Sampling homogenisation

Figure 5.1.2 Matrix solid-phase dispersion (MSPD) extraction as a micro-preparative extraction technique for an on-flow LC-NMR-MS screening. Since the latter requires only sample amounts in the 0.5-2 mg range, the sample preparation can be achieved by fast small-scale extraction procedures, such as MSPD. This is a sample preparation technique that combines both sample homogenisation and extraction of compounds of interest in one single step starting from the intact sample material. Thus, it simplifies the extraction and clean-up steps, reduces the sample manipulation and is much faster than conventional techniques. It is therefore very well suited for a rough separation of extracts into classes of compounds of similar polarities, which can then be submitted to LC-NMR-MS analysis...

In fact, sample homogenisation in most sequential injection systems is based on zone penetration (overlap of adjacent zones), which depends on the sample and reagent volumes involved, manifold geometry and timing. 

This book attempts to cover chemical and ecotoxicological analysis related to routine contaminated land investigations. It does not cover analysis related to research or specialist one-off project type investigations. The following chapter deals with soil analysis method requirements, how methods should be validated and the need for all methods to meet clearly defined performance requirements. It also covers quality assurance/quality control aspects. Chapter 3 covers the key, and problematic area of sample homogenisation and the initial sample preparation. Chapter 4 covers the analysis of metals and elemental... 

The use of HPLC-ED in the analysis of the anabolic steroids and metabolites, diethylstilbestrol, taleranol, zearalenol, zearalenone and zeranol (Figure 7.5), in mammalian tissue has been discussed.Diethylstilbestrol has been measured in animal tissue using an ODS-modified silica column with methanol-aq. phosphate buffer (50 mmol L pH 3.5) (67 + 33) as eluent and ED (GCE, +0.9 V vs Ag/ AgCl). Sample homogenisation was followed by LLE into MTBE, back-extraction into aqueous sodium hydroxide and SPE (ODS-modified silica). The LoD was approximately 0.5 pg kg wet weight (10 g sample). Clenbuterol assay in calf urine was discussed above (Chapter 6, Section 2). 

The homogenised sample shows an increase of hardness (30%) until 400°C, where a drop to the initial value is observed. 

Qualitatively, the process of re-ordering proceeds similar in deformed and homogenised samples. Yet, two differences between deformed and recrystallized samples are observed ... 

The typical for Ni-Al alloys 7R and 3R (LIq) structures of martensite were formed in the investigated alloy. The thermally induced martensite in the homogenised sample was mainly of 7R type (Fig.2b). The LIq martensitic structure was mainly observed in samples after the hot deformation. 

Protein concentration can be determined using a method introduced by Bradford,4 which utilises Pierce reagent 23200 (Piece Chemical Company, Rockford, IL, USA) in combination with an acidic Coomassie Brilliant Blue G-250 solution to absorb at 595 nm when the reagent binds to the protein. A 20 mg/1 bovine serum albumin (Piece Chemical Company, Rockford, IL, USA) solution will be used to prepare a standard calibration curve for determination of protein concentration. The sample for analysis of SCP is initially homogenised or vibrated in a sonic system to break down the cell walls. 

Preparation of AIR and extraction of pectic fractions For the preparation of the alcohol-insoluble residue (AIR) the apples were peeled, cut into small pieces and boiled in 96% ethanol for lOmin. After this enzyme inactivation step, the sample material was blended, homogenised and filtered through a G3 sintered glass niter funnel. The residue was washed with 96% ethanol, followed by acetone and diethyl-ether, dried overnight at 40°C under vacuum and stored at -20°C in the dark. Portions of about lOg of AIR were fractionated according to the method of Selvendran et al. [10] as shown in figure 1. 

P. Gy, Sampling of Heterogeneous and Dynamic Materials Systems. Theories of Heterogeneity, Sampling and Homogenisation, Elsevier, Amsterdam (1992). 

The DEP ends with a filament wire onto which a drop of sample is deposited. After evaporation to dryness, the probe is introduced into the source of the mass spectrometer and is rapidly heated to a temperature that can reach 1000°C. This probe is ideal for the study of high molecular weight or polymeric components. It is mostly dedicated to the analysis of samples in the liquid state. Although a small solid fragment of matter may be placed on the filament, this critical operation may lead to the loss of the sample, especially if it is particularly small. To avoid such a difficult handling, the sample may be ground and homogenised in a mini-mortar and then made into suspension with a few drops of appropriate solvent (Scalarone et al., 2003). 

Pretreatment of biological samples for surfactant analysis is usually straightforward and includes either homogenising with anhydrous sodium sulphate or freeze-drying. Below, the sample treatment methods for extraction and clean-up of non-ionic and anionic surfactants in biota that have been encountered in the literature are reviewed. 

Thibaut et al. [14] published a procedure for determination of NP and NP transformation products in snails, duckweed and trout liver and viscera. Samples were homogenised in MeOH, and either directly chromatographed on HPLC (liver, duckweed), or subjected to a further clean-up using L/L partitioning with methanol, chloroform and acetonitrile/isooctane, successively. 

Wahlberg et al. [20] determined NPEO in Blue mussels by GC-ECD after derivatisation of the phenols with PFBC1. To this end, samples were homogenised in acetone/hexane (5 2), followed by extraction with hexane/diethylether (9 1). Lipids were removed by L/L extraction with acetonitrile in 0.1 M NaOH followed by L/L extraction in TMP/sulphuric acid. Recoveries of 93, 34, 65 and 100% were reported for NP, NPEOi, NPEO2 and NPEO3, respectively. 

Fish. Solid biota samples, mainly fish, should be quickly killed by liquid N2 [28] or cervical dislocation [32] and kept at low temperatures (— 20°C). Some authors preferred desiccation of the sample at high temperature (70°C) [33,34] or lyophylisation [28]. The extraction and isolation steps would be combined when using lyophylisation and homogenisation, followed by a Soxhlet extraction, usually with MeOH, and a subsequent solid-phase extraction (SPE) clean-up, prior to the quantification. 

Biological tissues Add water to tissue sample (at 50 C) and homogenise extract with carbon disulfide and analyze Gas chromatography flame ionization detector 0.5 ag/g No data Letz et al. 1984... 

The tissue is homogenised with Chloroform Methanol (2 1, v/v) to a final volume 20 times the volume of the tissue sample (1 g in 20 ml of solvent mixture). 

Three peat samples (2 m each) were taken at two peat production areas in Finland, namely Kailasuo and Piipsanneva. They were homogenised and prepared as pieces of different density and diameter with laboratory-scale machines. Peat properties are shown in Table 3. Aho classified the peat into three groups with respect to degree of decomposition of chemical structure. The peat types were denoted by S for low decomposition degree, C for medium and LS for high degree of decomposition. 

The PT provider has to take care that all the distributed samples are comparable with each other. Therefore the provider has to ensme the homogeneity of the testing material before dividing it into sub samples. The provider must have a documented procedure for homogenisation and for homogeneity tests. It has to be assured that the evaluation of the laboratoiy results is not affected by inhomogeneities. 

Wet the lyophilized sample with 80 pi ddH20. After that, add 300 pi of Soln. A and homogenize the sample with a glass-Teflon homogenisator. After addition of 100 pi chloroform, centrifuge the mixture for phase separation. This extraction is repeated three to four times. 

The complexity of the pretreatment procedure chosen is largely determined by the nature of the sample and the information required. Most present-day analytical instruments are designed to process gas and/or liquid samples. These could, therefore, be used with the minimum of pretreatment. Solid samples, on the other hand, have to be brought first into solution. This can be accomplished by homogenisation of the sample. However, as already emphasised it is important to separate the various compartments. 

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