Acidity

Acidity is the quantitative capacity of a water sample to neutralize a base to a predetermined pH value. Greater acidity indicates higher concentration of acids present and more potentially corrosive the water. Acidity is caused by a variety of acids including mineral acids, organic acids, and even carbon dioxide in the form of carbonic acid. Today, our water supplies are becoming more contaminated with corrosive chemicals from industrial dumping and ever-growing amounts of carbon dioxide in the atmosphere. Acidity measurements are an essential means to define and control pollution in sewers, lakes, and rivers. Monitoring acidity in soils and fish farming helps to maintain an adequate growing environment. Acidity also affects the quality of food and beverages, such as wine, fruit juices, sauces, and olive oil.

The concept of pH and acidity are easily misunderstood. All aqueous solutions can have the pH measured but that is not the same as an acidity measurement. To determine the acidity of a solution it necessary to titrate the solution with a base, such as sodium hydroxide, to a pH endpoint. The most common pH endpoint is phenolphthalein, when the indicator is added to a solution the solution will change to a pink color at pH 8.2. Solutions of different acidities (regular orange juice versus low acid) can have the same pH value but require different amounts of base to reach the pH 8.2 end point.

The pH meter was invented to determine the acidity of orange and lemon juice. The meter was used in place of the indicator due interferences that caused the color change to not be seen. Many customers continue to use a pH meter and graduated burette to perform this simple titration.

Technology has advanced with automatic titration systems that have unique algorithms to dose the base precisely in order to determine either a pH endpoint or an equivalence point. Hanna offers a wide range of products from basic chemical test kits to advanced automatic titration systems.

Titration

Hanna Instruments offers a variety of titration systems.

Potentiometric titration systems include single and dual channel options and a version with a single or dual dosing pump. These sytems are the most accurate in dosing with a 40,000 step dosing pump that can deliver microliters of titrant. Some titration systems can perform two titrations consecutively such as salt and acidity performed in food analysis.

The mini-titrator is a Hanna Instruments innovation that brings the accuracy and precision of our potentiometric titration systems to the users performing manual titration with a pH meter. The mini-titrators use a syringe pump to accurately dose the titrant. The titrant is pre-standardized so no specialized glassware or analytical balances are need to make the titrant.

 

 

 

Portable pH Meters

We offer a wide range of portable pH meters that can be used for manual titrations for acidity. Each still requires a graduated burette filled with a base to determine the amount of base to reach the pH end point.

 

 

pH Electrodes

Many electrodes are available for measuring pH. The pH electrodes include those supplied with our mini-trators for wine and dairy products, others include versions made specifically for non-aqueous titrators.

The probes made for non-aqueous titrations use chemically resistant materials to withstand harsh chemicals, and offer a double junction design to replace the electrolyte with lithium chloride dissolved in the solvent used with the sample.

 

Solutions

Solutions required for performing acidity titrations include calibration buffers and maintenance solutions used for cleaning and storage.

Calibration Solutions

The quality of a titration is only is as good as the calibration of the meter. A wide variety of calibration buffers are available including pH 8.20 that is used with our mini-titrators. The pH 8.20 buffer can be used with other meters as long as the value can be entered as a buffer. Many portable and benchtop meters allow for a custom calibration point such as pH 8.20.

 

Chemical Test Kits

A variety of chemical test kits are available including those for basic acidity of water and one made specifically for determining olive oil acidity.

 

Portable Photometers

Portable photometers, like chemical test kits, are reagent based design in which there is a color change to indicate the endpoint. The portable photometers use the Beer-Lambert principle to determine the color change. Detection of the color change is more accurate than subjective visual interpretation.

 

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