Titrimetric determination of sulfate

Photometry

Article	Name
AB-140	Titrimetric determination of sulfate
This Bulletin describes three potentiometric and one photometric titration method for the determination of sulfate. Which indication method is the most suitable depends above all on the sample matrix and is illustrated with examples. Method 1: Precipitation as barium sulfate and back-titration of the Ba2+ excess with EGTA. The ion-selective calcium electrode is used as indicator electrode. Method 2: As in method 1, but with the electrode combination tungsten/platinum. Method 3: Precipitation titration in semi-aqueous solution with lead perchlorate using the ion-selective lead electrode as indicator electrode. Method 4: Photometric titration with barium perchlorate, thorin indicator and the 662 Photometer or 525 nm Spectrode. Particularly suitable for micro determinations!
AB-094	Potentiometric and photometric analysis of honey
Simple methods are described for the analysis of honey that permit any damage or adulteration to be detected. The pH and total acids are determined together with the lactone and formol numbers. The determination of the hydroxymethylfurfurol content (HMF) is carried out photometrically. A separate method exists for the determination of water by the Karl Fischer method.
AB-093	Potentiometric analysis of cadmium plating baths
This Bulletin describes titrimetric methods for the determination of cadmium, free sodium hydroxide, sodium carbonate and total cyanide. The free cyanide can be calculated from the total cyanide and the Cd content.
AB-063	Determination of silicon, calcium, magnesium, iron and aluminum in cements by photometric titration of the solubilized product
The insoluble silicon dioxide remaining after dissolution of cement is determined gravimetrically. The calcium, magnesium, iron and aluminium in the filtrate are determined by photometric EDTA (0.1 mol/L) titration using a 662 Photometer. The following instructions conform to the analytical methods of 11 November 1981 recommended by the Association of Austrian Cement Manufacturers.
AB-049	Colorimetric determination of copper
Application Bulletin no. 43 describes the polarographic determination of copper. For copper concentrations of 10 mg/L and below, however, colorimetric methods are also used, particularly in water analysis. The method using sodium diethyldithiocarbamate can be employed down to a minimum limit of 0.01 mg/L Cu, but suffers from the drawback that the determination can also be affected by other metal ions. The method using neocuproine has a minimum concentration limit of 0.1 mg/L Cu, but has the advantage of being unaffected by ions of other metals.
AB-033	Determination of the total, calcium and magnesium hardness of water samples by photometric titration
This Bulletin describes the determination of the total, calcium and magnesium hardness of water using the light-guide photometer and/or Spectrode.
AB-030	Photometric determination of chromium(VI)
With chromates and dichromates, diphenylcarbazide gives a red-violet coloration which can be measured with the 662 Photometer. The reaction is extremely sensitive, enabling concentrations of ρ(Cr) <> In electroplating effluents, chromium occurs as the Cr(VI) ion. It must first be reduced to Cr(III) and then precipitated as the hydroxide. With incomplete reduction, hexavalent chromium remains in solution in the effluent water. For this reason, periodic checks for chromium in the effluent are necessary.
AB-029	Determination of chlorine in water with the 662 Photometer
The well-known method for determining free chlorine in water with o-tolidine is described and the absorbance coefficients determined for the 662 Photometer are given.

Determination of the total base number (TBN)in petrochemical products by potentiometric HClO4 titration

Summary
The base numbers of three different lubricating oil samples were determined. Work was carried out using different electrode systems in different solvent mixtures (glacial acetic acid/toluene and glacial acetic acid/chlorobenzene) and with different titration modes (drift and time-controlled dynamic titrations). The results obtained displayed no significant differences in their reproducibility and were all within the tolerance limits.


Articles

Tin cans - a possible source of contamination of canned food

Food preservation Canning food is a good method of preservation which uses no chemical preservatives and is therefore widely used. Usually cans consist of tin plate which is tin coated steel. Tin is necessary to prevent iron from being corroded by the canned food. Unfortunately tin itself can slowly transfer into the food. The amount of tin taken up by the canned food is affected by many factors. Tin may cause stomach upsets and irritates the digestive tract of sensitive people when present in high concentrations. Fortunately there are no long-term effects due to normal intakes from tin in the food even if it is present in higher levels. An organic compound can be used to line the cans. These fully lacquered cans strongly reduce the levels of tin as long as this protective layer remains undamaged. Nevertheless a new problem arises due to the bisphenol-A which is contained in the lacquer paint and has a potential to interact (endocrine disrupter) with our hormone system.

Voltammetric analysis of tin Differential pulse anodic stripping voltammetry (DPASV) in combination with a hanging mercury drop electrode (HMDE) is an analysis method for determining the concentration of tin in canned food. Prior to the analysis the canned food has to be digested by means of a mixture of concentrated mineral acids. Lead, which was used with tin until lately as a solder (also for cans), can also be determined with the described method from Metrohm. There are a variety of methods described which allow a successful determination of lead even in presence of other metal ions as thallium or cadmium. A specification between Sn(II) and Sn(IV) is also possible. The anodic stripping voltammetry can be carried out on a MVA-2 system. The heart of this system is a 797 VA Computrace enriched with the unbeatable Dosino technique for liquid handling. For your convenience, the methods for the tin and lead determination are already implemented in Metrohm's 797 VA Computrace. Just press the button and start measuring.

Product information MVA-2 system intended for partly automated routine analysis and consisting of the 797 VA Computrace and two 800 Dosinos. MVA-2 Options MVA-3 system for fully automated analysis of small series of samples consisting of the 797 VA Computrace, a 813 Compact Autosampler, two 800 Dosinos, a 731 Relay Box and two 772 Pump Units MVA-3 Send me product information!

Get more information Order our free Monograph Practical Voltammetry (8.757.500X) in English or German. Find more application details in our Application Bulletin 176 (Info Center) Applications for Voltammetry and Polarography Overview of Metrohm VA Instruments

Tips Automation: Up to 18 samples are easily processed fully automatically by the MVA-3 system. Sample preparation: How digestion is done Validation: For the Validation of Metrohm VA instruments using Standard Operating Procedures see our Application Bulletin 276 (Info Center).

A test method for the determination of the liquid efflux rate (tightness) of Metrohm An- tidiffusion Tips via STAT Titration

Summary
The design of the Metrohm antidiffusion tips with the antidiffusion valve makes it possibleto do very accurate dosing. The principle is a ‘pressure valve’ which opens synchronously to the movement of the piston from the Dosing unit, depending on the pressure in the tubing, and relocks when the pressure in the tubing drops. This principle makes sure, that the volume
stream stops abrupt after stop of the piston movement and no formation of drops and no leakage of titrant occurs afterwards. If this mechanism doesn’t work properly then it is
possible that after a dosing step a volume different from the documented leaks from the anti diffusion tip. This ‘leakage’ may furthermore cause a delayed stabi-
lization of the measured signal and may hence create erroneous, inaccurate results.
Metrohm recommends the use of the titrimetric volume test method described below as the Standard Operating Procedure for validating Metrohm antidiffu-
sion tips (6.1543.200, 6.1543.130 & 6.1543.140, each with 62726.090 antidiffusion valve).
This titrimetric volume test can be used for the following purposes:
• Quality assurance by the manufacturer
• Quality assurance of analytical or other measuring systems by the user
The described method is not an official reference method.


Articles

NIO electrode for the titrimetic determination of non-ionic surfactants by Metrohm AG View catalog online Catalog: NIO electrode for the titrimetic determination of non-ionic surfactants Company/Brand: Metrohm AG Flippable HTML catalog PDF catalog Flippable Flash catalog Visitor statistics
Metrohm AG Contact Information Metrohm AG Oberdorfstr. 68 CH-9100 Herisau

NIO electrode for the titrimetic determination of non-ionic surfactants by Metrohm AG View catalog online Catalog: NIO electrode for the titrimetic determination of non-ionic surfactants Company/Brand: Metrohm AG Flippable HTML catalog PDF catalog Flippable Flash catalog Visitor statistics
Metrohm AG Contact Information Metrohm AG Oberdorfstr. 68 CH-9100 Herisau

Titration in use of fatty acid methyl esters

A Metrohm UK product story

Edited by the Manufacturingtalk editorial team Apr 27, 2006

The manufacture and use of Fatty Acid Methyl Esters (FAME), has implications for the environment.

The manufacture and use of Fatty Acid Methyl Esters (FAME), has implications for the environment. Bio diesel is the name of a clean burning alternative fuel, produced from domestic, renewable resources. Bio diesel contains no petroleum, but it can be blended at any level with petroleum diesel to create a bio diesel blend. It can be used in compression-ignition (diesel) engines with little or no modifications. Bio diesel is simple to use, biodegradable, non-toxic, and essentially free of sulphur and aromatics. Bio diesel is made through a chemical process called transesterification whereby the glycerine is separated from the fat or vegetable oil. The process leaves behind two products -- methyl esters (the chemical name for bio diesel) and glycerine (a valuable by-product usually sold to be used in soaps and other products). Fuel-grade bio diesel must be produced to strict industry specifications (ASTM D6751) in order to insure proper performance. Bio diesel is the only alternative fuel to have fully completed the health effects testing requirements of the 1990 Clean Air Act Amendments.

Articles