Selecting and Handling Reagents and other Chemicals in laboratory

The purity of reagents has an important bearing on the accuracy attained in any analysis. It is, therefore essential that the quality of reagents be consistent with their intended use and the selection and handling of reagents and chemicals, and the Rules of Handling reagents and Solutions.

 {tocify} $title={Table of Contents}

Classifying Chemicals

Reagent Grade

Reagents-grade chemicals conform to the minimum standards set forth by the reagents Chemical Committee of the American Chemical Society (ACS) and are used whenever possible in analytical work. Some label their products with the maximum limits of impurity allowed by the ACS specifications while others print actual concentrations for the various impurities.

Handling Reagents and other Chemicals in laboratory

Primary Standard Grade

The qualities required of a primary standard in addition to extraordinary purity. Primary standards reagents have been carefully analyzed by the supplier, and the results are printed on the container label. The agency also prepares and sells reference standards which are complex substances that have been exhaustively analyzed.

Special-Purpose Reagents Chemicals

Chemicals That have been prepared for a specific application are also available. Included among these are solvents for spectrophotometric and high-performance liquid chromatography. Information pertinent to the intended use is supplied with these reagents. Data Provided with a spectrophotometric solvent, for example, might include its absorbance at selected wavelengths and its ultraviolet cutoff wavelength.

Rules of Handling reagents and Solutions

A high-quality chemical analysis requires reagents and solutions of known purity. A freshly opened bottle of a reagent-grade chemical can usually be used with confidence. Whether this same confidence is justified when the bottle is half empty depends entirely on the way it has been handled after being opened. We observe the following rules to prevent the accidental contamination of reagents and solutions.

1.   Select the best grade of chemicals available for analytical work. Whenever possible, pick the smallest bottle that is sufficient to do the job.

2.   Replace the top of every container immediately after removing reagents. Do not rely on someone else to do so.

3.   Hold the stoppers of the reagent bottle between your fingers. Never set a stopper on a desk top.

4.   Unless specifically directed otherwise, never return any excess reagent to a bottle. The money saved by returning excesses is seldom worth the risk of contaminating the entire bottle.

5.   Unless directed otherwise, never insert spatulas, spoons, or knives into a bottle that contains a solid chemical. Instead, shake the capped bottle vigorously or tap it gently against a wooden table to break up an encrustation. Then pour out the desired quantity. These measures are occasionally ineffective, and in such cases, a clean porcelain spoon should be used. Every backer, flask, or crucible that will contain the sample must be thoroughly cleaned and then rinsed -initially with large amounts of tap water and finally with several small portions of deionized water. properly cleaned glassware will be coated with a uniform and unbroken film of water.

6.   Keep the reagents shelf and the laboratory balance clean and neat. Clean up any spills immediately.

7.   Follow local regulations concerning the disposal of surplus reagents and solutions.

Cleaning and marking of Laboratory wares

Chemical analysis is usually performed in duplicate or triplicate. Each vessel that holds a sample must be marked so that its contents can be positively identified. Flasks, beakers, and some crucibles have small etched areas on which semipermanent marking can be made with a pencil.

Cleaning and marking of Laboratory ware

Special marking inks are available for porcelain surfaces. The marking is baked permanently into the glaze by heating at a high temperature. A saturated solution of iron (III) chloride, although not as satisfactory as the commercial preparation, can also be used for marking. It is seldom necessary to dry the interior surface of glassware before use. Drying is usually a waste of time and is always a potential source of contamination.


Hi I'm Banti Singh, a Chemical Engineer! Welcome all of you to my blog. If you got the information right? Share the information. All of you Thank you

Thanks to visit this site.

Post a Comment (0)
Previous Post Next Post