Volumetric sampling and dispensing

To reliably perform qualitative and quantitative analyses on body fluids and tissue, the clinical laboratorian must understand the basic principles and procedures that affect the analytical process and operation of the clinical laboratory. These include the knowledge of (1) the concept of solute and solvent, (2) units of measurement, (3) chemicals and reference materials, (4) basic techniques, such as volumetric sampling and dispensing, centrifugation, measurement of radioactivity, gravimetry, thermometry, buffer solution, and processing of solutions, and (5) safety. ... 

Figure 3.5 Volumetric glassware. The beaker is only for estimating volumes. The taU graduated cylinder is used to measure volume more accurately. The flask with the tall neck (volumetric flask) and the pipet are used to obtain samples of fixed but precisely measured volumes. The buret is used to dispense variable volumes with high precision. 

As mentioned above, transport effects, suppression effects and drift can cause accuracy problems in ICP-MS. In environmental analysis, this is most commonly corrected for by the use of internal standards. An internal standard can be added to each solution either by volumetric addition or by mixing the flow of the internal standard solution and the sample (pumped separately) using a T- or Y-piece prior to the nebuliser. The latter option is often preferred as it does not require each sample to be accurately dispensed into a test tube. Since suppression and drift effects can be somewhat mass dependent, several internal standard isotopes are normally... 

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