The analytical chemistry techniques most commonly used today tend to fall into one of four major categories: spectroscopy, microscopy, calorimetry, or chromatography. The best way to understand each is to learn how they work and then see them applied in action.
The Four Major Analytical Chemistry Techniques Used Today
Spectroscopy
Spectroscopy measures and interprets the absorption, emission, transmission, and reflection of light radiation by matter. There are several different approaches to spectroscopy, but they all involve splitting light-based electromagnetic radiation into its waves of spectra. These include gamma rays, X-rays, ultraviolet rays, visible light, infrared waves, microwave waves, and radio waves.
No element or bond between two elements interacts with each wavelength of electromagnetic radiation in the same way. By studying a sample’s reaction to all of the wavelengths, spectroscopic analysts can determine which elements are present in a sample and how those elements are interacting with each other. This makes spectroscopy a highly valuable technique for understanding the composition of complex compounds in solid, liquid, or gaseous forms.
Microscopy
Microscopy is the field of using microscope technology to view and analyze parts of objects too small to be seen with the unaided eye. There are two major forms of microscopy (and microscopes): optical & electron.
Each of these forms of microscopy use a different means of producing a magnified image. For example, optical microscopy produces magnification by bending visible light through a system of lenses. Electron microscopy passes an electron beam over the surface of the sample to collect data on how it reacts. Microscopy is useful for analyzing a sample’s surface topography and composition.
Calorimetry
Calorimetry is the process of measuring the amount of heat released or absorbed during a chemical reaction. By studying how heat from a sample flows as it changes states (from solid to liquid or liquid to gas, for example), analysts can understand how the sample will react to different environments. This makes calorimetry a highly applicable quality control testing technique.
Chromatography
Chromatography is the process of separating the constituents of a mixture for qualitative or quantitative analysis. Chromatography works by dissolving the sample to be analyzed using a substance called a mobile phase, then passing it through a second substance called a stationary phase.
Every constituent element of the mixture passes through the stationary phase at a different speed, which is known as its retention time. By comparing retention times to confirmed references, analysts can determine the constituent makeup of the sample mixture. This makes chromatography great for identifying unknown contaminants or trace elements in complex mixtures.
Analytical Chemistry Techniques in Action
Innovatech uses each of the analytical chemistry techniques outlined above quite frequently. Here are examples of how we’ve used each technique in the past, and why they were the right solution for obtaining the information we required.
Spectroscopy
The case study: Good Part or Bad Part? Plastics Failure Analysis Using FTIR Sheds Some Light
After our client discovered that one of their plastic parts occasionally fractured during use, they had to find out why so they could adjust their manufacturing process. They provided two samples of the product to Innovatech to analyze: a “good” part that performed as expected and a “bad” part that had fractured during use.
Our team hypothesized that the reason for the fracture was that the bad part had a different chemical composition than the good part. To test this hypothesis, we analyzed both parts via Fourier Transform Infrared Spectroscopy (or FTIR), a form of spectroscopy that uses spectra within the infrared region.
Our initial FTIR analysis found that both parts had very similar compositions, meaning the chemical composition difference was extremely subtle. To find this difference, we soaked both parts in isopropyl alcohol to extract components from both samples.
Next, we conducted a second form of spectroscopy called attenuated total reflectance FTIR (or ATR-FTIR) on the remaining residues, which passes infrared light through a crystal interface that internally refracts it, creating an evanescent wave that penetrates the sample to provide even more incisive molecular information.
ATR-FTIR analysis of the residues found that while both parts contained a plasticizer called dioctyl phthalate (or DOP), the bad part contained significantly less. This demonstrated that the bad plastic part failed because it contained an insufficient amount of plasticizer to keep it from fracturing during use.
The client was able to use this information to adjust their production, ensuring all parts received the necessary amount of dioctyl phthalate and preventing future fractures.
Analytical Chemistry Techniques in Action
Innovatech uses each of the four analytical chemistry techniques outlined above quite frequently. These are just a few demonstrative examples of how chemical analysis can solve a wide range of problems for clients across industries.
Microscopy
The case study: Scanning Electron Microscopy: a Tool for Science and Business
Scanning Electron Microscopy (SEM) is very commonly used as a quality assurance technique in manufacturing. For example, stainless steel products must be evenly coated with special chemicals to perform to expectation. Innovatech frequently uses SEM to ensure that this coat is evenly applied or to identify tiny cracks, imperfections, and contaminants on the surface of coated stainless steel products.
Calorimetry
The case study: Using Differential Scanning Calorimetry to Identify Source of Epoxy Failures
Innovatech’s client designed a product using a carbon epoxy composite, but the substrates within the device were moving too much, adversely affecting the product’s performance. This suggested that the epoxy used to cure the carbon epoxy composite had not been cured correctly.
To determine if this was the case, the client cured four samples: samples 1 and 3 were cured in new ovens, while samples 2 and 4 were cured in old ovens. These samples were sent to Innovatech for evaluation.
Our team used a form of Calorimetry called Differential Scanning Calorimetry (or DSC) to analyze all four samples because DSC is capable of observing the especially subtle phase transitions carbon epoxy undergoes when exposed to heat.
DSC testing concluded that the glass transition temperature of samples 2 and 4 (cured in the old oven) was around 95°C. Meanwhile, the glass transition temperature of samples 1 and 3 (cured in the new oven) was 120°C. The client’s product was routinely exposed to temperatures of 95°C during use. These temperatures were triggering glass transition in the samples cured in the old oven, producing the micromovement the client was observing and leading to product failure.
Meanwhile, epoxies cured in the new ovens could resist 95°C temperatures without transitioning, preventing micro movements. As a result of the test, the client began curing all of their products in the new oven, preventing further product failures.
Chromatography
The case study: Ionic Contamination Testing Reveals Cause of Shorts in Circuit Boards
Innovatech’s client was an electronics manufacturer experiencing electrical shorts in their circuit boards. They suspected the rinse water they were using during production was responsible. To test this theory, they provided Innovatech with two samples: a “good” circuit board that didn’t short, and a “bad” sample that had failed following a short.
Our team tested material samples from both boards using High-Performance Liquid Chromatography (HPLC), which uses a liquid chromatography solution to separate elements of a mixture and a conductivity detector to qualify the separated anions and cations.
The HPLC testing found high levels of potassium and sodium cations present within the failing circuit board sample that were not present in the “good” sample. This suggested that the failing circuit board had been exposed to hard water and the good board hadn’t, confirming the client’s suspicions about their rinse water.
By changing out the rinse water used to ensure hard water wasn’t interacting with the circuit boards, the client solved their electrical shorting problem.
If you think you’d benefit from any of the analytical chemistry techniques covered here, Innovatech’s experts are ready to help. Get in touch for a quote today.
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