June 17, 2025 Other Open Access

NEXT Plant data: Results of Quality Assurance and Quality Control - Supplementary material for publications based on this data set

Pospiech, Solveig

Researcher(s)

Format: HTML document (bookdown format)
Purpose: This file provides a detailed description of the quality assurance and quality control (QA/QC) procedures applied to the plant concentration data collected during the study. It includes statistical analysis of reference materials, drift correction, uncertainty modeling, and evaluation of laboratory and field precision.

Description of the File Content

This file is part of a larger data publication and serves as a supplementary document to the main dataset. It outlines the QA/QC procedures used to ensure the accuracy, precision, and reliability of the plant element concentration data. The file includes:

1. Reference Material (RM) Analysis:

   • Statistical summaries of standard reference materials (SRMs) such as UPDEEP_SPRU_BARK_DRY, UPDEEP_SPRU_TWIG_DRY, and UPDEEP_SPRU_NEED_DRY.
   • Comparison of pre-analyzed SRM values with actual measurements.
   • X-charts showing the performance of SRMs over time and across different batches.

2. Drift and Offset Correction:

   • Visualizations of raw and corrected data for routine samples, laboratory, and field replicates.
   • Analysis of data trends and correction of analytical drift and offsets.

3. Uncertainty Modeling:

   • Calculation of relative standard deviation (RSD) from laboratory replicates.
   • Identification of elements with high uncertainty (RSD > 10%) that may be excluded from further analysis.
   • Tables and visualizations showing the distribution of uncertainties across different plant tissues.

4. Field Precision Assessment:

   • Evaluation of field replicate data to assess variability in field sampling.
   • Identification of elements with poor field precision (RSD > 20%).

5. Data Preparation and Processing:

   • R code for data loading, cleaning, and transformation.
   • Use of packages such as data.table, ggplot2, dplyr, and kableExtra for data manipulation and visualization.

Summary of Key Findings and Data Included

• Reference Materials: The file provides statistical summaries (mean, median, SD, RMAD) of SRMs used to monitor analytical performance. These are compared with actual measurements to assess accuracy and precision.
• Drift Correction: The data shows the effect of drift correction on plant concentration measurements, improving the consistency of results across different batches.
• Uncertainty Analysis: The RSD of laboratory replicates is calculated, and elements with high variability are flagged for exclusion.
• Field Precision: Field replicates are used to assess the variability of sampling and analysis in the field, with some elements showing poor precision.
• Visualizations: The file includes numerous plots (e.g., X-charts, scatter plots) to illustrate data trends, comparisons, and uncertainty levels.