NETCHEM Remote Access Laboratory Guide OPTIMISATION OF AASGF

NETCHEM Remote Access Laboratory Guide OPTIMISATION OF AAS-GF FOR METALS DETERMINATION In this laboratory work, you will: ü Learn about principles of atomic absorption spectroscopy as an analytical technique ü Get familiar with the basic parts of the atomic absorption spectrometer used for metals analysis in different types of samples. ü Perform optimization of instrumental parameters of the instrument aiming to get reliable results. ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

RESULTS AND OUTCOMES From you it is expected to: ü Understand the basic principle of atomic absorption technique ü Know each part of the instrument and its function ü Strictly follow the correct steps in optimizing each instrumental parameter ü Perform independently instrument optimization ü Perform instrument optimization in distance using the remote access control ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Background A graphite furnace analysis consists of measuring the signal that a known volume of sample gives when it atomizes into the furnace. The injected sample is subjected to a multi-step temperature program. When the temperature is increased to the point where sample atomization occurs, the atomic absorption measurement is made. Variables under operator control include the volume of sample placed into the furnace and heating parameters for each step. These parameters include: 1) temperature 2) ramp time 3) hold time 4) internal gas final temperature during step time for temperature increase time for maintaining final temperature gas type and flow rate ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Background (continued) The number of steps within each program is variable, but a typical graphite furnace program usually includes 6 steps as per below: Ø Drying Ø Pyrolysis Ø Cool down (optional) Ø Atomization Ø Clean out Ø Cool down ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Common problems in AA Sensitivity: • Sensitivity is worse compare to theoretical value Precision • Sensitivity is acceptable but precision is low Accuracy • Instrument does not give the “right” results Poor Sample Throughput • The instrument throughput needs to be improved ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Sensitivity depends in some main factors: – Sample introduction system - AA lamp optimization – Method parameters – Cleanliness – Quality of standards used for calibration ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

GFAA Sensitivity – Cleanliness Important to Check? – Clean windows? • Check lamp and sample compartment windows • Smudges or chemical residue reduces light throughput and increases noise – Sample Introduction System • Deposits on capillary tip can affect sample dispensing • Ensure no bubbles in dispensing syringe (current design is bubble free) • Residues in graphite tube impacts on sensitivity – may cause contamination, high noise or high background – Condition tube before use (even if starting with a new tube) – Helps to “bed” the tube in ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

GFAA Sensitivity – AA Lamp Alignment Light Beam Aligned Through Center of Graphite Tube Important to Check: – Lamp type and alignment • Alignment should be checked – gain setting should be consistent • Lamp type can improve performance by using lamps with higher intensity – Furnace tube • Furnace tube position must be optimized (the light beam should pass through center of graphite tube) – Align lamp first then place graphite tube in position and align ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

GFAA Sensitivity – Method Parameters Important to Check? – Wavelength/Slit selection and Lamp current • Using the most sensitive line? • Check you’re using the rec. lamp current and slit width (different for multi-element lamps) – Interferences? BC Correction? ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

GFAA Sensitivity – Sample Introduction Important to Check: – Sample Dispenser settings • Carefully adjust injection depth – control with the furnace camera or with a dentist mirror – Autosampler rinse • Acidify rinse with 0. 01 % (v/v) HNO 3 plus a few drops of Triton X-100 – Choice of inert gas impacts sensitivity • Argon gas preferred – ensures optimum sensitivity and best tube life • Nitrogen gas reduces sensitivity by up to 20 % and decreases tube life ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

GFAA Sensitivity – Correct Capillary Alignment • Correct dispensing • Capillary tip must remain in contact with solution during dispensing • Ensure there is no liquid on the outside of the capillary after dispensing • Ensure there is no liquid inside the capillary tip after dispensing • Sample should remain as a drop in the center of the tube ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

GFAA Sensitivity – Method Parameters Important to Check? – Furnace parameters • Set appropriate drying temperature and time (2 -3 sec/u. L of solution injected) • Optimize ashing temperature using ashing study • Ensure inner gas flow “off” just prior to atomization ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Automated Furnace Method Optimization • -Optimize absorbance as a function of ashing and atomization temperature. Optimization results for Pb determination - Chemical interferences can reduce atom formation -Use modifiers with temp. programming, matrix match & standard additions ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Furnace AA – Rec. Maintenance Schedule Daily: • • Empty waste container • • Check exhaust system • • Check condition of the graphite tube – replace as necessary – When replacing the tube, check the condition of the electrodes • • Clean the workhead around the sample injection hole • • Check dispensing capillary “free” and syringe • • Top up rinse reservoir as required • Check the gas delivery pressures & cylinder contents • Weekly: • • Check and clean furnace workhead windows (if required)

Materials and equipments For this laboratory, you will need the following materials: Equipments Atomic absorption spectrometer with graphite furnace atomizer, equipped with autosampler. Reagents q Nitric Acid q Pb(NO 3)2 in HNO 3 standard solution (1000 mg/l) q Pd(NO 3)2 – as matric modifier (250 ppm) Hazard Pictograms HNO 3: Pb(NO 3)2 in HNO 3 Pd(NO 3)2 ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Procedure: First step: Switch ON the instrument. Note that: You should follow a strict sequence of turning On the instrument. GAS COMPUTER FURNACE ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Procedure: Second step: Choose the element from the periodic table Follow the prementioned optimization steps ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

DESCRIPTION OF REMOTE ACCESS 1. NETCHEM COMMUNICATION SIDES (NOTE: NETCHEM Communication is defined as event that involves all kinds of internet interactions (in real time and not in real time) between participants via devices (PCs, laptops, tablets andmobilephones)) host side (NOTE: Host side of NETCHEM Communication is defined as PC who invites other users to join the session) guest side (NOTE: Guest side of NETCHEM Communication is defined as PC who joins the invitation to session) 1. Participants PC in classroom Participants PC in laboratory COMMUNICATION SOFWARE Meeting: No Team Viewer Remote control: No Meeting and Remote control simultaneously: Call 1: 1: NO Skype 1. Conference Call: YES COMUNICATION HARDWARE on host side 1 PC for each participant on guest side 1 PC with 1 head set, with microphone and camera 1. INFORMATION EXCHANGE TYPE YES Place of Educator participant: Educational (one side is dominantly receptive) Number of educator(s): Gest side 1 Place of student participant: Host side Number of student participant(s): 17 No Consultative (two sides are equal in giving-receiving information) Number of host side participant(s): No Number of guest side participant(s): No ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Remote Access Connection Instructions What makes these labs different and unique from other classroom experiments is that we have incorporated a section of live connection with the chemist to the lab as well as remotely control of instrument from your classroom. Request a remote lab session specifying information such as: the day, the time, and the instrument you are interested in using by visiting our web site: http: //netchem. ac. rs/remote-access You will see the list of partners with the instruments provided to chose from. You will be contacted by a Remote Access staff member to set up a test run to ensure you are set up properly and have the required infrastructure. Send samples or verify the in-house sample you would like us to prepare and load for characterization. Send your samples to the Remote Access center that you chose on your request. There are two communications soft-ware packages, that will allow us to communicate instructions and answer questions during the session. - Team. Viewer: You can obtain a free download at: https: //www. teamviewer. com/en/index. aspx -Skype -Whats app ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Remote Access Connection Instructions V. You will need: a) Computer with administrator access to install plug-ins and software b) An internet connection c) Speakers d) Microphone e) Projector connected to the same computer f) Web browser (Firefox preferred) VI. During the test run you can refer to this guide to perform the following steps, but it’s very important that you only proceed with these steps during your scheduled times. You may interfere with other remote sessions and potentially damage equipment if you log in at other times. a) Open and logon to your Zoom/Team-viewer account. You will be given the access code to enter at the time of your test and then again during the remote session. § If you are using the Zoom software, Remote Access staff will give you the access code. § If you are using the Team-viewer software, Remote Access staff will give you the ID & password. b) You should soon see the Remote Access desktop and at this point you can interact with the icons on the screen as if it were your desktop. c) Switch to full screen mode by selecting the maximize screen option in the top right corner of the screen. d) Upon completion of the session, move your mouse to the top right corner of the screen, and click on the X to disconnect the remote session. It will ask if you want to end the remote session. Click Yes. ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

EXAMPLE OF REMOTE ACCESS AND CONTROL RESEARCHER IN THE LABORATORY STUDENTS AND PROFESSOR IN THE OFFICE Communication Sides Host Side Guest Side Participant’s PC in IT-IMA classroom of FNS Participant’s PC in laboratory of instrumental analysis ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

SOFTWARES USED FOR COMUNICATION Communication software Meeting: Yes / No Team Viewer (free version) Skype – free version Remote control: Yes / No Meeting and Remote control simultaneously: Yes/No Call 1: 1 Conference Call ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

HARDWARES USED FOR COMMUNICATION Communication Hardware On Host Side On Guest Side 2 independent PCs 2 PCs (1 Instrument PC and 1 laptop) ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

EXAMPLE OF ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Author, Editor and Referee References This remote access laboratory was created thanks to work done primarily at University of Niš. Contributors to this material were: Alma Shehu Date of creation: September, 2018. Refereeing of this material was done by: ___________ Editing into NETCHEM Format and onto NETCHEM platform was completed by: __________________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

References and Supplemental Material The NETCHEM platform was established at the University of Nis in 2016 -2019 through the Erasmus Programme. Please contact a NETCHEM representatives at your institution or visit our website for an expanded contact list. The work included had been led by the NETCHEM staff at your institution. ___________________________________________________ This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.