1.2. Department of Chemical Engineering

So we have talked about extraction, we have talked about cleanup, we talked about concentration usually in this sequence. And there are a lot of QA/QC issues. In this you can imagine that you are taking a sample and doing a lot of processing with it sample can go can get lost somewhere. And you can also add sample in which where you don’t have we have a solvent that is not clean then you can get sample addition all these things.

In this introductory chunk, we set the stage for understanding the importance of sampling and processing in chromatography. When analyzing environmental samples, such as soil or water, several factors can complicate the process. Moisturizing issues can arise from contamination, loss of the sample during processing, or using unclean solvents, which could lead to inaccurate results. Therefore, Quality Assurance (QA) and Quality Control (QC) are crucial to ensuring the reliability of the analysis.

Think of this process like baking a cake. If you start with contaminated or incorrect ingredients, your cake will not taste right. Similarly, if the samples or solvents are not pure, the results of your chemical analysis will be flawed.

So now we go down to the instrument itself, analysis. So we look at the different possibilities for analyzing organic chemicals. This is just analytical chemistry we are getting into that, the reasons why most of the methods, when you have environmental samples, inevitably environmental samples, you take a sample solid soil samples, water samples, the analytes are usually mixtures.

In this chunk, we focus on the types of samples analyzed in environmental chemistry. Unlike theoretical scenarios where one might analyze a pure substance, in real-life situations, the samples we collect often contain multiple compounds (analytes) mixed together. For instance, a water sample usually has various dissolved substances, making it essential to separate the components for accurate analysis.

Imagine tasting a mixed fruit juice. If you want to identify the flavor of an orange in the mix, you can't evaluate it unless you separate the orange juice from the apple or grape. Similarly, chromatography helps in isolating these different 'flavors' or compounds from a mixture.

So, chromatography itself is separation, it is not analysis it’s separation, separation of compounds you still need something to analyze the compound at the end of it. So, we will talk about that also.

Here, we clarify an important distinction: chromatography is primarily a separation technique, not an analytical one. The chromatography process separates different compounds within a mixture. But this separation is just one step; to fully understand the characteristics of each compound, additional analysis is required after separation.

Think of a library. If you want to find a particular book, you first need to sort through the shelves to get all the books on a topic (separation). Only after that can you read and analyze specific books' content (analysis).

So, there are different kinds of chromatography. One, the oldest type of chromatography is called liquid chromatography, the older type is called LC, the more the later development is called gas chromatography or GC.

This chunk discusses two primary types of chromatography: Liquid Chromatography (LC) and Gas Chromatography (GC). LC is one of the oldest and widely used methods in analytical chemistry for separating and analyzing compounds dissolved in a liquid phase. GC, on the other hand, is a more recent development that analyzes gaseous compounds.

Think of LC as a washing machine that cleans clothes in liquid (water) and GC as a hair dryer that uses hot air to dry your hair faster. Each one serves a specific purpose and works best with certain materials.

So, the chromatography the separation is on the basis of like what we do what we have discussed what we have been discussing in our course right from the beginning based on relative affinity of the analyte between 2 phases.

In this chunk, we learn about the principle of separation in chromatography, which relies on the relative affinity of different analytes for two distinct phases: the stationary phase and the mobile phase. The stationary phase is often a solid, while the mobile phase is a liquid or gas that carries the sample through the stationary phase.

Imagine how clothes hang on a clothesline and dry (stationary phase) while the wind blows (mobile phase) passing through. Some items might dry faster based on their material and how much they cling to the line (relative affinity). The wind moves some items away faster than others.

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