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CHM 410/1410 Lecture 2 Environmental Sampling

CHM 410/1410 Lecture 2 Environmental Sampling. Environmental sampling. Two things to consider: Size of the samples required Number of samples required. Size is determined by detection limits Do you mind non-detects? Government monitoring programs vs. research into contaminant disposition.

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CHM 410/1410 Lecture 2 Environmental Sampling

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  1. CHM 410/1410Lecture 2EnvironmentalSampling

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

  3. Environmental sampling • Two things to consider: • Size of the samples required • 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

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

  5. Quality Control(QC) Extraction efficiency – need to understand loss of material during extraction This is done using a Spike and Recovery experiment Add chemical of interest “Spike” Extraction Conc in extract Extraction efficiency X 100 = Conc in spike “Clean” Matrix Extract 5 83% X 100 = 6

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

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