Systematic errors in chemical analysis

 

Systematic errors in chemical analysis

A flaw in the analytical procedure, or an ineffective instrument or analyst, causes a systematic error. A systematic error technique will always produce a mean value that differs from the true value. The term 'bias' is occasionally used to define and explain a systematic error. When a systematic error exists and the computed uncertainty of the measured value is small enough to distinguish a definite difference when compared to the conventional true value, the measured value is described as biased high or low. The exact value of a systematic error cannot be determined because the true value is unknown. Systematic errors can thus be avoided. They have a firm hold on things. The most common types of systematic errors are instrumental errors, method errors, and personal errors.

Instrumental errors occur when an instrument malfunctions, resulting in an error in the experiment. Pipettes, burets, and volumetric flasks can hold or dispense volumes that differ dramatically from the graduations on their sides. The majority of systematic errors of this type are eliminated by calibration.

Errors in method: Non-ideal chemical or physical behavior of the reagents and reactions used in an analysis typically introduces systematic procedure errors. Nonideality can be caused by the slowness of some reactions, the incompleteness of others, the instability of some species, the lack of specificity of most reagents, and the risk of side reactions interfering with the measuring process. Inherent flaws in a process are often difficult to detect, making them the most difficult to identify and correct.

Personal errors: As a result of the experimenter's inattention, carelessness, or personal limitations. Many measurements necessitate subjective judgments. Estimating the position of a pointer between two scale divisions, the color of a solution at the end point of a titration, or the level of a liquid with respect to a graduation in a pipet or burette are just a few examples.

Methods for lowering systematic errors, Collect typical samples. Analyze standard reference materials at known concentrations. Examine unprocessed samples Measuring should be done in a variety of ways. Participate in a round-robin study with other labs, with varying sample sizes.