Atomic Absorbtion Spectrometer Manual (PE)

Atomic Absorption Manual Introduction Atomic absorption (AA) is used to measure very low quantities of trace elements in aqueous samples. AA depends on the absorption of visible light by individual atoms while they are in a flame. The wavelength of light absorbed is dependent on the identity of the element present. The intensity of the absorbance is dependent on the concentration of the element in the solution. Safety Use extreme caution while operating this instrument. An open flame is present. DO NOT open the safety door at any time. NEVER block or come between the flame and the exhaust duct. Gases are released during the analyses that may be harmful. NEVER touch the kill switch located on the far left of the instrument. TOUCH nothing other than the screen, your samples and the sample capillary (intake) tube. If anything goes wrong during the experiment inform your instructor immediately. Figure 1: Instrument Schematic 1 Figure 2: Stylus Exhaust Vent Touch Screen Kill Switch Safety Door Single-Element Cathode Lamp Sample Capillary Tube Door Waste Tube Power Button Figure 3: Instrument Diagram 2 I. Set-up Procedures (For most students, these procedures will ONLY be carried out by the instructor.) Whenever you are interfacing with the screen, use the stylus. (See Figure 2.) NEVER use any other object. 1. Refer to Figure 3. Open the door on the right hand side (under the screen) and ensure that the lamp for the element you will be analyzing for is in place. If not: a. Obtain the lamp for the element you will be analyzing for. b. Insert the lamp into the lamp holder and plug in the cable. If the lamp cable does not have the correct pins, you will need to use the appropriate adapter. The adapters are stored on the shelves directly behind the instrument. 2. Open the gas cylinders in the following order. Do not adjust the regulators. a. air, first. b. acetylene, second. 3. Turn on the instrument using the power button. (See Figure 3 for location.) It will take approximately three minutes for the instrument to boot-up. 4. Once the instrument is on, the Startup dialog will appear. Confirm that: a. the selected Technique is Flame b. there is a green check mark in the box for All Systems OK. 5. Touch OK button. 6. You are now on the main screen. There are four tabs across the bottom: Lamp, Flame, Parameters and Analyze. 7. Ensure the lamp tab is selected. Then: a. Ensure that Signal says “Atomic Absorption”. b. Ensure that the Element matches the lamp you inserted. If not: i. touch on Install Lamps. ii. In the Install dialog box that appears, touch on the Elements field. iii. In the Select dialog box that appears, touch on the appropriate element. Click OK. 3 iv. In the Install Lamps dialog box that appears: 1. Ensure that the On/Off box is checked. 2. Click on OK. v. On the Lamp tab, touch the element box, select the correct element and touch on OK. vi. Touch on Setup Instrument. Wait a minute for setup to complete. 8. Click on the Flame tab on the bottom of the screen (Figure 3). The screen shows the Oxidant Flow (10.00 L/min) and the Acetylene Flow (2.50 L/min). a. Ensure there is a check mark in the Interlocks box. b. Ensure the sample capillary tube is in a container with plenty of water. c. Ensure the exhaust vent is in place and the safety door in front of the flame is closed. 9. Touch the “toggle” switch pictured on the screen to light the flame. 10. If you need to alter the Parameters, see the PE User Guide. II. Shut-down Procedures (For most students, these procedures will ONLY be carried out by the instructor.) Touch the Flame tab and touch the “toggle” switch pictured on the screen to turn off the flame. Then: 1. Turn off the acetylene tank. 2. On the Flame tab, touch the Bleed Gases box. Wait for the cycle to complete. 3. Turn off the air tank. 4. Turn off the instrument using the Power button. III. Analyzing the Samples 1. If the flame is not on, turn it on if you are permitted to do so. If not, see your instructor. 2. Click on the Analyze tab. 4 3. Place the sample capillary tube in the blank. 4. Touch on Analyze Blank. Wait for Autosample Performed to appear on the screen. 5. Ensure there are NO particulates in your sample. Place the sample capillary tube in the sample. 6. Touch on Analyze Sample. Wait for sample data to be collected. 7. Return the sample capillary tube to container with pure water. 8. Repeat steps 4 through 6 above for any remaining samples. 9. Record your data. 10. If there are no more samples to be run immediately, shut off the flame (if you are permitted to do so). If there are no more samples to be run for the day, shut-down the instrument (if you are permitted to do so) or inform your instructor. 5