Graphite Furnace Procedure for AAnalyst 800 in Room 109

BEFORE TURNING ON THE INSTRUMENT

1. Make sure the cooling system is filled to the maximum mark.
2. Turn on the inert gas main valve (argon) and adjust the outlet gauge pressures to the recommended value (50-58 psi).  Never exceed the maximum pressure.  Replace the tank before the main pressure gauge is shows less than 200 psi.

SETTING UP THE SYSTEM

1. Turn on the computer.
2. Install the requisite hollow cathode lamp, if it is not already installed.
3. Turn on the spectrometer.
4. Start the software. Before doing anything WAIT until the software detects the spectrometer and the instrument is initialized. The screen should look like Figure1, shown below.
Figure 1. Screen shot of WinLab software after turning on the equipment.

5. Select the technique and perform the analysis. Go to File > Technique. Select Furnace from the Flame or Furnace options.

6. Select the analysis method. If the desired method is already saved in the memory select it from the library. Go to File > Open > Method. The Open Method dialog window appears. Select the method and click OK. The name of the method should be now in the toolbar giving the name and the element to be analyzed.

7. Go through all the parameters in the method to be sure everything is correct. To do this click on Tools > Method Editor. The window to edit the current method appears. For a brief introduction of methods go to the end of this page.

8. Sample Information File (SIF). This file stores information related to the samples. If an SIF exits, go to File > Open > Sample Info file. To create a new method go to File > New > Sample Info File. Fill out the requisite information and confirm the position of all samples in the tray.

9. Setting up the lamp. Go to Tools > Lamp Set Up. In the column On/Off, click in the lamp to be used. Click in the button of the column Set Up to align the lamp. Allow lamps to warm up for 20 minutes before alignment.

10. Allign the furnace. Go to Tools > Furnace Control and click on Align Furnace. The align furnace wizard appears. Click on automatically align furnace. Click in adjust. Click finish.

11. Setting up the autosampler.

In the Furnace control window click on Align Tip, the Align Autosampler Tip wizard appears. In the task list select Align the autosampler tip in the graphite tube. Follow the instruction in the window. If the tip was correctly aligned the mirror image will look like the sketch at the right.

PERFORMING THE ANALYSIS

1. First, set up the automatic analysis control. Go to Tools > Automated Analysis Control. Methods needed to perform the analysis are added to the table. Double click in the table to add a method from the method list.
2. Sample information file may or may not be used. When a Sample Information is not used enter file the location in samples in the table.
3. When using SIF, go to the table and click in the column Sample Info File. From the drop box choose 'All' to use all the samples defined of choose the number to be used.
4. To save the data select a Result Data Set. Choose open and the window Select Result Data Set appears. Give a name and a description and click OK to add a new set. NOTE: Selection of an older set will cause prior results to be overwritten.
5. When the instrument is not being used, for a few hours, check the box "Lamps off at the end of the analysis".
6. In the analyze tab choose the correct analysis. Run the standards and the samples separately or in only one run. The system will then print the information and storage the results.

Shutdown procedure
1. In the Furnace Control window, click on Flush Sampler a number of times.
2. Empty the autosampler waste bottle. Dispose of waste solutions correctly.
3. Remove all the samples and reagents from the sample tray. Wipe up any spillages.
4. Switch off the spectrometer.
5. Turn off the gas supplies.
6. Exit WinLab: in the File menu, click Exit.
7. If there are no other applications for the computer for other tasks, shut down the computer and printer.

A method is a register that the software store in a database with all the parameters corresponding for every analysis. Many of these parameters are optimized by the factory, hence there is not need to change them unless the response of the machine is not as expected.

Opening the method editor will show the window in figure 3.

Figure 3. Main screen method editor.  In the bottom part of the screen there will be several tabs for the different parameters of the method.

Spectrometer Tab: When the method correctly selected, the name of the element to be analyze should be in the frame spectrometer. Do not change anything else in this tab. For information about a parameter press F1.

Sampler Tab: decide how the autosampler will handle the samples. There are three subtabs in this window.

a. Furnace program: it is also optimized in the factory. Unless there is a special sample, do not change these parameters.

b. Autosampler: In the sample frame introduce the volume of sample used for the furnace (20 µl is the standard). The diluent volume is used only with standard addition method. When using this calibration method tell the sampler how much to add and the diluent location, otherwise use 0. The matrix modifiers frame allows the introduction of a specific volume and location of two modifiers when the instrument does the preparation. When not in use the sample modifiers the volume should be 0 µl.

c. Sequence: in this subtab tell the instrument how to make the injection. Pressing the button custom the next window appears:

Figure 4. Custom sequence for injections.  The only step that may require modification is the pipette step. For example, to modify the step A for injecting only the sample go to the frame pipette and press Sample/Std. After that click on step A and the press Enter pipette.

Calibration Tab: There are also several subtab for this window.

a. Equation and units: Tell the instrument which type of mathematical relationship is going to be used to fit the data. For a large description of every equation press F1.

b. Standard concentrations: The positions of the standards and their concentrations have to be filled out in this table. There are two possibilities, first to prepare standards or let the instrument to prepare them. To prepare standards just fill out the values and position in the table and how much of the standard is required (use the same volume than for the samples). Except for standard addition and then need to introduce a specific volume of the diluent.

For the instrument to make the standards provide a stock solution and its position. Press Calculate Standard Volumes and in the table introduce the concentrations of the standards required and in the frame Stocks introduce the concentration of the stock and the location. The instrument will calculate the appropriate volumes and will fill out the table. In this case provide a diluent.

c. Initial calibration: nothing to do in this window unless the previous calibration curves is being used.

d. Calibration check: this option allows the program to stop if the correlation coefficient for the calibration is below a given value. Or specify if the instrument should repeat the calibration or what to do in case of a low correlation coefficient.

The basic set up of the method is complete. Other tabs are for more advance uses. Become familiar with the other options of the instrument press F1 in any window and information will pop up.