Difference between quality control samples and reference samples

What does a quality control sample mean? A quality control sample is generally used by laboratories to check whether the calibration curves are accurate; it is a sample with a known concentration, and this concentration may have positive or negative errors. For example, the concentration of an arsenic quality control sample might be 3.240±0.012 milligrams per liter. You bring him into your curve for analysis to see whether the data fall within the concentration error range of the quality control samples; if they are within that range, it indicates that there is nothing wrong with your curve and that the other corresponding data are also correct.

The importance of quality control samples in testing activities Many processes or steps are involved in the testing process, and there are often some uncertain factors that can affect the accuracy of our test results. So how can we ensure that our testing remains within controlled limits? In other words, how can we guarantee the validity and comparability of our test results? This requires quality control samples. When it comes to quality control samples, everyone is surely familiar with them; they are what we commonly refer to as QC samples. So, what are these quality control samples? I think there are mainly three types: blank sample, standard solution (substance), and repeat sample. Next, I will discuss the importance of these three in the detection process.

Let’s start with the blank sample (BLK). Every standard method we come across includes a statement stating that a blank sample should be prepared along with the test samples; in some cases, two blank samples are required. Why create blanks? What is the purpose of having blanks? Blank samples can be used to check whether the entire sample processing procedure has been contaminated, whether there are any components in the reagents that need to be detected and what their concentrations are, as well as to determine the detection limit of the instruments during testing and to account for matrix interference. 　　Next, let’s talk about standard materials STD (solutions). For standard materials, we generally choose those that have a matrix similar to or identical to that of the sample to be analyzed, with two samples having either higher or lower concentrations of the respective elements or components. Usually, one of these samples is placed after the blank sample, while the other is placed at a random position. The process for purchasing quality control samples and standard solutions is the same as that for samples, via **Standard Material Network**. During the pretreatment process, reference materials are primarily used to monitor whether there are any abnormalities in the treatment process, and to ensure that the treatment is thorough and complete ； During the instrument testing process, it mainly checks whether the instrument is in normal operating condition and whether there are significant deviations in the working curve.

Finally, let’s talk about duplicate samples (DUP). A duplicate sample is another portion of the sample that needs to be tested, taken from the same sample, with the same preprocessing as the original sample. The purpose of duplicate samples is mainly to verify the uniformity and representativeness of the sample. If the test results show a large difference, it is necessary to find out the reason – whether the wrong sample was used or if the poor uniformity of the sample is to blame 　　In summary: Quality control samples, which may seem unimportant, actually play a vital role in our testing processes. They monitor the quality of the entire testing procedure and provide clues and evidence to help us identify and analyze quality issues. Many people don’t pay attention to it, and by the time a problem arises, they don’t know where to start looking for the cause. Standard laboratories generally require the inclusion of quality control samples.

Quality control sample – three characters; reference sample – two characters. This is the biggest difference