Good day steemians and thanks for giving your precious time to read my post. This is a post on real sample analysis in the laboratory compare to general believe of people on real sample. What is a sample and real sample in analysis, take time to read through, it will be interesting.
By Alandmanson - Own work, CC BY-SA 4.0,
The analysis of real samplessuch as the soil and rock samples are usually quite complex compared with the analysis of other materials studied in the laboratory.
The choice of analytical method for real material is not simple, often requiring consultation of the literature, modification of existing methods and extensive testing to determine method validity.
By Alandmanson - Own work, CC BY-SA 4.0,
It is well known from analytical chemistry that a quantitative analysis include a sequence of steps which include the following;
- selecting a method
- sampling
- preparing a laboratory sample
- defining replicate sample by mass or volume measurement
- preparing solution of the sample
- eliminating interferences
- completing the analysis by performing measurements that are related in a known way to analyte concentration
- computing the results and estimating there reliability
Thus I will focus largely on steps 6,7 and 8 and to lesser extent steps 2 and 4. I have chosen to emphasis on this, not because the earlier steps are unimportant or difficult. Infact, the preliminary steps may be more difficut and time consuming than the two final steps of an analysis and may be greater sources of error.
The reasons for postponing a discussion of the preliminary steps to this point are pedagogical( strategy of instruction). Experience has shown that it is easier to introduce students to analytical techniques by having them perform measurements on sample materials for which no method selection and sampling required
Sample preparation and sample dissolution are been used largely for measuring the concentration of the analyte in sample aqueous solutions that have few interfering species.
Real sample
Real samples are far more complex than most of those that you encounter in the instructional laboratory. Determining an analyte in a simple sample is often easier than in complex material because the number of variables that must be controlled in simple samples is small and the tools available are numerous and easy to use when compared with some complex samples such as rock and soil samples. Also with simple systems are knowledge of the chemical and measurement principle allow us to anticipate problems to correct for them.
Infact, academic and industrial chemists are usually interested in materials that are not real. To the contrary most analytical samples are complex mixtures of species, in some cases, hundred of species such as materials are frequently far from ideal matters of solubility,volatility,stability and homogeneity and many steps must precede the final measurement. It may be easier and less time consuming than any of the preceding steps.
I have choosen the term real sample to describe materials such as those in the preceding illustration. In this context, most of the samples encountered in an elementary quantitative analysis in laboratory course definitely are not real but rather are homogenous, stable ,readily soluble and chemically simple.
Also, there are well established and thoroughly tested method for their analysis. There is considerable value in introducing analytical techniques with such materials because they permit you to concentrate on the mechanical aspect of an analysis.Even experienced analysts use such samples when learning a new techniques, calibrating an instrument or standardizing solutions.
Refrence