Equipo de Absorción Atómica utpl
New Section
This section provides an introduction to atomic absorption and its applications in analyzing various elements.
Introduction to Atomic Absorption
- Atomic absorption is an analytical technique used to analyze a wide range of elements from the periodic table, approximately 67 elements.
- It allows for the determination of metals and minerals in samples such as water, agricultural soils, mineralogical soils, fluids like blood, and food.
- The atomic absorption equipment consists of three main parts: atomization by flame, graphite furnace, and hydride generator.
New Section
This section explains the functioning of each part of the atomic absorption equipment.
Atomization by Flame
- In this part, samples are atomized using a flame.
- Prior to analysis, samples undergo digestion with strong acids to remove any interference that may affect readings.
- For example, if analyzing water for calcium content, 100 ml of water is mixed with 5 ml of nitric acid. After evaporation and dilution with distilled water, it is ready for analysis.
New Section
This section focuses on the process of atomization in the flame and its significance.
Atomization Process in Flame
- Atomization occurs in the flame where samples are decomposed into atoms.
- Only 20% of the sample passes through a premix chamber while the remaining 80% goes to a waste reservoir.
- The 20% sample in the premix chamber combines with combustible gas (acetylene) and oxidant (air) before entering the flame for atomization.
- Flame atomization requires high temperatures ranging from 22,000°C to 6,000°C.
- This method is suitable for determining relatively high concentrations, such as parts per million.
New Section
This section introduces the graphite furnace and its role in analyzing trace elements.
Graphite Furnace
- The graphite furnace is a crucial and expensive part of atomic absorption equipment.
- It allows for the determination of trace elements in various samples like soils, water, and food.
- The process in the graphite furnace involves two steps: pyrolysis and atomization.
- Pyrolysis involves drying and calcining the sample at around 2,100°C for about one and a half minutes.
- Atomization occurs when a droplet of the sample is deposited into the graphite tube and atomized at 2,600°C.
- An autosampler can hold around 120 to 140 samples, allowing continuous operation without constant technician presence.
New Section
This section discusses the hydride generator and its capabilities.
Hydride Generator
- The hydride generator is used to analyze specific elements like arsenic, mercury, and selenium.
- It requires manual operation by a technician using reagents such as sodium borohydride.
- Results are presented in trace concentrations (parts per billion).
New Section
This section highlights the different types of lamps used in atomic absorption equipment.
Lamps Used in Atomic Absorption Equipment
- There are two main types of lamps used:
- Hollow cathode lamps filled with inert gas and containing a cathode made of the metal being analyzed. Different metals require different lamps.
- Electrodeless discharge lamps that contain an inert gas and have a metal electrode for each element being analyzed. These lamps are used for specific elements like arsenic, lead, zinc, cadmium, barium, mercury, and selenium.
- Lamps provide the necessary energy for atomic absorption analysis.
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Electron Discharge Lamps vs Hollow Cathode Lamps
This section discusses the advantages of electron discharge lamps over hollow cathode lamps in terms of sensitivity and lifespan.
- Electron discharge lamps are more sensitive than hollow cathode lamps.
- Electron discharge lamps have a longer lifespan compared to hollow cathode lamps.
Gases Used in Atomic Absorption Spectroscopy
This section explains the gases used in atomic absorption spectroscopy for different metals and minerals, except for aluminum.
- High-purity grade 5 gases are used in atomic absorption spectroscopy.
- For flame analysis, acetylene and air are used for all metals and minerals except aluminum.
- For graphite furnace analysis, nitrous oxide and acetylene are used specifically for aluminum.
- Argon is exclusively used for the D2 lamp generator.
Precautions with Gas Valves
This section highlights the importance of keeping gas valves open during analysis to avoid potential explosions.
- Gas valves should be kept open during analysis to prevent any mixture of gases that could lead to an explosion.
- Specifically, the argon valve should not be closed when using the graphite furnace or D2 lamp generator.
Preparation of Iron Standards
This section explains how iron standards are prepared for flame analysis using known concentrations of certified substances.
- Iron standards are prepared from a mother standard with a concentration of 1000 ppm (parts per million).
- The analyst can prepare multiple standards with known concentrations based on their requirements.
- These standards are prepared by diluting the mother standard with distilled water.
Calibration Curve and Standard Concentrations
This section discusses the calibration curve and the concentrations of iron standards used in the analysis.
- The calibration curve ensures that the concentrations of the prepared standards are accurate.
- The mother standard has a concentration of 1000 ppm, and other standards can have concentrations such as 0.5 ppm, 1 ppm, and 1.5 ppm.
- The analyst can choose any desired concentration for preparing the standards.
Energy Requirement for Lamps
This section explains the energy requirement for lamps used in atomic absorption spectroscopy.
- Hollow cathode lamps should have an energy level greater than 50 to ensure optimal performance.
- The iron lamp used in this case has a maximum energy level of 69.
Control Icons and Reading Results
This section introduces control icons on the instrument and explains how to read results.
- Control icons allow users to turn on/off the flame, view calibration curves, and display results.
- The reading process involves igniting the flame using acetylene and air mixture.
- Different metals present in samples can affect flame color and size.
Reading Standards
This section describes how to read different iron standards prepared by the analyst.
- Iron standards are read from lowest to highest concentration.
- A blank sample containing only distilled water is analyzed first to eliminate interference.
- Each standard is then analyzed using atomic absorption spectroscopy.
Program Features
This section highlights program features that help determine accurate concentrations during analysis.
- The program allows users to set time or number of replicates for analysis.
- It also enables users to control the flame or lamp and record readings.
- These features aid in determining the exact concentration of elements in various samples.
Conclusion of Analysis
This section concludes the analysis process and discusses turning off the flame.
- After analyzing all samples, the flame can be turned off to conclude the analysis process.
Concentration Analysis and Results
This section discusses the atomic absorption equipment used for determining the concentration of metals in various samples.
Atomic Absorption Equipment and Software
- The atomic absorption equipment is connected to a software program called Windla32a.
- The software is essential for the functioning of the equipment, as it controls the flame and other parameters.
- Continuous connection between the equipment components (flame, furnace, generator) is required for readings.
Sample Preparation and Analysis
- Samples are suctioned into the system using acetylene and air.
- The graphite furnace is used for atomization by flame extraction.
- The analyst can load samples into an autosampler, allowing it to work overnight without supervision.
- The furnace injects micro-liters of sample into it after calibration.
- Atomization occurs at high temperatures (up to 2600 degrees Celsius) using hollow cathode lamps filled with inert gas.
Sensitivity and Lamp Types
- Each metal being analyzed requires a specific discharge lamp without electrodes.
- These lamps have longer lifespans and higher sensitivity compared to cathode lamps.
- Energy consumption of these lamps is minimal (up to 50 watts).
Gas Lines and Standards Preparation
This section covers gas lines, preparation of standards, and calibration curves.
Gas Lines
- Two gas lines are present in the setup - one for acetylene and another for argon.
- These lines connect to a central gas storage area.
Standards Preparation
- Distilled water is used in preparing standards for calibration curves.
- A standard mother solution with a known concentration (e.g., 1000 ppm) serves as a reference point.
- Technicians prepare multiple standards based on their choice of concentrations.
Calibration Curves
- The prepared standards are used to create calibration curves.
- A minimum of three standards is recommended for accurate calibration.
- The concentration of the standard is plotted on the x-axis, and absorbance is plotted on the y-axis.
- Calibration curves should have a correlation coefficient of 0.99 for acceptance by analysts.
Flame Control and Lamp Selection
This section discusses flame control and lamp selection in atomic absorption analysis.
Flame Control
- The software interface allows for flame ignition and extinguishing.
- Different lamps are used for different elements, such as an iron lamp for iron analysis.
Please note that these summaries are based solely on the provided transcript and may not capture all the details or nuances present in the video.