1. Metric System and Lab Skills

2. What the heck is it? How do you use it?
a. Every country in the world uses the metric system… …except 3.
b. The metric system was devised by French scientists in the late 18th century to replace the chaotic
collection of units then in use.
i. The goal of this effort was to produce a system that did not rely on a miscellany of separate standards, and to use the decimal system rather than fractions.

3. To obtain a standard of length…
i. One quadrant of the earth (one-fourth of a circumference) was surveyed from Dunquerque, in France, to Barcelona, in Spain along the meridian that passes through Paris.
ii. This distance, from the North Pole to the equator, was divided into ten million parts to constitute the meter (spelled metre in some countries).

4. FUN FACTS!
The definition of the meter has become more and more precise through the years since, even though its length has not changed.
On April 5, 1893 the inch was redefined as precisely 1/39.37 meter, and in a very real sense we have been using the metric system ever since. In 1959 the length of the inch was shortened slightly to its present definition of centimeters.
The speed of light, a universal constant, is almost exactly 300 megameters per second.
The circumference of the earth is 40 megameters (by the original definition of the meter in the eighteenth century).

5. The Metric Roots a. Meter – Measures Length (abbreviated m).
b. Liter – Measures Volume (abbreviated L).
c. Gram – Measures Mass (abbreviated g).

6. Abbreviations: a. milli = m b. centi = c c. deci = d d. deka = dk
e. hecto = h
f. kilo = k

7. Writing in Scientific Notation
a. Step 1: Move decimal left. Leave only
one number in front of decimal.
b. Step 2: Write the number without zeros at the end.
c. Step 3:Count how many places you moved decimal. Make that your
power of ten
i. 93,000, Standard Form
ii. 9.3 x Scientific Notation

8. Micropipettes!

9. Automatic pipettes are used to accurately transfer small liquid volumes
a. Glass pipettes are not highly accurate for volumes less than 1 milliliter (1 ml), but the automatic pipettes are both accurate and precise.
b. Each micropipette can be set to transfer any volume within its own volume range

10. Purpose of the micropipette:
Biotechnologists use a them to transfer precise amounts of liquids from one container to another.
b. The measurements are in microliters. i. 1 ml = 1000 µL.

11. Care of the micropipette:
a. Misuse can result in damage that causes incorrect measurements affecting your investigation.
b. Do not drop the micropipette.
c. Do not adjust the volume below its lower (or upper) limit.

12. Parts

13. Selecting the correct micropipette:
a. Micropipettes have a maximum & minimum volume size that they can handle.
b. Choose the micropipette that accommodates the volume needed.

14. Volume Adjustment
a. Step 1 - In the display window are three vertical numbers.
i. The top number is tens µl (10.0).
ii. The middle number is ones µl (02.0).
iii. The bottom number tenths µl (00.9).
b. Step 2 - Set the pipette to the desired volume by turning the calibration knob until the volume display reads the desired numbers.
c. Attach the Disposable Tip.

15. Transferring Liquids
a. Step 1 = Adjust the pipette to the desired volume.
i. Hold the pipette so the display is facing the user and the thumb can easily depress the top pushbutton.
b. Step 2 - Depress the pushbutton to the first stop before placing the pipette tip in the liquid.
c. Step 3 - Place the tip in the liquid.
d. Step 4 - Slowly release the pushbutton and draw the liquid into the tip. This draws the exact calibrated volume into the tip if the tip remains below the liquid surface during withdrawal

16. f. Step 6 - Press down on the tip ejector button to eject the tip.
i. NEVER LET THE PLUNGER SNAP UP! Remove the tip from the liquid and visually check for liquid in the tip.
ii. Remove the tip from the sample liquid. No liquid should remain on the OUTSIDE of the tip. Wipe away any droplets on the outside of the tip with a lint-free tissue, such as KIMWIPES, but only wipe droplets from the side of the tip. NEVER TOUCH THE TIP OPENING or you may absorb part of your sample.
e. Step 5 - Place the tip into the container which is to receive the liquid.
i. Slowly depress the pushbutton as far as it can go.
ii. With the pushbutton fully depressed, withdraw the tip.
f. Step 6 - Press down on the tip ejector button to eject the tip.
i. Dispose of the tip in an appropriate container.

17. Accuracy vs. Precision
a. Accuracy means the closeness with which the dispensed volume approximates the volume set on the pipette.
b. Accuracy is specified as mean error, the average deviation of replicate measurements from the expected set volume.
c. Precision is the "scatter" or reproducibility of individual measurements of the same volume.
d. Precision can also be expressed as standard deviation.
e. Accuracy is affected by the micropipette.
f. Precision is affected by how well you use it.

18. For optimal results:
a. Consistent SPEED and SMOOTHNESS when you press and release the PLUNGER.
b. Consistent pressure on the PLUNGER at the FIRSTSTOP.
c. Consistent and sufficient IMMERSION DEPTH.
d. Nearly VERTICAL POSITIONING of pipette.
e. AVOID ALL AIR BUBBLES: Since the plastic pipette shaft can be damaged if liquids are drawn beyond the tip into the shaft.
f. NEVER lay the pipette on its SIDE nor INVERT the pipette if liquid is in the tip