Application Finder

A corrosion inhibitor is a substance that reduces the corrosion rate of a metal. A corrosion inhibitor is usually added in a small concentration to the corrosive environment. This application note shows how Metrohm Autolab instruments can be used to check the quality of inhibitors.

Electrochemical methods provide an alternative to traditional methods used to determine the rate of corrosion. For example, corrosion rates, the rates at which a specimen corrodes, can be calculated from simple electrochemical measurements like a linear sweep voltammetry (LSV).

Corrosion refers to a process that involves deterioration or degradation of metal. The most common example of corrosion is the formation of rust on steel. Most corrosion phenomena are of electrochemical nature and consist of at least two reactions on the surface of the corroding metal.

White paper on monitoring corrosion and the benefits of online or inline chemical analysis over manual sampling and offline laboratory methods for corrosion monitoring. Online and inline process application solutions for corrosion prevention with related application notes for further information are presented.

Determination of fluoride, chloride, nitrate, and sulfate in corrosion powder using anion chromatography with conductivity detection after chemical suppression.

Free white paper describes the effective use of electrochemical techniques to measure corrosion and the effectiveness of inhibitors.

Tafel analysis is an important electrochemical technique used to understand reaction kinetics. By studying the Tafel slope, it reveals the rate-determining steps in electrode reactions, aiding fields like corrosion and fuel cell research. This method helps industries optimize processes and improve device performance by tailoring materials and conditions for greater efficiency.

The rotating cylinder electrode (RCE) is successfully used in a laboratory environment to generate a turbulent flow at the surface of a sample, simulating realistic pipe flow conditions. In this application note, the corrosion rate is measured and compared between quiescent and turbulent flow conditions, while keeping all the other experimental conditions unchanged. The linear polarization (LP) technique was used together with the RCE (with and without rotation).

The rotating cylinder electrode (RCE) is a technique used in corrosion research to simulate in a laboratory environment the turbulent flow which usually occurs when liquids are transported through pipelines. The RCE is used to generate a turbulent flow at the surface of a sample, simulating the pipe flow conditions. Experiments that involve an RCE are regulated by the ASTM G185 standard. In this application note, The RCE with a 1018 carbon steel cylinder sample was used with the linear polarization (LP) measurement technique.

Electrochemical measurements utilizing a rotating cylinder electrode (RCE) are widely used in industrial corrosion applications when simulation of realistic pipe conditions are necessary in a lab environment. This white paper allows further insight into the particularities and parameters which govern the electrochemical measurements, in particular measurements performed in turbulent flow conditions, and shows a complete picture of the best practice use of this technique. The annexes provide an overview and short explanation of the parameters and laws specific to the fluid behavior in electrochemical cells with RCE.

In industrial cooling water systems, copper and its alloys are widely used because of their superior heat transfer properties. These materials are, however, susceptible to corrosion. Azoles are commonly used to protect copper and its alloys from corrosion. These corrosion inhibitors are quantified by ion chromatography with UV/VIS detection.

Electrochemical impedance spectroscopy or EIS has been used effectively to measure the polarization resistance for corrosion systems and for the determination of corrosion mechanisms.

Corrosion of metals is a problem seriously affecting not only many industrial sectors, but also private life, resulting in enormous costs. In this application note, the results gained during electrochemical corrosion studies on different metals are compared to literature data.

Copper is used widely in industrial cooling water systems for its heat transfer properties, although it is susceptible to corrosion. Corrosion can cause a loss of efficiency and eventually a failure of equipment, leading to costly maintenance, replacement, and downtime. Corrosion inhibitors (triazoles) can be added to the water chemistry, which form sparingly soluble protective layers on the surface of the metal. Triazole concentrations must be maintained to protect the copper, which necessitates regular concentration determinations in cooling water. The 2060 IC Process Analyzer with UV/VIS detection is well-suited for this application, able to precisely and reliably measure multiple ionic and UV-active compounds simultaneously in cooling water.

Corrosion in the water-steam circuit of power plants leads to shorter lifetimes of most metal components and potentially dangerous situations. Flow Accelerated Corrosion (FAC) is a specific case, leading to thinned pipes and elevated Fe concentrations in the circuit. Additionally, metal transport issues such as with Cu from copper heat exchangers can lead to deposition on the high pressure turbine blades, decreasing their efficiency. Current methods can monitor but not prevent these issues, and analysis times are extremely long (up to three weeks). In combination with the power plant’s Distributed Control System (DCS), online monitoring of Fe and Cu with the 2060 Process Analyzer from Metrohm Process Analytics ensures that corrosion can be controlled before it affects the power plant efficiency, ultimately decreasing downtime and lowering maintenance costs. Results are offered within 20 minutes, allowing fast adjustments to the water-steam circuit to protect company assets.

Many refiners look at discounted opportunity crudes as a means to improve their margin spread. The varieties of these cheap crude oils on the market are growing in number, but they have hidden risks for the purchaser caused by factors such as high naphthenic acid and sulfur content. Sulfur compounds and naphthenic acids are among the substances that contribute to the corrosive nature of crude oils and petroleum products. This is why the risk of corrosion is increased when processing crude oils with high naphthenic acid and sulfur content. The refiner must balance the cost benefit versus the risk and the cost of corrosion control when processing these crudes. A reliable acid number determination is a crucial part of corrosion control. Guest authors Bert Thakkar, Bryce McGarvey, and Colette McGarvey of Imperial Oil and Larry Tucker and Lori Carey of Metrohm USA were involved in the development of the new ASTM Method D8045 for acid number determination. Here, they report on the method and how it came to be.

This Application Note evaluates corrosion in Type 430 stainless steel according to ASTM G5 with VIONIC powered by INTELLO and an ASTM-compliant corrosion cell setup.

Polarization resistance (Rp) can quantify the corrosion resistance of metals as an alternative to Tafel analysis. Its methodology and practical use as described in ASTM G59 are discussed.

This Application Note details ASTM G61-compliant corrosion measurements performed with VIONIC powered by INTELLO using Metrohm’s ASTM-compliant corrosion cells.

The ASTM B825 is used to determine the corrosion and tarnish film on metal surfaces. This is achieved by using the so-called cathodic reduction method. With the help of a Metrohm Autolab PGSTAT302N and a Metrohm Autolab 1 L corrosion cell, a procedure to replicate the ASTM B825 is shown.

Electrochemical impedance spectroscopy (EIS) is a widely used multidisciplinary technique for characterizing the behavior of complex electrochemical systems. EIS is employed in the study of a range of complex systems including batteries, catalysis, and corrosion processes. This Application Note focuses on the basic principles of EIS measurements.

The ASTM standard G100 is an electrochemical method to test localized corrosion of aluminum 3003-H14 and other alloys. A cyclic galvanostatic staircase polarization (galvanostaircase) is composed of an upward and a downward scan. The potential values at the end of each step are collected and linearly fitted, and the potential values at zero current are found.

In this Application Note, stepwise dissolution measurement (SDM) is applied to aluminum samples coated with different materials, in order to gain insights in corrosion protection. The combination of the Autolab PGSTAT204 with the 1 L Autolab corrosion cell and the NOVA software provides the suitable setup to perform SDM and other corrosion experiments.

Denatured fuel ethanol may contain additives such as corrosion inhibitors and detergents as well as contaminants from manufacturing that can affect the acidity of produced ethanol fuel. An increased acid content in solvents could lead to a variety of problems like a shorter storage stability or chemical corrosion.Using the dSolvotrode for indication, the acidity is determined as acetic acid by titration with sodium hydroxide as titrant.

Feedwater for steam generation in boiling water reactors (BWR) needs to be analyzed for corrosion products. Presence of transition metals, mainly nickel and iron, indicates corrosion problems. Traces of these ions are determined using Inline Preconcentration (MiPCT). After separation, post-column reaction with 4-(2-pyridylazo)resorcinol (PAR) allows VIS detection at 510 nm.

Denatured fuel ethanol may contain additives such as corrosion inhibitors and detergents as well as contaminants from manufacturing that can affect the acidity of produced ethanol fuel. An increased acid content in solvents could lead to a variety of problems like a shorter storage stability or chemical corrosion. Using the Optrode with phenolphthalein as indicator, the acidity is determined as acetic acid by titration with sodium hydroxide as titrant.

Water of the water-steam cycle of boiling water reactors (BWR) needs to be free of corrosive anions. Analyzing these trace anions allows the parallel determination of chromate, which is a potential corrosion product. Automated sample preparation includes variable Inline Preconcentration (MiPCT) and automatic calibration with a single multi-ion calibration standard.

Ethanol, bio-ethanol and biofuel (E85) are increasingly used as substitutes for petroleum-based fuels. During storage, they often come into contact with metallic substrates or surfaces, e.g., in barrels, tanks, or other containers. Excessive concentrations of ions in the stored fuel promotes corrosion. Monitoring the total concentration of the ions present in the fuel matrix should be the first step of an effective anti-corrosion strategy.An easy, fast, and cost-effective method to determine the total amount of ions is by measuring the electrical conductivity according to DIN 15938.

Measures to monitor or prevent corrosion are crucial in nuclear power plants, where significant risks to health and safety can occur if corrosion is left unchecked. Anions corrode metals under high temperature and pressure, therefore their concentrations must be monitored at all times. The analytical challenge in the primary circuit is detection of anions in the μg/L range alongside gram quantities of boric acid and lithium hydroxide. Precise, reliable trace analysis requires the method to be automated as much as possible. The 2060 IC Process Analyzer from Metrohm Process Analytics can measure several anions from a single injection, with combined Inline Preconcentration and Inline Matrix Elimination to measure low anion concentrations precisely and reliably time after time.

Anodizing metal surfaces improves resistance against corrosion and wear. Etching baths can be monitored precisely online with the 2060 TI Process Analyzer or 2026 HD Titrolyzer.

A typical electrochemical impedance spectroscopy (EIS) experimental setup consists of an electrochemical cell, a potentiostat/galvanostat, and a frequency response analyzer (FRA). This Application Note introduces common EIS experimental setups as well as details of the main experimental parameters.

In power plants, corrosion is the greatest enemy. If corrosive impurities are present in the circuit streams (e.g., chlorides and hydroxides), deposition of an insulating layer of scale on the heat transfer surfaces occurs, resulting in costly and critical downtimes. To ensure high throughput of power plants, online analysis of critical parameters such as sodium is highly advantageous for safety, protection, and process optimization. With the 2035 Process Analyzer from Metrohm Process Analytics, operators gain the information they need to accurately identify trends, reduce downtimes, and address operational issues before costly problems arise.

In this Application Note, hydrogen permeation experiments are conducted following the procedure described in the ASTM standard G148.

In power plants, corrosion is the primary factor leading to costly and critical downtimes. In a nuclear power plant, a separate water circuit known as the Pressurized Water Reactor (PWR) ensures radioactive material stays contained while still transferring heat and energy to the other circuits. Boric acid and lithium hydroxide are added specially to the PWR circuit in amounts which can complicate other analytical measurements. Lithium prevents corrosion and must be monitored, along with other cations such as zinc, nickel, and ammonium. In order to measure these cations online at sub-µg/L range in a single analysis, the 2060 IC Process Analyzer is offered with combined Inline Preconcentration and Inline Matrix Elimination. Several cations can be analyzed in a single injection, with automated sample preparation making precise and reliable measurements easier.

Neutralizing amines are added to adjust pH levels within the water-steam circuit of power plants to avoid corrosion-inducing conditions. This preventive maintenance can reduce costly and critical downtimes due to corrosion, however frequent monitoring of the amine chemistry is necessary to ensure conditions stay optimal. The 2060 IC Process Analyzer featuring the Metrohm intelligent Partial Loop Technique (MiPT) option is ideal for this application, with the ability to measure trace amounts of the analytes precisely and reliably through an automated method. The benefit of using IC is that multiple analytes can be monitored simultaneously, and here the ability to measure the presence of sodium next to the high ammonium or amine concentrations could indicate that cooling water is seeping into the circuit, indicating a problem upstream.

The 2060 XRF Process Analyzer continuously monitors elemental concentrations online within zinc-nickel electroplating baths to precisely guide chemical dosing.

In municipal water supplies, higher dissolved oxygen (DO) content is desirable because it improves the taste of drinking water. However, high DO levels also speed up corrosion in water pipes. For this reason, industries utilize water with as little DO as possible, and add scavengers such as sodium sulfite to remove any oxygen from a water supply. Municipal water supply pipes are normally coated inside with polyphosphates to protect the metal from contact with oxygen, thus allowing higher DO contents. Therefore, monitoring the DO content online in a water supply is important to assess its DO content to either improve taste or minimize pipe corrosion. Using an optical sensor, such as the O2-Lumitrode, allows a fast and reliable determination according to ISO 17289.

Electroless Ni plating offers superior surface finish and corrosion resistance. Anodic stripping voltammetry allows Bi stabilizer to be monitored in Ni plating baths.

Electroless nickel plating ensures low-cost wear and corrosion resistance. Monitoring lead stabilizer levels in Ni plating baths is possible with the Bi drop electrode.

Water in steel-based cooling systems requires a pH value slightly above 7 to prevent corrosion. Often ammonium or organic amines are applied for pH adjustement. This application shows the separation of typical amines besides inorganic cations. Sample preconcentration applies combined Inline Preconcentration and Matrix Elimination (MiPCT-ME).

Even in low concentration, sulfide ions cause odor and corrosion problems in ground water and waste water. They can release hydrogen sulfide in acidified water, which is toxic in even minuscule amounts. This Application Note describes the determination of sulfide concentration in water via direct measurement with the Ag/S-ISE in accordance with ASTM D4658.

In pressurized water reactors (PWRs), light water is used as primary coolant. Boron (as boric acid) readily absorbs neutrons and is added to the coolant to control reactivity. Lithium hydroxide assures a pH value greater than 7 to prevent corrosion. This application allows to measure sub-ppb levels of zinc, nickel, calcium, and magnesium besides high boric acid and lithium hydroxide concentrations.

Pickling baths are used in the galvanic industry to clean steel surfaces and prevent corrosion through passivation. Maintaining specific Fe2+/Fe3+ and free acid/total acid ratios is vital to ensure the baths' optimal performance, which directly impacts the final product quality and reduces production costs by minimizing reagent consumption. This application presents a method to regularly monitor the acid and iron composition in pickling baths online by using a process analyzer from Metrohm Process Analytics.

In pressurized water reactors (PWRs), light water is used as coolant in the primary side. Boron (as boric acid) is added to the coolant to absorb neutrons, thus controlling reactivity. Lithium hydroxide assures the alkaline pH value to prevent corrosion. This application allows to measure lithium content besides high boric acid concentrations. AN-C-138 shows the respective trace metal determination on the same system setup.

Water chemistry of the water-steam cycle is crucial for maintaining plant reliability and for ensuring optimal plant operational conditions. Impurities such as corrosion products in ionic, colloidal, or oxide forms are ubiquitous in feedwater, condensate, and reactor coolant. This application shows the determination of sub-ppb levels of Cu, Ni, Zn and standard cations (e.g., Na+, NH4+, Mg2+, Ca2+) in the water-steam cycle of a BWR.

Abrasive machining of e.g., metal parts requires a cooling lubricant. Their purpose besides cooling and lubrication is to inhibit corrosion. Amines are added to the emulsion to keep the pH high. In the actual application, DCHA and MDCHA have to be analyzed besides other amine components and inorganic cations. To avoid oil contamination on the IC system, Inline Dialysis is applied. The detection is performed by direct conductivity detection.

The Benfield Process is a well known procedure to remove H2S and CO2 from petroleum and industrial gases. Vanadium pentoxide is added as a corrosion inhibitor and is most effective in a certain V(IV)/V(V) ratio. Therefore, speciation and determination of V(IV) and V(V) is important. This speciation is easily achieved on A Metrosep A Supp 5 - 50/4.0 column with EDTA as an eluent and UV/VIS detection at 282 nm.

Phosphoric acid is a triprotic inorganic acid used for many purposes: as a raw material for the production of phosphate fertilizers, detergents, as an electrolyte in phosphoric acid fuel cells, rust removers, and for the passivation of iron and zinc to protect against corrosion. This Application Note presents an acid-base titration where the concentration of phosphoric acid is determined over all three of its dissociable protons by titrating it with sodium hydroxide.

Boiler feed water is a working medium in thermal power plant. To keep corrosion low, the pH value should be in the slightly alkali range, which is why amines are added to the feed water. This addition must be monitored regularly. Also important is the monitoring of the sodium concentration, because an increase of this indicates that cooling water is seeping into the condenser. Ion chromatography with conductivity detection following sequential suppression is the optimum system for monitoring, particularly in combination with intelligent Sample Preconcentration and Matrix Elimination.

Crude oil typically contains no organic halides. These are introduced at production sites, in pipelines, or in storage tanks. These components produce HF, HCl, and other acids in reforming and hydro-treating processes, leading to corrosion and catalyst poisoning. Speciation of the halides is an important parameter to measure in order to trace the contamination source. The current specifications expect to find less than 2 mg/kg organic chlorine in crude oil. Sulfur in crude oil could be quantified on the fly. Due to the specific request in this application, only the halogens are determined.

The presence of acidic components in volatile solvents could be a result of contamination, decomposition during storage, distribution or manufacture. An increased acid content in solvents could lead to a variety of problems like shorter storage stability or chemical corrosion. Using the Optrode for indication, the acidity is determined by photometric titration with sodium hydroxide as titrant and phenolphthalein as indicator. If the volatile solvent is water soluble, it is dissolved in deionized water, if not, it is dissolved in carbon-dioxide free ethanol.

Basic chemicals are added to petroleum products to prevent corrosion as they neutralize acidic components that form during the use and aging of these products. The base number (BN) gives an indication regarding the amount of these basic additives present, and it can be used as a measure for the degradation of the petroleum product.This Application Note describes the potentiometric determination of the base number according to ISO 3771, ASTM D2896, and IP 276 using the Metrohm Solvotrode easyClean and a fully automated OMNIS system.

Knowledge of the water content in lubricating oils, additives, and similar products is important in the manufacturing, purchase, sale, or transfer of petroleum products to help estimate their quality and performance characteristics. Monitoring the water content in such products can prevent damage to infrastructure and ensure safe operation by avoiding corrosion processes and subsequent engine wear. This White Paper explains the easy determination of moisture in petroleum samples by coulometric Karl Fischer titration according to the three procedures outlined in ASTM Method D6304. A comparison is given between the procedures to determine which is most suitable for different sample types.

Harmful industrial flue gases like H2S and CO2 cause corrosion of pipes and damage the environment. Adding the correct amount of amines in scrubber solutions, e.g. ethanolamines and methylamines, will neutralize these gases («gas sweetening»). Non-suppressed cation analysis with direct conductivity detection is a straightforward and robust technique for the quantification of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA) via ion chromatography. Thanks to the high capacity of the Metrosep C 6 column, large volumes can be injected without compromising the peak shapes. The analytical technique can be used at laboratory scale but also for process analysis.

Thermal power plants require enormous amounts of water, using high purity steam at high pressure to rotate turbines. A separate cooling water circuit is implemented, which helps to form a vacuum when the steam condenses after the turbines. Maintaining this vacuum with optimal condensation parameters is critical for the power plant efficiency. The copper condensers are susceptible to corrosion by ammonia, leading to an upper limit of 2 mg/L NH3 set by EPRI in cooling water. Small cracks in the condenser combined with the large pressure differential between the steam circuit and the cooling water circuit will contaminate the high purity water in the boiler, causing major problems and necessitating a shutdown for plant maintenance. Monitoring NH3 online in cooling water with a process analyzer can signal early problems in a plant before significant intermediation is necessary.

Alkaline additives in engine lubricants are used to prevent the build-up of acids and as a result, they inhibit corrosion. The total base number (TBN) indicates the amount of basic additives present in samples and thus can be used as a measure for the degradation of the lubricant. The standard test method for TBN in lubricants is potentiometric titration according to ASTM D2896. This method requires the use of toxic reagents involves a labor-intensive cleaning procedure. In contrast to the primary method, near-infrared spectroscopy (NIRS) is a fast analytical technique which does not produce any chemical waste and completes the TBN analysis in less than one minute.

Basic additives are added to petroleum products to inhibit corrosion as they have a neutralizing effect on acidic compounds, which are formed as a result of degradation processes. Total base number (TBN) indicates the amount of basic additives present and thus can be used as a measure for the degradation of the petroleum product.Using an automated titration system with a photometric sensor to detect the end point ensures that the titrations are always carried out under the same conditions. This improves the precision and reliability of the results.This Application Notes describes the fully automated photometric determination of TBN in used engine oil using the Metrohm Optrode for the indication of the methyl orange endpoint (at 520 nm).

The pHe is a measure of acid strength in alcohol fuels and in ethanol. It can be used as predictor of the corrosion potential of an ethanol-based fuel. The determination of the pHe is preferred over the total acidity, because total acidity overestimates the contribution of weak acids (e.g., carbonic acid) and underestimates the contribution of strong acids (e.g., sulfuric acid). Furthermore, the acid strength is an important parameter to determine in order to reduce the risk of failing motors.This Application Note describes the determination of the pHe value using the 913 pH Meter and the EtOH Trode according to ASTM D6423, which covers denatured fuel ethanol and ethanol fuel blends.

Tartaric Sulfuric Anodizing (TSA) is an established technique for corrosion protection in the aerospace industry. It is an alternative to the environmentally harmful chromic anodizing process. As such, a method to monitor the levels of sulfuric acid and tartaric acid in TSA plating baths is required. Potentiometric titration methods have been developed, and are widely used across the industry. Their disadvantage is that two titrations with different electrodes and solvents are required.In this Application Note, an alternative method is presented, where the concentration of both acids is determined in sequence using a thermometric sensor. Compared to potentiometric titration, thermometric titration is faster and more convenient (no sensor maintenance required). On a fully automated system, the determination of both parameters takes about 7 minutes.

Moisture in petroleum products causes several issues: corrosion and wear in pipelines and storage tanks, an increase in debris load resulting in diminished lubrication, blocked filters, or even harmful bacterial growth. As a result, increased water content can lead to infrastructure damage, higher maintenance costs, or even unwanted downtimes.Coulometric Karl Fischer titration is the method of choice for low water content in petroleum products. Using a Karl Fischer oven to vaporize the water present in the sample prior to titration not only greatly reduces matrix interferences, it can also be fully automated. This allows a reliable and cost-efficient analysis of the water content according to ASTM D6304 (Procedure B) in products such as diesel, hydraulic oil, lubricant, additive, turbine oil, and base oil.

Electroplating processes are used in several different industry sectors to protect the surface quality of various products against corrosion or abrasion and significantly improve their working life. It is essential to check the bath composition on a regular basis to ensure that the process is operating correctly. Typical examples of electroplating baths include alkaline degreasing baths or acidic or alkaline baths containing metals e.g. copper, nickel, or chromium, or components like chloride and cyanide. It is crucial that the chosen analysis technique fulfills high safety standards for these kinds of analyses and produces reliable results. The OMNIS Sample Robot system automatically pipettes and analyzes aggressive electroplating bath samples on different workstations, increasing the safety in the lab. This provides more reliable results in comparison to manual titration and is more time efficient as different parameters can be analyzed in parallel.

Iron is an essential element in human nutrition. It can be present in drinking water as a result of water treatment or from corrosion in the water piping system. There is no guideline value for iron in the World Health Organization’s «Guidelines for Drinking-water Quality» because typical levels usually found in drinking water are of no concern. However, there are national limit values in various countries. The European Union has set a guideline indicator value for iron of 200 μg/L. Voltammetry is a viable, less sophisticated alternative to atomic absorption spectroscopy (AAS) for the determination of iron in drinking water. While AAS (and competing methods) can only be performed in a laboratory, anodic stripping voltammetric determinations can be done used conventionally in the laboratory or alternatively in the field using the with 946 Portable VA Analyzer. The determination is carried out with adsorptive stripping voltammetry (AdSV) using 2,3-dihydroxynaphthalene (DHN) on the scTRACE Gold electrode.

The acid number (AN) is a measure for the quality of oils and their potential to enhance corrosion. When analyzing fresh, unused oils, the AN is used to ensure the specified quality from the manufacturer, whereas for used oils the AN is determined to observe its increase until a critical level is reached. Although it is generally assumed that the AN correlates to the corrosive potential of the oil, this is not exactly correct, as it is the change of the AN value which indicates this issue. Therefore it is necessary to determine the AN on a regular basis.Several standards already exist to determine AN via titration methods, however it is also possible to measure this parameter via spectroscopic (NIRS) methodology. No matter which technique you choose, Metrohm has you covered with high-performance instruments suitable for these published norms.

In this White Paper, details of the electronic (PGSTAT) and electrochemical cell grounding are presented together with the necessity of using a floating PGSTAT for different application and experimental examples. Due to the wide variation of experimental requirements and kinds of electrochemical cells, the use of an electrochemical instrument with a selectable floating feature (such as VIONIC) which brings additional versatility to the user is recommended.

Corrosion of metallic components is an inherent problem for engines, because metals naturally tend to oxidize in the presence of water and/or acids. Increased acid content is indicated by a low pH value, and could lead to a variety of problems like a shorter storage life (stability) or a reduced buffer capacity of the used engine coolant or antirust.In this Application Note, engine coolants or antirust samples are dissolved in water, and the pH measurement using the Profitrode is carried out according to ASTM D1287.

This application explains ohmic iR drop in electrochemical cells, its causes, and strategies to minimize its impact for accurate and reliable potential measurements.

Corrosion of metallic components is an inherent problem for engines, because metals naturally tend to oxidize in the presence of water and/or low pH value. The reserve alkalinity of engine coolants and antirusts is a measure of the buffering ability to absorb acidity. The reserve alkalinity is frequently used for quality control during production and often listed in the specifications of the coolants. A fast and accurate determination is therefore important.This Application Note describes the straightforward determination of reserve alkalinity according to ASTM D1121. Using a fully automated system allows an accurate and reliable determination due to the reduction of human errors. Furthermore, the operator is free to carry out other tasks increasing the efficiency of the laboratory.

Explore how to construct simple and complex equivalent circuit models for fitting EIS data in this Application Note. Nyquist plots are shown for each example.

Determination of sulfate, molybdate, and chromate in a plating bath using anion chromatography with conductivity detection after chemical suppression.

This Application Note is based on the ASTM standard G150, developed to test the resistance of stainless steel, and otheralloys related to stainless steel, on pitting formation at elevated temperature. This is achieved by determining the potential-independent critical pitting temperature (CPT), defined as the lowest temperature at which pitting evolution occurs. The CPT experiment consists of applying a potential to the specimen while the cell temperature is raised and recording the current.

The Devanathan-Stachurski cell (or «H cell») is successfully used to evaluate the permeation of hydrogen through sheets or membranes. As small amounts of hydrogen pass through the sheet or membrane, a very sensitive potentiostat is required for its detection. A study of the hydrogen permeation properties of different iron sheets is discussed in this Application Note while taking the instrumental requirements into account.

Acid throwing, a historical method for retribution against women, has become a modern threat of a different nature. Concentrated acids and other corrosive substances have emerged as modern tools of social violence. Aggressors use common plastic containers with openings that create a powerful directional spray, such as lemon juice squeeze bottles. Sulfuric and phosphoric acids were chosen for analysis here due to their highly corrosive nature- acid attacks in London most commonly use sulfuric, phosphoric, and nitric acids.2017 saw a remarkable number of acid attacks in the UK, with reported incidences averaging 2x a day. Detection and regulation of acids may contribute to prevention of this social scourge.

Mercaptans in fuels are corrosive and regulated at trace levels. SERS enhances Raman signals to enable their accurate detection and quantification below standard LODs.

The acid number (AN) of insulating, transformer, and turbine oils is crucial to ensure safe operation, operating equipment control, and corrosion prevention. These oils generally have low AN specifications and their AN determination by manual color-indicator titration is difficult, especially when analyzing colored samples.Using a Titrator with a photometric sensor to detect the end point ensures that the titrations are always carried out under the same conditions. This greatly increases the precision and reliability of the results, which in turn results in improved monitoring for your operations.

Coal contains a certain amount of fluorine, chlorine, and sulfur compounds. During combustion of the coal, these components release corrosive acids (e.g., fluorine compounds form hydrofluoric acid). Thermal power plants therefore request low-fluorine coal to avoid massive hydrofluoric acid production. In this application note, fluorine content in coal is determined by ion chromatography after pyrohydrolysis.

Monoethylene glycol (MEG) is used to remove water from natural gas before further processing. Due to high temperatures applied, glycol degradation to glycolic, formic, and acetic acid may occur. These reactions are unwanted as the emerging acids are corrosive. The determination of the organic acids is achieved by ion-exclusion chromatography with conductivity detection after inverse suppression.

Monoethylene glycol is used for dehydration of the natural gas before liquefaction and has to be checked for its purity on routine basis. Inorganic anions and their corresponding acids are corrosive. Therefore, they have to be kept at minimum level. The separation is performed on a microbore Metrosep A Supp 16 - 250/2.0 column and quantified by conductivity detection after sequential suppression.

Bicine (2-(Bis(2-hydroxyethyl)amino)acetic acid) is a corrosive component. It has to be avoided in acidic gas sweetening solvents. These solvents are based on organic amines. Bicine is amphoteric, holding a carboxylic and an amine group. Under the applied conditions, the amine groups are at least partially protonated and therefore may be separated by cation chromatography. The detection mode is direct conductivity detection.

Iron ore is an important resource for steel production. Its natural content of halogens is a quality characteristic due to the corrosiveness of the respective halogenides. Combustion IC applying the sacrificial vial technology is used for the analysis of fluorine and chlorine in ore. WO3 usually is added to improve the release of SO2 and therefore sulfur recovery. In this application, it also significantly improves the recovery of fluoride.

The pH value and oxidation reduction potential (ORP) of soil provide important information about soil properties, such as solubility of minerals and ion mobility. Knowledge of these properties allows making predictions concerning plant growth, bacterial activity, nutrients that may be needed, possible corrosive effects on buildings, etc.Here, the determination of the pH value is described according to ISO 10390, EN 15933 and ASTM D4972. Th oxidation reduction potential determination is carried out in a suspension.

A combination of the 850 Professional IC and the 872 Extension Module Liquid Handling opens the field of Metrohm’s online monitoring by IC. In this application, Inline Preconcentration is coupled to Matrix Elimination (MiPCT-ME). By removing excess matrix components, corrosive anions can be sensitively determined. Additionally, this technique allows automated calibration using a single multi-ion standard solution. Online trace analysis for chloride and sulfate is possible for several different sample lines.

Latex gloves are used in clean room environments in order to prevent contaminations. The use of gloves that release corrosive halogenides or sulfate is forbidden in nuclear power plants. The total content of halogen and sulfur is determined by means of Combustion Ion Chromatography. An eluate test is carried out to check the elutable percentage of halogens and sulfate from gloves. Sample preparation is comprised of preconcentration and matrix elimination (MiPCT-ME), as described in AN-S-304.Keyword: pyrohydrolysis

Toxic and corrosive chemicals such as p-toluenesulfonyl isocyanate (TSI) and tetrabutylammonium hydroxide are used for the Hydroxyl Number analysis of polyols by titration according to ASTM D4274-16. This application note demonstrates how the XDS RapidLiquid Analyzer operating in the visible and near-infrared spectral region (Vis-NIR) provides a cost-efficient and fast solution for the determination of the hydroxyl (OH) number of polyols. With no sample preparation or chemicals needed, Vis-NIR spectroscopy allows for the analysis of polyols in less than a minute.

Ion chromatography (IC) is the method of choice to determine the concentration of common ions in water. This information is crucial as drinking water must meet certain standards to guarantee health (e.g., nitrite and nitrate), as well as technical suitability (e.g., corrosiveness of chloride and sulfate). The Eco IC is an ion chromatograph suitable for economical routine water analysis. Using an A Supp 17 anion column, the analysis of major anions in drinking waters is robust and can be performed at ambient temperatures without additional temperature conditioning.

Copper concentrate is an important raw material for copper mills. The concentrate is often contaminated with corrosive fluorine, which is why the fluorine concentration must be checked at regular intervals. A convenient and reliable determination method is Combustion IC in combination with sacrificing vial technology. The sample is placed inside the quartz combustion pipe in a horizontally positioned quartz vial, both ends of which are sealed with glass wool. During combustion, the quartz-destroying components (e.g., fluoride, alkali and earth alkali metals) that are released are captured by the quartz vial and the quartz wool, ensuring that they are thus unable to reach the quartz combustion pipe at all.Keyword: pyrohydrolysis

Natural liquefied petroleum gas (LPG) is a mixture of hydrocarbon gases (e.g. propane and butane), but it also contains acidic contaminants (e.g. carbon dioxide or hydrogen sulfide). These gases need to be scrubbed from the petroleum gas as they are highly corrosive. This purification step, referred to as «sweetening», is often performed by using alkaline amine solutions. Thereby the amine solution absorbs the acidic gases, while the raw LPG is neutralized. To guarantee that amine residues in the sweetened gas do not influence the gas quality, the amines in the final LPG are determined by scrubbing the gas with acetic acid as described in UOP 936-96. The recent method enables the quantification of the amines dimethylamine (DMA), diethylamine (DEA), dipropylamine (DPA), and dibutylamine (DBA) by separation from standard cations.

In the petrochemical industry, natural gas is processed to remove contaminants and meet product specifications. Process contaminants include acidic gases such as hydrogen sulfide and carbon dioxide, which can corrode costly refinery equipment downstream. Typically, the acidic gases are removed via alkanolamine treatment using monoethanolamine (MEA) or methyldiethanolamine (MDEA). The amine solutions absorb the acidic gases, and then the amine compounds are removed from the natural gas. In addition to the acidic gases, heat stable salts (HSS) that remain in the natural gas are also corrosive to the treatment plants. These are also removed via gas sweetening and need to be determined in the used gas sweetening amine solution. Some typical heat stable salts of interest include acetate (1), formate (2), chloride (3), phosphate (4), sulfate (5), oxalate (6), thiosulfate (7), and thiocyanate (8).

Higher levels of copper in drinking water are usually caused by corrosive action of water leaching copper from copper pipes. While copper is an essential nutrient for the human organism, ingestion of higher concentrations have an adverse effect on human health. The current World Health Organization’s «Guidelines for Drinking-water Quality» recommend a maximum concentration of 2000 μg/L. With a limit of detection (LOD) of 0.5 μg/L, anodic stripping voltammetry is a viable, less sophisticated alternative to atomic absorption spectroscopy (AAS) for the determination of copper in drinking water. While AAS (and competing methods) can only be performed in a laboratory, anodic stripping voltammetry can be used conventionally in the laboratory or alternatively in the field with the 946 Portable VA Analyzer. The determination is carried out on the scTRACE Gold electrode.

OMNIS Client/Server boosts business performance with scalable server management, cutting costs by reducing hardware, energy use, and maintenance across locations.

Online mercaptan and H₂S monitoring with the 2060 TI Ex Proof Analyzer certified for Zone-1 and Zone-2 areas.

A safer way to monitor moisture content in crude distillation unit overhead fractions is with inline near-infrared spectroscopy using the 2060 The NIR-Ex Analyzer.

This Process Application Note details the simultaneous online analysis of H2S and NH3 in sour water which was previously treated in the sour water stripper (SWS). The method includes automatic cleaning and calibration. Fast and accurate results are continuously supplied for process control.

Carbon capture systems strip carbon dioxide from flue gases. Online analysis of amines and carbon dioxide enhances amine usage efficiency and reduces operational costs.

Online acid number analysis in various oil products is possible with thermometric catalytic titration according to ASTM D8045 using the 2060 TI Ex Proof Process Analyzer.

In an electroless plating bath, the consumed ingredients have to be regularly replenished to ensure an even layer of nickel-phosphorus alloy. This requires online monitoring of the active bath constituents. Parameters to be controlled are pH value (4.5–5.0) as well as nickel (NiSO4 < 10 g/L) and hypophosphite concentration (NaH2PO2: 1–12%). Other measurement options include sulfate, alkalinity, and organic additives (via CVS).

Automated online analysis with the 2060 TI Ex Proof Process Analyzer facilitates constant monitoring of the crude oil desalting process according to ASTM D3230.

This Application Bulletin describes the determination of the total acid number in various oil samples by catalytic thermometric titration as per ASTM D8045.

One way to maximize heat transfer efficiency and reduce costs in a power plant is by controlling the water chemistry in the cooling circuit. This cooling water is kept alkaline to maintain the protective oxide layer on the metal piping throughout the water circuit. However alkalinity above the recommended range increases the probability of scale formation (deposition), so it is buffered with carbonate (CO32-) and bicarbonate ions (HCO3-). Titration of the cooling water to pH 4.5 gives the so-called "M-Alkalinity" (methyl orange alkalinity), a measure of total alkalinity. Below this pH, there is no more alkalinity present, only free acid (H+), carbonic acid (H2CO3), and CO2.

Accurate analysis of complexing agents in galvanic baths is possible with inline Raman spectroscopy. This Application Note shows an example using a 2060 Raman Analyzer.

The acid value of fatty acid methyl esters (FAME) like biodiesel can be determined according to EN 14104 using photometric titration with OMNIS and the Optrode.

This Application Note explains how the 2060 XRF Process Analyzer enables real-time chemical monitoring of copper, tin, and zinc concentrations in white bronze plating baths.

Boric acid requires precise monitoring in the primary circuit to control nuclear reactor reactivity. The 2060 TI Process Analyzer monitors boric acid online in near-real time.

Here, the most common circuit elements for EIS are introduced which may be assembled in different configurations to obtain equivalent circuits used for data analysis.

Zirconium can be analyzed quickly and easily in slightly acidic solutions with back titration. The ion-selective copper electrode is used in this Application Note to determine zirconium in aqueous solution.

This application note describes the fast, accurate determination of cobalt with a copper ion-selective electrode (Cu ISE) and Cu-EDTA complex as an indicator.

Determination of Total Acid Number (TAN) values in biodiesel to <0.05 mg KOH/g sample.

Automated determination of total acid number (TAN) in new and used lubricating oils and crude oils using the 814 USB Sample Processor. Dissolve oil sample in mixture of toluene and 2-propanol, add paraformaldehyde and titrate with 0.1 mol/L or 0.01 mol/L KOH in propan-2-ol. The endpoint is indicated by an endothermic response caused by the base-catalyzed depolymerization of paraformaldehyde.Reference: 1. M. J. D. Carneiro, M. A. Feres Júnior, and O. E. S. Godinho. Determination of the acidity of oils using paraformaldehyde as a thermometric end-point indicator. J. Braz. Chem. Soc. 13 (5) 692-694 (2002)

The thermometric titration method presented here permits a simple and direct determination of the total acid number (TAN) in petroleum products. It is an invaluable alternative to current manual and potentiometric methods. Thermometric titration uses a maintenance-free temperature sensor that does not require rehydration and is free of fouling and matrix effects. The procedure requires minimal sample preparation. Results agree closely with those from the potentiometric titrimetric procedure according to ASTM D664, but the thermometric titration method is far superior in terms of reproducibility and speed of analysis, with determinations being complete in approximately one minute.

The iron concentration in boiler feed water has to be monitored to ensure reliable and safe operation of the water-steam circuit. Various guidelines set limits for the maximum iron content.The concentration of total iron in boiler feed water can be determined with high sensitivity using adsorptive stripping voltammetry (AdSV) using 2,3- dihydroxynaphthalene (DHN) as complexing agent. Voltammetry is a viable, less sophisticated alternative to atomic absorption spectroscopy (AAS) or inductive couple plasma (ICP) for the determination of iron with only a moderate investment in hardware required and low running costs.

Monitoring Sb(III) stabilizer levels during electroless Ni plating is critical for high-quality coatings. Anodic stripping voltammetry offers fast, reliable Sb(III) analysis.

To determine water in crude oil, ASTM D4928 recommends coulometric Karl Fischer titration with the oven method, allowing full automation for high reproducibility.

The total acid number (TAN) is an important parameter for assessing the acidity of oils and fuels. This Application Note determines TAN using conductometric titration.

Lead is commonly used as stabilizer in electroless nickel plating processes. The regular and precise determination of the electrochemically active Pb(II) concentration is essential to keep the plating process running optimally under stable conditions. Differential pulse anodic stripping voltammetry can be used to determine the active lead content after dilution. The voltammetric determination has been established as a straightforward, sensitive, selective, and interference-free method for this application.

Electroless nickel plating is an important and well established process in the surface finishing industry. In the past, the addition of small amounts of lead has widely been used to stabilize the plating bath. With the increasing number of restrictions in recent years on the use of lead in consumber products, particularly electronics, alternative stabilizers were developed and introduced. One of the stabilizers used as lead replacement is iodate. It can be used as a single additive or in combination with bismuth or antimony. This method allows the determination of iodate directly in the plating bath sample by polarography. The method is simple and fast, however, sensitive and robust.

Near-infrared spectroscopy streamlines ethylene tetrafluoroethylene production by offering rapid, chemical-free analysis of melt flow rate and moisture content.

This Application Note describes the conductometric determination of the total base number in engine oil according to IP 400.

This Application Note highlights near-infrared spectroscopy as a faster, cost-effective alternative to KF titration for predicting water content in diesel fuel.

This Application Note presents a walkthrough of an experiment on 4-nitrothiophenol using hyphenated EC-Raman, a combination of Raman spectroscopy and electrochemistry.

This Application Note describes carbonate determination with ion chromatography in a 50% sodium hydroxide solution. Sodium hydroxide solutions form carbonates through the absorption of carbon dioxide from ambient air. The carbonate content of an NaOH solution is determined using ion-exclusion chromatography with subsequent conductivity detection following inverse suppression. The samples are diluted 1:20 prior to the analysis and – in order to prevent CO2 absorption – stored in closed sample vessels.

Raman spectroscopy with PLS modeling enables rapid, accurate, nondestructive quantification of the total phosphate content in solution with minimal sample preparation.

Excessive silica concentrations in the boiler feed water can lead to deposits on turbine blades and must therefore be avoided. Silica analysis is carried out via differential photometry using a leading-edge technology thermostatic cuvette module for non-sample contact at the detector. Typical concentration ranges for silica are 0–50 ppb and 0–1 ppm or higher.

Metrohm’s MIRA XTR handheld Raman spectrometer enables fast, reagent-free identification of phosphate species, enabling continuous monitoring of dynamic systems.

This Application Note presents the Mott-Schottky measurement, an extension of electrochemical impedance spectroscopy (EIS), on a popular semiconducting material.

This application note demonstrates EQCM D for simultaneous mass and dissipation analysis of Ni(OH)₂ electrodeposition.

The determination of the acid number plays a significant role in the analysis of petroleum products. This is manifested in the numerous standard procedures in use over the world (internal specifications of multinational companies, national and international specifications of ASTM, DIN, IP, ISO, etc.). These procedures differ mainly in the composition of the used solvents and titrants.This bulletin describes the determination of the acid number in petroleum products by applying different types of titration.The potentiometric determination is described according to ASTM D664, the photometric according to ASTM D974 and the thermometric titration according to ASTM D8045.

This Application Note presents a potentiometric titration method for trace H2S analysis in water on an OMNIS system using silver nitrate and an Ag Titrode.

The Kraft process is the dominant pulping process in the pulp and paper industry with the highest chemical recovery efficiency. In order to run each part of the papermaking process optimally, constant quality checks and analyses should be performed. This Process Application Note illustrates the straightforward online analysis of alkali (active, effective, total titratable alkali (TTA)), carbonate, hydroxide, sulfide and the causticizing degree (CE%) in pulping liquors using a 2060 Process Analyzer from Metrohm Process Analytics.

Lithium is a soft alkali metal that is typically obtained from salt lake brines. Lithium is used for many applications, but especially for production of lithium-ion batteries in electric cars, mobile phones, and more. This Process Application Note presents a method to monitor lithium as well as other cations in brines by online process ion chromatography (IC), a multiparameter analytical technique that can measure ionic analytes in a wide range of concentrations.

This application note presents near-infrared spectroscopy (NIRS) for the rapid and reliable simultaneous quantification of ethanol, glycerol, hydrogen peroxide, and water content in hand sanitizer formulations.

The Metrosep A Supp 21 column and 948 Continuous IC Module, CEP enable efficient, automated single-run analysis of major anions and disinfection byproducts in water.