Winkler’s method

Winkler s method [30] for the determination of dissolved oxygen is based on the reaction of O2 with Mn(OH)2 (MnSO and KOH are added to the... 

Winkler s method cannot be used for the determination of oxygen if nitrites are present in water, since weakly bound oxygen from nitrites oxidizes the iodide ion in the acid medium... 

By Alsterberg s modification of Winkler s method [31] (the method which is used at present) the disturbing effect of NO2 is suppressed by reaction... 

Dissolved oxygen Winkler s method - Specific electrode method. 

Winkler s method or electrometric method (oxygen meter). 

The determination of aqueous dioxygen can be achieved by indirect iodometry. This is Winkler s method. It is based on the oxidation of iodide ions by Mn02 (manganese dioxide). The first time, there is a reaction between dioxygen and a suspension of manganese(II) hydroxide in strongly alkaline medium according to the reaction... 

Fig. 4.5.4. Dependence of progress in drilling rocks on their hardness determined by Shore s and Brinell s methods. According to data of Mueller (1963), supplemented by Winkler (1973).

The foregoing results are of little or no value in comparison with those that have been subsequently obtained. They vary very considerably, but undoubtedly point to a value round about 59 for the atomic weight of cobalt. The results obtained by Schneider, Som-maruga, and Winkler are much higher than all the others, and it will be noticed that in the hands of Lee, Sommaruga s method gave a much lower value. 

Standard Method 4500-0 describes two methods for determination of dissolved oxygen (DO) in water Winkler s iodometric method and the elecrometric method (Standard Methods, 1998). The iodometric method is very accurate and precise, but the electrometric method is far more convenient for field use (e.g. in wastewater treatment system monitoring and control) and produces an electronic output that can easily be converted to digital form for microprocessor monitoring or control of wastewater treatment systems. Also, electrometric methods are not subject to certain interferences (i.e. oxidation or reduction of the iodine indicator). In addition, the iodometric method end point may be obscured by the presence of turbidity or color in textile wastewater samples. The electrochemical method is almost exclusively used in testing of textile wastewater. 

Although the method of t-z and Q-z curves employs localized springs, the calculated settlements are usually within a reasonable range since the curves are backfitted directly from test results. Factors of nonhnear behavior of soil, complicated stress conditions around the pile, and partial corrections to the Winkler s assumption are embedded in this methodology. Besides, settlement of a pile can be estimated for complicated conditions such as varying pile geometry, different pile materials, and different soil layers. 

One of the most commonly used methods for analyzing laterally loaded piles is the p-y method, in which soil reactions to the lateral deflections of a pile are treated as localized nonlinear springs based on the Winkler s assumption. The pile is modeled as an elastic beam that is supported on a deformable subgrade. 

Several methods including spectrophotometric or chromatographic techniques have been proposed for the determination of furans such as HMF or furfural, or developed to determine both furan compounds simultaneously. The spectrophotometric methods do not differentiate between HMF and furfural without the need of a previous separation procedure. The commonly employed colorimetric method for HMF is Winkler s 38), which is based on the use of barbituric acid and p-toluidine. Toxicity of p-toluidine, instability of the color complex formed, and interference of sulfurous acid and possibly other compounds present in the fruit juice 40) are known to be problems. Unlike HMF, the colorimetric method for furfural was based on a previous distillation of juice and the colorimetric analysis of distillate for furfural based on colorimetric reaction with aniline acetic acid in juices 41). However, distillation procedure with poor recovery (about 34%) and long reaction time for color development (approximately 1 h), and requirement of hazardous chemical aniline 20) are known to be the drawbacks of the colorimetric method for furfural. Also, colorimetric method generally requires strict control of reaction time and temperature to achieve stable and reproducible color development. 

B W K Diehl, W Ockels, H Herling, R Unger, S Winkler, (1996) Quantitative Determination of Egg-Lecithin in a Liposome-Preparation, Validation of the P NMR Method 7 International Congress on Phospholipids Brussels, Belgium, September (1996)... 

Although Baldwin and Whitehead s perceptive biosynthetic hypothesis serves as a useful framework from which to develop a coherent synthetic approach towards manzamine A (1), other elegant solutions to the problems posed by this complex molecular architecture based on stepwise chemical synthesis are also conceivable. In this chapter, we shall focus in detail on two such constructions of manzamine A from the groups of Jeffrey Winkler at the University of Pennsylvania and Stephen Martin at the University of Texas, Austin. While both serve to illustrate the current state-of-the-art in methods for complex molecule construction through routes that effectively combine modem and classical reactions, perhaps the more significant feature of each approach resides in the... 

---