Alkalmazások

The Restriction of Hazardous Substances (RoHS) Directive 2002/95/EC stipulates maximum limits for the hazardous metals cadmium, lead and mercury as well as the hexavalent chromium and the brominated flame retardants in electrical and electronic products. To ensure compliance, reliable analysis methods are required.This poster deals with the wet-chemical determination of trace concentrations of the six RoHS-restricted substances in a wide variety of materials including metals, electrotechnical components, plastics and wires. After sample preparation according to IEC 62321, the metals lead, cadmium and mercury are best determined by anodic stripping voltammetry (ASV) and the flame retardants PBB and PBDE are quantified by direct-injection ion chromatography (IC) using spectrophotometric detection. Chromium(VI) can be determined either by adsorptive stripping voltammetry (AdSV) or IC. Both methods are very sensitive and meet prescribed RoHS limits.

By combining the information from electrochemical and spectroscopic techniques, UV/VIS spectroelectrochemistry (UV/VIS-SEC) allows a comprehensive analysis of electron-transfer processes and complex redox reactions. The anodic oxidation of a N-aryl-D2-pyrazoline derivative was investigated by combining cyclic voltammetry and UV/VIS spectroscopy. In-situ measured UV/VIS absorbance depicted the absorption changes that accompanied the anodic oxidation and could therewith prove the stability of the electrogenerated radical cation. UV/VIS-SEC provides a powerful tool for the in situ study of shorter-lived species, reaction mechanims, and kinetics in a wide variety of electrochemical active organic, inorganic, and biological molecules.

The quantitative determination of the alkaloid nicotine, which is an essential constituent of the tobacco plant, can be carried out by polarography. The quantification limit is less than 0.1 mg/L in the polarographic vessel.

This Bulletin is a supplement to Application Bulletin no. 36 (Half-wave potentials of inorganic substances) in the sense that the half-wave potentials of 100 different organic substances are listed. At the same time the supporting electrolytes used and the limits of determination are given.The various substances are listed in alphabetical order. The most important polarographically active functional groups are taken into consideration. This means that substances for related structures can also be determined polarographically in the same or similar supporting electrolytes, although they may not appear in the list.Unless otherwise stated, the half-wave potentials refer to a temperature of 20 °C, and the potentials are given in volts, measured with a sat. KCI-Ag/AgCl electrode assembly.The determination limits give the smallest concentrations which can be measured without risking serious errors in the results. In all cases, the limit of detection lies below the limit of determination.

This Application Bulletin describes a simple polarographic method to determine monomeric styrene in polymers. The limit of determination lies at 5 mg/L. Before the determination, styrene is converted to the electrochemically active pseudonitrosite using sodium nitrite.

4-Carboxybenzaldehyde, in the following referred to as 4-CBA, can be reduced directly at the dropping mercury electrode (DME) in an ammoniacal solution. After a very simple sample preparation it is now possible to determine the concentration of 4-CBA in terephthalic acid quickly and precisely by polarography down to the lower ppm range.

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.

Determination of benzylamine in a beta blocker (Nebivolol) using cation chromatography with direct conductivity detection. A step gradient for fast elution of the main component is applied.

Chipped wood and sawdust may be used in production of feed e.g., for ruminants. Melamine, a raw material for resins in wood adhesives, is limited to be used in feed. Therefore, the melamine concentration in sawdust has to be analyzed. Melamine determined after ion chromatographic separation with UV/VIS detection.

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

Determination of tar acids in coal tar products. This procedure may also be applied to the determination of a range of weakly acidic organic compounds such as carboxylic acids, hydroxy acids, phenols, phenolic acids, keto-enols, imides, and aromatic nitro compounds.11 Vaughan, G. A. Thermometric and Enthalpimetric Titrimetry. Van Nostrand Reinhold Co. Ltd (1973)

Weak, organic bases that are soluble in nonaqueous solvents (including nonpolar solvents) are determined in glacial acetic acid using titration with strong acids, e. g., anhydrous perchloric acid or trifluoromethanesulfonic acid. The endpoint of such titrations can be determined thermometrically, insofar as a suitable thermometric endpoint indicator exists. The exceptional suitability of isobutyl vinyl ether (IBVE) as indicator has been demonstrated.

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 phenol, m-cresol, 2,6-dimethylphenol and 2,3,6-trimethylphenol in tap water with amperometric detection using a glassy carbon electrode.

This Application Note describes how NIR spectroscopy can be used to determine residual lignin content in wood pulp. Using the major absorbance peaks of both lignin and cellulose in the second derivative spectra, the residual lignin content in wood pulp can be monitored during paper production.

In recent years, there has been a significant push to reduce the environmental impacts of fuels through improvements to fuel quality. The determination of key quality parameters of gasoline, namely research octane number (RON, ASTM D2699-19), motor octane number (MON, ASTM D2700-19), anti knock index (AKI), aromatic content (ASTM D5769-15), and density, conventionally requires several different analytical methods, which are laborious and need trained personnel. This application note demonstrates that the XDS RapidLiquid Analyzer, operating in the visible and near-infrared spectral region (Vis-NIR), provides a cost-efficient and fast solution for the multiparameter analysis of gasoline.

This Application Note describes the determination of various indices (mainly with ASTM and ISO conformance) for the characterization of kerosene as aviation turbine fuel using near-infrared spectroscopy. The following parameters were determined with the aid of an NIRS XDS Process Analyzer: degree of density in accordance with the American Petroleum Institute (API), aromatics content, Cetane Index, distillation characteristics pursuant to ASTM D86, flash point, freezing point, viscosity and hydrogen content. All of these parameters are determined quickly and easily with just a single measurement.

This Application Note shows how, with the help of Vis-NIR spectroscopy and a special plant library, 46 different medicinal and aromatic plants, e.g., Organicum majoricum and Tilia cordata, can be conveniently identified on the basis of their spectrum. In comparison with alternative methods for the determination of plants, which are elaborate and require experienced scientists for their performance, the Vis-NIR method permits rapid and uncomplicated identification.

This Application Note shows the determination of two important additives – butylglycol and propylheptyl alcohol – in water-soluble lacquers using Vis-NIR spectroscopy. Other lacquer constituents can also be determined in addition to the two additives.

Naphtha is the first petroleum product during the distillation process of crude oil or coal tar. It is primarily used as a base material for the production of gasoline or as a solvent. Accidental spills occur regularly at many locations throughout the world, leading to soil contamination.Investigation of contaminated sites is usually performed using gas chromatography, for which the soil sample has to be frozen, grinded, and subsequently extracted prior to the analysis. Using Visible-Near Infrared Spectroscopy such sample preparation steps are not necessary at all, making this method a viable, fast, and simple to use alternative.

The determination of key quality parameters of reformate—namely research octane number (RON, ASTM D2699-19), aromatic content (ASTM D5769-15), benzene content, olefin content, and density—requires time-consuming and laborious conventional methods. In contrast, the Metrohm DS2500 Liquid Analyzer can measure all of these parameters, providing results within one minute without any sample preparation.

Determination of sorbate and benzoate in a functional drink using ion-exclusion chromatography with suppressed conductivity detection.

Determination of phenol, m-cresol, 2,6-dimethylphenol, and 2,3,6-trimethylphenol in tap water using amperometric detection and a glassy carbon electrode.

Traditionally, catecholamines are separated using reversed-phase chromatography followed by amperometric detection. This Application Note describes the determination of catecholamines in an emergency medication for life-threatening allergic reactions.

To prevent styrene from polymerization at ambient temperature, tertiary-butylcatechol (TBC) must be added as a stabilizer during storage and transport. TBC concentration levels in styrene need to be maintained between 10 - 15 mg/L. With optimum storage conditions, the process analyzers from Metrohm Applikon for photometric analyses ensure that the TBC concentration in styrene does not fall below this value. The method is based on ASTM D4590.

The size of the indigo molecule makes it difficult to dye synthetic fibers, but the large pores of cellulose (such as in cotton) accept it readily. Indigo is insoluble in water, so it must first be reduced to the water-soluble leuco-indigo form by sodium hydrosulfite in a strong alkaline bath. Good circulation within the bath is imperative for consistent dye coverage, but care must be taken not to introduce any oxygen. Fabrics must be oxidized between dips in the dye bath in order to set the indigo within the pores of the fibers, but multiple dips are necessary for darker, uniform coverage. Many parameters need to be monitored and controlled to ensure high quality of the end product: the pH value for proper NaOH (alkali) dosage, the concentrations of both hydrosulfite and indigo, as well as the temperature of the bath and even the redox potential.

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.

Determination of hypophosphite, formate, phosphate, adipate, p-nitrobenzoate, and sebacate in ethylene glycol using anion chromatography with conductivity detection after chemical suppression.

Determination of acetate, chloride, nitrite, nitrate, benzoate, phosphate, and sulfate using anion chromatography with conductivity detection after chemical suppression.

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

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

Determination of fluoride, chloride, nitrite, nitrate, benzoate, and sulfate in PVC film using anion chromatography with conductivity detection after chemical suppression.

Determination of adipic acid and phthalic acid in an alkaline ester digestion solution using anion chromatography with conductivity detection after chemical suppression.

Determination of 2-fluorobenzoate in a water deposit from the oil production industry using anion chromatography with conductivity detection and chemical suppression.

Determination of fluoride, acetate, propionate, formate, butyrate, chloride, nitrite, bromide, nitrate, benzoate, phosphate, sulfate, malonate, and oxalate in an industrial process water using anion chromatography with conductivity detection after sequential suppression.

Aromatic dicarboxylic acids, e.g., terephthalate, isophthalate and 5-sulfoisophthalate, are important monomers in the manufacture of polyesters and alkyd resins. The monomer ratio of the dicarboxylic acids has an enormous influence on polymerization. The separation of the late-eluting components is completed within 15 minutes if a short Metrosep A Supp 15 - 50/4.0 type column is used together with high eluent concentrations and flow rates.

Determination of phenylglycine through nonaqueous potentiometric titration with sodium methylate using a special combined glass electrode. Keyword: Antibiotics

This Application Note describes the nonaqueous acid-base titration of ketoconazole in accordance with the European Pharmacopoeia. The Solvotrode easyClean was used as the electrode.

The purity of sulfanilamide was determined by means of automatic potentiometric titration using sodium nitrite as the titrant. The solution was spiked with potassium bromide, because bromide ions catalyze diazotization titration.

Boehm titration is a quantitative analysis of functional groups on the surface of carbon materials based on their reactions with basic solutions of NaHCO3 (pKa = 6.4), Na2CO3 (pKa = 10.3), and NaOH (pKa = 15.7). This is a cost-efficient method that gives absolute values with high precision of the accessible, mainly oxygen-containing functional groups on the surface. Originally, Boehm titration was developed for carbon materials like conductive carbon black (CCB), activated carbon, porous carbon, and graphite. Modern carbon-based materials like graphene, graphene oxide (GO), or carbon nanotubes can also be analyzed this way.

Determination of N-acetylcysteine and phenylalanine in tablets against sinusitis by anion chromatography with UV/VIS detection according to USP.

Determination of saccharin, benzamide, and o-toluenesulfonamide in a nickel electroplating bath using RP chromatography with UV detection.

Determination of phenylalanine, aspartame, caffeine, and benzoate in a soft drink using RP chromatography with UV detection.

Determination of cefazolin in accordance with USP 28-NF 23 (Appendix 2) using RP chromatography and subsequent UV detection. Keyword: Antibiotics

Determination of salicylic acid and acetylsalicylic acid according to USP 28-NF 23 (second supplement) using RP chromatography with UV detection.

Determination of cloxacillin sodium in accordance with USP 28-NF 23 (Appendix 2) using RP chromatography and subsequent UV detection. Keyword: Antibiotics

Determination of amoxicillin in accordance with USP 28-NF 23 (Appendix 2) using RP chromatography and subsequent UV detection. Keyword: Antibiotics