Assessment tools are shown below and are intended to assess performance as well as progress of the student or worker. The tools are application-based in that they do not ask the student to regurgitate memorized information, but rather test the student's ability to apply the information learned to real-world problems in atomic absorption spectroscopy. The problems shown below are multi-level in that the solution to one problem will lead to another question, simulating the experience that a technician might encounter when working with actual instrumentation. To return to this page from within each multi-part question, either use the "back" function of your browser or click on the "Assessment tools" link in the left hand frame.
Problem 1. A technician has supervised the setup of an atomic absorption instrument in her company's new laboratory. The instrument is shown at the left (click on the image to enlarge it). The technician connects the gases (air and acetylene), puts the flame shield in place, turns on the computer and affirms that the instrument is working properly. She then presses the flame ignite button. The flame igniter jet attempts to light the flame but the flame does not light. Since the instrument monitors gas flows and there are no error messages, air and acetylene must be flowing through the burner head slot, but not being ignited. What is the problem and how should she solve it?
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Problem 2. A technician wishes to determine the zinc concentration in a large number samples of acid plating bath that he believes should contain approximately 20 ppm Zn in 10% nitric and hydrochloric acids. To save time, he decides not to dilute the samples but to introduce them directly into the flame and measure them versus standards that he prepared. What must he change about the instrument configuration shown in the figure at the left (click on the image to enlarge it) and how should he prepare the standard solutions?
Problem 3. A technician who runs an AA in a water quality laboratory is asked by her supervisor to help a friend analyze his well water for alkali, alkaline earth, and trace metals that might be toxic. She agrees and the friend shows up the next day with a beautiful blue glass bottle filled with water. How should she proceed with the analysis?
Problem 4. You are a technician working in a clinical laboratory that determines electrolytes (Na, K, Ca, Mg) in serum. Your job today is to determine calcium in the serum of a very important person. Therefore, your measurements must be made to an accuracy and precision better than 2% relative (your measured values of Ca in serum must be within 2% of the true value and the method you use must have a total uncertainty that is smaller than 2% of the mean). This is important since calcium is an indicator of either dietary deficiency (low Ca values) or degenerative bone disease (high Ca values). You are limited to using 1 mL of serum for the determination. How will you set up the AA instrument (wavelength, burner position, flame type and stoichiometry, etc.)? What standards (express in µg/mL) and blanks will you prepare and how will you prepare them to cover the normal range of calcium in human serum? Since you want to be sure of the accuracy of your results, what reference materials are available for you to use as your controls? Are any standard methods for calcium in serum available? What calibration method will you use to establish the concentration of calcium in the serum samples to the highest accuracy and with the best precision?
Problem 5. You are a forensic technician working for the FBI in the area of inorganic elemental analysis. You are assigned to a poisoning case in which the victim may have been done in by a relative using either arsenic or mercury. Since arsenic and mercury may be concentrated in fingernails and hair of the victim, you are given samples of both and told to perform the analysis. Your laboratory has a flame AA, electrothermal AA, as well as capability for gas generation and cold vapor AA. How will you prepare and analyze the sample? What precautions must you take?
Return to Skill Development Module L6.12 Atomic Absorption Spectroscopy Introduction