Introducing Joe: the Quality Control Chemist

Hello to all the Chemistry enthusiasts reading this and welcome to my blog that is all about Quality Control Chemists! Please do consider that I am not an actual QC professional, and that this blog is written about an actual QC chemist that I met and interviewed with in order to gain insight into the field of quality control and its relations to high school chemistry.

Here's a little bit about this occupation and my agent of chemistry. Due to privacy issues, I will now be referring to my agent as "Joe" instead of releasing his real name.
Joe works for the company Javo-Mex, which is a manufacturer of soap, detergent, body wash, and more cleaning products which are then distributed to large cleaning companies such as P&G and Mr. Clean. He is the lead quality control chemist, and his job consists mostly of lab work, executing several chemical reactions and tests on either the raw materials or samples of products in the making. Many of these QC tests are actually very similar to the labs carried out at school, which will be explained more in further posts. As a QC chemist, Joe performs these tests and reactions in order to ensure that the raw materials or products meet all qualifications and standards set by the company, so that the products produced are of the highest quality and most importantly, safe to use. Joe also wanted me to mention that is job is completely different from what a chemical engineer does. While the engineer is part of the development, design, and processing of the product, Joe doesn't really have much say in that.
Joe's typical day at work consists of taking raw samples or samples of the products into the lab for analysis. He then follows different chemical methods such as titration, and using the HPLC to test the samples. If the sample does not meet the qualifications, then he must inform the supervisor in order to resolve the issue. Joe then fills out a sample report on the product or raw materials, and if the quality of the sample is poor, then the report is given to another department. If the sample is approved by Joe, then the product moves onto the packaging department, and approved raw materials are sent to the processing/manufacturing department to start production. A very important part of Joe's job is proper lab technique and safety, because he is working with hazardous chemicals frequently. This is similar to the importance of safety and proper lab practice in my school labs.

Educational Background

Joe received an undergraduate degree in organic chemistry in China. He then went on to study in America, and got his master's degree in chemistry (concentrating in polymer chemistry) at the University of Detroit. He says that organic and inogranic chemistry, analytical chemistry, and physical chemistry were all extremely important courses in university that were vital to his career and field.

 

pH & Acidity/Alkalinity

An important quality control indicator is pH, which is important in both raw materials and midstage products. Joe checks the pH of raw materials or product samples daily before sending them off to the next stage. Besides modifying the pH of samples, it is also important that Joe does calibration checks on his pH meters by using standard buffer solutions (which, the pH is known) with a pH usually between 4 and 7. A pH meter is an essential piece of equipment in Joe's lab, and it is used to check the pH. I was so shocked when I heard him say that he uses a pH meter! I couldn't believe that a professional like him actually used equipment similar to what I use in my simple school labs. I guess there are a lot more similarities than I thought there would be.

Sodium hydroxide and hydrochloric acid are also common substances used by Joe to make adjustments to the pH. Therefore, they are known as pH buffers. Of course, NaOH is used to make the sample more basic, and HCl is used to make it more acidic. This is something that I am familiar with, as these are also two common chemicals we use in the lab. These two compounds are used to adjust the pH because they are strong bases and strong acids, and dissociate 100% in water, in order to maximize the amount of pH change. When a strong acid is used, hydronium ions (H3O + (aq)) are formed since the acid donates a proton to water, and the high levels of H3O+ cause the solution to be more acidic. When a strong base is used, many hydroxide ions will be formed in solution, thus raising the pH.

Above is an illustration of sulphuric acid, a strong acid, forming a hydronium ion.

pH is important in the field of quality control, because there are specific, optimal ranges that the pH of specific products have to fall under. It's almost like how an enzyme works (but not quite)! When we were first introduced to the concepts of pH, acid, and base, we learned the approximate pH ranges of products, such as cleaning products (soap, detergent, etc.) having to be basic, and other commercial products like shampoo having to be slightly acidic. Well, this seemingly simple information is actually vital to Joe's field. I also learned that most cleaning products are basic because dirt often has a surface layer of carboxylic acid groups, and when placed in a basic solution (which they are soluble in due to the carboxylic acid's polar nature), they are netrualized to produce a carboxylic acid salt and water (something that I learned in organic chemistry!). Then the dirt is suspended into the water and is removed from the surface being cleaned.

Examples of netrualization of carboxylic acids with a strong base is shown above.

Titration

Titration is a vital lab method used by Joe in his lab, because many of the products manufactured in the cleaning industry, such as detergent, are composed of an amalgamation of chemicals that do not directly contribute to the main usage of the product. This may include substances for fragrance, "padding/filling", and other additives. The usage of compounds for scent reminds me of esters, because they are known for giving off flavourful aromas, as shown in the esterification lab. A common "padding/filling" substance is soldium sulfate, which is cheap, and can be easily manufactured by reacting sodium chloride with sulphuric acid or sodium oxide with sulphuric acid. Also, it is a relatively stable compound that won't decompose, and it doesn't react with oxidizing or reducing agents at room temperature. Alright, on to titration.

Structural formula of sodium sulphate is shown above.

Joe uses titration to check the percentage of "efficient chemicals" in product samples, and makes sure that it isn't too low or too high. An example of an "efficient chemical" in detergent would be an active ingredient such as sodium lauryl sulfonate. Just like in school labs, a titrant (chemical which the concentration is known) is used to quantitatively determine the concentration of a specific substance in the sample. Even though there is modern technology developed to perform the titration more efficiently, Joe still uses the traditional method --manually ading the titrant through a burette into the sample which has an indicator in it, and looking for the perfect colour change that indicates the endpoint.
One of the simpler titrations that Joe performs is an acid-base titration, which is similar to the ones I carried out in the lab last year. He performs this titration in order to determine the alkalinity of certain cleaning products that are basic. To do this, he adds the cleaning product into a beaker, and hydrochloric acid (the titrant) into the burette. An indicator (Joe actually does use phenolphthalein!) is added into the beaker as well. Joe adds HCl into the titrate until the endpoint, indicated by a faint pink colour in the beaker, is reached, reads the volume off the burette, and calculates the concentration of the cleaning product, making sure that it is at an appropriate level. This method is practically the same as the titrations I performed in school labs, except it is applied to a professional industry. Mole calculations, acid-base neutralizations, and concentration --concepts that I have studied intensely-- are all put to use here.

What a titration looks like. Except, at the endpoint, the colour of the titrate should be pale pink, not as intensly pink as the one shown above.

Viscosity

An important piece of equipment in Joe's lab is the viscometer, used to check the viscosity of the samples. Viscosity measurements can be used to determine the product's quality and efficiency, and this method is also very quick and reliable for analyzing product performance. By controlling the viscosity of products, and ensuring that they are in proper ranges, Joe enhances the quality and performance of the product as well as reduce production cost. There are many types of viscometers that Joe uses, such as a rotational viscometer, a capillary viscometer, and a vibro viscometer. A rotational viscometer works by inserting a cylindrical rotor into the sample and the rotor starts to rotate at constant speed. By using the principle that viscosity is directionally proportional to running torque, the twist angle caused by the torque is then proprtional to viscosity. This value is shown on the a meter on the viscometer.

Above is an illustration of how a rotational viscometer works.

Viscosity is a liquid's resistance to flow, but it is also dependent on the strength of intermolecular forces as well as the shape of the molecules. Usually, liquids that have higher intermolecular forces, which are polar molecules and/or can form hydrogen bonds, are more viscous than non-polar liquids. Sulfuric acid is a good example of this. It's intermolecular forces due to hydrogen bonding causes it to viscous, whereas an non-polar liquid with weak intermolecular forces like liquid nitrogen have low viscosity. A larger molecule may also be much more viscous, because of stronger dispersion forces as well as how relatively easy it is for the molecular chains to be "tangled" together. This is why long chained alkanes like fuel oil, and saturated fats are extremely viscous. Joe uses various substances to adjust the viscosity of products to a desired value. For instance, propylene glycol (1,2-propanediol) is used to increase the viscosity, due to its two hydroxyl groups which enable it to hydrogen bond, therefore increasing its intermolecular forces. Sodium xylene sulfonate is also used to lower the viscosity of cleaning products, because it is a hydrotrope. The concept of intermolecular forces that I learned in organic chemistry can be applied to viscosity which is vital to the chemistry of quality control in the cleaning industry.Viscosity is important to these products because of the importance of the texture and thickness of the liquid (like in shampoo and detergents) that feels nice to the hands, as well as produce a good amount of lather.

Above is the structure of propylene glycol. 

Above is the structure of sodium xylene sulfonate.

Lab Safety and Hazards

Besides the qualitative, quantitative, and analytical chemical methods used in quality control, Joe must also be familiar with lab safety and be aware of potentially threatening hazards. Therefore, he must have proper lab technique and be able to handle the equipment and chemicals properly and safely. He must also wear goggles at all times, similar to when I am performing labs in school. Eye protection is vital when it comes to working in the lab. Joe must also wear gloves and a lab coat in order to prevent any hazardous staining, and physical contact with corrosive materials. Procedures that are dangerous such as highly exothermic reactions must be performed in the fume hood to minimize exposure to toxic fumes. This is similar to the usage of the fume hood in the evaporation and intermolecular forces lab, where I had to handle substances that gave off highly harmful fumes.

Joe must also safely dispose of chemicals (he never puts the sample that he tested on back into the source where he got it from!) depending on the type of waste, just like the simple hazardous waste bins we have at school. He also mentions that he must be very careful when handling highly concentrated sulphuric acid, which is a common catalyst in organic reactions, because it is a strong acid that is extremely corrosive and should be handled with great care. Material safety data sheets (MSDS) are also available to Joe and necessary to read, because they inform him on how to handle the materials properly to reduce risk. This is a real-world application of the MSDS that I used to filled out before school labs in grades 9 and 10. I didn't really enjoy doing that, but it was imperative.

High-Performance Liquid Chromatography (HPLC)

High-performance liquid chromatography is a form of more advanced liquid chromatography that Joe uses commonly in the lab. He uses this method to separate compounds that are dissolved in a solution. With this, Joe can then figure out the chemical composition of the sample and if there are proper amounts of all the different compounds according to the formulations of the products.When the sample solution comes in contact with a particular solvent in liquid state, the different solutes in the solution interact with the solvent differently depending on several factors such as molecular size, absorption, ion-exchange, polarity, and more. These differences are what allow the components of the sample to be separated from each other. For instance, different polarities of the compounds in the solute (also depending on the polarity of the solvent) cause the different retention times, allowing the substances to be extracted and separated. This is due to "like dissolves like", causing polar to dissolve in polar, and non-polar to not dissolve in polar. Also, usually the smaller the molecular weight, the easier it is to travel through the solvent and therefore the difference in molecule sizes can cause separation.

What an HPLC instrument looks like.

HPLC works differently than traditional simple chromatography, since it uses an HPLC instrument that consists of a resevoir mobile phase, a pump, an injector, a separation column, and a detector. The compound is separated by injecting the sample onto the column. The different moleules and ions in the sample pass through the column of the solvent at different rates due to many factors and characteristics as mentioned in the above paragraph. Here is more on how the HPLC instrument works in detail:
The liquid sample is introduced into a "loop" with a syringe. The sample will then travel through the column (also known as the HPLC tube), and the time it takes for the compound to travel through the column to the detector is know as the retention time. The retention time is based once again on characteristics like molecular size, polarity, temperature, etc. The substance will then reach the detector, and the detector detects the arrival of the substance with ultra-violet absorption. The UV detector reads how much light is absorbed by the chemical, and if it reads something, then that signifies the compound has passed through. The output is recorded as a series of peaks, and each peak represents a compound that was in the sample mixture. The peaks can be used to measure the quantity of the substances and determine more information.

Schematic of an HPLC instrument.