SIST EN 16693:2015
(Main)Water quality - Determination of organochlorine pesticides (OCP) in whole water samples using solid phase extraction (SPE) with SPE-disks combined with gas chromatography mass spectrometry (GC-MS)
Water quality - Determination of organochlorine pesticides (OCP) in whole water samples using solid phase extraction (SPE) with SPE-disks combined with gas chromatography mass spectrometry (GC-MS)
Development of a method for the quantitative determination of organochlorine pesticides in whole water samples using GC-MS.
This analytical method specifies the determination of OCPs meeting the following requirements:
- The analysis of whole water samples containing up to 0,5 g/l of suspended solids;
- The limit of quantification (LOQ) shall be equal or less than 30 % of the EQS;
- The measurement uncertainty shall be equal or less than 50 %;
- The methods shall be fully in-house validated and tested for ruggedness prior to interlaboratory validation;
- A European interlaboratory comparison study will be conducted according to ISO 5725.
Wasserbeschaffenheit - Bestimmung von Organochlorpestiziden (OCP) in Gesamtwasserproben mittels Festphasenextraktion (SPE) mit SPE-Scheiben in Verbindung mit Gaschromatographie-Massenspektrometrie (GC-MS)
Diese Europäische Norm legt ein Verfahren für die Bestimmung von ausgewählten Organochlor¬pestiziden (OCP, siehe Tabelle 1) in Wasserproben fest. Das Verfahren nutzt die Festphasenextraktion mit SPE Scheiben, gefolgt von Gaschromatographie-Massenspektroskopie (GC MS). Die Norm gilt für die Analyse von OCP in Oberflächenwasser, mit einem Schwebstoffanteil bis zu 500 mg/l (Gesamtwasserproben), Trinkwasser und Grundwasser. Der untere Grenzwert des Arbeitsbereiches hängt von der Matrix, der jeweils zu untersuchenden Verbindung und der Empfindlichkeit der Detektoreinheit des Massenspektrometers ab. Für die in Tabelle 1 angeführten Verbindungen beträgt die Bestimmungsgrenze mindestens 30 % des jeweiligen AA EQS-Werts (0,000 15 µg/l bis 0,1 µg/l) entsprechend den Anforderungen der Europäischen Richtlinie über Umweltqualitätsnormen im Bereich der Wasserpolitik (2008/105/EG).
Dieses Verfahren kann für die Analyse weiterer OCP, die nicht in Tabelle 1 angeführt sind, oder andere Arten von Wasser angewendet werden, dies muss jedoch vorher verifiziert werden.
Qualité de l'eau - Dosage des pesticides organochlorés (POC) dans la totalité de l'échantillon d'eau par extraction en phase solide (EPS) avec disques EPS, avec couplage chromatographie en phase gazeuse-spectrométrie de masse (CG-SM)
La présente Norme européenne spécifie une méthode pour le dosage d'une sélection de pesticides organochlorés (POC, voir Tableau 1) dans des échantillons d'eau. Cette méthode utilise une extraction en phase solide avec disques SPE suivie d'une chromatographie en phase gazeuse-spectrométrie de masse (CG-SM). Elle s'applique à l'analyse des POC dans les eaux de surface, lesquelles peuvent contenir jusqu'à 500 mg/l (totalité des échantillons d'eau) de matières en suspension (MES), dans l'eau potable et dans les eaux souterraines. La limite inférieure du domaine de travail dépend de la matrice, du composé à analyser et de la sensibilité du détecteur par spectrométrie de masse. Pour les composés répertoriés dans le Tableau 1, la limite de quantification (LQ) correspond à au moins 30 % de la valeur MA-NQE correspondante (0,00015 µg/l à 0,1 µg/l) conformément aux exigences de la Directive 2008/105/CE sur les NQE européenne pour les eaux de surface intérieures et autres eaux de surface.
Cette méthode peut être utilisée pour analyser d'autres POC non mentionnés dans le Tableau 1 ou d'autres types d'eau ; cependant, il est nécessaire de vérifier son applicabilité avant de l'employer.
Kakovost vode - Določevanje organoklornih pesticidov (OCP) v celotnem vzorcu vode z ekstrakcijo na trdni fazi (SPE) s SPE-diski v kombinaciji s plinsko kromatografijo/masno spektrometrijo (GC/MS)
Razvoj metode za kvantitativno določevanje organoklornih pesticidov v celotnih vzorcih vode z uporabo plinske kromatografije/masne spektrometrije (GC-MS).
Ta analitska metoda določa določevanje organoklornih pesticidov, ki izpolnjujejo naslednje zahteve:
– analiza celotnih vzorcev vode, ki vsebujejo do 0,5 g/l trdnih delcev;
– meja določljivosti (LOQ) mora biti enaka ali manjša od 30 % EQS;
– merilna negotovost mora biti enaka ali manjša od 50 %;
– pred medlaboratorijskim potrjevanjem morajo biti metode v celoti preverjene interno in testirane glede robustnosti;
– evropska medlaboratorijska študijska primerjava bo potekala v skladu s standardom ISO 5725.
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wasserbeschaffenheit - Bestimmung von Organochlorpestiziden (OCP) in Gesamtwasserproben mittels Festphasenextraktion (SPE) mit SPE-Scheiben in Verbindung mit Gaschromatographie-Massenspektrometrie (GC-MS)Qualité de l'eau - Dosage des pesticides organochlorés (POC) dans la totalité de l'échantillon d'eau par extraction en phase solide (EPS) avec disques EPS, avec couplage chromatographie en phase gazeuse-spectrométrie de masse (CG-SM)Water quality - Determination of organochlorine pesticides (OCP) in whole water samples using solid phase extraction (SPE) with SPE-disks combined with gas chromatography mass spectrometry (GC-MS)13.060.50VQRYLExamination of water for chemical substancesICS:Ta slovenski standard je istoveten z:EN 16693:2015SIST EN 16693:2015en,fr,de01-december-2015SIST EN 16693:2015SLOVENSKI
STANDARD
SIST EN 16693:2015
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16693
September
t r s w ICS
s uä r x rä w r English Version
Water quality æ Determination of organochlorine Qualité de l 5eau æ Dosage des pesticides organochlorés avec couplage chromatographie en phase gazeuseæ Wasserbeschaffenheit æ Bestimmung von SPEæDisks in Verbindung mit Gaschromatographie æ This European Standard was approved by CEN on
t y June
t r s wä
egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä
translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä
CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey andUnited Kingdomä
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels
9
t r s w CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN
s x x { uã t r s w ESIST EN 16693:2015
EN 16693:2015 (E) 2 Contents Page European foreword . 3 Introduction . 4 1 Scope . 5 2 Normative references . 7 3 Principle . 7 4 Interferences . 7 4.1 Interferences with sampling and extraction . 7 4.2 Interferences with GC-MS . 8 5 Reagents . 8 6 Apparatus . 9 7 Sampling . 10 8 Procedure. 10 8.1 Sample preparation and extraction . 10 8.2 Extraction by SPE-disks . 11 8.3 Solvent concentrating . 11 8.4 Gas chromatography . 12 8.5 Identification of individual compounds by means of GC-MS . 12 8.6 Blank value measurements . 12 9 Calibration . 13 9.1 General requirements . 13 9.2 Calibration of the GC-step . 14 9.3 Calibration of the total procedure using the internal standard . 14 9.4 Determination of procedural recovery values . 15 10 Calculation of the results . 16 11 Expression of results . 17 12 Test report . 17 Annex A (informative)
Suitable gas chromatographic conditions and example chromatograms — GC-conditions of example chromatograms in Figure A.1 . 18 Annex B (informative)
Repeatability and reproducibility data . 23 Annex C (informative)
Examples of suitable SPE-disks . 27 Annex D (informative)
Examples of internal standards . 28 Bibliography . 29
SIST EN 16693:2015
EN 16693:2015 (E) 3 European foreword This document (EN 16693:2015) has been prepared by Technical Committee CEN/TC 230 “Water analysis”, 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 March 2016, and conflicting national standards shall be withdrawn at the latest by March 2016. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. 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 16693:2015
EN 16693:2015 (E) 4 Introduction WARNING — Persons using this European Standard should be familiar with usual laboratory practice. This European Standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. IMPORTANT — It is absolutely essential that tests conducted according to this European Standard be carried out by suitably trained staff. Organochlorine pesticides (OCP) are priority substances listed in Annex X of the EU Water Framework Directive (WFD, Directive 2000/60/EC) for which environmental quality standards (EQS) have been set at EU level for inland waters as well as other surface waters to protect the aquatic environment against chemical pollution (Directive 2008/105/EC). With the exception of metals, the EQSs are expressed as total concentrations in the whole water sample. Furthermore, analytical methods used in WFD monitoring need to meet certain requirements as regards the minimum limit of quantification and the maximum tolerable measurement uncertainty (Directive 2009/90/EC). So far, there is no European-wide standardized method available for the determination of OCP in whole water samples fulfilling those requirements. Hence, the European Commission mandated CEN to develop or improve standards in support of the implementation of the monitoring requirements of WFD. Directive 2008/105/EC has been amended by Directive 2013/39/EU, however this standard has been developed for the analysis of OCP as listed in Annex A of Directive 2008/105/EC. The priority substances list in Annex X of the WFD includes various OCPs such as alachlor, endosulfan, hexachlorobenzene, hexachlorocyclohexane isomers, pentachlorobenzene, aldrin, dieldrin, endrin, isodrin, DDT and its metabolites. Annual average environmental quality standards (AA-EQS) values for individual OCP range from 0,000 5 µg/l to 0,3 µg/l and are defined for the concentration in the whole water sample, including suspended particulate matter (SPM) present in the sample. As long as compounds such as OCP, in particular the larger molecular weight ones, sorb strongly to environmental solids, the fraction bound to particles may be substantial. Therefore it is important to be able to handle whole water samples within the analytical process. Identification and quantification of OCP at trace level concentrations often require both high sensitive chromatographic equipment and effective enrichment steps. SIST EN 16693:2015
EN 16693:2015 (E) 5 1 Scope This European Standard specifies a method for the determination of selected organochlorine pesticides (OCP) (see Table 1), in water samples. The method uses solid-phase extraction with SPE-disks followed by gas chromatography-mass spectrometry (GC-MS). It is applicable to the analysis of OCPs in surface water containing suspended particulate matter (SPM) up to 500 mg/l (whole water samples), drinking water and groundwater. The lower limit of the working range depends on the matrix, on the specific compound to be analyzed and on the sensitivity of the mass spectrometric detection unit. For compounds listed in Table 1 the limit of determination (LOQ) is at least 30 % of the corresponding AA-EQS value (0,000 15 µg/l to 0,1 µg/l) according to the requirements of the European Quality Standards Directive (Directive 2008/105/EC) for both inland surface waters and other surface waters. This method may be used for the analysis of other OCPs not listed in Table 1 or other types of water. However, it is important to verify its applicability before use. SIST EN 16693:2015
EN 16693:2015 (E) 6 Table 1 — Organochlorine pesticides (OCP) determined by this method Substance Molecular formula Molar mass EC Number a CAS RN b
g/mol
Alachlor C14H20ClNO2 269,77 240–110–8 15972–60–8 Cyclodiene pesticides: Aldrin
Dieldrin Endrin
Isodrin
C12H8Cl6 C12H8Cl6O C12H8Cl6O C12H8Cl6
364,91 380,91 380,91 364,91
206–215–8 200–484–5 200–775–7 207–366–2
309–00–2 60–57–1 72–20–8 465–73–6 DDT-total: op´-DDT
pp´-DDT
pp´-DDD
pp´-DDE
C14H9Cl5 C14H9Cl5 C14H9Cl4 C14H9Cl4
354,49 354,49 320,04 318,03
212–332–5 200–024–3 200–783–0 200–784–6
789–02–6 50–29–3 72–54–8 72–55–9 Hexachlorobenzene (HCB) C6Cl6 284,80 204–273–9 118–74–1 Hexachlorobutadiene (HCBD) C4Cl6 260,76 201–765–5 87–68–3 Hexachlorocyclohexane c: alpha-HCH
beta-HCH
delta-HCH
gamma-HCH
C6H6Cl6
C6H6Cl6 C6H6Cl6 C6H6Cl6
290,83 290,83 290,83 290,83
206–270–8 206–271–3 206–272–9 200–401–2
319–84–6 319–85–7 319–86–8 58–89–9 Pentachlorobenzene C6HCl5 250,34 210–172–0 608–93–5 Trichlorobenzene c: 1,2,3-TCB
1,2,4-TCB
1,3,5-TCB
C6H3Cl3 C6H3Cl3 C6H3Cl3
181,45 181,45 181,45
201–757–1 204–428–0 203–608–6
87–61–6 120–82–1 108–70–3 Endosulfan c: Endosulfan-I (alpha)
Endosulfan-II (beta)
C9H6Cl6O3S C9H6Cl6O3S
406,93 406,93
– –
959–98–8 33213–65–9 a EC Number: European inventory of existing commercial substances (EINECS) or European list of notified chemical substances
(ELINCS). b CAS RN: Chemical Abstracts Service Registry Number. c Mixture of isomers. SIST EN 16693:2015
EN 16693:2015 (E) 7 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696) EN ISO 5667-3, Water quality - Sampling - Part 3: Preservation and handling of water samples (ISO 5667-3) 3 Principle Organochlorine pesticides present in the whole water sample are extracted by means of solid-phase extraction using solid-phase extraction disks (SPE-disks). Samples shall not be filtered. An internal standard mixture is added to the sample prior to extraction. Extraction by SPE-disks is a fully automatable procedure. It includes a combined extraction of both the analytes dissolved in the liquid phase of the sample and those adsorbed to the suspended particulate matter. The latter is extracted within the elution step of the procedure. The extract is concentrated by evaporation and the analytes are separated, identified and quantified by capillary gas chromatography with mass spectrometric detection (GC-MS) using electron impact (EI) ionization mode. The compounds endosulfan-I (alpha) and endosulfan-II (beta) may require additional efforts on either enlargement of sample enrichment and/or large volume injection (LVI) of sample extract. Enlargement of sample enrichment can be achieved by using 2 000 ml sample volume and/or an evaporation of solvent extracts down to a final volume of 0,2 ml or 0,1 ml. 4 Interferences 4.1 Interferences with sampling and extraction To avoid interferences, collect samples according to Clause 7. Sample containers shall consist of materials that do not alter the sample during the contact time. Plastics and other organic materials shall be avoided during sampling or sample storage. Commercially available SPE-disks can differ frequently in quality. Variations in the selectivity of the materials can occur from batch to batch, and therefore might cause significant deviations in the extraction yield. This does not basically impair their suitability, apart from a resulting higher detection limit of individual substances. To ensure that the measuring results have a high accuracy and precision, use materials of one batch for both measurement and calibration. Avoid major fluctuations in the extraction times and elution procedures within one sample sequence when analyzing the samples. Make sure that the disk is effectively dried. This can be achieved by using e.g. a vacuum device equipped with a device to dry a stream of nitrogen or air before it is applied to the disk. If the vacuum based automated or manually driven equipment uses ambient air from the laboratory environment, which often contains a certain degree of humidity, drying of the disk is, depending from the moisture content of the air, not effective and often results in a high amount of residual water in the disk (e.g. > 200 µl). Therefore additional drying of air before it is applied to the disk is required, e.g. by integration of a drying flask containing calcium chloride (5.9) or another drying agent (desiccant). This procedure results in very effectively dried disks with low remaining water (<10 µl per disk). If the applied automated system is not able to process disk drying by using dry nitrogen or dry air, take out the disk for drying and continue, if appropriate, manually as described above. Extending the drying time does not lead to efficiently dried SPE-disks. Avoid any prolongation of the recommended disk drying process (see 8.2), because this results in low recoveries for some of the SIST EN 16693:2015
EN 16693:2015 (E) 8 medium volatile compounds (e.g. 1,2,3-TCB, 1.2.4-TCB and 1,3,5-TCB). The use of a labelled standard for TCBs is recommended. Acetone is the recommended solvent for extraction and elution (see 8.2). Do not apply any solvent drying step on acetone. As long as the residual water in the disk after disk drying is, as described above, within the range of just a few µl per disk, there will no interferences occur in GC-MS analysis. 4.2 Interferences with GC-MS Interferences may be caused, e.g. by the injection system used or by inadequate separation of the analytes. Substances with similar retention times and producing similar masses compared with the analytes to be determined may interfere with the determination. These interferences may lead to incompletely resolved signals. Experienced operators, using the information given in the instrument manuals, may be able to minimize this type of interference. Regular checking of the chromatographic and spectrometric system is required to maintain adequate performance. Required system stability should be checked regularly using a GC standard. 5 Reagents The reagents shall be free from impurities possibly interfering with the GC-MS analysis. Use solvents and reagents of sufficient purity, i.e. with negligibly low impurities compared with the concentration of analytes to be determined. As reagents use, as far as available, “residual grade”, “picograde” or better in order to obtain clean blanks. Check blanks regularly and establish proper charge control. If necessary, apply additional cleaning steps. 5.1 Water, complying to grade 1 according to EN ISO 3696, or equivalent. 5.2 Operating gases for the gas chromatography mass spectrometry, of high purity and according to the manufacturer's specifications. 5.3 Nitrogen of high purity, i.e. minimum 99,996 % by volume, for concentration by evaporation. 5.4 Solvents for extraction, chromatography and preparation of reference solutions. A variety of solvents may be used depending on the procedural step and the availability of commercial stock solutions, e.g. — acetone, C3H6O (boiling point: 56 °C), — ethyl acetate, C4H8O2 (boiling point: 77 °C), — iso-octane (2,2,4-trimethylpentane), C8H18 (boiling point: 99 °C), — cyclohexane, C6H12 (boiling point: 81 °C), — toluene, C7H8 (boiling point: 111 °C). 5.5 Sodium hydroxide solution, w(NaOH) = 25 % mass fraction. 5.6 Hydrochloric acid, w(HCl) = 25 % mass fraction or sulfuric acid, w(H2SO4) = 12,5 % mass fraction. SIST EN 16693:2015
EN 16693:2015 (E) 9 5.7 Internal standard It is highly recommended to use a deuterium-labelled or 13C-enriched substance of those listed in Table 1 as internal standard. Examples for suitable internal standards are given in Annex D. For further information see 9.3. Prepare stock solutions of individual internal standard substances in the same way as specified for individual reference substances (5.8.2) or use commercially available certified solutions of individual substances (e.g. in acetone). Prepare spiking solutions for spiking the samples (see 8.1) by further diluting the stock solutions with a water soluble solvent e.g. acetone (5.4). 5.8 Reference substances 5.8.1 General requirements Reference substances (OCP, listed in Table 1) of defined concentration, suitable for the preparation of reference solutions used for gas chromatography and spiking of water samples for calibration of the total procedure (see 9.3) and calculation of the overall recovery (see 9.4). 5.8.2 Stock solutions of individual reference substances For example, place 50 mg of a reference substance and/or the internal standard substances (5.7) into a 100 ml volumetric flask (6.2), dissolve in an appropriate solvent (5.4) and make up to the mark with the same solvent. Store stock solutions at temperatures between 1 °C and 5 °C, protected from light. Stock solutions are stable for at least 12 months. NOTE Deep freezing of stock solutions is also possible and commonly applied. 5.8.3 Multi-component stock solutions of individual reference substances For example, transfer 1 ml of each of the solutions of the individual substances (5.8.2) into a 100 ml volumetric flask (6.2) and make up to the mark with solvent (5.4). NOTE Alternatively, commercially available certified stock solutions of individual (or mixtures of several) reference substances in solvent (5.4) can be used for preparing multi-component stock solutions. Store multi-component stock solutions at temperatures between 1 °C and 5 °C, protected from light. Multi-component stock solutions are stable for at least 6 months. 5.8.4 Multi-component reference solutions of reference substances Prepare multi-component reference solutions of defined concentration suitable for multipoint calibration (working solution for GC-MS) or spiking of blank samples. Prepare solutions by dilution of the multi-component stock solutions (5.8.3) using an appropriate solvent (5.4). Store multi-component reference solutions at temperatures between 1 °C and 5 °C, protected from light. Multi-component reference solutions are stable for at least 6 months. 5.9 Calcium chloride, CaCl2, for drying of air. 6 Apparatus Equipment or parts of it which have contact with the water sample or its extract shall be free from residues causing interferences. The use of vessels made of glass, stainless steel or polytetrafluoroethylene (PTFE) is recommended. SIST EN 16693:2015
EN 16693:2015 (E) 10 6.1 Sample flasks, e.g. brown glass, flat bottomed, with glass or PTFE coated stoppers, e.g. 1 000 ml or 2 000 ml. 6.2 Volumetric flasks, capacity, e.g. 10 ml, 25 ml, 50 ml and 100 ml. 6.3 Single volume pipettes, capacities between 1 ml and 50 ml. 6.4 Capillary gas chromatograph with mass spectrometric detector, (GC-MS) using EI ionization mode, gas supply in accordance with the respective manufacturer's instructions. 6.5 Non-discriminating GC injector, e.g. splitless mode of a split or splitless injection system or programmable temperature vaporizer (PTV) programmable for large volume injection (LVI). 6.6 Automatic sampler with option for large volume injection (LVI), including syringes for normal injection (e.g. 1 µl and 2 µl) and LVI (e.g. 10 µl, 50 µl and 100 µl). 6.7 Capillary columns, for gas chromatography (examples of chromatograms appear in Annex A). It is advantageous to use non-polar columns (e.g. low-bleed 5 %-phenylsiloxane column). 6.8 Solid-phase extraction disks (SPE-disks), wide inner diameter between 40 mm and 60 mm, packed with an appropriate reversed phase adsorbent material, e.g. C18-based or SDB-based adsorbent (for examples see Annex C). 6.9 Vacuum device for solid-phase extraction, e.g. vacubox, extraction box or automated workstation for solid-phase extraction procedure capable for processing SPE-disks. 6.10 Equipment for concentrating the eluates by evaporation, e.g. a rotary evaporator, adjustable for constant vacuum and with a temperature-controlled water bath, or stripping equipment using nitrogen gas. 6.11 Pasteur pipettes. 6.12 pH-meter, with electrodes. 6.13 Drying flask. 7 Sampling For sampling, use thoroughly cleaned sample flasks (6.1) (see EN ISO 5667-3). Fill the bottles completely with the water to be examined. If storage is necessary, store the samples according to EN ISO 5667-3 at (3 ± 2) °C, protected from light. It is generally recommended to carry out the extraction as soon as practicable to minimize potential adsorption to the glass wall. 8 Procedure 8.1 Sample preparation and extraction The pH value of the water sample only requires adjustment if it is below (5 ± 0,2) or above (9 ± 0,2). In this case, adjust to pH (7 ± 0,2) with hydrochloric acid (5.6), sulfuric acid (5.6) or sodium hydroxide solution (5.5). In general, samples are examined without pre-treatment, e.g. suspended particulate matter is not removed prior to analysis. Do not filter the sample. SIST EN 16693:2015
EN 16693:2015 (E) 11 Large particles (e.g. leaves, little branches) should be removed using a sieve (screening gap 1 mm). For the extraction process, add a precisely defined amount (between e.g. 50 µl to 100 µl) of the internal standard (5.7) dissolved in an appropriate solvent (water miscible solvent, e.g. ethyl acetate or acetone, see 5.4), to e.g. 1 000 ml of the whole water sample. Calculate the exact volume of the water sample by weighing the sample flask before extraction and after emptying. 8.2 Extraction by SPE-disks For conditioning of SPE-disk add an amount of acetone (6 ml to 10 ml) and let it pass through the disk in about 20 s, e.g. using a vacuum device. Ensure that the adsorbent does not run dry. Repeat this step once. Add an amount of water (6 ml to 10 ml) and let it pass through the disk in about 20 s, e.g. using a vacuum device. Ensure that the adsorbent does not run dry. Repeat this step once. For sample loading and extraction of analytes dissolved in the water phase take, e.g. 1 000 ml of the sample to be examined (8.1) and pass it through the disk conditioned as described above at a flow rate of about 50 ml/min. To transfer particulate matter to the disk that might have remained in the bottle, rinse the sample reservoir (e.g. the sample bottle) twice with e.g. 9 ml of water and pass it through the disk as described above. Effectively dry the disk using e.g. a vacuum device supported by a stream of dry nitrogen or dry air in front of the disk for about 15 min. When using ambient laboratory air to dry the disks, additional drying of air before applying it to the disk is necessary (see 4.1). This can be achieved e.g. by integration of a drying flask (6.13) containing calcium chloride (5.9) or another drying agent. NOTE Drying of ambient laboratory air prevents reabsorption of moisture by the disk from the air sucked in. Add an amount of acetone (6 ml to 10 ml), allowing 5 min for the solvent to soak. Collect the eluate by passing it through the disk in about 20 s. Add an amount of acetone (4 ml to 8 ml), allowing 5 min for the solvent to soak. Collect the eluate by passing it through the disk in about 20 s. Repeat the last step twice. Collect the combined eluates in a glass vessel. No extract-drying step is required. Carefully evaporate the solvent and concentrate the eluate as specified in 8.3. Other solvents may be used for extraction and elution. However, their suitability should be established in preliminary tests with blank water samples spiked with certified sediment up to 500 mg/l and processed according to Clause 8. Recoveries for each substance under investigation should be
70 %. 8.3 Solvent concentrating Concentrate the SPE eluate (8.2) carefully to a final volume of about 0,5 ml to 1,0 ml (e.g. in a gentle stream of nitrogen or on a rotary evaporator under reduced pressure). To achieve higher sensitivity, solvent evaporation can be continued to smaller final volumes (e.g. 0,1 ml). The temperature of the eluate during concentration should be kept below 20 °C. If a solvent change is planned, add e.g. 1 ml of an appropriate solvent (e.g. toluene) prior to solvent concentration. If an injection standard for volume control is intended to be used, for example, add a defined amount of injection standard (e g. fluoranthene-D10) dissolved in acetone. In case of a planned solvent change, injection standard may be dissolved in the appropriate solvent, e.g. toluene. SIST EN 16693:2015
EN 16693:2015 (E) 12 8.4 Gas chromatography Check the required system stability regularly. Adjust and optimize instrument parameter settings in accordance with the respective manufacturer's instructions. For separation, use appropriate capillary columns (6.7) and adjust chromatographic conditions for maximum selectivity (see Annex A for examples). 8.5 Identification of individual compounds by means of GC-MS Identify a compound in the sample by comparing the measured retention times and the corresponding relative intensities of selected identification masses (Table 2) with those of the references substances in the multi-component reference solution (5.8.4). The target compound in the sample shall be regarded as identified if: — the relative or absolute retention time (RT) of the substance in the SIM chromatogram matches the relative or absolu
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