Applications

The present article addresses the theory, practical aspects and troubleshooting of potentiometry.

This white paper presents six technical tips that you should consider before taking a pH measurement.

With significant global viral outbreaks becoming the norm rather than generational outliers, it is imperative that fast, sensitive, and cost-effective testing is available to the masses. Screen-printed electrodes (SPEs) allow rapid, widespread testing of populations for infectious disease, without the need of skilled personnel or burdensome equipment in the field. The possibility of point-of-care (POC) testing with SPEs has been exhibited in several recent studies. Metrohm DropSens combines high production capabilites of custom-made SPEs with a valid ISO 13485 certification "Manufacturing of sensors for medical devices", meaning testing procedures developed on these SPEs can be reliably scaled up for larger operations, with easier regulatory approval for commercialization.

In this work, time resolved Raman spectroelectrochemistry measurements with screen printed electrodes are shown. The instrument used combines in a totally integrated box: a 785 nm laser source, a high resolution Raman spectrometer and a bipotentiostat/galvanostat. Experiments are controlled with an excellent spectroelectrochemical software which allows real time data collection and useful data treatment.

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.

Ion chromatography mass spectrometry (IC-MS) is a powerful tool that can handle many challenging analytical tasks which cannot be performed adequately by IC alone. IC-MS is a robust, sensitive, and selective technique used for the determination of polar contaminants like inorganic anions, organic acids, haloacetic acids, oxyhalides, or alkali and alkaline earth metals. After separation of the sample components via IC, mass selective detection guarantees peak identity with low detection limits. The inclusion of automated Metrohm Inline Sample Preparation (MISP) allows not only water samples, but also chemicals, organic solvents, or post-explosion residues to be readily analyzed without need for extensive manual laboratory work. This White Paper explains the benefits of IC-MS over IC in certain cases, the hyphenation of IC and different MS systems, as well as related norms and standards.

This White Paper introduces seamless measurements that are possible with VIONIC powered by INTELLO and applications that can benefit from this unique feature. The combination of software and new generation electronics provides data in real-time with no gaps or missed reactions.

White paper about Raman spectroscopy and electrochemistry and their combination (electrochemical Raman).

This White Paper focuses on selected IC-MS applications for the straightforward identification and quantification of organic acids and inorganic anions in different matrices.

Free White Paper outlines the fundamental principles of the nitrogen reduction reaction. It then delves into the technical barriers hindering the industrialization of green ammonia production, their impact on final yield and selectivity, and potential strategies or research gaps to overcome these issues.

This work was carried out with a Metrosep C 2 - 150 separation column, the following eluent parameters being investigated: nitric, tartaric, citric and oxalic acid concentration and concentration of the complexing anion of dipicolinic acid (DPA). The aim was to determine the effect of these parameters plus that of the column temperature on the retention times of alkali metals, alkaline earth metals, ammonium and amines using ion exchange chromatography with non-suppressed conductivity detection. Due to similar affinities for the ion exchange column, transition metals are difficult to separate with the classical nitric, tartaric, citric and oxalic acid eluents. Partial complexation with the dipicolinate ligand significantly shortens the retention times and improves the separation efficiency. However, too strong complexation results in a rapid passage through the column and thus in a complete loss of separation. Apart from a change in the elution order of magnesium and calcium at high DPA concentrations, other non-amine cations are only slightly affected by the eluent composition. Irrespective of the tartaric acid and nitric acid concentration in the eluent, an increase in column temperature shortens the retention times and slightly improves the peak symmetries of organic amine cations, particularly in the case of the trimethylamine cation. In contrast, an increase in column temperature in the presence of DPA concentrations exceeding 0.02 mmol/L increases the retention time of the transition metals. Depending on the separation problem, variation of the pH value, the use of a complexing agent and/or an increase in column temperature are powerful tools for broadening the scope of cation chromatography.

By using the 800 Dosino and the 849 Level Control as the only additional devices, Metrohm`s intelligent ion chromatography (IC) systems - the 850 Professional IC and the Compact IC family - can be easily extended to perform any unattended inline eluent preparation. Fully controlled by MagIC NetTM, the 849 Level Control monitors the eluent level while the Dosino performs all dosing and liquid handling tasks. Consecutive injections of a 250-µg/L standard over approximately 20 days revealed an excellent retention-time stability. After more than 800 consecutive injections, relative standard deviations for anions (F-, Cl-, NO2-, Br-, NO3-, PO43-, SO42-) and cations (Li+ , Na+, NH4+, K+, Ca2+, Mg2+) were smaller than 0.55 and 0.41%, respectively. In the case of a 24-hour sequence, retention-time precision for anions and cations was better than 0.09 and 0.08%, respectively. The presented inline eluent preparation system increases the retention-time reproducibility and allows the determination of anions and cations over a one-month period without manual eluent preparation.

Metrohm`s intelligent Preconcentration Technique with Matrix Elimination (MiPCT-ME) excels in its capacity to perform automatic ion chromatographic determinations over 6 orders of magnitude. Crucial requirements for this are the system`s intelligence and the exact measurement of the sample volume. While the intelligence allows to compare results and take decisions, the dosing device takes over the high-precision liquid handling of even single-digit microliter volumes to the preconcentration column. By using only one analytical setup and without additional rinsing, samples containing both ultratraces and high concentrations can be analyzed.As the other Metrohm Inline Techniques, the MiPCT-ME technique presented reduces the workload, ensures complete traceability, is free of carryover effects and significantly improves accuracy and reproducibility of the results.

Raman spectroscopy is an advantageous analytical tool that allows for the measurement of molecular structure and identifying chemical composition of materials based on the rotational and vibrational modes of a molecule. With advanced technology and an optimized optical design, the B&W Tek BAC102 series E-grade probe can access lower frequency modes down to 65 cm-1, providing key information for applications in protein characterization, polymorph detection, and identification, along with material phase and structure determination.

The benefits of a TE-cooled spectrometer in Raman systems are discussed to deliver lower system noise over longer integration times, resulting in lower limits of detection.

This article demonstrates the utility of portable Raman spectroscopy as a versatile tool for process analytical technology (PAT) for raw material identification, in-situ monitoring of reactions in developing active pharmaceutical ingredients (APIs), and for real-time process monitoring. Raw material identification is done for verification of starting materials as required by PIC/S and cGMP, and can be readily done with handheld Raman. Portable Raman systems allow users to make measurements to bring process understanding and also provide proof of concept for the Raman measurements to be implemented in pilot plants or large-scale production sites. For known reactions which are repetitively performed or for continuous online process monitoring of reactions, Raman provides a convenient solution for process understanding and the basis for process control.

Lithium-ion batteries must be completely free of water (concentration of H2O < 20 mg/kg), because water reacts with the conducting salt, e.g., LiPF6, to form hydrofluoric acid.The water content of several materials used in lithium ion batteries can be determined reliably and precisely by coulometric Karl-Fischer titration. In this Application Bulletin the determination for the following materials is described:raw materials for the manufacture of lithium-ion batteries (e.g., solvents for electrolytes, carbon black/graphite); electrode coating preparations (slurry) for anode and cathode coating; the coated anode and cathode foils as well as in separator foil and in the combined material; electrolytes for lithium-ion batteries;

This bulletin contains two parts. The first part gives a short theoretical overview while more details are offered in the Metrohm Monograph Conductometry. The second, practice-oriented part deals with the following subjects:Conductivity measurements in general; Determination of the cell constant; Determination of the temperature coefficient; Conductivity measurement in water samples; TDS – Total Dissolved Solids; Conductometric titrations;

This Bulletin, using practical examples, indicates how the user can achieve optimum pH measurements. As this Bulletin is intended for actual practice, the fundamentals - which can be found in numerous books and publications - are treated only briefly.

Standardisation of sodium tetraphenylborate (NaTPB) solution for the determination of potassium and for nonionicsurfactants.

Standardization of cetyl pyridinium chloride solutions for use as a cationic surfactant titrant in the determination ofanionic surfactants such as sodium lauryl ether sulfate.

This Application Note explains how to use magnesium to standardize tetrasodium EDTA titrant.

Standardization of 0.1mol/L perchloric acid in glacial acetic acid by catalyzed endpoint thermometric titration.

Standardization of 1 mol/L tetrasodium EDTA (Na4EDTA) solutions by titration with standard magnesium solution.

Standardization of disodium dimethylglyoximate by thermometric titration with standard Ni(II) solution.

This Application Note shows that the parameter of surface basicity of zeolites can be measured by thermometric titration.

This Application Note describes in detail how to determine the blank value and the titer for thermometric titrations using tiamo™.

Combustion ion chromatography (CIC) measures AOX (adsorbable organically bound halogens, i.e., AOCl, AOBr, AOI) and AOF as well as CIC AOX(Cl) according to DIN 38409-59 and ISO/DIS 18127.

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

Determination of lithium, sodium, ammonium, potassium, manganese, calcium, magnesium, strontium, and barium using cation chromatography with direct conductivity detection.

Fast IC means short run times and a high sample throughput on columns with a relatively high flow rate and the standard eluent. Mono-, di- and trimethylamine are separated with the Metrosep C 4 - 150/2.0 within four minutes.

The use of an appropriate full scale together with the zero function of the 732 IC Detector minimizes baseline noise dramatically. Much lower detection limits are achieved.

Determination of aluminum using cation chromatography, post-column reaction and UV detection.

Determination of traces of ammonium in the presence of sodium, potassium, magnesium, and calcium using cation chromatography with direct conductivity detection.

The Metrosep C 6 columns have a higher capacity than those of the Metrosep C 4. The present Application Note describes the exceptional separating efficiency for standard cations with the three Metrosep C 6 column lengths available. The outstanding sodium-ammonia separation is particularly noteworthy.

Sample dilution is a work-intensive routine task in the analysis laboratory. An automatic two-step dilution exponentiates the dilution factor – 1:100 – thus incorporating a dilution factor of 10,000. The intelligent dilution is made possible by MagIC Net, which calculates the essential dilution steps, and by the dosing properties of the 800 Dosino and the Liquid Handling Station. The Application Note shows statistical results of a 1:10,000 dilution.

The high-capacity Metrosep C 6 - 150/4.0 cation column convinces with outstanding separations, narrow peaks, and a multitude of available eluents. In this Note, the selectivity for alkali, earth alkali, and certain transition metals, in addition to methyl and ethanol amines, is shown using a nitric acid eluent and direct conductivity detection.

Determination of hydroxylamine, ethanolamine, triethanolamine, and hydrazine using cation chromatography with direct conductivity detection.

Determination of chromate using anion chromatography with post-column reaction and UV/VIS detection.

Determination of organic acids and phosphate using ion-exclusion chromatography with direct conductivity detection.

Determination of gluconate, fluoride, formate, chloride, nitrate, and salicylate using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride and sulfate in an electrolyte used in sensors for transcutaneous CO2 measurement using anion chromatography with conductivity detection after chemical suppression.

OpenLab CDS is the newest generation of the Agilent chromatography data systems platform. The Metrohm IC Driver 1.0 for OpenLab CDS enables introducing Metrohm IC instruments to this platform for full control and data acquisition. This application shows the analysis of iodide by amperometric detection, enabling detection at trace levels. The eluent is produced automatically by the 941 Eluent Production Module. In this way, amperometric detection can be executed with the same functionality and performance as with MagIC Net.

Determination of 1 (3) µg/L of chloride, nitrite, bromide, nitrate, phosphate, and sulfate after direct injection using anion chromatography with conductivity detection after chemical suppression.

Determination of bromide, sulfate, and iodide in 1 g/L sodium chloride using anion chromatography with conductivity detection after chemical suppression.

Determination of iodide, thiosulfate, and thiocyanate in the presence of fluoride, chloride, nitrite, bromide, nitrate, phosphate, and sulfate using anion chromatography with a high-pressure gradient and conductivity detection after chemical suppression.

Calibration of fluoride, chloride, nitrite, bromide, nitrate, phosphate, and sulfate using intelligent partial loop injection technique and anion chromatography with conductivity detection after sequential suppression. This technique allows a calibration range of 1:100 (e.g. 1 μg/L to 100 μg/L corresponding to 2 μL to 200 μL injected volume) out of 1 calibration solution. Applying the full range of partial loop injection to the samples one calibration covers a sample concentration range of 1 to 10'000.

Determination of fluoride, chloride, nitrate, phosphate, sulfate, silicate, and hexafluorosilicate (calculated) using anion chromatography with conductivity detection after chemical suppression and subsequent UV/VIS detection with post-column reaction (see AN U-48). Hexafluorosilicate is hydrolyzed into fluoride and silicate. Both anion concentrations can be used for the calculation of the SiF62- concentration.

The state-of-the-art tri-chamber suppressor technology provides a fresh suppressor chamber for each measurement. The complete regeneration of the chamber after each sample ensures highly efficient cation exchange – today, tomorrow, and even after years of continuous operation.The chromatograms as well as the statistical data demonstrate the outstanding reproducibility of the measurements with the Metrohm Suppressor Module.

Fast IC means a high sample throughput. This is attained with short columns, relatively high flows and strong eluents. Malate, tartrate, oxalate as well as sulfate are separated within three minutes.