What is a Trend Chart used for?

• A. Consists of quantitative plots representing laboratory sample results for specific contaminants of concern over time.
• B. A plot of calibration curves against time.
• C. A chart showing the distribution of results per batch.
• D. A figure used to demonstrate instrument drift.

Answer: (A)

Trend charts are used to monitor how laboratory results for specific contaminants of concern change over time. By plotting quantitative sample results on a time axis, you can see patterns, detect unusual spikes, or observe gradual drift, and determine whether the results stay within regulatory or QA/QC limits. This makes trend charts a practical tool for ongoing data review and early issue detection in a monitoring program. The other descriptions fit different kinds of plots—calibration data plotted over time, distributions per batch, or a chart focused on instrument drift—whereas a trend chart specifically illustrates results for contaminants over time, which is the essence of trend monitoring.