Buffer Solution Preparation: An Essential Skill for Researchers

Many high school and college students realize that having research experience in an academic or industry lab has many benefits. Many search for paid or unpaid internships, part-time employment or propose a research project in their instructor’s lab, working independently, applying what they already know and building expertise in experimental design, instrumentation, and data analysis.

Working with other researchers in an adult science environment to collect meaningful, valid data is different than the typical lab activity in most lab classes. Since making research progress is important, student researchers need an arsenal of skills to work professionally and productively in a lab.

To be productive in a bioscience environment, student researchers must demonstrate a variety of “soft skills” including a pleasant, positive attitude. They should show an appropriate enthusiasm, be able to accept constructive criticism, and act in an alert and safe manner. Obviously, independent research requires self-directedness and the ability to recognize tasks that need to be done. Student researchers also must be able to collaborate with other team members. Research students should be able to reflect on their experimental results and see the values and applications of their work.

There are several basic standard lab techniques and methods that a beginning student researcher must master. In a bioscience environment these “hard skills” might include record keeping, measurement, microscopy, cell culture, electrophoresis, spectrophotometry, and dissection, to name a few. Of all the hard skills needed in a bioscience research lab, the most important may be the ability to prepare solutions. Solution preparation is the “gatekeeper” of bioscience research and without it being mastered student researchers get stalled and cannot work independently in a lab.

Virtually all macromolecules (DNA, RNA and/or protein) used in a research lab must be in a buffered solution. Student researchers must be able to prepare any solution at any volume, concentration or pH.

Although it is taught in introductory chemistry courses, most students and many teachers never master solution prep because they don’t have a chance to practice and apply it. The math (dimensional analysis) used in solution preparation often causes anxiety in bioscience majors. Biology teachers lose any skill they had in preparing solutions when the activities in their classrooms have them “mix bottle A into bottle B.” Rarely, do they know the concentration or pH of the solutions they are using.  They unlearn any solution prep the used to know. Biology teachers are often “mole-phobic” and usually have solution anxiety.

It is worth the time it takes for biology teachers to learn and have their students learn solution preparation. It can be fun and easy if teachers teach it in small, progressive steps using hands-on activities and having students self evaluate their skill development. The math and science skills used in making solution are those that apply the concepts (metrics, measurement, mass, volume, concentration, pH and buffers) that are taught in integrated biology and chemistry courses.

Biotechnology Science for the New Millennium, 2017 Laboratory Manual covers solution preparation instruction, practice and self-evaluation in Chapter 3. Download a PowerPoint® presentation (May10_BIO_5Steps_SolnPrep.ppt) covering how to teach solution preparation.

Here is a scope and sequence of skill development activities to master solution preparation. 

• Metric Measurement and Conversion   Cover the use and units of measurements of rulers (cm), graduated cylinders (mL), and a scale/balance (g). Next, conversion (factors) between units moving the decimal point to change between metric unit equivalents.
• Measurement of Small Volumes Use of pipets and micropipets to measure diluted food coloring solutions of different volumes into test tubes, microtubes and/or culture plates.
• Mass Measurement Use of electronic tabletop and analytical balances to weigh out glucose of different masses. Glucose can be dissolved in a specific volume of water and then tested with glucose test strips to check concentration and thus mass measurement.
• Introduction to Concentration Measurement Using salt in water (or sugar in water) introduce the terms “solute”, “solvent”, “solution” and “concentration” (mass of solute / total volume of solvent). Demonstrate how concentration of the same solution can be reported in different ways i.e.. g/mL, %, and molarity.
• Solutions Preparation Calculations and Preparations Students prepare copper sulfate solutions (blue) of different concentration using the three concentration equations to determine the mass of solute to use in the solution. Prepare solutions can be evaluate by measuring the blue color light absorbance at 595 nm on a spectrophotometer.
• pH Measurement and Adjustment  Students learn to measure pH of different solutions with pH paper and a pH meter and then prepare buffers (a specified volume, concentration, and pH) to use later as the solvent in different protein or DNA solutions.

 Solution preparation taught in this way, give all students a good foundation for making solutions in current courses, future courses and when working with biomolecules in a research lab. Start teaching measurement and solution prep early and reinforce it regularly as students progress through their high school science courses. Solution preparation skills are lost if not practiced regularly and science teachers should give students regular opportunities to demonstrate these skills in each bioscience course.

Solution preparation makes math abstraction more concrete and provides students with an absolute requisite skill needed for independent bioscience research.

Ellyn Daugherty is the author of Biotechnology: Science for the New Millennium.  Her teacher support website is www.BiotechEd.com