Uygulamalar

The study of adverse effects of air pollution requires semi-continuous, rapid and accurate measurements of inorganic species in aerosols and their gas phase components in ambient air. The most promising instruments, often referred to as steam collecting devices, are the Particle-Into-Liquid-Sampler (PILS) coupled to wet-chemical analyzers such as a cation and/or anion chromatograph (IC) and the Monitoring instrument for AeRosols and GAses (MARGA) with two integrated ICs. Both instruments comprise gas denuders, a condensation particle growth sampler as well as pump and control devices. While PILS uses two consecutive fixed denuders and a downstream growth chamber, the MARGA system is composed of a Wet Rotating Denuder (WRD) and a Steam-Jet Aerosol Collector (SJAC). Although the aerosol samplers of PILS and MARGA use different assemblies, both apply the technique of growing aerosol particles into droplets in a supersaturated water vapor environment. Previously mixed with carrier water, the collected droplets are continuously fed into sample loops or preconcentration columns for on-line IC analysis. While PILS has been designed to sample aerosols only, MARGA additionally determines water-soluble gases. Compared to the classical denuders, which remove gases from the air sample upstream of the growth chamber, MARGA collects the gaseous species in a WRD for on-line analysis. In contrast to the gases, aerosols have low diffusion speeds and thus neither dissolve in the PILS denuders nor in the WRD. Proper selection of the ion chromatographic conditions of PILS-IC allows a precise determination, within 4 to 5 minutes, of seven major inorganic species (Na+, K+, Ca2+, Mg2+, Cl-, NO3- and SO4 2-) in fine aerosol particles. With longer analysis times (10-15 minutes) even airborne low-molecular-weight organic acids, such as acetate, formate and oxalate can be analyzed. MARGA additionally facilitates the simultaneous determination of HCl, HNO3, HNO2, SO2 and NH3.PILS and MARGA provide semi-continuous, long-term stand-alone measurements (1 week) and can measure particulate pollutants in the ng/m3 range.

This poster presents a straightforward ion chromatographic determination of HF, HNO3, short-chain organic acids and H2SiF6 in etching bath samples. Standard ions such as fluoride, nitrate, acetate and sulfate are determined via suppressed conductivity detection while dissolved silicate is spectrophotometrically detected in the same run after downstream post-column reaction (PCR) as molybdosilicic acid. Analytical results of several commercial HF-HNO3-H2SiF6 mixtures obtained by ion chromatography (IC) and titration showed good agreement, which confirms the applicability of the presented «dual» detection IC method for controlling the composition of acidic texturing baths.

A potentiometric, nonaqueous method is described for analyzing nitrating acid using cyclohexylamine as titrant. Both sulfuric and nitric acid can be determined quantitatively.

Boric acid is used in many primary circuits of nuclear power plants, in nickel plating baths, and in the production of optical glasses. Furthermore, boron compounds are found in washing powders and fertilizers. This bulletin describes the potentiometric and thermometric determination of boric acid. The determination also covers further boron compounds, when acidic digestion is applied.

This Bulletin describes potentiometric titration methods for checking sulfuric acid and chromic acid anodizing baths. In addition to the main components aluminum, sulfuric acid, and chromic acid, chloride, oxalic acid, and sulfate are determined.

Potentiometric titration methods for the analysis of acid and alkaline tin plating baths are presented. The following methods are described: tin(II) / tin(IV) / total tin, free fluoroboric acid, or free sulfuric acid, chloride in acidic tin baths, free hydroxide, and carbonate in alkaline tin baths.

This Bulletin describes the potentiometric determination of lead, tin(II), and free fluoroboric acid.

This Bulletin describes the simultaneous potentiometric titration of free boric acid and free tetrafluoroboric acid in nickel plating baths. After addition of mannitol, the formed mannitol complexes are titrated with sodium hydroxide solution. The determination is carried out directly in the plating bath sample; nickel and other metal ions do not interfere.

The Bulletin describes the determination of the following parameters in wine: pH value, total titratable acid, free sulfurous acid, total sulfurous acid as well as ascorbic acid (vitamin C) and other reductones.

In titration, the titrant reacts with the analyte either exothermically (gives off heat) or endothermically (absorbs heat). The Thermoprobe measures the temperature change during titration. When all of the analyte has reacted with the titrant, the temperature of the solution will change, and the endpoint of the titration is indicated by an inflection in the temperature curve. Catalytically enhanced titrations using paraformaldehyde as catalyst are based on the endothermic hydrolysis of the paraformaldehyde in the presence of excess hydroxide ions. Edible oils are dissolved in a mixture of toluene and 2-propanol (1:1) and titrated with standardized TBAH (0.01 mol/L) in 2-propanol to a catalytically enhanced endpoint.