Chapter 46

A sticky situation: a client is afraid a blockage could grind their Pressurized Solvent Extraction to a halt

📂 After a successful case helping a client monitor fructose in corn syrup, the detective’s joyous mood is suddenly interrupted as Shallot Holmes presents the team with the latest case. A client is using a new Pressurized Solvent Extraction (PSE) and is afraid a blockage could slow the process to a crawl. The team needs to find out everything about it and get things moving again as quickly as possible.

The detectives are enjoying their breakfast, waiting for the arrival of Shallot Holmes and discussing the intricacies of their latest cases. Lieutenant Cornlumbo is still cracking corny puns, much to the dismay of Miss Mapple and Nancy Drew. The conversation then turns to how each of the detectives prefers their eggs. Miss Mapple says her favorite is boiled eggs, and Lieutenant Cornlumbo agrees. Nancy Beef disagrees and explains that scrambled eggs are far superior. Neither of the detectives noticed the look on Eggcule Poirot’s face! As Eggcule Poirot is about to explode with rage, Shallot Holmes comes crashing frantically through the door.

Shallot Holmes explains that time is of the essence and that the team must work quickly to increase the client’s knowledge about how to avoid blockages in their speed extraction system. Nancy Beef reminds the detectives that the first case they ever worked on involved extraction and food analytics. Miss Mapple remembered the case well and noted that she had previously given a workshop on extraction methods. She also recollected a case she had solved whereby a client’s extraction had also ground to a halt as his methods did not comply with industry standards. Miss Mapple hopes her knowledge can help in solving this latest case.

Characteristically, Shallot Holmes provides the facts as they are known to him. He explains that the instruments used for PSE can have capillaries with small diameters to minimize solvent consumption. This is great for reducing costs and making the process more environmentally friendly, but being so small, there is a risk of getting blocked.

Several practical steps exist to remedy the situation. PSE instruments display several error messages, and these will give a clue as to how to fix the problem.

Shallot Holmes explains to the team that these are technical factors that solve a blockage once it has happened and that he has already given the client this knowledge. However, he really needs the detective’s help with how to prevent a blockage in the first place. This, he says, is a trickier dilemma. The client needs to understand why the blockage occurred to ensure it doesn’t happen again.

Against the clock, Shallot Holmes suggests that the detectives focus on the most likely suspect of a blockage: polymers. These macromolecules are used in extractions for quality control, determining the degree of branching, and determining plasticizers. Due to their large size, they are the most likely culprit for a blockage. Miss Mapple knew a lot about the types of instruments used for PSE and also about various samples and analytes from her previous cases. She explained to the team that the case wasn’t straightforward as each polymer has different properties; therefore, there is no general application. Knowing as much as possible about the sample and analyte to be extracted was essential.

Lieutenant Cornlumbo, with breakfast still on his mind, told the team that temperature was a significant factor. He explained that the difference between a great boiled egg and a bad one was due to temperature. The perfect runny egg would go hard if overheated. If the sample being processed were like a raw egg, it would get blocked if overheated. Your right exclaimed Shallot Holmes; Polymers have low melting points, and molten samples can get stuck.

PRESSURE! Screamed Eggcule Poirot, now furious. The other detectives finally realized how inconsiderate they had been discussing how to cook an egg in front of Eggcule. In an attempt to release the tension in the room, Shallot Holmes tells Eggcule Poirot how right he is. Pressure does indeed affect the melting point. Shallot Holmes tries quickly moving the discussion on and asks the team what could be done to prevent these possible issues.

Miss Mapple takes over by explaining the importance of sample preparation and method development in preventing blockages. She explains that samples need to be homogenous and that this could be achieved using a mixer . She continues to explain that once the sample is ready, the cell must also be prepped. Miss Mapple remembered how important this was in fat extraction , a process that could be prone to causing a blockage. She explains that the top and bottom of the extraction cell could be closed with different materials and that some of these materials were better for certain types of samples. She recalled that glass fiber filter paper was best for fatty samples , fine powdery samples, and polymers. Glass fiber filters had a better retention capacity, so they would be the best for samples likely to cause a blockage. Thimbles could also be used for samples that get sticky as they prevent the sample from flowing through the bottom filter.

For these reasons, Miss Mapple explained, method development is critical. She points out that all the things the detectives had mentioned: temperature, solvent, and pressure, had to be accounted for.

For PSE, the temperature is usually 20ºC higher than the solvents boiling point. The analyte and sample must be temperature stable so that the sample does not get molten and the analyte does not decompose.

For PSE, the same solvents as Soxhlet extraction are used. The Hildebrand solubility parameter can be used to find a suitable solvent for polymers.

Extraction under pressure requires fewer cycles but a higher frequency. Saturated extracts may cause a blockage though this problem can be avoided by adjusting the number of cycles and the hold time. Avoid causing a blockage with more cycles and short hold times rather than one long cycle.

Shallot Holmes was very impressed with Miss Mapple’s knowledge of the subject and summarised that the client would not receive blockages following the guidelines: optimize the sample prep and choose the correct extraction parameters. The whole team agreed that, armed with their findings; the client should no longer be afraid of having blockage issues in their PSE process. Even Eggcule Poirot was so content with their findings that he had calmed down completely.