Introduction
This guide contains the basic information for proper use of your new Dual Pin Platinum Karl Fischer Titration electrode.
Karl Fischer titration is a widely used analytical method for quantifying water content in a variety of products. The fundamental principle behind it is based on the Bunsen Reaction between iodine and sulfur dioxide in an aqueous medium. Karl Fischer discovered that this reaction could be modified to be used for the determination of water in a non-aqueous system containing an excess of sulfur dioxide. He used a primary alcohol (methanol) as the solvent, and a base (pyridine) as the buffering agent.
What is the Karl Fischer Reaction?
The ALCOHOL reacts with SULFUR DIOXIDE (SO2) and BASE to form an INTERMEDIATE ALKYLSULFITE SALT, which is then oxidized by IODINE to an ALKYLSULFATE SALT. This oxidation reaction consumes water.
Preparation of electrode –
The Double Pin Platinum electrodes are delivered ready to use.
Application –
Water and iodine are consumed in a 1:1 ratio in the above reaction. Once all of the water present is consumed, the presence of excess iodine is detected voltametrically by the Dual Pin Platinum Indicator electrode. That signals the end-point of the titration.
The amount of water present in the sample is calculated based on the concentration of iodine in the Karl Fisher titrating reagent (i.e., titer) and the amount of Karl Fisher Reagent consumed in the titration.
Specifications –
BODY – PTFE
SENSOR – 2 Pin Platinum 0.75mm ø with 1.50mm balled end
TEMPERATURE RANGE – 0 – 600 C
ELECTRODE LENGTH (OVERALL) – 120mm / 96mm
BARREL DIAMETER – 12mm / 8mm
CONNECTOR (OTHERS ON REQUEST) – TNC(BNC) / Lemmo5
pH RANGE – 0 to 14
Cleaning
Dirt and contamination at the Platinum sensor will lead to measurement inaccuracies. They can be removed with the following procedure:
• Deposits and Scale – with diluted mineral acids
• Organic contamination – with the aid of suitable solvents
• Fats, grease and Oil – with acetone followed by Methylated spirits
• Proteins – with hydrochloric pepsin solution
• Persistent films by carefully rubbing down with fine sandpaper or a diamond file.
DO NOT BEND THE PLATINUM PIN!
CHECK COMPATIBILITY OF PTFE PRIOR TO USING
After the procedure the electrode must be rinsed with distilled water & stored dry with PINs covered with a cap to protect from dust and deposits.