Pre Lab Test Notes PDF

*feel free to add anything* TEST FORMAT: BELL RINGER DEMONSTRATION SECTION: You will proceed from station to station in a timed limited fashion identifying laboratory Chemicals, Laboratory Equipment, or parts of equipment and answering questions concerning its proper use and maintenance. PERFORMA...

*feel free to add anything* TEST FORMAT: BELL RINGER DEMONSTRATION SECTION: You will proceed from station to station in a timed limited fashion identifying laboratory Chemicals, Laboratory Equipment, or parts of equipment and answering questions concerning its proper use and maintenance. PERFORMANCE SECTION: You will measure volumes of liquids using glassware from the list below: -pipettes (serological, volumetric, Mohr, micropipette) -graduated cylinders -volumetric flasks Pipette Image Serological pipette *2 lines ○ Calibrated to tip Volumetric pipette Mohr pipette *not calibrated to the tip Micropipette You will use laboratory instruments from the list below: Laboratory instrument Image TOP LOADING BALANCE ANALYTICAL BALANCE pH meter WEEK 1: LABORATORY SAFETY AND RULES Safety Picture Other Information: Specify Safety Equipment Instructions, Purpose and regular maintenance Fume Hood Purpose: to protect against inhalation of hazardous substances Safety instructions: should not be used to store primary containment of explosive reactions or to store chemicals -Keep the fume hood clean and organized, only bringing in materials that are necessary for your work to prevent clutter and potential hazards. -Always keep the fume hood sash at the recommended height to ensure proper airflow and protect yourself from exposure to hazardous fumes. Maintenance: daily,periodic and annual inspections Eye wash Purpose: for those who accidentally station have chemical splashed into eyes Safety instructions: Rinse open eye for 15 minutes. If you have contact lenses, gently remove them Maintenance: checked weekly and annually Safety Shower Purpose: used when large quantities of chemicals are spilled on person. It’s a necessary backup to minimize effects of accidental exposure to chemicals→ flushes contaminants off clothing Safety use: remove contaminated clothing and run with cold water for 15 minutes Maintenance: checked weekly and annually Flammable Purpose: to separate flammable storage chemicals from other categories of cabinet hazardous materials/provide protection from fire Safety instructions: Always ensure that the cabinet is clearly labeled and that only flammable materials are stored inside, keeping incompatible substances separate to prevent reactions. Regular maintenance: daily, weekly Examples of chemicals that can be stored: propane, methane Acid Bottle Purpose: to safely transport and carriers handle acid containers, minimizing the risk of spills and injuries while providing secure support during movement. Safety instructions: Always use appropriate personal protective equipment (PPE), such as gloves and goggles, when handling acid bottle carriers to protect yourself from potential spills or splashes. -Never pick up by the cap or lid -Label the bottle of chemical name Examples: Hydrochloric acid (HCl), Sulfuric acid (H₂SO₄), Nitric acid (HNO₃),Acetic acid, Phosphoric acid Safety Cans Purpose: storage & dispense chemicals that are flammable,corrosive, and hazardous → reduces risk of spills and fire Safety instructions: store only flammable liquids, label the can to know what is inside -Always keep safety cans tightly closed when not in use to prevent vapors from escaping and to reduce the risk of fire. Maintenance: Regular Example: alcohol, acetone, benzene WEEK 2: LABWARE (important on test) Importance of Labware Labware made of glass (glassware) or plastic (plasticware). Must meet NIST (National Institute of Standards and Technology) standards for accuracy and tolerance. Types of Laboratory Glassware 1. To Deliver (TD): Delivers the exact amount indicated. 2. To Contain (TC): Contains the amount indicated. Detailed explanation: TD (To Deliver)  Definition: Glassware labeled as TD is calibrated to deliver a specific volume of liquid. Key Feature: When you fill a TD vessel to its mark and then pour out the liquid, it is designed to deliver that exact amount, even if a small amount remains in the vessel. Examples: Volumetric pipettes and some graduated cylinders are typically marked as TD. Usage: Useful for precise measurements where you need to ensure that a specific volume is transferred, such as in titrations or preparing solutions. TC (To Contain) Definition: Glassware labeled as TC is calibrated to contain a certain volume of liquid. Key Feature: When filled to the mark, it holds that exact amount, but it may not deliver the full volume if poured out, as some liquid will remain in the container. Examples: Erlenmeyer flasks and beakers are usually classified as TC. Usage: Commonly used for mixing or holding liquids where exact delivery is less critical. TD is focused on delivering a precise volume, while TC emphasizes containing a volume. Common Types of Glass Used Soda-Lime Glass ○ Composition: 70% silica, 15% soda, 9% lime. ○ Characteristics: Inexpensive, low heat resistance. ○ Uses: Test tubes, beakers, Erlenmeyer flasks. Borosilicate Glass ○ Composition: Silica and boron trioxide. ○ Characteristics: Non-reactive, high thermal resistance. ○ Uses: Beakers, volumetric flasks, graduated cylinders. Quartz/Silica Glass ○ Composition: Natural quartz crystals. ○ Characteristics: Excellent optical qualities, expensive. ○ Uses: Spectrophotometry cuvettes, optical lenses. Classes of Glassware Class A Glassware ○ Made according to NIST standards. ○ High accuracy and tolerance. ○ Examples: Volumetric flasks, graduated cylinders. Detailed explanation Definition: Class A glassware is made to the highest standards of accuracy and precision, often adhering to specifications set by organizations like NIST (National Institute of Standards and Technology). Calibration: These pieces are calibrated to deliver or contain specific volumes with a high degree of accuracy, typically within ±0.1% of the stated volume. Examples: Common examples include volumetric flasks, graduated cylinders, and some pipettes. Use Case: Ideal for critical measurements in experiments where precision is crucial, such as in analytical chemistry. Class B Glassware ○ Generally less accurate. ○ Made from soda-lime glass. ○ Examples: Erlenmeyer flasks, beakers. Detailed explanation Definition: Class B glassware is made with less strict standards compared to Class A. It is generally considered to be less accurate. Calibration: This glassware is calibrated for approximate measurements and may have a tolerance of ±0.5% to ±1.0% of the stated volume. Examples: Common examples include beakers, Erlenmeyer flasks Use Case: Suitable for general laboratory use where high precision is not necessary, such as mixing or holding solutions. Beaker: Calibration: Useful only for estimating volumes. Primary Use: Holding or mixing liquids. Volumetric Flask: Calibration: Calibrated to contain (TC) a specific volume with high accuracy. Primary Use: Preparing standard solutions for critical measurements. Erlenmeyer Flask: Calibration: More accurate than beakers, but still for estimating volumes. Primary Use: Mixing solutions; conical shape aids in swirling. Accurate to the WHOLE NUMBER → For example: if you have a 250 mL Erlenmeyer flask, it can accurately measure volumes like 100 mL, 200 mL, or 250 mL Florence (Boiling) Flask: Calibration: Holds an estimated volume. Primary Use: Heating liquids and observing reactions (primarily in chemical/biological labs). Graduated Cylinder: Type: Volumetric glassware. Calibration: Can measure accurate volumes (TD or TC). Uses: Measuring urine volumes and volumes of solutes/solvents for solution preparation. Test Tubes: Primary Use: Holding small volumes of liquids. Calibration: Some, like centrifuge tubes, are calibrated for non-critical measurements (e.g., urine volumes). Laboratory Plasticware Cost-effective, less breakable than glass. Issues: Potential leaching, increased evaporation. Common types: Polyethylene, polypropylene, polystyrene. Types of Plastic Polyethylene ○ Commonly used, clear or opaque.  ○ Examples: Disposable test tubes, graduated cylinders. Polypropylene ○ More heat-resistant, opaque. ○ Example: Test tube racks. Polystyrene ○ Clear, brittle; used for disposable items. ○ Examples: Petri dishes, test tubes. Pipettes Used to transfer measured volumes of liquid. Types: Volumetric, serological, Mohr, micropipettes. Pipette Classifications Volumetric Pipette ○ Class A, fixed volume delivery. ○ Used for precise measurements. ○ Calibration: Designed to deliver (TD) a single, specific volume with high accuracy. *1 volume* (intended for one specific measurement rather than a range of volumes.) ○ → For example: if you have a 10 mL volumetric pipette, it is designed to deliver exactly 10 mL of liquid when filled to the calibration mark. Serological Pipette ○ Graduations extend to tip; variable volume. (Calibrated to tip) ○ Calibrated to deliver the stated volume when drained completely, including the last drop. Useful for serial dilutions and viscous liquids. ○ Used in microbiology, often disposable. ○ For example → if you fill a serological pipette to the 5 mL mark and then empty it, you should have delivered exactly 5 mL of liquid, including any liquid that remains in the tip when you let it drain completely. Mohr Pipette ○ Calibration marks do not reach the tip. ○ Not calibrated to the tip; the stated volume is delivered only if not drained beyond the last calibration mark. ○ Variable volume, less accurate than volumetric. ○ For example → you use a Mohr pipette to measure 5 mL, you'd fill it to the 5 mL graduation mark and then release the liquid. If you drain it too far (beyond that mark), you may end up delivering less than 5 mL, making it less reliable for precise measurements compared to a volumetric pipette.  Serological, Graduated Cylinder, Mohr pipette => if the liquid level falls between two calibration lines, you can estimate the volume with a precision of up to 0.01 (or one-hundredth) of the smallest graduation mark. → For example, if the smallest division is 1 mL, you could accurately read and report a volume as 2.34 mL if the liquid level is between 2.3 mL and 2.4 mL. This allows for more precise measurements than simply rounding to the nearest whole number. Another example: Let’s say you have a graduated cylinder marked with lines at every 10 mL, and the smallest division is 1 mL. If the liquid level is at 25.3 mL, you can read that it’s between the 25 mL and 26 mL marks. In this case, you can accurately estimate the volume to the hundredth, reporting it as 25.3 mL instead of just rounding it to 25 or 26 mL. This precision is particularly useful in experiments where exact measurements are crucial. Type of Glassware Image Beaker Volumetric Flask Erlenmeyer Flask Florence or Boiling Flask Graduated cylinder Test tubes !!Safety!! First Aid for Cuts: Wash cuts and inspect for contaminants (glass/chemicals). Apply gentle pressure to control bleeding. Consult a lab instructor or Help Desk immediately. Glassware Safety: Do Not Use: Cracked or broken glassware (beakers, tubing, flasks, cylinders).  Report: Damaged glassware to your instructor. Disposal of Broken Glassware: Use designated containers marked “Broken Glass ONLY.” NEVER dispose of in regular trash bins. Inserting Glass Tubing/Thermometers: Lubricate tubing and stopper hole with glycerol or water. Wrap glass in a towel and hold close to the insertion end. Protect hands during insertion. Pipetting Safety: Prohibited: Mouth pipetting. Required: Use a propipette or pipetting bulb (included in lab kits). Measurement Technique: Ensure the liquid surface is at eye level. Read the measurement at the bottom of the curved meniscus (the curve formed at the liquid's surface). Types of Graduated Glassware: Graduations indicate various volumes. Some graduations are approximate, while others are precise. WEEK 3: BALANCES AND THEIR CALIBRATION, AND PIPETTE CALIBRATION (Important on test) Laboratory Balances Used to determine the weight of substances in grams, milligrams, or micrograms. Distinction between "balance" (small amounts) and "scale" (larger amounts in kilograms). Common Types of Laboratory Balances  1. Analytical Balance ○ Sensitivity: Measures small amounts (milligrams to grams); resolution up to 0.0001 g. ○ Design: Enclosed with three doors (two sides, one top) to minimize air currents and vibrations. ○ Usage: Best for precise measurements; keep doors closed while weighing. ○ Ranges: Available in different capacities (e.g., 210 g, 300 g). ○ 3 or 4 numbers after decimal ○ Tolerance: Standard weight x d value (0.01mg) = ____ ○ 2. Top Loading Balance ○ Sensitivity: Measures larger amounts (20 g to 64.1 kg); resolution of 0.01 g or 0.001 g. ○ Design: Open design; more susceptible to air currents and movement. ○ Usage: Suitable for general weighing, not for very precise measurements. ○ 2 numbers after decimal ○ Tolerance: Standard weight x d value (0.001g) = ____ Accuracy: Refers to how correct a measurement is. Depends on the calibration of the instrument. Ex: differing readings (e.g., 2.5 g vs. 2.8 g) suggest possible inaccuracies. Accuracy assesses the proximity of obtained values to the true or standard values. Precision: Indicates the level of uncertainty in a measurement. Influenced by the detection limits of the measuring device. For example, a top-loading balance might display 2.50 g, while an analytical balance could show 2.5002 g; the top loading balance is considered more precise. Why?: because it can give you the same results repeatedly unlike the analytical balance. Precision evaluates how closely obtained values align with one another. Accurate: Close to the true value. Precise: Consistent results, regardless of whether they are close to the true value. Ensuring Accurate Balance Readings: Compare readings to a known mass for verification. Use weights from a "standard weight set." Most electronic balances have internal standards. The instrument compares its readings to these standards each time it's powered on. Tare: Refers to the process of zeroing the scale. Involves removing the weight of a known object. Ensures that only the weight of the substance being measured is displayed. Tolerance: Allowable degree of variation What your machines can weigh (maximum and lowest) Calibration of Balances Importance: Ensures consistent and accurate weighing results. Frequency: Daily calibration recommended before lab work. Calibration Methods 1. External Calibration ○ Process: Verify accuracy using external standard weights (up to 99.999% accuracy). ○ Handling: Use gloved hands and Kimwipes to prevent contamination. 2. Internal Calibration ○ Process: Automatic calibration using built-in weights, often initiated with a button press. Calculations: Care and Maintenance of Balances  Avoid spills on the weighing pan; clean using a brush. Turn off the balance when not in use. Place on a vibration-free surface away from airflows. Always calibrate before use. Pipette Calibration Purpose: Maintains accuracy and precision; detects faulty pipettes. Importance: Compliance with lab accreditation; ensures quality of test results. Types of Pipettes Covered: Volumetric, serological, Mohr pipettes. WEEK 4: MICROPIPETTES Micropipettes: Can deliver fixed or variable volumes; adjustable via push button. Use disposable tips; tips ensure a good seal for complete delivery. Calibrated to contain the stated volume (both TC and TD). Purpose: Transfer small quantities of liquid with high accuracy, down to 0.1 µL. Common Uses: Chemistry, molecular biology, microbiology, medical labs, academics, forensic, research labs. Common Micropipette Sizes and Volume Ranges P2: 0.2–2 µL P10: 1–10 µL P20: 2–20 µL P100: 20–100 µL P200: 20–200 µL P1000: 100–1000 µL Note: Never exceed or go below specified volume ranges. Parts of a Micropipette Plunger Button: Used to draw and dispense liquid. Tip Ejector: Mechanism for removing tips. Volume Adjustment Knob: Sets the desired volume. Micrometer: Helps in precise volume adjustments. Volume Indicator: Displays the set volume.  Body: Main structure of the micropipette. Shaft: Connects the tip to the body. Tip: Disposable part that holds the liquid. Proper Use of a Micropipette Importance: Accurate pipetting is crucial, especially in clinical settings. Techniques: Proper handling techniques should be followed to ensure accuracy. Calibration of Micropipettes Purpose: ○ Maintain accuracy and precision. ○ Document performance. ○ Ensure compliance with lab accreditation. ○ Detect faulty pipettes. ○ Improve overall performance. Frequency: Regular calibration is essential. How to Read Volume on the Micropipette: Display Window: Most micropipettes have a front window showing three digits. Maximum Values: Always refer to the maximum volume indicated for each pipette size. Do not exceed the specified range to avoid calibration issues. Example (P1000): ○ The window shows "1" in the thousands place, "0" in the hundreds place, and "0" in the tens place, indicating the value is 1000 µL. ○ To pipette 900 µL, set the window to "090." Decimal Place: Smaller models like P20 display one decimal place (e.g., "0" in red). Calibration Importance: Regular calibration is essential to ensure accurate measurements, which affects control values and patient results. Manufacturer Tolerances: Each manufacturer provides specific tolerance values for accuracy and precision. Ergonomics in Pipetting Common Issues: ○ Ergonomic stressors include thumb force, repetitive motions, and awkward postures.  Injury Prevention: ○ Proper technique and posture can prevent injuries like Carpal Tunnel Syndrome. ○ Pay attention to wrist positioning, elbow placement, and overall sitting posture. WEEK 5: GRADES OF CHEMICALS AND HPLC WATER GRADES OF WATER There are three types of grade water recognized by the College of American Pathologist (CAP). These are similar to the CLSI and ASTM classifications. Types Description Examples TYPE I Water of the highest Purity (ultra HPLC WATER pure) Use in analytic labs for Used when maximum accuracy and research, DNA testing, precision are required atomic absorption, Trace metals removed chromatography, coagulation tests, cell and Used for sensitive analytical tissue culturing, molecular procedures biology and other sensitive analytic techniques. TYPE II Less pure than Type 1 REAGENT GRADE WATER For general lab procedures Used for prep: stains, buffers, reagents, blanks Conductivity 7: Basic/Alkaline Methods to Measure pH 1. pH Indicators ○ Description: Liquid compounds that change color in response to pH. ○ Accuracy: Provides approximate pH values; subjective interpretation. ○ Common Indicators: Universal Indicator: 0.0 to 14 (0-1 is red, 2-4 is orange to yellow, 4-7 is light green to green, 8-12 is light blue to dark blue, and 12-14 is blue to violet) Phenolphthalein: 8.3 to 10.0 (colorless to pink) Methyl Orange: 3.1 to 4.4 (red to yellow) Thymol Blue: 1.2 to 2.8 & 8.0 to 9.6 (pink to blue) Bromothymol Blue: 6.0 to 7.6 (yellow to blue) Phenol Red: 6.4 to 8.0 (yellow to red) ○ Usage: Commonly used in chemistry labs for titrations and microbiological mediums.  2. pH Strips ○ Description: Paper/plastic strips impregnated with pH indicators. ○ Function: Change color upon dipping in a solution, indicating pH. ○ Accuracy: Quick but relatively imprecise; subjective interpretation. ○ Common Uses: Testing pH of saliva, urine, and other body fluids. ○ Comparison Method: Color-coded scale provided with strips. 3. pH Meter ○ Description: Electric device measuring hydrogen-ion activity. ○ Accuracy: Highly precise, usually to two decimal points; objective measurement. ○ Function: Measures potential difference between two electrodes (reference and test). ○ Combination Electrodes: Include both H⁺ sensitive electrode and reference electrode. ○ Calibration: Regular calibration with standardized buffers (pH 4, 7, 10) is essential for accurate readings. Factors Affecting pH Carbon Dioxide (CO₂): ○ Distilled water can form carbonic acid, making it slightly acidic. ○ pH electrodes should be stored in a pH 7 buffer. Temperature: ○ pH decreases ↓with increasing ↑temperature; solutions become more acidic. ○ Measurements should be taken at room temperature for accuracy. For example → You have a solution of pure water at 25°C (room temperature). The pH is measured at 7.0, indicating it is neutral. You then heat the water to 60°C. After measuring the pH again, you find it has dropped to 6.8. The decrease in pH from 7.0 to 6.8 signifies that the solution has become more acidic as the temperature increased. This change occurs because higher temperatures can affect the ionization of water and the concentration of hydrogen ions (H⁺), leading to a more acidic environment. Calibration of pH Meters Importance: Ensures accuracy and reliability of pH readings. Temperature Correction: Most meters automatically adjust for temperature. Standardized Buffers: Used for calibration (pH 4, 7, 10) to correct any deviations. → pH 4 = standardized acidic buffer  pH 7 = standardized neutral buffer pH 10 = standardized basic buffer