1. CHM 410/1410 Lecture 2 Environmental Sampling

2. Environmental sampling Two things to consider: 1.Size of the samples required 2.Number of samples required Size is determined by detection limits -Do you mind non-detects? -Government monitoring programs vs. research into contaminant disposition

4. Environmental sampling Two things to consider: 1.Size of the samples required 2.Number of samples required Size is determined by detection limits -Do you mind non-detects? -Government monitoring programs vs. research into contaminant disposition Number is determined by spatial resolution required -Trying to see differences? -How well characterized does the situation have to be? Use these principles to design a sampling protocol

6. Quality Control (QC) Contamination – an analytical chemist’s worst enemy Need to control and understand contamination at all steps: Find Contamination – work backwards to identify the source Field blanks SamplingExtractionAnalysis Extraction blanksInstrumental blanks Once source is identified, make changes to reduce contamination -Change sampling technique or container -New extraction reagents or location or technique -Clean instrument

7. Quality Control (QC) Extraction efficiency – need to understand loss of material during extraction This is done using a Spike and Recovery experiment “Clean” Matrix Add chemical of interest “Spike” ExtractionConc in extract Conc in spike X 100 = Extraction efficiency Extract5 6 X 100 = 83%

8. What if you can’t find a “clean” matrix?