EN 16179-2012 pdf download.Sludge , treated biowaste and soil – Guidance for sample pretreatment.
NOTE 1 A drying temperature of 40 C in an oven Is preferable to air drying at room temperature because the increased speed of the drying limits variability caused by to microbial activity.
NOTE 2 Storing samples, including samples that are as received, air dried, refrigerated or stored in the absence of light, for a long time may have an influence on a number of parameters. especially solubility of both inorganic and organic fractions.
NOTE 3 Keeping an archive sample (see Figure 1) is optional and should be clearly stated In the overall description of the investigation programme.
5.5 Pretreatment in the laboratory for determination of organic volatile compounds
The method of pretreatment depends on the volatility of the compound(s) or group(s) of compounds to be determined.
NOTE The selection of the categories for volatile and moderately volatile compounds can be related in principle to the vapour pressure However, as the vapour pressure of only a small number of compounds is known, and considering the relationship of vapour pressure and boiling point, the boiling point has been chosen as the criterion for distinction. See Annex B.
For determination of volatile organic compounds, test portions are taken from the field sample and extracted according to the specific analytical procedure. If composite samples are required extracts of individual samples are mixed. It is not possible to obtain composite samples without severe losses of volatiles. The procedure is described in 10.3.2.
5.6 Pretreatment in the laboratory for determination of moderately volatile organic compounds
Samples are either chemically dried and ground at a low temperature, e.g. with liquid nitrogen or dry ice (6.4), or freeze dried. The dried samples are cooled and cryogenically ground. Direct cryogenical grinding of the sampte is also possible, see 10.3.3. Grinding results in suitable test portions. Composite samples are prepared by mixing the ground samples. This procedure is described in 10.3.3.
If the extraction procedure requires a field moist sample. drying and grinding is not possible.
If the original samples only contain a small fraction of particles greater than 2 mm, and the distribution of contaminants is likely to be homogeneous, grinding may be omitted. In these two cases, suitable test portions are directly taken after mixing of the sample. This procedure is described in 10.3.4. If hand mixing is used this shall be stated clearly in the report; a remark shall be made that the results are indicative.
NOTE I It a laboratory wants to claim the results to be more than indicative, It should support this In the report by clear reasoning that the sample itself was already homogeneous.
NOTE 2 To distinguish the volatile organic compounds from the moderately voLatile organic compounds, boiling points are used instead of the vapour pressure at ambient temperature. This is explained in Annex B. Annex B also provides boiling points and vapour pressures of compounds regularly determined in soil Investigations.
NOTE 3 For some speafic components In the group ol moderately volatile orgarc compounds freeze drying may give good results. In this European Standard freeze drying is not descnbed For freeze drying see EN ISO 16720
For practical reasons the pretreatment for moderately volatile compounds should be prescribed for the determination of mineral oil. As a result of cryogenic crushing, an improvement in the extraction yield occurs for compounds with a boiling point above 300 °C. The possible losses of the lower boiling hydrocarbons (ClO to C16) are assumed to be low due to the retaining effect of the higher boiling hydrocarbons present in mineral oil. The loss is also compensated by the higher extraction yield of the other hydrocarbons present. As the total yield is used to determine the mineral oil as a group parameter, it is assumed that pretreatment using the method for moderately volatile compounds presently provides the best results. It is important to realise that some mineral oils (gasoline, petroleum) have high fractions of compounds with boiling points below ClO. Losses of these fractions will be severe when using the method described in this European Standard.
6 Reagents
Use only reagents of recognised analytical quality. Check samples of each batch of the reagents for the presence of contaminating compounds.
6.1 Sodium sulfate, Na2SO4, anhydrous
Heat the sodium sulfate before use for at least 6 h at about 550 °C to remove crystalline water and organic materials. After heating, allow to cool in a desiccator and store in a closed container.
Heating of the Sodium sulfate at 550 °C may be necessary in order to ensure that it contains no organic compounds. Heating at a lower temperature. e.g. 150 °C during at least 16 h may be also enough to dry the sodium sulfate. It shall be shown that the sodium sulfate is clean enough.
6.2 Magnesium silicate, Mg3Si4O10(OH)2, (talcum powder)
6.3 Sand or gravel
Before use, wash the sand or gravel at least twice with an equivalent quantity (same mass) of demineralised water. If the washed sand or gravel proofs to be contaminated, It may be required to heat the material before use; heating for 6 h at about 550 °C to remove organic materials may be necessary. See also the NOTE in 6.1.
6.4 CoolIng aid, liquid nitrogen, N₂, dry ice. CO₂.EN 16179-2012 pdf download.