in an oven (5.2.3.4) at 102 °C ± 2 °C until completely dry. In practice, it is sufficient to wait for between 1 and 2 h. The small quantity of sodium nitrite shall be cooled at ambient temperature before weighing. It is necessary to cool in a dry atmosphere, for example using a desiccator (see 5.2.3.6). Special care shall be taken to avoid contamination during handling by using gloves and a glass container for weighing.
It is also possible to use commercially available certified standards (typically at the level of 1 g/l of nitrite) to eliminate the possibility of errors due to inaccurate standard preparation.
5.2.2.3 Orthophosphoric acid (PA) To be used for the preparation of colorimetric reagent. 85 % in water (density =1,70 g/cm3). Only use acid of high purity. NOTE Commercial trade qualifications of appropriate purity grades are “type AR grade”, “pro analysis grade” and “grade trace analysis”. 5.2.2.4 Sulphanilamide (SA)
To be used for the preparation of the colorimetric reagent. Purity ≥ 99 % (see Table 1). 5.2.2.5 Sulphanilic acid (SAc)
To be used for the preparation of the colorimetric reagent. Purity ≥ 99 % (see Table 1). 5.2.2.6 N-(naphthyl-1) ethylene diamine dihydrochloride (NEDD) To be used for the preparation of the colorimetric reagent. Purity ≥ 98 %. 5.2.2.7 Colorimetric reagent The compositions of the colorimetric reagent are given in Table 1. SIST EN 16339:2013
EN 16339:2013 (E) 11
Table 1 — Commonly used compositions of reagentsa Sampler type Reagent A Reagent B Reagent mixture Tube-type sampler with a cylindrical tube
Dissolve 10 g of SA in 300 ml of water. Add 25 ml of PA. Add water up to 500 ml Dissolve 70 mg NEDD in 300 ml water; add water up to 500 ml Equal volumes of reagents A and B Tube-type sampler with a slightly conical tube Dissolve 10 g of SAc and 25 ml of PA in 500 ml water. Add 500 ml of water and heat the solution to boiling Dissolve 72,8 mg NEDD in 100 ml water After cooling of solution A to room temperature, the two solutions are combined. The colour reagent is ready after 24 h a The compositions specified have been demonstrated to be fit for purpose in the validation studies of the two sampler types.
It is important to ensure that the pH of the solution being analysed remains below 2 [18, 19] when: the proportions of the reagent are modified;
the sample to be analyzed is diluted; dilutions shall be performed with the colorimetric reagent only. 5.2.2.8 Sodium carbonate Anhydrous, purity ≥ 99,8 %.To be used for the preparation of the eluent for ion chromatography.
5.2.2.9 Sodium bicarbonate Purity ≥ 99,0 %. To be used for the preparation of the eluent for ion chromatography.
5.2.2.10 Eluent for ion chromatography The composition of the eluent will depend on the ion chromatography column being used. Generally, the eluent is an aqueous solution of sodium carbonate and sodium bicarbonate.
5.2.3 Equipment 5.2.3.1 Colorimeter With wavelength settings in the range of 500 to 600 nm. The volumes of the cuvettes of the colorimeter shall be consistent with the volumes of mixed reagents used for derivatization (see Table 2). 5.2.3.2 Ion chromatograph With anion column and conductivity detector. Select a column that allows sufficient separation of chloride and nitrite. SIST EN 16339:2013
EN 16339:2013 (E) 12 5.2.3.3 Sample shaker For the extraction of nitrite from the sampling support. A vibrating tray or a vortex shaker have been found to be acceptable. 5.2.3.4 Oven For drying parts of diffusive samplers before assembling. Only use electric ovens and do not use gas ovens because flame combustion generates oxides of nitrogen. 5.2.3.5 Balance Laboratory balance with a resolution ≤ 0,1 mg. 5.2.3.6 Desiccator Airtight chamber made of glass containing a substance with a strong affinity for water such as calcium chloride or silica gel. 6 Sampling
6.1 Calibration of the diffusive uptake rate Information about the diffusive uptake rates and (potential) effects of concentration and environmental factors is provided in Annex C. This information will cover most practical conditions under which the samplers are used. When a sampler is to be used outside the range of concentration and environmental factors specified by the manufacturer, the diffusive uptake rate and its uncertainty shall be determined experimentally. This shall be done – where practicable – by a combination of laboratory and field experiments. Information about experimental approaches and evaluation of results can be found in [4]. 6.2 Siting criteria When measuring for the purpose of checking compliance with the requirements of EU Directive 2008/50/EC, the siting criteria of this Directive for fixed monitoring shall be met.
Information on siting criteria can also be found in [18]. Further information for determining appropriate monitoring sites for diffusive samplers can be found in [20] and [21]. 6.3 Protective measures
Samplers shall be transported to and from the sampling site in suitable plastic containers and/or sealable clean plastic bags in order to avoid contamination during transport.
During sampling the sampler shall be protected from influences of environmental conditions that can adversely affect its performance, for example by using a protective device (see 5.1.2).
When a protective device is used, it shall be suitable for the particular sampler used. A protective cover or box may be an integral part of the sampler, thereby affecting its uptake rate (see Annex A). 6.4 Exposure All handling of samplers shall be done in such a way that contamination of the sampler or re-usables such as caps is avoided. Follow the manufacturer’s instructions for specific sampling handling, for example, for opening and closing of samplers.
SIST EN 16339:2013
EN 16339:2013 (E) 13 Mount the sampler at the appropriate site, using the support (5.1.3), and fit the protective cover (5.1.2) if needed. The actual permissible period of sampling may vary with the sampler design, e.g., due to the presence of a membrane. Different designs of diffusive samplers have different diffusive uptake rates; the exposure time shall be such that the mass of nitrite is within the minimum and maximum capacity of the sampler specified by the manufacturer.
NOTE
A simple method for predicting the mass of nitrite in a sampler is to multiply the sampling time by the expected highest NO2 concentration and the nominal uptake rate. Prepare field blanks by using samplers identical to those used for sampling and subjecting them to the same handling procedure as the samples except that they will be kept unopened. The number of blanks shall be ≥ 10 % of the number of samplers exposed. When the number of samplers exposed simultaneously exceeds 30, it is sufficient to use 3 field blanks. After exposure, collect and close the samplers, and store these as described below. 6.5 Storage after sampling After sampling, samples shall be sealed and stored under cool conditions, for example at temperatures between 0 °C and 4 ºC, in the dark in order to minimize any undesired reactions.
Although samples may be stable
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