The Buffer solution is used to resist the change in pH. Because all reactions between metal ions and EDTA are pH dependent. Change in pH may lead to the improper reaction between Metal ion and EDTA.

Human error can also pose many limitations to a titration experiment. For example, if a sample solution has been left open, a small amount of the solution may have evaporated. If the pipette was not washed with distilled water between measuring the titrate and the analyte, the analyte could be contaminated.

There are few disadvantages of complexometric titration. However, this method has some disadvantages. It is a destructive method as it use relatively large quantities of the substance being analysed. It can produce chemical waste which has to be then disposed of. It has limited accuracy.

Direct determination of aluminum with EDTA is impossible – complexation reaction is too slow, making titration impractical. If solution was prepared by dissolving sample containing Al in a strong acid, it may have very low pH.

This is because all the reactions between the metal ions and EDTA are pH-dependent. During titration Eriochrome Black T is used as indicator. This buffer is also called Ammoniacal Buffer, Dissolve 90 g of ammonium chloride in 375 mL of 28–30% ammonium hydroxide, and dilute to 500 mL with water.

ethylene diamine tetra acetic acid (EDTA)

Since both EDTA and the indicator are themselves weak acids, a buffer solution , which is able to maintain a fairly constant pH even when acids and bases are added, is used. This may not sound simple at all. You may have many questions: How does the indicator cause the solution to change color?

# The buffer adjusts the pH to ensure that the reaction goes to completion.

A buffer is a solution that can resist pH change upon the addition of an acidic or basic components. It is able to neutralize small amounts of added acid or base, thus maintaining the pH of the solution relatively stable. This is important for processes and/or reactions which require specific and stable pH ranges.

Calcium and magnesium salts dissolved in water cause water hardness. Water hardness can be measured using a titration with ethylenediaminetetraacetic acid (EDTA). The ionised form of EDTA is shown on the right. EDTA dissolved in water forms a colourless solution.

In the determination of water hardness, ethylene- diaminetetraacetic acid (EDTA) is used as the titrant that complexes Ca2+ and Mg2+ ions. This color change signals the end point, as it takes place when the EDTA, after complexing all of the unbound Ca2+ and Mg2+ ions, removes the Mg2+ ion bound to the indicator.

EDTA is produced as several salts, notably disodium EDTA, sodium calcium edetate, and tetrasodium EDTA.

BD Vacutainer Plus Blood Collection Tubes contain K2EDTA, which is spray-dried to the walls of the tube. Vacutainer glass blood collection tubes contain K3EDTA, the liquid form of EDTA.