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- AB-225Simple wine analysis
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.
- AB-226Determination of arsenic by stripping voltammetry at the rotating gold electrode
This Bulletin describes the determination of arsenic by anodic stripping voltammetry (ASV) at the rotating gold electrode. A determination limit of 0.5 μg/L can be achieved with 10 mL sample solution. A differentiation between the As(III) concentration and the total arsenic concentration can be made by appropriate selection of the deposition potential. The analyses are performed with a special gold electrode whose active surface is located laterally; c(HCl) = 5 mol/L is used as supporting electrolyte. For the determination of the total arsenic content, As(III) and As(V) are reduced at -1200 mV by nascent hydrogen to As0, which is preconcentrated on the electrode surface. If the deposition is carried out at -200 mV then only As(III) is reduced; this allows the differentiation between total arsenic and As(III). During the subsequent voltammetric determination the preconcentrated As0 is again oxidized to As(III).
- AB-230Potentiometric determination of nonionic surfactants based on polyoxyethylene adducts with the NIO electrode
The titrimetric determination of nonionic surfactants on the basis of polyoxyethylene adducts (POE adducts) is described in the Bulletin. The basis for the determination is the transfer of the nonionic surfactant into a pseudo-cation compound and its precipitation titration with sodium tetraphenylborate (Na-TPB). The NIO electrode is used for the indication of the potentiometric titration. This Bulletin describes determinations in raw products, formulations and wastewater and draws attention to special features, possibilities, limits and disruptions.
- AB-231DIN 38406-16に則したアノードおよび吸着ストリッピングボルタンメトリーによる、水サンプルに含まれる亜鉛、カドミウム、鉛、銅、タリウム、ニッケル、およびコバルトの測定
DIN 38406 Part 16 を条件とした標準メソッドでは、飲料水、地下水、地表水、および降水 (雨水など) に含まれるZn、Cd、Pb、Cu、Tl、Ni、およびCoの測定について説明しています。水サンプル中に含まれる有機物質は電圧電流法による測定に強い干渉を与え得るため、過酸化水素を用いたUV分解による前処理が必要となります。この分解により、ブランク値の導入なしですべての有機物質を確実に除去することができます。これらのメソッドはもちろん、例えばシリコンベースの半導体チップの製造における微量分析など、他の物質の微量分析にも応用することができます。Zn、Cd、Pb、Cu、およびTlはアノードストリッピングボルタンメトリー (ASV) を用いてHMDEで測定され、NiおよびCoは吸着ストリッピングボルタンメトリー (AdSV) を用いて測定されます。
- AB-232Determination of antioxidant activity in accordance with the Rancimat method
The effectiveness of antioxidants can be expressed as antioxidant activity. It can be readily determined using the Rancimat method. This is accomplished by first determining the induction time of a mixture made up of hog fat and the antioxidant to be investigated and then by determining the corresponding time for hog fat alone. The quotient expresses the efficiency of the respective antioxidant and is referred to as the antioxidant activity index (AAI).This Application describes the determination of the antioxidant activity index of five common antioxidants.
- AB-233Potentiometric determination of anionic and cationic surfactants with surfactant electrodes
Anionic surfactants can be titrated with cationic surfactants and vice-versa. The Bulletin describes a multitude of substances that can be determined in this fashion and specifies the respective working conditions and parameters. In contrast to the classic two-phase titration in accordance with Epton, the titration with the anionic and cationic surfactants electrodes can be performed without chloroform. Furthermore, the equivalence point of the titration is difficult to determine in some cases with the Epton method and the titration cannot be automated.In many cases, a surfactant ISE is a remedy that is both environmentally friendly and suitable here. It was developed specially for application with potentiometrically indicated surfactant determinations.
- AB-235Potentiometric titration of calcium (magnesium) in dairy products
This Bulletin describes a simple method for the determination of the calcium content in dairy products. The use of CuEGTA and the ion-selective copper electrode (Cu ISE) as indicator electrode allows the determination to be performed without time-consuming sample preparation. If the complexing agent EDTA is used as titrant instead of EGTA, the sum of calcium and magnesium is obtained. The magnesium content can then be calculated from the difference between the results of the two titrations.
- AB-237Determination of the stability index of solid foods with the Rancimat method
Determination of the oxidation stability of foods with a low fat content is a challenge. As an alternative, the oxidation stability can be specified indirectly. To accomplish this, a determination is made as to the extent that a sample that has been mixed with a fat as a standard solution, e.g., hog fat, will change the oxidation stability of that standard solution. This is accomplished by first determining the induction time of the mixture made up of hog fat and the sample and then by determining the corresponding time for the lard alone. The quotient is referred to as the stability index (SI).
- AB-241Determination of cadmium and lead by anodic stripping voltammetry at a mercury film electrode
This Application Bulletin describes the determination of cadmium and lead at a mercury film electrode (MFE) by anodic stripping voltammetry (ASV). The mercury film is plated ex situ on a glassy carbon electrode and can be used for up to one day. With a deposition time of 30 s, the limit of detection is ß(Cd2+) = 0.02 µg/L and ß(Pb2+) = 0.05 µg/L. The linear working range for both elements goes up to approx. 50 μg/L using the same deposition time.
- AB-242超微量グラファイトRDEを用いたアノードストリッピングボルタンメトリーによるタングステンの測定
ここで説明されているメソッドにより、0.2~50 µg/L (ppb) 範囲の微量の W(VI) を測定することが可能となります。サンプル (天然水など) に含まれる微量の有機化合物は干渉します。それらはUV分解によって除去しなければなりません (705 UV Digester など)。100 mg/L までの濃度のFe(III) による干渉は、アスコルビン酸を用いた Fe(lI) への還元によって除去します。もしサンプル中の Cu(II) の量が係数200またはそれ以上で W(VI) の量を上回る場合、Cuイオンはチオ尿素によって固定されなければなりません。さらに、Cu(II) 濃度が 5 mg/L を超えてはなりません。測定はDPモードにおいて吸着ストリッピング分析によって実施されます。