Introduction to the Analytical Laboratory
Spring 2012 Edition
Welcome to the analytical laboratory! Welcome also to the newest edition of this laboratory manual, and the third time it’s entirely online! This semester will be the third implementation of a new model for conducting this laboratory – a model made possible by a grant from the National Science Foundation (NSF) – but more on that later.
Analytical chemistry seeks to answer the questions What? and How much?. This means that our goal as analytical chemists is typically to determine the identity of one or more chemical species in a sample, as well as the amount of these species in the sample. Often times these questions are referred to as qualitative analysis and quantitative analysis, respectively. Most of our laboratory projects in this class will focus on quantitative analysis. We will be trying to determine the amount of a specific chemical component present in a mixture, with both high accuracy and high precision. In fact, a significant portion of your grade will be determined by how well you answer the question How Much?. With this in mind, your technique in the laboratory is more important than ever before. You must learn to be patient, yet efficient, and you must always pay attention to the details.
It’s important to keep in mind the objectives of the laboratory aspect of a course in analytical chemistry. I see our objectives as the following:
- To refine laboratory skills and develop confidence in using these skills
- To become comfortable with the routine operation of common analytical instruments
- To learn to critically evaluate scientific data and draw conclusions from that data
- To gain a practical understanding of the use of statistics for interpreting and reporting scientific data
- To develop skills in the clear and concise presentation of experimental results
- To gain experience in carrying out each step of the analytical process: gathering samples, preparing samples, acquiring data, interpreting data, reporting results, drawing conclusions, and disseminating information
Another overall goal for this course is to help each of you develop the skills of a “professional” chemist. In other words, I want you to leave this course prepared to begin a position as an entry-level chemist in a typical analytical laboratory. Many of the skills you will need involve very traditional laboratory procedures such as solution preparation, sample preparation, etc. The skills of today's professional chemists, however, must go far beyond good laboratory technique. Today's chemist must be:
- Able to work both individually and in a team
- Adept at keeping clear and accurate records
- Able to communicate scientific information both orally and in writing
wHAT'S NEW IN 2012?
As mentioned above, a new model for conducting this laboratory is being implemented for the third time this year. This lab used to follow a fairly traditional format in which students were provided with a set of detailed step-by-step instructions for each experiment and were then expected to carry them out. These experiments were usually based on the quantitative determination of some specific chemical component of a sample (i.e. the determination of iron in a salt). Grades for each experiment were based on how close the student’s answer was to the “correct” answer. This traditional format had many merits. Principally, it forced students to focus on using good laboratory technique to obtain accurate results. But it focused almost entirely on acquiring data and reporting results – ignoring all the other steps in the analytical process. Our new format does not completely abandon the old way of doing things, but we do add a new project component in which you’ll design and carry out a quantitative analytical determination of your own choosing. Also, new experiments have been written so that the entire lab is nowfocused on the use of modern analytical instrumentation for our determinations.
Here is a summary of the major changes associated with the new format:
- The traditional format (determining the amount of a particular species in a sample) will only be followed for half of the semester. Six experiments of this type will be performed before spring break.
- The experiments have been redesigned to focus on analytical instrumentation, with each one requiring the use of a major piece of instrumentation for data collection. The six instruments we will use are the following:
- Atomic absorption spectrometer (AA)
- Gas chromatograph-mass spectrometer (GC-MS)
- High-performance liquid chromatograph (HPLC)
- Inductively-coupled plasma atomic emission spectrometer (ICP-AES)
- Ion chromatograph (IC)
- UV-Vis spectrophotometer
- To accommodate the fact that up to six different experiments (with six difference instruments) will be running each day the lab is open, the entire lab manual is online and incorporates video links to individual steps in the procedures.
- The second half of the course will be dedicated to a multi-week project in which you will design and complete an instrumentation-based chemical analysis – with emphasis placed on each step in the analytical process.
As always, I look forward to your comments and suggestions. So over the course of the semester, please help me determine the ways I can make this experience run more smoothly. Here we go...