Combustion Elemental Analysis

In the field of combustion elemental analysis we offer versatile solutions regardless of the complexity of your sample matrix or your throughput needs. Our combustion elemental analysis devices of robust methods and reliable analysis results for parameters such as organic halogens (AOX/TOX, EOX, POX), and carbon, sulfur, nitrogen and chlorine in solid, liquid and gaseous samples.

Combustion Elemental Analysis

The living world around us is made primarily of the building blocks carbon, hydrogen, nitrogen, oxygen and sulfur. Understanding the composition of carbon-rich compounds and mixtures has contributed greatly to human progress across all aspects of our lives. Organic chemistry has enabled tremendous advances in health, nutrition, clothing and consumer goods.

Knowing the composition of materials – made possible by the field of elemental analysis – continues to play a key role. Science and industry need efficient methods of elemental analysis whether in production, recycling, disposal or research into new materials. Increased challenges and the steadily growing demand for this type of analysis are driving a higher sample throughput and tightening the demands on measurement accuracy and sensitivity. Future-proof elemental analyzers meet these challenges with high flexibility in terms of sample type and matrix properties together with a level of automation that can be individually customized.

Key Analytical Methods

In elemental analysis, non-metallic elements can be measured with a variety of methods. It’s important to distinguish between organic elemental analysis, the analysis of carbon and sum parameters, and the analysis of inorganic elements. The combustion method is considered to be the standard for elemental analysis.

This type of elemental analyzer combusts the prepared sample at high temperatures with or without the aid of catalysts before using a carrier gas to move the combustion gases through the analyzer. The combustion gases are then separated to measure the content of each element, which can be performed by the most appropriate detector for the element:

• UV fluorescence detector (UVFD): Sulfur
• Nondispersive infrared sensor (NDIR): Carbon
• Chemiluminescence detector (CLD): Nitrogen
• Coulometric titration: Halogens, sulfur

The analyzer produces a quantitative measurement of the elements using the signals from one or more detectors. Wet chemical UV oxidation is another measurement method besides high-temperature combustion.

Combustion Elemental Analysis and Measuring Environmental Sum Parameters

Analysis at the level of the individual elements C, N, S, and X, for example, using a multi EA 5100 or multi EA 4000 is integrated in a variety of applications. One example is quality control in the chemical industry. Synthetic rubbers are the precursors for many products with elastic properties such as tires and gaskets with vulcanization being the key process step during production. Sulfur is used for this purpose in common materials such as styrene-butadiene rubber (SBR). The rubber molecules link together via sulfur bridges under the influence of heat and transition from a plastic to an elastic state. This makes the measurement of sulfur content an important tool in process control. As a raw material, the monomers must have very low sulfur content to avoid uncontrolled cross-linking, and in the finished product, the sulfur content provides a measure of the quality of the cross-linking.

Sum parameters group similar characteristics across different substances. For example, it is possible to categorize on the basis of a common element. The result of the elemental analysis with respect to this sum parameter allows for statements about the quantitative proportion of this element in the sample. Based on this result, and depending on the application, it is possible to make statements about important factors:

• Quality
• Purity
• Safety & compliance

An example from fuel production is the determination of total sulfur (TS) in fuels. This quality assurance process is part of the daily routine in refineries. They continuously monitor the sulfur content of their products and rely on up-to-the-minute information. After all, failure to meet legal limits, corrosion of plant components, or simply poor product quality are all significant risks. Businesses in this industry typically opt for analyzers from the compEAct series. Reliable sulfur determination in a wide range of concentrations, rapid measurement times, and suitability for continuous operation are major considerations. A UV fluorescence detector (UVFD) is used as a detection system.

Combustion Elemental Analysis: Key Parameters

Two factors predominantly determine the scope of applications for elemental analyzers. First, many users need flexibility due to the varying consistency of samples. Some highly versatile analyzers combine capabilities for analyzing solid, liquid and gaseous samples in one device. Factor number two for many applications is how many different parameters the elemental analyzer can cover when analyzing organic liquids, gases and solids. The most relevant parameters can be distinguished based on their use in quality control and environmental analysis:

• TN: Determining the total nitrogen content, for example, is relevant for operations in the oil and gas industry, renewable energy sources, and plastics. Including additives with nitrogen compounds makes it possible to specifically improve the ignition properties of fuels. When processing petroleum, refineries also monitor the nitrogen content of their wastewater to make sure the pollutant load is within limits. Nitrogen is an important additive in refinement.
• TS: Total sulfur is a routine parameter for monitoring the product quality of fuels. The limit values for sulfur content in gasoline and diesel fuels are continuously being reduced. Nitrogen interference presents a challenge during measurement. It can throw off the result and must be avoided by using suitable analytical devices. Advanced detection technology can distinguish between sulfur and nitrogen interference.
• TC: Total carbon is used, for example, when monitoring the quality of construction materials such as cement. This value is also relevant for businesses engaged in recycling and thermal waste recovery. For instance, calculated CO₂ emissions are based on the measurement of the total carbon content in the dry substance.
• TX: Total halogen content is measured when used oils and lubricants are used as fuel. Burning halogens releases toxic and corrosive gases. Common sum parameters from environmental analysis also fall into the halogen group: AOX (adsorbable organic halides) and EOX (extractable organic halides) are used primarily in assessing wastewater or sludge. Monitoring is sometimes required by law to control the entry of organic halogen compounds into the environment. Halogen compounds are pollutants that take a long time to degrade, and therefore they accumulate in the food chain.

Overview: The Most Important Applications for Elemental Analysis

Elemental analysis is used in many areas of science, industry, and conservation. Here, the focus is on ensuring the required technical characteristics of a product, adhering to limit values, and demonstrating safety for people and the environment. The most important applications for elemental analysis are as follows:

• Materials science: Surface technology plays a crucial role in the development of high-tech materials used in advanced devices. As part of special surface treatments, substrates are given properties specifically designed for the intended use, for example, the resulting surface might be very low in friction or highly electrically conductive. During the process it must be possible to continuously monitor the composition and any possible contaminants, for example in the dip tank when electroplating.
• Oil and gas, petrochemicals: Fuels and lubricants derived from fossil hydrocarbons are still as ubiquitous as ever. For many applications, their composition must be within strict tolerances as otherwise the smooth operation of many devices cannot be guaranteed. This therefore requires constant monitoring of production.
• Environment: Emissions can never be avoided completely. Which makes it even more important to reduce the environmental pollution from potentially harmful substances as much as possible to safely meet legal limits. Elemental analysis guarantees the safety of wastewater, sludge, soil and/or waste products.
• Agriculture: Detailed analyses of soil composition play an important role in soil evaluation. Contract laboratories, research institutes and government authorities also test fertilizers and plants for their elemental content.

As the applications show, users should not compromise when it comes to the accuracy of results and ease of operation. After all, whether ensuring the required technical characteristics of a product or demonstrating safety for humans and the environment, risks must be avoided if at all possible. The challenge lies in meeting these requirements in a way that makes economic sense.

Combustion-Based Elemental Analysis: Step-by-Step Process

Small samples and quality results: The potential for optimizing elemental analysis lies in how well the device hardware and process steps interact. To explain what this means, let's take a look at the process:

1. Sample preparation: In the first step, the laboratory worker decides whether sample preparation is necessary and, if so, how the sample will be prepared. Samples can be prepared by dilution, homogenization, or separation of sample components through an adsorption or extraction stage. Then the required sample amount is determined. This step is often not required when measuring elemental content.
2. Insertion: Elemental analysis generally requires very small amounts of a substance, although accuracy and reproducibility are deciding factors for the quality of the result when dosing the sample. Handling may pose a challenge depending on the consistency of the material. For example, oily or very volatile substances can only be dosed with the greatest care and the most sophisticated dosing techniques (active cooling/heating of the dosing needle and sample); dosing techniques must also be sufficiently precise. Gaseous substances also require special dosing techniques. If sample throughput is high, autosamplers are recommended, facilitating rapid and reliable sample processing.
3. Combustion and detection: After the sample is dosed, all sample components are subjected to controlled combustion in an oxygen-rich environment. The elements in the sample are transformed into their oxides. These combustion gases are purified and dried before they are diverted to the selective detectors (for example, UVFD for sulfur). The resulting signals, along with a stored calibration, are used to calculate the results.
4. Report: A software program generates the analysis report. This contains the measured element content or sum parameters together with additional data about the analysis and the sample.

Case Study: Detection of Chlorine in Palm Oil

It's everywhere: Palm oil is more than just a common ingredient in food. Today, this naturally derived oil is also found in cleaning agents and cosmetics. There are two secrets to its success. The first is its exceptional yield per acre in the oil palm plantations of Asia and Africa. Second, the end product has very high heat resistance, making it suitable for many applications.

Fatty Acid Esters Form During Refining

So, what's the problem? Even with palm oil, there's one catch – actually, two. Growing palms for palm oil has become a major revenue source in the producer regions and as a result, natural rainforests fall victim to deforestation. The refining process is the second area of difficulty. This process can cause the impurity 3-monochloropropane-1,2-diol (3-MCPD), which is hazardous to human health. For this reason, cooking oils are tested for this toxic chemical compound to minimize risks and encourage other improvements in the manufacturing process.

Challenges and Trends in Combustion Elemental Analysis

Fast results, small footprint, economical operation and maintenance: Users are always demanding more from elemental analysis devices. At the same time, the relevant authorities continue to impose stricter limits on hazardous substances for humans and the environment.

One solution lies in the increasing level of automation in elemental analyzers. Especially when it comes to sample delivery, state-of-the-art devices save the labor-intensive and error-prone manual component. But automation at all costs is not the goal: Rather, modular equipment designs allow analyzers to be adapted to suit the conditions in the laboratory.