The Basic Skills of the. Biotechnology Workplace

Transcription

1 The Basic Skills of the Biotechnology Workplace

2 Learning Outcomes Determine the most appropriate tool for measuring specific volumes of masses Describe how to select, set, and use a variety of micropipets within their designated ranges to accurately measure small volumes Convert between units of measure using the B <- -> S rule and appropriate conversion factors Recognize the different expressions for units of concentration measurements and use their corresponding equations to calculate the amount of solute needed to make a specified solution Define the term buffer and calculate a specified dilution from a concentrated stock solution or buffer

3 Measuring Volumes in a Biotechnology Facility

4 Volume is a measurement of the amount of space something occupies Volume can be measured in Liters (L) Milliliters (ml) Microliters (ml) Different tools are used to measure volume Graduated cylinder Pipet Micropipet

5 Converting Units Often volumes are measured in one unit of measurement and reported in another Use metric units Will Need Conversion Factors To measure larger volumes, technicians usually use a graduated cylinder

6 Pipets are available that measure volumes between 0.1 ml and 50 ml. In the lab, common graduated cylinders include 10 ml, 25 ml, 100 ml, 250 ml, 500 ml, and 1 L.

7 Using Micropipets When measuring volumes less that 1 ml, a micropipet is used. Volumes are reported to nearest microliter. A micropipet has four parts Plunger button Ejector button Volume display Dispensing tip

8 Picking and Using the Appropriate Micropipet P-100 or P-200 micropipet P-10 or P-20 micropipet P-1000 micropipet

9

10 Metric Conversions

11

12 The plunger has two stops. Pressing to the first stop evacuates air to the volume in the display. Pressing to the second stop evacuates that volume plus another 50% or so. To ensure accurate measurement, feel the difference between the first and second stop before using the pipet. Inaccurate measurement could waste costly reagents and cause invalid experiment results.

13 The p20 is used for volumes between 2 μl and 20 μl. The p200 is used for volumes between 20 μl and 200 μl Attempting to set the volume beyond the pipette s minimum or maximum values can damage it.

14 P-10 micropipets are common in biotechnology labs. A P-10 micropipet will measure volumes as small as 0.5 ml and has precision to 0.02 ml. A P-10 uses tiny tips that are usually white.

15 P-100 Micropipet. This micropipet will measure volumes as small as 10 ml and has precision to 0.2 ml.

16 A P-1000 micropipet will measure up to 1000 ml, or 1 ml, and uses large tips that are usually blue or white in color.

17 Using a micropipet P1000 The first red digit is thousands of µl The middle digit is hundreds The third is tens. Therefore = 350µL You will set it up as 035

18 P200 The first digit is hundreds of µl The second is tens The third is units Therefore = 95µL You would set it up as 095.

19 P20 The first digit is tens of µl The second is units (ones) The third red digit is tenths Therefore = 2.5µL You will set it up as 025

20 P2 The first digit is units (ones) of µl The second red digit is tenths The third red digit is hundredths Therefore = 0.5µL You would set it up as 050

21 P20 Recall that the p20 measures volumes from 2-20 μl. See how the dial is set = 153 The tenths place is in red to remind the user that it is the p20 The volume = 15.3 μl.

22 P200 Recall that the P200 measures volumes from μl. See how the dial is set = 097 Volume = 97 μl.

23

24

25 One useful way to convert units is to use the metric "staircase"

26 EXAMPLE: Convert kilometers to centimeters km = 1,254,000 cm km x cm 1km

27 Convert 457 ml to hl 457 ml = hl 457mL x 1hL ml

28 Calculate the following using the metric ladder: 1000 mg = g 1 g 1 L = ml 1600 ml 160 cm = mm 1600 mm 14 km = m m 109 g = kg.109 kg 250 m = km.250 km

29 Convert 100 µl to cc

30 Vocabulary Graduated cylinder a plastic tube with marks (or graduations) equally spaced to show volumes; measurements are made at the bottom of the meniscus, the lowest part of the concave surface of the liquid in the cylinder Pipet an instrument usually used to measure volumes between 0.1 ml and 50 ml Micropipet an instrument used to measure very tiny volumes, usually less than a milliliter Unit of measurement the form in which something is measured (g, mg, mg, L, ml, ml, km, cm, etc.) Conversion factor a number (a fraction) where the numerator and denominator are equal to the same amount; commonly used to convert from one unit to another Metrics conversion table a chart that shows how one unit of measure relates to another (for example, how many milliliters are in a liter)

31 Vocabulary Volume a measurement of the amount of space something occupies Mass amount of matter (atoms and molecules) an object contains Liter abbreviated L ; a unit of measure for volume, approximately equal to a quart Milliliter abbreviated ml ; a unit of measure for volume; one one-thousandth of a liter (0.001 L) or about equal to one-half teaspoon Microliter abbreviate ml ; a unit of measure for volume; equivalent to one-thousandth of a milliliter or about the size of the tiniest teardrop

32 Review Questions 1. What instrument would you use to measure and dispense the following volumes? Pick the instrument that is likely to give you the least error for each measurement ml 6.5 ml 125 ml 7mL 2.87 ml 555mL 2. Convert the following units to the requested unit: 1.7 L = ml ml = ml 2.37 ml = ml 3. What numbers should be dialed into a P-10 display if a volume of 3.7 ml is to be measured?