Chapter 5: Q5-6 P (page 114)

What is a blank and what is its purpose? Distinguish method blank, reagent blank, and field blank.

Short Answer

Expert verified

A blank is a sample supposed to have no analyte. Blank is commonly used to calibrate instruments such as calorimeters.

A method blank is taken through all the steps in the chemical analysis and used to evaluate the contamination from the preparation and analytical process.
A reagent blank and a method blank can be considered similar, but the reagent blank is not subjected to all sample preparation procedures.
A field blank is similar to a method blank, but it is taken into the field and exposed to the field environment.

Step by step solution

Definition of Blank

A blank is a sample supposed to have no analyte.

Purpose of blank and its types

Blanks are introduced into the experiment to take into account the interference made by the other species present in the system. Also, these blanks help to keep a record of the traces of analyte. These analytes are often used for sample preservation, preparation, and analysis.

Method blank -– It is a type of blank which contains all the present components in the system except the analyte. This type of blank is subjected to all sample preparation procedures. Before we can solve for the quantity of the analyte present in the sample, the response of the method blank must be deducted first from the response of a real sample.

Reagent blank - Unlike the method blank, this type of blank is NOT subjected to all sample preparation procedures. Moreover, it depends upon complete approximation regarding the amount of response introduced by the blank.

Field blank -– It is used in the same way as a method blank; however, this type of blank is exposed to the environment where the collection of samples is performed