Applications

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.

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

UV/VIS detection is one of the most sensitive detection techniques in trace-level chromatography. Sometimes, however, spectrophotometric detection lacks sensitivity, selectivity or reproducibility and chemical derivatizations are required. By using Metrohm`s rugged and versatile flow-through reactor, single- or multi-step derivatizations can be done fully automatically, in either pre- or post-column mode at any temperature between 25…120 °C. The variable reactor geometry allows to adjust the reactor residence time of the reactants according to derivatization kinetics. The flexibility of the reactor is demonstrated by optimizing four widespread post-column techniques: the relatively slow ninhydrin reaction with amino acids and the fast derivatizations of silicate, bromate and chromate(VI).

A high throughput automated system was developed to determine pH of culture media using a pH module equipped with an external flow cell. A custom septum-piercing, vented needle was developed to accommodate the shape and size of the customer sample vials. For this application, both accurate and precise pH measurements were required. The data presented in this document was collected by a customer as a part of their validation process and was provided for use with their consent.

Sodium fluoride is used as a preservative in biological samples for alcohol analysis. All submitted blood samples, including those taken from vehicle drivers suspected of driving under the influence of liquor, have to be tested for adequate preservation prior to alcohol determination by gas chromatography. This is critical to ensure adequate sample preservation. Inadequate sample preservation may allow glycolysis and/or microorganism growth to produce ethanol.In the past this has been done by direct potentiometric measurement using a fluoride-selective electrode (F ISE), an ion meter and certified NaF standards. The sodium fluoride level was determined manually by dipping the electrode directly into the blood sample. Results were recorded manually. This poster describes two independent automated methods of analysis that allow the minimization of this tedious and time-consuming procedure.In the first one, the fluoride content in a blood aliquot is measured by direct potentiometric measurement after the addition of TISAB and deionized water. The second method employs the titration of the sample aliquot with La(NO3)3 after adding a buffer solution.

Ion chromatography is used as a high-performance analysis method in numerous applications. For complex analysis tasks, alternative detectors such as the amperometric detector or the UV/VIS detector are often also used in addition to the conductivity detector. This article describes the areas of utilization of the amperometric detector. Catchword: Antibiotics

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.

This Bulletin describes fluoride determination in various matrices with the help of the ion-selective fluoride electrode (F-ISE). The F-ISE is comprised of a lanthanum fluoride crystal and exhibits a response in accordance with the Nernst equation across a wide range of fluoride concentrations.The first part of this Bulletin contains notes regarding the handling and care of the electrode and the actual fluoride determination itself. The second part demonstrates the direct determination of fluoride with the standard addition technique in table salt, toothpaste and mouthwash.

This Application Bulletins describes the polarographic determination of thiamine (vitamin B1). The procedure allows an analysis in monovitamin preparations. The linear range of the determination is also given. The limit of detection is approx. 50 µg/L thiamine.

Determination of acetic anhydride in the presence of acetic acid in acylation mixtures.

Raman spectroscopy offers a fast, nondestructive way to identify microorganisms and analyze metabolites directly from culture media, without complex genetic sequencing.

Tris(hydroxymethyl)aminomethane (TRIS) is often used in life science applications and its purity must be monitored. This analysis is possible with ion chromatography.

Lucigenin is one of the most often used chemiluminescent reagents and might be used for e.g., the indication of the presence of superoxide anion radicals.Lucigenin is rather expensive to buy, however, its synthesis only includes a two stage synthesis starting from acridanone. The first stage includes an Nmethylation, the second forms the lucigenin chloride, which is finally transformed into lucigenin nitrate. To check the purity of the synthesized lucigenin, ion measurement can be applied using a nitrate selective electrode. This is a fast and inexpensive method compared to competing methods such as ion chromatography.

Determination of chloride, nitrate, phosphate and sulfate in plant leaf extracts using anion chromatography with direct conductometric detection.

Determination of citrate, succinate, lactate, β-hydroxybutyrate, and acetate in dry albumin powder using ion-exclusion chromatography with suppressed conductivity detection and dialysis for inline sample preparation.

This Application Note describes the separation of inositol, mannitol, glucose, xylose, fructose, lactose, sucrose and cellobiose on a column of the Metrosep Carb 2 - 150/4.0 type with subsequent pulsed amperometric detection (PAD).

Determination of formate, acetate, chloride, benzoate, and oxalate in phenolic extracts using anion chromatography with conductivity detection after chemical suppression.

Determination of α-glycerophosphate and β-glycerophosphate in amino acids 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.

Determination of sulfate, phosphate, and pyrophosphate in human urine and mice urine using anion chromatography with conductivity detection after chemical suppression.

Cell culture growth media contain all required components to keep cells alive. Here the amino acid composition is analyzed. A binary gradient separates in this example amino acids. The post-column reaction with ninhydrin requires a temperature of 120 °C, while the samples need to be cooled for stability.

Determination of 1-methyl-nicotinamide hydrochloride in a standard using Na2CO3 as electrolyte.

Determination of cysteine and cystine in caseinate after sample preparation with NaOH.

Platinum in urine can be determined by adsorptive stripping voltammetry (AdSV) after UV digestion of the sample.

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

A reference electrode has a stable and well-defined electrochemical potential (at constant temperature), against which the applied or measured potentials in an electrochemical cell are referred. A good reference electrode is therefore stable and non-polarizable. In other words, the potential of such an electrode will remain stable in the used environment and also upon the passage of a small current. This application note lists the most used reference electrodes, together with their range of use.

In-situ spectroelectrochemistry provides dynamic electrochemical and spectroscopic information concurrently with the redox reaction occurring on the electrode surface. Although different spectroelectrochemical configurations can be used, simple equations explain how to relate electrochemistry and spectroscopy for each experimental setup. This Application Note describes how the quantification of one electrochemical parameter (the diffusion coefficient) is calculated from the spectroscopic data as a proof of this concept.

The FOS/TAC value, sometimes referred to as VFA/TA, is a meaningful parameter for assessing both the current condition and the development of anaerobic digestion processes in a digester of a biogas plant. Knowledge of this value can help decrease the risk of acidification problems, which can result in a costly crash of the entire digestion process. Therefore, an accurate and reliable determination of the FOS/TAC value is important for both efficient and cost-effective production operations. This value is determined by an acid-base titration. Using the Eco Titrator from Metrohm equipped with an Ecotrode plus electrode, a reproducible and accurate determination of the FOS/TAC value is possible.

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

This Application describes the determination of moisture, nitrogen, and fat in stool samples using near-infrared spectroscopy. These parameters are of great importance in medical diagnostics.

Qualitative determination of chloride, phosphate, and sulfate as well as chlorite, nitrite, chlorate, bromide, and chromate in urine using anion chromatography with conductivity detection after chemical suppression.

In this application note, the advantage of recording the raw time domain data for each individual frequency during an electrochemical impedance measurement is described.

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.

In the application note AN-EIS-004 on equivalent circuit models, an overview of the different circuit elements that are used to build an equivalent circuit model was given. After identifying a suitable model for the system under investigation, the next step in the data analysis is estimation of the model parameters. This is done by the non-linear regression of the model to the data. Most impedance systems come with a data-fitting program. In this application note, the way NOVA is uses to fit the data is shown.

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.

Sequential suppression in cation chromatography significantly improves detection limits. The determination of the blank value of the sample vial being used is thus essential for being able to achieve such low detection limits. The leaching tests of various sample vials proceed with the intelligent Preconcentration Technique with Matrix Elimination on the Metrosep C Supp 1 - 250/4.0 column with conductivity detection following sequential suppression. The 50 mL Corning® Cell Culture Flasks from Sigma-Aldrich (CLS430168) exhibit the lowest blank values.

The coupling of ion chromatography and inductively coupled plasma mass spectrometry (ICP/MS) leads to a high-performance measurement system that masters several particularly challenging analyses. It enables for example reliable determination of element compositions, oxidation states and chemical bonds. This information is used, for example, for assessing the toxicity of medications, environmental and water samples as well as foods and beverages.

The fermentation of corn starch to produce ethanol is a complex biochemical process that requires monitoring of many different parameters (e.g., solids, pH, sugar profile, glycerol, lactic and acetic acid, and water and ethanol content). Traditional laboratory analysis using primary methods (e.g. Karl Fischer titration) takes about an hour to complete and is a limiting step for increasing plant capacity and efficiency. As a fast and non-destructive analytical technique, near-infrared spectroscopy (NIRS) can replace routine laboratory analysis, decreasing operating costs and increasing plant efficiency and capacity. This White Paper describes the capabilities of the modern analytical method near-infrared (NIR) spectroscopy for monitoring and improving the fermentation process of corn to ethanol.

Psychoactive gamma-hydroxybutyrate (GHB) and its prodrug gamma-butyrolactone (GBL) are substances that are increasingly abused as date-rape and recreational (party) drugs. Since the non-controlled GBL converts into the illicit GHB both in-vivo and in-vitro, their legal distinction is of crucial importance.For the forensic determination of illegally added GHB and GBL in commonly consumed beverages, this work presents a simple and sensitive method that employs direct-injection ion chromatography combined with spectrophotometric detection. The method allows to trace GHB-GLB interconversion, whether in vivo or in vitro lactone cleavage or intramolecular GHB esterification, and thus complies with pertinent requirements of law enforcement agencies.

Raman spectroscopy is a well suited spectroscopic technique for process development and control within development laboratories in chemical, pharmaceutical, and other industries. This article demonstrates the utility of portable Raman spectroscopy as a simple and versatile tool for in situ monitoring of reactions using univariate analysis techniques such as peak trending, as well as multivariate analysis approaches to predict the end point of chemical reactions.

Raman spectroscopy and surface enhanced Raman spectroscopy (SERS) are proving to be invaluable tools in the field of biomedical research and clinical diagnostics. Raman systems are also being developed for molecular diagnostic testing to detect and measure human cancer biomarkers. This review highlights two applications realting to breast cancer and pancreatic cancer diagnosis together with examples of the use of Raman spectrometry in biomedical research areas such as the identification of bacterial infections, showing that Raman is an important part of the medical toolbox, as we continually strive to improve diagnostic techniques and bring a better health care system to patients.

This Application Bulletin describes …

This Application Bulletins describes the determination of nicotinamide (vitamin PP), a vitamin of the B series. Instructions for the determination in solutions (e.g. fruit juice), vitamin capsules and multivitamin tablets are given. The linearity range of the determination is also specified. The limit of detection is approximately 50 μg/L nicotinamide.

Diazepam belongs to the 1,4-benzodiazepine group of compounds, which are used for medical purposes as tranquilizers and antidepressants. This Bulletin describes the determination of diazepam in tablets and body fluids (blood, serum, urine) by means of differential pulse polarography. If a Britton-Robinson buffer pH = 2.8 with a methanol volume fraction of 20% is used as the supporting electrolyte then a pronounced reduction peak is obtained at -0.73 V; this allows diazepam concentrations even below 0.05 µg/mL to be determined in blood. The necessary sample preparation steps are also dealt with in this Bulletin.

The presented Application Bulletin describes the apparatus and methods that are used for acid-base analysis of whole blood and blood plasma by Joergensen and Stirum. Evaluation of the measured data is performed with a software sold by Komstar AG.

This Application Bulletin describes two methods for the determination of iron at the Multi Mode Electrode.Method 1, the polarographic determination at the DME, is recommended for concentrations of β(Fe) > 200 μg/L. For this method the linear range is up to β(Fe) = 800 μg/L.For concentrations < 200 μg/LMethod 2, the voltammetric determination at the HMDE, is to be preferred. The detection limit for this method is β(Fe) = 2 μg/L, the limit of quantification is β(Fe) = 6 μg/L. The sensitivity of the method cannot be increased by deposition.Iron(II) and iron(III) have the same sensitivity for both methods.These methods have been elaborated for the determination of iron in water samples. For water samples with high calcium and magnesium concentrations such as, for example, seawater, a slightly modified electrolyte is used in order to prevent precipitation of the corresponding metal hydroxides. The methods can also be used for samples with organic loading (wastewater, beverages, biological fluids, pharmaceutical or crude oil products) after appropriate digestion.

This document explains how to measure Na ion concentration in diverse matrices with a sodium ion-selective electrode (Na-ISE) using direct measurement and standard addition.

This Application Bulletin describes the polarographic determination of folic acid, a vitamin of the B series, also known as vitamin B9 or vitamin BC. Instructions for the determination in solutions (e.g. fruit juice), vitamin capsules and multivitamin tablets are given. The linear range of the determination is also specified. The limit of detection is approx. 75 µg/L folic acid.

This Application Bulletin describes the polarographic determination of riboflavin (vitamin B2). The procedure allows an analysis in monovitamin preparations. The limit of determination is approx. 100 μg/L.

This document outlines Rancimat testing for both liquid and solid food samples, including direct and PEG methods, for oxidation stability QC in the food industry.