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Peter Halpin Caltest Analytical Laboratory Napa California 1Caltest Analytical Laboratory.

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Presentation on theme: "Peter Halpin Caltest Analytical Laboratory Napa California 1Caltest Analytical Laboratory."— Presentation transcript:

1 Peter Halpin Caltest Analytical Laboratory Napa California 1Caltest 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! 2Caltest 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. 3Caltest 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 4Caltest 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 7Caltest 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 9Caltest 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 2x 4 10Caltest Analytical Laboratory

11 Relating to Small Distances The Meter is 39.37 inches (just over a yard) The centimeter is 1/100 th 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) 11Caltest Analytical Laboratory

12 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 12Caltest Analytical Laboratory

13 Courtesy and © Quantum Dot CorporationQuantum Dot Corporation 13Caltest 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. 14Caltest 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 15Caltest 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 16Caltest Analytical Laboratory

17 PrefixSymbolMultiplierExponential yottaY 1,000,000,000,000,000,000,000, 000 10 24 zettaZ1,000,000,000,000,000,000,00010 21 exaE1,000,000,000,000,000,00010 18 petaP1,000,000,000,000,00010 15 teraT1,000,000,000,00010 12 gigaG1,000,000,00010 9 megaM1,000,00010 6 kilok1,00010 3 hectoh10010 2 decada1010 1 110 0 decid0.110¯ 1 centic0.0110¯ 2 millim0.00110¯ 3 microµ0.00000110¯ 6 nanon0.00000000110¯ 9 picop0.00000000000110¯ 12 femtof0.00000000000000110¯ 15 attoa0.00000000000000000110¯ 18 zeptoz0.00000000000000000000110¯ 21 yoctoy0.00000000000000000000000110¯ 24 17Caltest Analytical Laboratory

18 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! 18Caltest 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 19Caltest 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 20Caltest 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 21Caltest Analytical Laboratory

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23 Zeros to the right of the one indicate less and less of a thing 23Caltest Analytical Laboratory

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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) 25Caltest 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 26Caltest 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 27Caltest 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) 28Caltest 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? 29Caltest Analytical Laboratory

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33 1,000 fold increase 33Caltest Analytical Laboratory

34 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 34Caltest 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, 10-50 part per trillion. Blanks were under control, accuracy and precision good in the range of interest Caltest Analytical Laboratory35

36 Example of PCB Congeners Common method reporting limit is about 100-1000x 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 Laboratory36

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