Sampling of particulate solids

Minkkinen, P., Evaluation of the Fundamental Sampling Error in the Sampling of Particulate Solids, Analytica Chimica Acta 196, 1987, 237-245. 

P. Minkkinen, Evaluation of the fundamental sampling error in the sampling of particulate solids. Anal. Chim. Acta, 196, 237-245 (1987). 

That portion of a sample of particulate solids which is between two particle sizes (see cut) or in a stated range (e.g. fine, coarse, etc.). 

It refers to a number of other International Standards, notably ISO 607 [2], covering methods of sample division, and ISO 8213 [3], covering the sampling of particulate solids of a wide range of particle sizes, and the reader is strongly advised to consult these. 

Use of the mathematics for plane parallel described in the last section requires that each layer in a sample has a single set of spectroscopic properties an absorption fraction, a remission fraction, and a transmission fraction. This mathematics may be straightforwardly applied to homogeneous layers such as plastic sheets. In order to apply the mathematics to samples of particulate solids meaningfully, we need to establish a method for determining the properties of a layer of the sample from the properties of the individual particles. 

Estimating Minimum Sample Quantity for Moisture Measurement Estimates of material quantity for testing moisture content depend on mechanisms of moisture distribution in the material. Moisture is physically retained on particle surfaces, chemically adsorbed on surfaces and within pores of particulate solids, and contained as an internal constituent of solids. Significant internal moisture is most often encountered in organic and agricultural source materials. 

Harnby, N. The sampling of particulate mixtures. In Powtech 75. Proceedings of the 3rd International Powder Technology and Bulk Solids Conference, A.S. Goldberg, Heydon Son Ltd. London, 1976. 

Especially for process control it is often necessary to determine particle size distributions of particulate solids that are in motion. The material may be transported either on or by a moving device, e.g. belt, vibrating, or drag chain, screw, bucket, and other conveyors, or in a carrier medium such as gases or liquids it may also fall freely or slide down chutes of various configurations. The best method to obtain a representative sample from such situations is to temporarily divert the entire stream into a container. If the particulate matter... 

Sieve analysis (screen analysis) n. The separation of particulate solids into sequentially finer size fractions by placing a weighed sample into the topmost of a stack of graded standard sieves, mechanically shaking and tapping the stack for 10 min, then weighing the material collected on each... 

Particulates may be liquids or solids. Most often air passes through a collection device to obtain a sample of particulates. Collection may involve filtration, impactors, impingers, or other devices for liquids. The method used depends on the information desired and other factors, such as particle mechanics in an airstream. 

Equations analogous to (2) and (3) can be derived for the more complex situations that arise in stratified random sampling [1], [6]. A computer program has been developed [7] to assist in the solution of sampling problems it is especially directed at geochemical and other areas where the sizes and shapes of particulate solids may affect R. ... 

Particulate interferents can be separated from dissolved analytes by filtration, using a filter whose pore size retains the interferent. This separation technique is important in the analysis of many natural waters, for which the presence of suspended solids may interfere in the analysis. Filtration also can be used to isolate analytes present as solid particulates from dissolved ions in the sample matrix. For example, this is a necessary step in gravimetry, in which the analyte is isolated as a precipitate. A more detailed description of the types of available filters is found in the discussion of precipitation gravimetry and particulate gravimetry in Chapter 8. 

Finally, in particulate gravimetry the analyte is determined following its removal from the sample matrix by filtration or extraction. The determination of suspended solids is one example of particulate gravimetry. 

Gravimetric methods based on precipitation or volatilization reactions require that the analyte, or some other species in the sample, participate in a chemical reaction producing a change in physical state. For example, in direct precipitation gravimetry, a soluble analyte is converted to an insoluble form that precipitates from solution. In some situations, however, the analyte is already present in a form that may be readily separated from its liquid, gas, or solid matrix. When such a separation is possible, the analyte s mass can be directly determined with an appropriate balance. In this section the application of particulate gravimetry is briefly considered. 

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