Unveiling Detection Limits: Methods, Samples, and Distinctions

For analytical testing professionals, we are all aware that the detection limit is a crucial indicator in analytical testing, and it is one of the essential parameters for evaluating instrument performance and establishing methods. In routine testing, the detection limit serves as a specific measurement, particularly in trace analysis, where the error in trace analysis is related to the multiple of the sample content concerning the detection limit. Determining the detection limit holds significant importance in selecting analytical methods. Let’s unravel the various “detection limits” together today!

01 What is the Detection Limit?

The detection limit was first introduced by H. Kaiser, a German scientist, in 1947, as a concept related to the detection capability of analytical methods. It was proposed that, similar to precision and accuracy, the detection limit is a crucial indicator for evaluating the performance of an analytical testing method.

The detection limit refers to the minimum concentration or quantity of the analyte that can be reliably detected from a sample using a specific method at a given confidence level.

02 Classification of Detection Limits

Detection limits can be classified into three categories: instrument detection limit, method detection limit, and sample detection limit.

Image This refers to the smallest reliable signal detectable by an instrument relative to the background. It is typically expressed using the signal-to-noise ratio (S/N). When the S/N ratio is equal to or greater than 3, it is defined as the instrument detection limit. The instrument detection limit is a measure of the instrument’s inherent noise that causes fluctuations and drifts in measurement readings when the instrument is in a stable state. The level of the instrument detection limit provides valuable information on the signal-to-noise ratio, detection sensitivity, distinction between signal and noise, and the lowest limit achievable in analytical methods under specified instrument conditions.