BS EN ISO 23161 pdf download

BS EN ISO 23161 pdf download Soil quality — Determination of selected organotin compounds — Gas- chromatographic method
The properties, such as particle size distribution, water content and organic matter content of the solids to beanalysed using this International Standard vary widely.Sample pretreatment is designed adequately withrespect to both the properties of the organotin compounds and the matrix to be analysed.
2Normative references
The following referenced documents are indispensable for the application of this document.For datedreferences，only the edition cited applies. For undated references，the latest edition of the referenceddocument (including any amendments) applies.
ISO 3696,Water for analytical laboratory use – Specification and test methods
ISO 11465,Soil quality —Determination of dry matter and water content on a mass basis — Gravimetricmethod
ISO 16720,Soil quality — Pretreatment of samples by freeze-drying for subsequent analysis
ISO 22892, Soil quality —Guidelines for the identification of target compounds by gas chromatography andmass spectrometry
3Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
organotin compound
substance containing 1 to 4 Sn-C bonds
NOTE The number of Sn-C bonds is a measure for the degree of substitution.
3.2
organotin cation
part of the organotin compound(3.1) that contains all Sn-C bonds and is formally charged
3.3
organotin cation derivatives
non-dissociated tetrasubstituted organotin compounds which are produced by derivatization
3.4
solid
soil, sediment,sludge and waste (soil-like material)
4Principle
For the ionic and the non-ionic organotin compounds (see Table 1), a different sample pretreatment andsample preparation are necessary.For the determination of organotin cations，laboratory samples arepretreated by freeze drying and grinding. This procedure enables homogeneity of the sample to be achieved.The determination of non-ionic TTBT cannot be carried out with freeze-dried materials due to evaporationlosses, thus, it shall be determined in the field-moist sample. Organotin cations can only be determined afterderivatization，whereas TTBT is already peralkylated and can be determined without derivatization (see theflowchart in Figure 1).
The internal standard mix comprises four compounds representing four alkylation states in order to mimic the behaviour of the target compounds. After alkylation, they cover a wide range of volatility. A recovery of at least 80 % for derivatization/extraction and again 80 % for each clean-up step of the internal standard compounds should be achieved. (For more information, see A.3.) Tetraalkylborate is very reactive and will also alkylate other compounds in the matrix. Those compounds (and also boroxines) may interfere with the target compounds during gas chromatographic determination and influence detection. In order to protect the column and to reduce the interference in chromatography, it will be necessary to apply a precleaning step to most samples. Clean-up with silica or aluminium oxide is the minimum; further clean-up steps (e.g. aluminium oxide/silver nitrate, silica/silver nitrate, pyrogenic copper; see Annex B) may be applied if necessary.