How do Electrostatic Charges Affect Analytical Weighing?   

Analytical weighing is such a delicate process that absolute accuracy is needed. 

Unfortunately, such accuracy can often be difficult to achieve, due to a variety of 

factors. These include changes in temperature, barometric pressure or even the 

gravitational pull of a particular location, which can seriously affect the readings of a 

weighing device. Such problems can be avoided simply by calibrating the balance 

before each use. Further details on the subject can be found in the article When and 

Why You Should Calibrate Your Balance. 

However, there is another factor which affects weighing output readings – 

electrostatic charges. This one is not so easily solved by simple calibration. 

Electrostatic Charges and Analytical Weighing 

Charge that flows through a conductor is simply called electricity. However, charges 

can also be produced in insulators (material which do not conduct the electricity) 

when they come into contact with another surface (a process called friction). In a 

laboratory setting, this most often occurs when a beaker or other vessel is rubbed 

(normally for cleaning purposes) with a dry cloth. 

This friction disrupts the balance of the positively charged nucleus with its 

surrounding negatively charged neutrons, and creates electricity. But because there 

is nowhere for this energy to go (being trapped in an insulator), it remains static, and 

thus becomes known as electrostatic energy. 

The presence of electrostatic energy can be quite a problem when it comes to 

analytical weighing because the charge can affect the material being weighed, thus 

yielding skewed results. Though the charges do fade and dissipate over time, their 

very presence in the first place is a cause for concern when absolute accuracy is 

required. The possibility of static charges developing upon the weighing vessels is 

dependent largely on the humidity of the location. A room with higher humidity levels 

will pose less of a threat to incorrect calculations than one with humidity levels lower 

than 45%. 

How to Avoid Skewed Results from Electrostatic Charges 

Luckily, technology has risen to meet the challenge of interference from electrostatic 

charges. Manufacturers of balances have developed a new sensor which can detect 

the presence of electrostatic charge, and in doing so, offset the discrepancies in 

weighing caused by the charge. This makes the process easier and more reliable. 

For a more in-depth discussion of this innovative new method of analytical weighing, 

please check out the article Integrated Electrostatic Detection in Analytical Weighing. 

Another method of avoiding such discrepancies is by introducing a static eliminator 

into the laboratory. This is especially pertinent in laboratories where a humidity level 

of under 45% is present, and should be used before weighing to achieve maximum 

accuracy.