Entry Level: BioTech

Graphing Data for Standard Curves

Simulation vetted by professionals from CMDOs in the Greater St. Louis Region

A lab technician stands at a spectrophotometer handling a sample, wearing the appropriate protective equipment.

Simulation Objective:

Create a standard curve to determine the concentration of dye needed to color plant fibers

Associated Simulation Library:

Entry Level Sim
A pair of glasses and a mug sit on the center of a newspaper talking about vaccinations.

Background

A standard curve is a technique done in the lab to find out the concentration of unknown substances, and to help you determine if your experiment is within a desired range.

A standard curve is visualized as a graph of a set of known standards. You use this curve to determine the measure of unknown substances. For example, to determine the length of a string of unknown size, we can use a 12-inch ruler as a measurement tool. The ruler would be the standard. If you compare the string to the ruler, you can figure out how long the string is. To measure concentration, you would essentially create your own “ruler” or standard curve.

Why do we use standard curves?

(Expand each entry for a full explanation)

  • They allow us to accurately determine the concentration of substances, even when they are present in very small amounts.

  • They help ensure that our instruments are working correctly and that our results are trustworthy.

  • Standard curves provide a reliable way to compare different samples and ensure that measurements are consistent across experiments.

The Process

  1. Make standard solutions.

  2. Measure the absorbance of the standard solutions with the spectrophotometer.

  3. Generate the standard curve by plotting the concentrations with the absorbance of each solution. Plot the concentrations on the x-axis and absorbance on the y-axis. Draw your line!

  4. Measure the absorbance of the unknown solution with the spectrophotometer

  5. Graph the unknown absorbance on the standard curve to determine its concentration.

Resources

Standard curves

Absorbance readings and spectrometry

The Exercise

You are a laboratory technician at a plant fiber hair company. As part of your role, you do routine standard curve measurements to determine what concentrations of dyes successfully color the plant fibers that will later be used to create the hair. The lab just received requests to test a new color, burgundy.

Your goal is to create a standard curve and determine the concentrations of the new dyes being tested.

Task 1 - Plot the standard curve with the absorbance readings, and calculate the linearity values for correlation coefficient, slope, and y-intercept.


The table below represents the readings from prepared solutions. Use this spreadsheet to plot the absorbance versus concentration of the standards provided below. See resources to get you going for info on how to create a curve in excel.

Task 2 - Plot the absorbance readings of the dye samples to determine their concentration. 

Using the formula mx + b = y, find the absorbance of each sample on the y-axis and follow along horizontally until you hit the line. Then trace down to the concentration on the axis. Your answers may be approximate.

Task 3 - Calculate the average for each sample.

Deliverables

After measuring each sample, you might return a list or table of the final concentrations to a supervisor or manager. You might present these findings with the lab so everyone knows what concentrations to move forward with.

Answer Key

Additional Tasks

  • Prepping DNA- tissue type and cell types

  • Isolating/extracting dna from blood

  • Depts - Molecular and microbiology; biology; genomics and genetics; tissue procurement; neurology and neuroscience; cell biology; pathology and immunology (basic science depts); bioengineering

  • Nucleic acid quantification using Qbit

  • Nanodrop and purity readings 260/280 readings; reading protocols and understand readings

  • Sizing readings using Bioanalyzer and Tape station - is it fully entact and not fragmented or degraded; interpreting quality and quantity of DNA

  • Safety training

  • Lab culture - where and how is data stored (notebook, excel, databases, locations)

  • Cleanliness - keeping bench clean and non-contamination

  • Personal safety and sample safety

  • Hazardous materials - BSL2, hepatitis vaccine

  • Maintain lab records

  • Prepare solutions

  • Order lab supplies

Skills Used to Perform this Task

  • Ability to ask questions; if doing manually

  • Systematic, Repetitive, consistent mindset

  • Attention to detail

  • Cleanliness and organization

  • Responsible and self-starter

  • Confidence to ask questions when uncertain

  •  Presentation skills (putting data into a presentable format. Can be Microsoft Powerpoint, spreadsheets, or lab notebook, or written reports)

Biotechnology Skills Used to Perform this task

  • Volume calculations for small dilutions

  • Proper use of the following equipment: micropipettes and small tubes, nanodrop, potentially gel electrophoresis chamber and gel imager)

  • Following documentation requirements

Career Progression

Lab technician I > Lab technician II > Research Scientist

Sample Job Postings

Typical Pay Range $18-22/hr

Research/Laboratory Technician I - Biology

Washington University in St. Louis | Pay rate: $16.21-21.69/hr

Research Laboratory Technician II

Washington University in St. Louis | Pay rate: $16.59-24.00

Laboratory Technician (Full time)

Danforth Plant Science Center | Pay rate: $17.00-19.23

Laboratory Technician (Part-Time)

Danforth Plant Science Center | Pay rate” $17.00-21.94

Sample Job Posting: Laboratory Technician

Seeking a Research Technician to conduct research projects and assist with research activities of Dr. Jennifer’s lab at Washington University in St. Louis. The lab is interested in understanding the cell biological mechanisms underlying the formation of centrosomes and cilia in mammalian cells, using high-resolution microscopy, biochemistry, and genome engineering.

  • Primary Duties and Responsibilities

    • Assists with research studies, experiments, and assays; including the collection of data, preparation of solutions, and the set-up/maintenance of equipment.

    • Ensures lab conditions and equipment are properly cleaned and maintained in accordance with established procedures.

    • Orders lab supplies and maintains cell cultures.

    • Performs with compliance standards and established safety procedures.

    • Maintains required documentation on laboratory conditions.

    • Performs other duties as assigned.

    Working Conditions

    This position works in a laboratory environment with potential exposure to biological and chemical hazards. The individual must be physically able to wear protective equipment and to provide standard care to research animals.

    Preferred Qualifications

    • Experience in recombinant DNA methods, mammalian cell culture, recombinant protein expression, or microscopy is strongly preferred.

    • Experience in the care and use of general biological lab equipment is strongly preferred.

    • Excellent oral communication skills and ability to work well with others.

    • High attention to detail and can follow directions and protocols.

    • Ability to multi-task effectively.

    Required Qualifications

    High school diploma or equivalent high school certification.