Familiarize yourself with the Calibration Plot

校准对于建立可以放置在测量技术上的依赖程度至关重要。同样，绝对有必要使用经过认证的参考资料准备校准曲线，并在决定进行定量估计之前，无论多么复杂是您决定的分析技术。

A calibration plot in simple language is a graphical representation of the change in response of the measurement device with respect to change in concentration of the analyte under determination. A clear understanding of the concepts of calibration and a visual examination of the calibration plot will help you decide whether you should proceed with the adopted analytical technique for estimations over the desired concentration range of the analyte or look for alternate options. For this there is no necessity to go into the mathematical analysis of the plot but a simple visual look should help you take your decision.

The steeper the calibration line the higher is the sensitivity of the adopted technique.

在通过大多数现代分析仪器上可用的应用软件，可以在系统屏幕上自动显示校准图或图表纸张上的校准图或曲线图。在这个阶段，快速参考关于这个主题的早期文章是个好主意顾idelines on generation and interpretation of calibration plots‘ and ‘Understanding the linearity of a calibration plot’.

The ideal graph shown above is one in which all the measurements recorded are in direct proportion to respective changes in concentration. All the points lie in a straight line and it passes through the origin. Such a plot can be ideally used for arriving at a known concentration over a wide range of measurements. However, in real situations, the calibration plot deviates from ideal behaviour due to several reasons and may appear like the representation below:

You will be able to make the following important observations by simply observing its characteristics:

• The straight line may intersect the response or Y axis at a point different from origin. In other words there can be a residual response even at zero concentration due to matrix interferences.
• 观察到的点不一定呈直线。这实质上明确表示直线是一种近似，它手动绘制以通过最大点数或通过系统软件自动生成，从而产生最佳合适的线路。重要的是要记住，不能通过在任何测验练习中加入观察到的点来产生校准线。
• Beyond a certain concentration the plot is no longer linear and tends to flatten out. This means that inference can be drawn with a certain degree of confidence only in the linear range of the plot.
• 曲线的线性部分越越好越好是给定分析的选择技术。这也称为线性动态范围，它可以延伸到几个数量级，比如\（10 ^ 3 \）到\（10 ^ 6 \），用于敏感分析技术。

Calibration plots are prepared using standards and the approaches used to overcome matrix interference will be discussed in a subsequent article.