1、June 2007DEUTSCHE NORM English price group 7No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 13.080.20!,y$“9860157www.d
2、in.deDDIN EN ISO 16720Soil quality Pretreatment of samples by freeze-drying for subsequent analysis(ISO 16720:2005)English version of DIN EN ISO 16720:2007-06Bodenbeschaffenheit Vorbehandlung von Proben durch Gefriertrocknung fr die anschlieende Analyse(ISO 16720:2005)Englische Fassung DIN EN ISO 16
3、720:2007-06SupersedesDIN ISO 16720:2005-09www.beuth.deDocument comprises 9 pages 09.07DIN EN ISO 16720:2007-06 2 National foreword This standard has been published in accordance with a decision taken by Technical Committee CEN/TC 308 “Characterization of sludges” (Secretariat: AFNOR, France) to adop
4、t, without alteration, International Standard ISO 16720 as a European Standard. ISO 16720 was prepared by Technical Committee ISO/TC 190 “Soil quality”. The responsible German body involved in its preparation was the Normenausschuss Wasserwesen (Water Practice Standards Committee), Technical Committ
5、ee NA 119-01-02 AA Abfall- und Bodenuntersuchung. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. DIN shall not be held responsible for identifying any or all such patent rights. The DIN Standards corresponding to the Internationa
6、l Standards referred to in clause 2 of the EN are as follows: ISO 11464 DIN ISO 11464 ISO 11465 DIN ISO 11465 Amendments This standard differs from DIN ISO 16720:2005-09 as follows: a) The number of the standard has been changed. Previous editions DIN ISO 16720: 2005-09 National Annex NA (informativ
7、e) Bibliography DIN ISO 11464, Soil quality Pretreatment of samples for physico-chemical analyses DIN ISO 11465, Soil quality Determination of dry matter and water content on a mass basis Gravimetric method EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 16720 March 2007 ICS 13.080.20 Engli
8、sh Version Soil quality - Pretreatment of samples by freeze-drying for subsequent analysis (ISO 16720:2005) Qualit du sol - Prtraitement des chantillons par lyophilisation pour analyse subsquente (ISO 16720:2005)Bodenbeschaffenheit - Vorbehandlung von Proben durch Gefriertrocknung fr die anschlieend
9、e Analyse (ISO 16720:2005) This European Standard was approved by CEN on 25 February 2007. 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 l
10、ists and bibliographical references concerning such national standards may be obtained on application to the CEN 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 r
11、esponsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary
12、, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre:
13、rue de Stassart, 36 B-1050 Brussels 2007 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 16720:2007: EForeword The text of ISO 16720:2005 has been prepared by Technical Committee ISO/TC 190 “Soil quality” of the International O
14、rganization for Standardization (ISO) and has been taken over as EN ISO 16720:2007 by Technical Committee CEN/TC 308 “Characterization of sludges”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identica
15、l text or by endorsement, at the latest by September 2007, and conflicting national standards shall be withdrawn at the latest by September 2007. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European St
16、andard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. E
17、ndorsement notice The text of ISO 16720:2005 has been approved by CEN as EN ISO 16720:2007 without any modifications. 2 EN ISO 16720:2007 (E) 1 Scope This International Standard specifies a method for pretreatment of soil samples by freeze-drying for subsequent analysis. This International Standard
18、is applicable to soil samples for subsequent determination of elements or organic compounds recognized as non-volatile under freeze-drying conditions. Generally, this International Standard can also be applied to samples from sludges and sediments. This method is also applicable as a first step for
19、the determination of dry matter (or water) content, for instance in the case of samples with high water content. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated referen
20、ces, the latest edition of the referenced document (including any amendments) applies. ISO 11464, Soil quality Pretreatment of samples for physico-chemical analyses ISO 11465, Soil quality Determination of dry matter and water content on a mass basis Gravimetric method 3 Principle and general requir
21、ements Before freeze-drying, samples shall be cooled below their eutectic points. These are rarely known, but freezing the samples below 40 C is usually sufficient. During freeze-drying, water is removed from the sample under vacuum conditions by direct conversion from ice to vapour (sublimation) wh
22、ich is collected in a condenser where it releases its heat energy and turns again into ice. Generally a temperature below 50 C inside the condenser is suitable for usual applications. Sublimation requires heat in order to take place within an acceptable range of time. When the frozen sample containe
23、rs are connected to an external inlet manifold (see 5.1.2), heat energy is supplied by the laboratory atmosphere. In case of a drying chamber equipped with temperature-controlled carriers (see 5.1.1), this energy is provided by heating the carriers. Vacuum conditions shall allow the generation of va
24、pour pressure difference needed for sublimation and the continuous evacuation of water vapour from the sample. Throughout the drying process, the pressure inside the apparatus and the temperature of the sample(s) shall be such as to avoid sample thawing and loss of any compound of interest. This las
25、t point may be difficult to achieve due to the large range of possible energy levels of the bonds between compounds of interest and the solid phase. For compounds known as non-volatile, a final temperature of the sample between 20 C to 25 C is suitable. Other final temperatures may be needed for com
26、pounds recognized as more volatile. In all cases, the final step shall be as short as possible. 3 EN ISO 16720:2007 (E) A sample in thin layer form is required for suitable freeze-drying. Whatever the kind of sample container, the thickness of the sample should not exceed 2 cm. If the representative
27、 amount exceeds a thickness of 2 cm, multiple drying may be applied. The quantity of sample treated depends on the representativeness, the dry matter content and the number of subsequent determinations. Sample containers for freeze-drying are selected accordingly. NOTE Soil samples often need to be
28、dried before analysis. In the case of very humid or clayey soils, the technique of freeze-drying compared with air or oven drying at temperatures 40 C in accordance with ISO 11465 has the advantage of a quicker drying process and provision of a dried sample that can be reduced in size more easily. 4
29、 Interferences Substances may volatilize during freeze-drying and may partly be released to the ice condensate or be found in the gas released to the vacuum pump. If compounds lost due to valatilization are amongst those included in the list of parameters to be determined subsequently, analysis resu
30、lts are then directly affected. In contrast, mass losses only affect the dry matter content and this effect is generally negligible. NOTE For example, ammonia nitrogen is lost during freeze-drying of sludges, the intensity of loss depending on the dry matter content. Therefore determination of ammon
31、ia nitrogen content should be avoided after freeze-drying, at least for liquid sludges, but in such a case the dry matter content is not significantly affected. In the final step of freeze-drying, samples become pulverulent and turbulences induced by the vacuum pump may carry away smaller solid part
32、icles. Samples can be protected by means of a wire mesh. Achieving total dryness is difficult and may consume too much time, especially when several samples are treated at the same time. In these case, a level of dryness should be achieved which merely allows the samples to be handled, ground and ho
33、mogenized, and residual water content determined afterwards on a sub-sample. If not free, water may interact more or less strongly with the solid phase, leading to residual water contents depending on the selected drying method. For a standard determination of dry matter or water content, drying at
34、105 C in accordance with ISO 11465, is required after freeze-drying. 5 Apparatus 5.1 Freeze-drying apparatus, composed of a drying device (5.1.1 or 5.1.2) connected to a condensing chamber (condenser), a vacuum system, a cooling system and the appropriate controls. 5.1.1 Thermally isolated drying ch
35、amber equipped with temperature controlled carriers. The temperature of the samples, measured by inserted probes, is controlled by heating or cooling the carriers during freeze-drying. Generally, samples can be frozen on the carriers prior to freeze-drying. 5.1.2 External inlet manifold to which the
36、 frozen sample containers (generally flasks, but a few apparatus allow the use of trays instead of flasks) are connected. Heat energy is supplied by exchange with the laboratory atmosphere. 5.2 Suitable sample containers for freeze-drying, trays or flasks, forms and sizes are depending on the type o
37、f apparatus selected or available and on the quantities of sample treated. 5.3 Freezer for pre-cooling of samples, if possible with contact freezing facilities, minimum temperature 35 C, explosion-protected. Instructions of the manufacturer shall be followed. 4 EN ISO 16720:2007 (E) 5.4 Pre-cooling
38、equipment with a rotating system and a cooling bath containing ethanol at 40 C. Instructions of the manufacturer shall be followed. 5.5 Suitable storage containers for freeze-dried material, e.g. brown glass bottles. 6 Procedure 6.1 Pre-cooling of samples Transfer a representative amount of the samp
39、le into a suitable container (5.2). The thickness of the layer in the plate should not exceed 2 cm. Multiple drying is allowed if the thickness of the representative amount exceeds 2 cm. NOTE Layers with thickness 2 cm accelerate the freezing and drying process. Transfer the container with the sampl
40、e into the freezer (5.3) or drying chamber (5.1.1), taking care to obtain a horizontal alignment. If necessary, stick a temperature probe into the sample (see 5.1.1). Follow the instructions of the manufacturer of the freeze-drying device. For apparatus operating with flasks (5.1.2), the thickness o
41、f the layer on the flask wall shall be as thin as possible. Use of a rotating system (5.4) is recommended. If determination of dry matter content is required, weigh the empty container and record the mass (m1). Then weigh the container with the sample and record the mass (m2) (see 6.5). 6.2 Freeze-d
42、rying When using device 5.1.1, allow the drying chamber to cool (if not already achieved with pre-cooling). Pre-cool the condenser in accordance with instructions of the manufacturer. When using device 5.1.1, place the tray(s) with the frozen sample(s) on the carrier(s) of the drying chamber. If nec
43、essary connect the temperature probe(s). Close the chamber door tightly. Start the heating and temperature regulation of the carriers in accordance with the instructions of the manufacturer, so that the sample will not thaw. When using device 5.1.2, connect the flask(s) to the inlet manifold. Start
44、the vacuum pump and wait until the vacuum is stable and the pressure is between 37 Pa and 63 Pa, so that the sample(s) will not thaw. NOTE A pressure of 37 Pa equals an ice temperature of approximately 30 C. A pressure of 63 Pa equals an ice temperature of approx. 25 C. 6.3 End of drying process The
45、 detection of the end of the drying process is crucial. The treatment of several different samples in a single batch increases the difficulty. The end of the process can be observed using the following parameters: specific instructions of the manufacturer; pressure rise is minimal, or no further cha
46、nge in pressure occurs; NOTE Compared to the empty system, the pressure does not increase when all the ice has been sublimed. final temperature of the condenser approaches its minimum value and remains constant (within 2 h, for example); temperature of the dried product starts to rise to ambient (5.
47、1.2) or to the maximum temperature selected for the carriers (5.1.1) (see Clause 3). 5 EN ISO 16720:2007 (E) Following freeze-drying, carefully open the appropriate valve to return the drying chamber to atmospheric pressure, stop the vacuum pump and condenser cooling system. 6.4 Dried-sample treatme
48、nt and handling Due to the tendency of freeze-dried samples to produce dust particles, hygienic requirements shall be observed while preparing the sample. If dry matter content (mass fraction) is required, weigh the container with the dried sample and record the mass (m3) (see 6.5). For the determin
49、ation of inorganic substances, prepare the sample in accordance with ISO 11464 prior to analysis. For the determination of organic substances, sieve the sample to obtain particle size 2 mm. For further analytical treatment, transfer the prepared sample into a container (5.5). Depending on the level of dryness, the dried sample may be hygroscopic and may absorb atmospheric water. In such a case special care shall be taken, because the residual water content just after freeze-drying (m3) may be significantly different to the water cont
