Table 2 Get acquainted with your data

1. Verify chemical identities.

 ○ Check CAS number, chemical name, isomer type of reported analytes vs. analytical standards purchased by lab (see Additional file 2 for example correspondence).

2. Count (overall and by batch) the number of:

 ○ “Real” samples – compare these to the chain of custody that lists the samples submitted for analysis to make sure all submitted samples were analyzed

 ○ Lab control and/or matrix spike recoveries

 ○ Reference samples (e.g., CRMs)

 ○ Surrogate spike recoveries

 ○ Blanks (solvent method, field, matrix, other)

 ○ Duplicates

3. Examine any data qualifier flags reported by the lab and make sure interpretation is clear.