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Trying to Comprehend Concentrations of Environmental Measurement

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Presentation on theme: "Trying to Comprehend Concentrations of Environmental Measurement"— Presentation transcript:

1 Trying to Comprehend Concentrations of Environmental Measurement
Peter Halpin Caltest Analytical Laboratory Napa California Caltest Analytical Laboratory

2 Making Sense of Measurements
A constant comparison to something we can relate to We need a known concept for reference Tangible, real, or at least very familiar! Caltest Analytical Laboratory

3 Familiar Volumes With kids you buy a_______ of milk
With friends you might buy a ______ of beer With soft drinks you have a _______ can. Caltest Analytical Laboratory

4 Relating to Distances The length of a football field 100 yds 300 feet
10 yards to a first down 1 yard hash marks Caltest Analytical Laboratory

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7 Relating to Distances Remembering the High School Track
The straight way is the 100 yd dash Half of the track is the 220 yd dash One full lap is the Quarter Mile, 440 yd dash Two laps is the 880 yd or Half Mile Four laps is the Mile run The mile is 5280 feet Caltest Analytical Laboratory

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9 Relating to Distances In Basketball The Rim is 10 feet off the floor
The Free Throw Line is 15 feet from the rim The court length is 94 feet The basketballs are 28.5” or 29.5” Caltest Analytical Laboratory

10 Relating to Distance: Building
Carpenters tape measures use 1/16, 1/8, ¼, ½ inch, then feet, then 16 inch for stud spacing Tiles on floor are often 12” square Ceiling tiles in T bar ceilings are 2’x 4’ Caltest Analytical Laboratory

11 Relating to Small Distances
The Meter is inches (just over a yard) The centimeter is 1/100th of a meter (0.39 inch) with 2.54 cm per inch The millimeter is 1/1000 of the meter The Micron is 1/1000 of 1 mm ( a millionth of a meter) The nanometer is 1/1000 of a Micron (a billionth of a meter) Caltest Analytical Laboratory

12 Most of us Relate to Something Familiar
Most of us Relate to Something Familiar! Smaller is usually less Familiar Nano-tech typically is referring to the range of 1 to 100 nm “A typical human hair is 40,000 nm”! What does that mean? For the hair part, that equates to 0.04 mm. For the nm part, that is 40,000x smaller than a typical hair width Caltest Analytical Laboratory

13 Courtesy and © Quantum Dot Corporation
Caltest Analytical Laboratory

14 Another perspective: a nanometer is about the width of six bonded carbon atoms, and approximately 40,000 are needed to equal the width of an average human hair. Caltest Analytical Laboratory

15 Red blood cells are ~7,000 nm in diameter, and ~2000 nm in height White blood cells are ~10,000 nm in diameter A virus is ~100 nm A hydrogen atom is .1 nm Caltest Analytical Laboratory

16 Nanoparticles range from 1 to 100 nm Fullerenes (C60 / Buckyballs) are 1 nm Quantum Dots (of CdSe) are 8 nm Dendrimers are ~10 nm DNA (width) is 2 nm Proteins range from 5 to 50 nm Viruses range from 75 to 100 nm Bacteria range from 1,000 to 10,000 nm Caltest Analytical Laboratory

17 Prefix Symbol Multiplier Exponential yotta Y 1,000,000,000,000,000,000,000,000 1024 zetta Z 1,000,000,000,000,000,000,000 1021 exa E 1,000,000,000,000,000,000 1018 peta P 1,000,000,000,000,000 1015 tera T 1,000,000,000,000 1012 giga G 1,000,000,000 109 mega M 1,000,000 106 kilo k 1,000 103 hecto h 100 102 deca da 10 101 1 deci d 0.1 10¯1 centi c 0.01 10¯2 milli m 0.001 10¯3 micro 10¯6 nano n 10¯9 pico p 10¯12 femto f 10¯15 atto a 10¯18 zepto z 10¯21 yocto y 10¯24 Caltest Analytical Laboratory

18 For Concentrations we need a familiar Reference Too
DOE Analytical Services Workshop September 19, 2011 For Concentrations we need a familiar Reference Too Most Common is Percent, or parts per 100 100% is all of it! 99% is pretty close, unless we are talking about a toxicant or contaminant! Sewage is >99% ‘pure’ water! July 4, 2011 Chemical and Engineering News magazine editorial remarked on the City of Portland dumping 8 mg because video showed a man urinating in the open air reservoir. Converts to about 15 parts per trillion urine, in open reservoir that already has bird, mouse, lizard etc. excrement! Caltest Analytical Laboratory Caltest Analytical Laboratory

19 Most Environmental Issues are “trace contaminants”
‘Trace’ usually means lower than what you are used to looking for! Usually not obvious, measured by advanced techniques Caltest Analytical Laboratory

20 Ever Wonder Why Such Low Environmental Limits?
Sometimes the analyte is just that toxic! Usually the analyte Bio-Accumulates Concentration builds up in tissue faster than rate of loss mechanisms Often also involves Bio-Magnification One organism consumes the accumulated analyte concentration in its food, and when the next organism up the chain consumes it, the analyte concentrates further Caltest Analytical Laboratory

21 Example of Mercury The difference between the methyl mercury in the water and the methyl mercury contamination in the fish is a million fold! Both bioaccumulation and biomagnification through the food chain Caltest Analytical Laboratory

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23 Zeros to the right of the one indicate less and less of a thing
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25 The Units of Concentration
Orders of Magnitude are ten-fold differences Units of measure of concentration vary by three orders of magnitude (three zeros between the respective units) Caltest Analytical Laboratory

26 More on Units mg/L (milligrams per Liter) Parts per million (ppm)
µg/L (micrograms per Liter) Parts per billion (ppb) One microgram per Liter (µg/L) is a thousand times lower concentration than one milligram per Liter ng/L (nanograms per Liter) Parts per trillion (ppt) One nanogram per Liter (µg/L) is a thousand times lower concentration than one microgram per Liter pg/L (picograms per Liter) Parts per quadrillion Caltest Analytical Laboratory

27 Fractions of 1000 Milli means 1/1000 so why is milligrams per Liter called parts per million instead of parts per thousand? 1/1000 of one gram per one Liter. One Liter is 1,000 grams, so 1/1000 of a gram per 1,000 grams is 1/1,000,000 of a gram, also known as 1 part per million Caltest Analytical Laboratory

28 Comparing Expressions of 1%
1% (very little in composition) is equal to 10,000 parts per million (lots with respect to contamination!) 10,000 mg/L (parts per million) 10,000,000 µg/L (parts per billion) 10,000,000,000 ng/L (parts per trillion) 10,000,000,000,000 pg/L (parts per quadrillion) 10,000,000,000,000,000 fg/L (parts per quintillion) Caltest Analytical Laboratory

29 The Water Reservoir Story
1 person adds 1 pint to 8 million gallons ~ 16 µg/L (parts per billion) contaminating fluid If 1,0o0 persons add a pint (125 gallons) to 8 million gallons ~ 16 mg/L (parts per million) contaminant Its just a change of units, but represents a large change in concentration (1,000 fold) Then the questions still arises, is it environmentally, ecologically relevant? Caltest Analytical Laboratory

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33 1,000 fold increase Caltest Analytical Laboratory

34 Map out the Zeros and Compare
DOE Analytical Services Workshop September 19, 2011 Map out the Zeros and Compare Get a better grasp by finding where your measurement units line up on the scale Keep relating to knowns with relevance i.e. Limitations of the instrument and method Comparison to regulatory limit Comparison to average concentrations Comparison to blanks! Comparison to variability of the measurement As percent, and as reportable units Caltest Analytical Laboratory Caltest Analytical Laboratory

35 Example of Mercury The common reporting limit of 0.2 part per billion was too high to adequately monitor this bioaccumulative toxic analyte Many measurements turned out to be “analytical noise”! Reporting Limit on new method of 1 part per trillion (0.001 part per billion) allowed accurate measurements in the range of interest, part per trillion. Blanks were under control, accuracy and precision good in the range of interest Caltest Analytical Laboratory

36 Example of PCB Congeners
Common method reporting limit is about x too insensitive New method about 10x lower than the target concentrations Blanks can approach the RL to target concentrations! Method optimizations required to make the data useful! Caltest Analytical Laboratory

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