Sample Preparation for Analytical Characterization

Overview

Source: Laboratory of Dr. B. Jill Venton - University of Virginia

Sample preparation is the way in which a sample is treated to prepare for analysis. Careful sample preparation is critical in analytical chemistry to accurately generate either a standard or unknown sample for a chemical measurement. Errors in analytical chemistry methods are categorized as random or systematic. Random errors are errors due to change and are often due to noise in instrument. Systematic errors are due to investigator or instrumental bias, which introduces an offset in the measured value. Errors in sample preparation are systematic errors, which will propagate through analysis, causing uncertainty or inaccuracies through improper calibration curves. Systematic errors can be eliminated through correct sample preparation and proper use of the instrument. Poor sample preparation can also sometimes cause harm to the instrument.

Procedure

1. Making a Solution from a Solid

Choose the correct glassware to make solution.
Clean the glassware thoroughly via an acid bath of 1% HCl or HNO₃ along with soap to remove any impurities (safety warning: with any strong acid use gloves, goggles, and other appropriate personal protective equipment).
Rinse the glassware several times with distilled water. Dry in an oven if needed.
To make a solution from a solid, mass out the correct amount of solid.
Put the s

Application and Summary

Spin filters are often used in biological analyses to clean up samples. If cellular debris from cell lysis is a problem, then the sample can be spin filtered and the filtrate at the bottom will be free from particles. If you wish to concentrate a protein or other bigger analyte, a filter with a small pore membrane can be used that the protein cannot pass through. After spin filtering the smaller molecules will be in the filtrate at the bottom and will be discarded. When the filter is inverted and spun again in anoth