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AAnalysis 800 Atomic Absorption Spectrometer

These are Specific Procedures for the Graphite Furnace and Flame operations.

GENERAL INFORMATION: The AAnalyst 800 atomic absorption (AA) spectrometer features a combined flame/graphite furnace. It provides automatic exchange of the atomizers (controlled via computer), no longer necessary for them to be changed by hand. Solid-state detector technology and simultaneous background correction have quieted background noise and boosted detection sensitivity anywhere from 5 to 20%.

800 AAnalyst Features:
Real Time Double Beam Spectrometer with Wavelength Range 190 - 870 nm.
Diffraction grating used is dual blazed with ruling density of 1800 lines /mm, dual blazed and RLD 1.6 nm/mm.
Lamps position Automatic Turret with computer controlled lamp selection. Built-in power supply for 4 EDL's.   

 Built-in Atomizer for Both Flame and Graphite Furnace (Stabilized Temperature Platform Furnace conditions).
The Detector is Solid-State Detector.
Total Gas Flow Control System.
 All safety interlocks built-in.
Computer controlled motorized burner adjustments.
 Software control by AA Winlab 32 for the Spectrophotometer and all major accessories including Graphite Furnace, Burner Heads, FIAS, Autosampler etc.
TotalFlow™ gas controls for flame AA and a Transversely Heated Graphite Furnace (THGA) with longitudinal Zeeman-effect background corrector.

An Optical system for lowest detection limits is at the heart of the system. It features a unique solid-state detector with a photoactive surface optimized to provide the highest quantum efficiency in the UV region. A state-of-the-art detector and efficient monochromator allows elements such as As and Ba to be measured with outstanding signal-to-noise ratios.

Longitudinal Zeeman-effect
background correction provides lowest detection limits With longitudinal Zeeman-effect background correction, the amount of light throughput is doubled by eliminating the need for a polarizer in the optical system. All other commercial Zeeman designs incorporate inefficient polarizers that reduce light throughput and diminish performance. With this unique design, the AAnalyst systems provide the lowest detection levels available. To further improve detection levels and accuracy, the AAnalyst systems also include optimized sampling frequency and interpolated background correction.

 

 

 

 

 

THGA furnace provides uniform temperature distribution -- The patented THGA tube used in the AAnalyst systems provides a uniform temperature distribution along its entire length. This eliminates cooler temperatures at the tube ends and removes most interferences. With the THGA tube design, accuracy and sample throughput are improved by reducing the need for the time-consuming standard additions technique.

Optical System: Real-time double-beam optical system (single-beam for Zeeman furnace operation with the AAnalyst 800). Front-surfaced, reflecting optics with protective coating. Optical system sealed within protective cover.

Monochromator: Littrow design with motorized drive for automatic wavelength selection and peaking. Wavelength range: 190 - 870 nm. Diffraction grating: 1800 lines/mm blazed at 236 nm and 597 nm. Grating area:
64 x 72 mm. Reciprocal linear dispersion: 1.6 nm/mm (nominal). Focal length: 267 mm. Spectral bandwidths: 0.2, 0.7 and 2.0 nm, dual height; motorized slit drive for automatic slit selection.

Detector: Wide-range segmented solid-state detector, including a built-in low-noise CMOS charge amplifier array.

Automatic Lamp Selection: 8-lamp holder with built-in power supplies for hollow cathode and electrodeless discharge lamps. Computer-controlled lamp selection and alignment via AA WinLab™ software. Lamp elements and recommended operating currents are automatically recognized and set when using Perkin-Elmer Lumina™ hollow cathode lamps.

Flame System Gas Controls: Fully computer-controlled with oxidant and fuel monitoring. Keyboard-actuated remote ignition system with air-acetylene. Acetylene flow is automatically adjusted prior to the oxidant change when switching to or from nitrous oxide-acetylene operation. TotalFlow™ control of the oxidant and fuel gases for constant fuel:oxidant ratio.

Safety Functions: Interlocks prevent ignition if the proper burner head, the nebulizer/end cap, or the burner drain system is not correctly installed; the liquid level in the drain vessel is incorrect; or gas pressures are too low. Interlocks also will automatically shut down burner gases if a flame is not detected, or if any of the other interlock functions are activated. Provision is included for safe shutdown from all operating modes in the event of a power failure.

Burner SystemPremix burner design that can be moved automatically into the sample compartment via software control and a motorized carriage. Alignment of the flame in the light beam is fully automatic, using a motorized burner mount for vertical and horizontal burner adjustment and automatic software-controlled self-optimization of the burner position. The burner is equipped with a high-strength inert mixing chamber, angled to ensure proper drainage. Includes adjustable Universal GemTip™ corrosion-resistant nebulizer and an all-titanium, 10-cm, single-slot burner head for air-acetylene operation.

Consistent temperature control enhances performance -- In conventional furnace systems, the heating rate during atomization depends on the input-line voltage. As voltage varies from day to day, season to season or among laboratory locations, so does the heating rate. The AAnalyst high-performance systems use enhanced power control circuitry to maintain a uniform heating rate, so no matter where a system is located, you can be sure that it provides outstanding, consistent performance.

WinLab32 software

Designed with extensive input from laboratory managers and AA users around the world, WinLab32 software provides all the tools and features needed to start running samples quickly and meet the requirements of today’s laboratory. Easy to learn and easy to use The extensive Wizard features of WinLab32 make complex tasks easy with step-by-step instructions and Tool Tips, provides additional information about screen text and entry fields. Status panels display the status of each instrument component for easy monitoring. The Analysis List combines standard, sample and method information into one list, showing the exact order in which the analysis will be run. This list also displays the analysis status at all times and can be printed as a summary at the end of the run. Improved productivity WinLab32 software improves laboratory productivity
by reducing the time required for method development, sample analysis and report generation. Furnace method development is completely automated, helping to optimize the pyrolysis and atomization temperatures as well as sample and modifier volumes. You can create methods, review or reprocess data offline, even add samples anytime during an analysis, without
interrupting the active analysis. Recall Calibration eliminates the need for initial calibration, while Edit Calibration gives you complete control over the quality of your calibration curve before you proceed with QC and sample analysis.

Step by step AAS instructions for an analysis of Iron by flame AAS.

1. Turn on AAS, computer, and printer.
2. Double click on the Instrument Icon from Windows initial screen.
3. The WinLab32 for AA window will open - do not proceed until the AAS icon is highlighted.
4. While you're waiting for the icon to light up, open the acetylene tank and air line. Acetylene pressure should be at 14 psi and air pressure should be about 45-50 psi. The gauge that reads pressure in the tank is the gauge on the right. The gauge on the left reads how much fuel is in the tank. NOTE: when first opened, the acetylene tank, will usually read above 15 psi (red zone). Don't adjust the pressure right away, because 93% of the time, after about 10 minutes, it will have decreased to 14.1 psi always check the pressure after you light the flame. NOTE: the acetylene tank should be replaced when the fuel level drops below 75 psi (using the scale on the inside of the circle on the left hand gauge). Since contaminants sink to the bottom of the tank, it is not advisable to drain a tank to absolute empty .
5. Under "Windows" at the top of the page, scroll down and open the Element Parameter file. This file is the method file and must be defined before analysis.
6. The Element Parameter file will ask if there is a previously defined file, or if a new one is required. It is possible to use the same method for different sample runs. In the Element Parameter file, complete tree pages: Main, Calib, and Options.
7. Main
8. - Specify the element (standard wavelength and slit width will automatically appear), select an appropriate sampling time (default is 5 sec), make sure the flame sensor is turned on. Confirm the fuel is acetylene and the oxidant is air. "Time average" and "AA" are not modified.

Calibration
9. (Calibration) - enter the concentration of the standards and there name (i.e. S_l, AA01, etc). Make certain the units are correct. For example, for a 10 ppm standard, the standard units are set at mg/L. To change standard and sample units you just double click on the line. It is possible to have standard units and sample units at different levels. Decide the number of significant digits by entering "5.0" as a standard, or "5.00", etc. Last, click on Nonlinear to change the type of standard curve that will be drawn; absorbance vs. concentration for iron is only linear up to about 10 mg/L.

Options
10. - Select the printing options and type in any comments about the samples. This page automatically prints out at the beginning of any run. Save the Element Parameter file. The computer will always use the Element Parameter file most recently opened when you begin running samples. Close the newly named file.
11. The screen will return to the Lab Benchtop menu. Open four files needed to manually run your samples. Under Windows, scroll down and select "Flame Control", "Manual Control", "Display Calibration", and "Display Data"
12. Before running samples, adjust the lamp, and then optimize the burner head position, the fuel, and the nebulizer.
13. Use the single slot acetylene and air burner head. The system has not been configured for use of higher temperatures nitrous oxide analyses.
14. Adjust the lamp by first opening "Adjust Lamp". The Element Parameter file has automatically selected the Fe lamp. Lamp current should read 25 or 30, and with lamp energy should be around 65.

15. Adjust the lamp position horzonatly and vertically.
16. Visually optimize the vertical position of the burner head by first lowering the burner head. Then open align it with the software.
17. Light the AAS flame, click on the Flame Control Window. The air and acetylene lines must have been turned on. The exhaust system must also be turned ON.
18. Adjust the fuel and oxidant levels by using the Fuel Up/Down and Oxidant A lean flame (meaning the blue line on the burner head at the bottom of the flame is about 1/8" high). You don't want a rich flame, which is the result of a high fuel level and reduced sensitivity.
19. Optimize the burner head horizontally and diagonally while aspirating a standard.
20. Optimize the nebulizer. Bubbles must come OUT of the tube.
21. Nebulizer rate does not change much at all in between running samples.
22. Select the Manual Sampling window, to indicate where to "save data" icon, to name the file where sample data will be stored. A un-named file "save data on/off" icon to be highlighted, and data will not be saved!
23. Begin running your standards/samples. Always begin a sample run by running a standard curve. Simply put the nebulizer tube in your first standard ("zero or blank" standard") and scroll down under Calibration to autozero . When the READ icon stops being highlighted, that means the AAS is finished reading that standard, remove the tube, wipe it with a ChemWipe, put it in the second standard, and scroll down to your next standard . Repeat this process until all standards have been analyzed. NOTE: One precaution might include the use of a DI water rinse between samples. Or it may be possible to avoid the DI rinse if the nebulizer tube aspirates the standard for one second before its analyzed. Give the AAS delay time by adding a1.0 second Delay in the Element Parameter file, Main section.
24. After the first standard curve is analyzed, rinse the nebulizer with de-ionized water and then put the nebulizer tube in your first sample. Always run a standard curve after every 10 to 15 samples. In between every sample, always wipe the nebulizer tube with a ChemWipe.
25. The Display Data window shows you the concentration of your most recent sample/standard. To edit a standard curve, click on Edit Calibration.
26. When you've finished running all your samples and standards, turn off the flame, close the acetylene/air lines, and bleed the gases remaining in the lines.
27. To save the data file as an ASCII file, for a spreadsheet application, go to the Data Benchtop.
28. To view an ASCII file, exit the software. At the C prompt, type x. Scroll up using the arrow keys until you find Data - AAS. Hit return twice and you will see a listing of all the Data files. Then follow the commands at t he bottom of the page: hit V to view the document, C to copy it onto a disk, etc.

Additional Equipment Specifications

AAnalyst 800 is an Atomic Absorption Spectrometer with the following Specifications. System Design: The AAnalyst™ 800 is a fully-integrated benchtop design atomic absorption spectrometer, incorporating all spectrometer, flame and graphite furnace components in a single instrument,with an automated exchange of flame and furnace atomizers at the touch of a button.

Background AAnalyst 800: Continuum source double-beam background correction using a high-intensity deuterium arc lamp. Correction AAnalyst 800: Longitudinal AC Zeeman-effect background correction using a modulate 0.8 Tesla magnetic field oriented longitudinal to the optical path. The magnet is automatically switched on during the atomization step only. Rollover detection is built-in. Also built-in is continuum source double-beam background correction for uses with flame operation.

Furnaces AAnalyst 800: Built-in fully computer-controlled Transversely Heated Graphite Atomizer (THGA™). The graphite tube is transversely heated providing a uniform temperature profile over the entire tube. AAnalyst 800: The graphite furnace can be moved automatically into the sample compartment and positioned via software control and a motorized carriage. An external protective gas stream around the graphite tube prevents the entrance of outside air to maximize tube life. An internal purge gas goes through the graphite tube to remove the volatilized matrix vapors during drying and thermal pretreatment. The two gas streams are computer-controlled independently. Pneumatic opening and closing of the furnace for easy tube change.

Common Furnace Program Flexibility: Analytical programs with up to 12 steps can be set up. Each step can be programmed Features: with the following parameters.

Temperature: Ambient up to 2600°C (up to 3000 °C with AAnalyst 800) in steps of 10 °C. Ramp Time: 0 to 99 s in steps of 1 s. Hold Time: 0 to 99 s in steps of 1s. Internal Gas Flow: 0 mL/min (gas stop), 50 mL/min (mini-flow), 250 mL/min (full flow); can be switched over to another type of gas (Alternate Gas). Furnace Opening and Closing: Pneumatically-operated by software command. Required Inert Gas: Argon. inlet pressure 300 kPa (3 bar) minimum. Maximum gas consumption is 700 mL/min with the AAnalyst 800, 1220 mL/min with the AAnalyst 800.

Water Coolant: A circulatory cooling system is included with the AAnalyst 800.
When operating the AAnalyst 800 without the circulatory cooling system, cooling water meeting the following specifications should be used: Sediment-free drinking water; 20-40 °C; flow rate not less than 2 L/min; pressure between 2.5 and 4.5 bar; pH between 6.5 and 7.5; hardness not greater than 14°dH or 100 ppm.

Furnace Sampler Table: Installed in front of the furnace unit. Removable sample tray with 88 and 146 sampling Autosampler positions for sample and reference solutions and 1 overflow container for pipet washing. Minimum sample requirement: ca. 0.1 mL.

Dispensable Volume: Sample and Reagent: 1...99 mL, selectable in increments of 1 mL. Max. dispensable Vol. 99 mL (sample volume + reagent volume). Flushing volume 1.3 mL, fixed.

Electronics: The autosampler is powered from the spectrometer and is software-controlled. Data Control Complete PC control using AA WinLab software operating under the Microsoft® Windows 95® operating System environment. Provides complete control of the instrument and its major accessories plus data handling and storage.

Data Handling: Instrument readings linear in absorbance (-0.500 A to +2.000 A), concentration or emission intensity with continuously variable scale expansion from 0.01 to 100 times. Integration times operator-selectable from 0.1 to 60 sec. in increments of 0.1 sec. Reading modes include time-averaged integration, non-averaged integration (peak area), and peak height measurement. Includes built-in statistics. Up to fifteen (15) standards and a choice of proven calibration equations. Reslope of the analytical curve using a single operator-selected
calibration standard. Built-in IEEE-488 interface for computer connection and use of optional accessories.

Minimum PC Configuration: Intel® Pentium® processor; 90 MHz; 16 MB RAM; 1 serial, 1 parallel (bidirectional) interfaces; 500 MB hard disk drive; 3.5" disk drive; CD-ROM drive; SVGA graphics board and compatible monitor; mouse pointer; MS Windows 95. A compatible printer is required for hard copy data display.

Dimensions AAnalyst 800: 110 cm wide x 65 cm high x 70 cm deep (104 cm deep with furnace autosampler).

AAnalyst 800: 187 kg (without controller and cooling system). Power 230 V (+5%/-10%), 50/60 Hz; 5000 VA (AAnalyst 800). Requirements Electrical Protection: As defined in EN 61010-1-1993 (IEC 1010-1); insulation class I; insulation category (overvoltage category) II; pollution degree 2. Technical Certification: Designed and tested to be in compliance with the legal requirements for technical instruments Standards including IEC 348 and VDE 0411 and CSA 22.2 No. 151 and the U.S. Federal Communications Commission standards for radio frequency interference. The instrument is developed and produced in compliance with ISO 9001.

The AA WinLab software provides required control parameters for GLP and instrument performance validation.

Safety and EMC standards: EN 61010-1-19993 (IEC 1010-1: 1990 + A1, A2, modified). Electromagnetic compatibility: EN 50 081-1:92 for emission, EN 50 082-1:92 for immunity. Environmental Ambient temperature: +15 °C to +35 °C. Relative Requirements humidity: 20 to 80% non-condensing. Cooling System Self-priming recirculatory system with fan-assisted heat exchanger (standard with the AAnalyst 800) for constant cooling of the graphite furnace. Water temperature during operation approx. 36 °C; water flow 2.5 L/min. Power requirements: 230 V (+5%/-10%), 50/60 Hz; approx. 140 VA. Dimensions: 20 cm wide x 375 cm high x 50 cm deep, 18 kg with coolant.