Aplikace

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.

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.

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.

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.

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

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.

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 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.

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 Application Bulletin describes …

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.

Determination of lysine as well as sodium, ammonium, potassium, and calcium in bulk lysine using cation chromatography with direct conductivity detection.

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

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.

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

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.

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 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.

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

Electrochemical impedance spectroscopy (EIS) is a powerful technique which provides information about the processes occurring at the electrode-electrolyte interface. The data collected with EIS are modeled with a suitable electrical equivalent circuit. The fitting procedure will change the values of the parameters until the mathematical function matches the experimental data within a certain margin of error. In this Application Note, some suggestions are given in order to get acceptable initial parameters and to perform an accurate fitting.

In recent years, field-effect transistors (FETs) have become more commonly used as a sensing platform for a multitude of electrochemical and biological applications. These devices are promising bioelectronic transducers that allow both low-potential operation and stable potentiometric measurements. FETs are now seen as an attractive alternative to using conventional electrochemical detection systems in the scientific community. This Application Note gives in-depth guidance about how to operate Metrohm DropSens bipotentiostat devices for the characterization of FETs and their use as transducers. A single μStat-i 400 device, a small and portable bipotentiostat and galvanostat, is used to demonstrate the experiments.

Alamar Blue is monitored with fluorescence spectroelectrochemistry during its irreversible reduction to resorufin and further reversible reduction to dihydroresorufin.

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

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 acetate, chloride, citrate, and sulfate in a concentrate of an infusion solution using anion chromatography with direct conductivity detection. Non-suppressed IC is used to avoid interferences by the amino acids.

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.

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.

The lactulose/rhamnose (L/R) intestinal permeability test is used for the diagnosis of dysfunctional intestinal permeabilities. This test comprises the determination of mannitol, rhamnose, lactose and lactulose in addition to the usual blood sugars, e.g. glucose, galactose and saccharose. This Application Note presents the analysis of a blood plasma sample enriched with the four sugars mentioned above.Key word: leaky gut syndrome

A low-pressure gradient enables the separation of sugar acids strongly retained on the column and sugars within an appropriate analysis time. The saccharides are separated on a column of the Metrosep Carb 2 - 250/4.0 type with subsequent pulsed amperometric detection (PAD). Galactose and arabinose are not completely separated under the selected conditions.

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).

The separation of lactose, lactobionic acid, sialic acid*, 6’-sialyllactose, and 3’-sialyllactose is shown as a proof of concept for the control of these components in fermentation process for a pharmaceutical product. The acceptance criterion of a minimum resolution of the peaks (< 1.3) is reached. The separation is achieved on a Metrosep Carb 2 - 250/4.0 column with subsequent pulsed amperometric detection.

This Process Application Note presents a method to accurately monitor lactic acid and glucose inside a bioreactor in «real-time» with the 2060 Raman Analyzer from Metrohm Process Analytics.

Low sensitivity has limited the use of Raman spectroscopy as a detection method. However, the surface-enhanced Raman scattering (SERS) effect has improved its effectivity for analytical use. Aldehyde dehydrogenase (ALDH) and cytochrome c are analyzed by Raman spectroelectrochemistry as a proof of concept in this Application Note.

Determination of fluoride, chloride, phosphate, and monofluorophosphate in glutamine monofluorophosphate using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride, nitrate, phosphate, and sulfate in a protein formulation using anion chromatography with conductivity detection after chemical suppression and dialysis for sample preparation.

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

Determination of chloride, nitrate, phosphate, sulfate, and oxalate in human urine using anion chromatography with conductivity detection after chemical suppression and dialysis for sample preparation.

Determination of α-glycerophosphate and β-glycerophosphate in amino acids using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, chloride, bromide, nitrate, sulfate, and trifluoroacetate (TFA) in a peptide sample using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride in a child's sweat using anion chromatography with conductivity detection after chemical suppression.

Determination of iodide in a human 24 hour urine sample using anion chromatography with amperometric detection after chemical suppression. The result agrees with that of the photometric method. UV detection did not work.

Determination of oxalate and citrate in human urine using anion chromatography with conductivity detection after chemical suppression.

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.

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