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Atomic Absorption Spectrophotometer. Operating instructions 1. Change welding grade acetylene cylinder if bottle pressure is below 6 Bar 2. Ensure drain water container on floor is empty. 3. Switch power on and switch ventilation on. 4. The right-hand keyboard keys are used to move the cursor and select certain pages of the menu, [->] [<-] up down, [Home] ( goes up through pages) , [Return] (executes a command) , key  (select an option) and key F1 ( to exit). Input numbers using the main keyboard top row. Ensure the Num Lock is deselected. 5. When the AAS is switched on the Initialisation page appears, move down to the Home page, select 'Flame' mode. 6. The UV radiation from the deuterium lamp and some hollow cathode lamps is harmful, minimize exposure and ensure the lamp compartment door is always shut. 7. From the Applications page select 'Setup Instrument' and install lamps. This page senses fitted coded lamps automatically , for uncoded lamps the elements and max current must be defined. There is capacity for eight stores, two for each turret lamp 8. Switch acetylene and air outlets on. Compressed, clean and dry air at an outlet pressure of 2 Bar and acetylene at 0.6 Bar should be used. 9. Select 'Setup Optical System' , switch 'intelligent setup' off and initiate (press return), when the Ready message appears you can align new lamp/cradle assemblies. 10. Move sideways to the Setup Flame System page, ensure the sample compartment door is closed and the Flame On key is flashing, then press and hold the key until the gases are ignited. 11. To optimise the flame parameters you first optimise the burner head position, then the impact bead position, and finally the fuel/air ratio. 12. Move up to the Applications page and select 'Normal Use' once all optimisation is complete. 13. Any or all of the eight stores may be activated by setting to Y , then calibration and sample selection and aspirating time data can be entered by selecting 'Edit Store' and then selecting ‘Standards’ or ‘Spectrophotometer Manual’. 14. Press the Analyse soft key on the Normal Use page to start the analysis, the operator may follow the progress of the analysis on any of the results pages. Shut Down 1. Aspirate water for 10 minutes. 2. Press the flame off soft key, when the flame has gone out, turn off the fuel gas then the air supply. 3. Press the flame off key for 20 secs to vent the lines. Lamp use and Optimisation If a multi-element lamp is in use, the system will use the first two of the elements displayed, and will assign them to the A and B stores of the appropriate turret. Since the lamp-cradle assembly can only be fitted in the top position of the turret disc, the required turret position must be selected before the assembly is installed in the turret. If a complete lamp/cradle assembly has been used previously, do not re-align the lamp in the turret. To align new lamp-cradle assemblies adjust the horizontal adjustment screw until the 'Hc lamp' bargraph on the Optical Setup page is at a maximum, then repeat with the vertical. Optimisation Use a 10 ppm Nickel standard ( or any std between 0.1 and 1.0 A ) with an air/acetylene flame Burner position 1. Move height to 0.7mm and make minor adjustments to maximize abs. 2. Move rotation to 0.0 and make minor adjustments to maximize abs. 3. Adjust the lateral position to maximize abs. 4. The tilt position is factory set. Fuel/air ratio Use the Fuel up and Fuel down soft keys in the Flame Setup page to maximize absorbance. Ensure the flame remains stable, of the usual height , and free from carbon deposits Impact bead position Adjust the position of the impact bead to maximize absorbance. For normal instrument use 250 mm of the 0.38 mm capillary tubing should be fitted which will give an uptake rate of 4.1 ml/min, a longer length will decrease the uptake and sensitivity ( 300mm = 2.6 ml), using the 0.5 mm tubing will increase uptake and sensitivity ( 480 mm =4.3 ml is optimum). Drain system The drain trap ( below the burner head ) should be kept filled with water to prevent gases escaping down the drain tube. The drain system may be cleaned by removing the burner and pouring 0.5M H Cl down the burner stem, then rinsing and refilling with distilled water. The drain extension tubing must provide a free flowing outlet and must not be immersed in the liquid of the plastic drain container. General information 1. Background correction will be automatically selected if the wavelength chosen is below 350 nm. 2. Minor cleaning of the spray chamber during operation can be achieved by aspirating a 2% to 5% solution of Decon for 5 mins followed by water for 5 mins. 3. Most accurate scale range is 0.4 to 0.8 A. 4. Rotating the burner at right angles decreases the signal by a factor of about twenty. 5. Prepare 3 or 4 standards. About 2 mls of sample is required for each test. 6. It is not economic to use a multilamp for single element analysis.
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