Dipartimento di Scienze della Vita e dell'Ambiente - Guida degli insegnamenti (Syllabus)
Knowledge of the topics related to the classical chemical analyses (gravimetry, volumetry) and basic instrumental methods (potentiometry, conductimetry, UV-Vis spectrophotometry).
The course consists of theoretical lectures (5 credits, 40 hours) and laboratory practical work carried out individually or at small groups (1 credit, 8 hours) and fieldwork. An e-learning didactic activity is available in parallel to the normal frontal course. It includes: the didactic material, the self-evaluation tests, booking for the laboratory exercises, a section for the upload of laboratory reports from the students, information and booking for the field work, attendances to lectures and laboratory exercises, results of examinations.
The course enables students to acquire the fundamental knowledge of the theoretical and methodological basis of the advanced instrumental techniques of Polarography/Voltammetry and Fluorimetry/Spettrofluorimetry for chemical analysis, and their applications in environmental field (spring waters, river waters, snow, atmospheric aerosol, organisms, food and beverages). He should acquire knowledge also of the principles of quality control and of the accreditation of chemical analytical laboratories.
Ability to apply the knowledge:
At the end of the course, the student should acquire the ability to carry out laboratory chemical analyses based on advanced polarographic techniques (SWASV) devoted to the analytical control of environmental matrices included the step of field sampling.
The execution of laboratory analyses, as well as the drafting and editing of reports on the exercises carried out, contribute to improve for the student the degree of judgement autonomy in general, the communicative capacity, the learning capacity in autonomy, and the ability to draw conclusions from experimental data.
Content. Polarography and advanced voltammetric techniques. Introduction. Relationship with other electrochemical techniques. Polarographic cell: two and three electrodes. Dropping mercury electrode (DME). Electrostability range. Polarogram. Polarographic wave. Half wave potential. Limiting diffusion current. Residual current. Supporting electrolyte. Theoretical aspects: diffusion current at a planar electrode, diffusion limiting current ad a dropping mercury electrode and relationship with concentration. The Ilkovic equation. Current-potential curve. Amplitude of the polarographic wave. Semilogaritmic diagram. Pseudopolarograms. Measurement modes of the limiting current and halfwave potential. Simultaneous, multielemental quali-quantitative analysis. The problem of the presence of oxygen: outgassing. Absorption maxima and their elimination. Qualitative and quantitative analysis. Methods: calibration curve, standard additions, piloti on (or internal standard). Modern techniques: Polarography/Voltammetry with linear scan (LSV), pulses (NPP), differential pulses (DPP), square wave (SWV), Anodic (or cathodic) stripping voltammetry (ASV, CSV) with differential pulses (DPASV) or square wave (SWASV). Sensitivity. Trace determination. Examples of environmental applications: seawater and estuarine waters; marine organisms, tissues and spicules of sponges, teleosts, bivalves; Antarctic atmospheric aerosol, snow and ice; spring and river waters; wine and food. Fluorimetry and Spettrofluorimetry. Photoluminescence: fluorescence and phosphorescence. Stokes’ shift. Power of fluorescence radiation. Direction of the observation. Quenching. Quantic yield. Effect of the concentration: direct proportionality. Deviation from linearity: self-quenching, self-absorption. Comparison of fluorescence and absorption measurements. Fluorimetry and structure. Effect of temperature, solvent, pH and oxygen. Excitation and emission spectra. Instruments for fluorescence measurements: fluorimeters and spectrofluorimeters. Spectrofluorimeters with two monochromators: execution of excitation and emission spectra. Sources. Detectors. Single-beam and double-beam instruments. Corrected and uncorrected spectra. Corrected excitation spectrum and absorption spectrum. Calibration. Quantitative analysis (calibration curve, standard addition method, analysis of mixtures). Indirect determinations (titrations). Sensitivity. Contamination. Precision and accuracy. Resolution. Selectivity. Total luminascence spectrum (fluorogram). Practical aspects. Analytical applications. Exhample: determination of sulfur dioxide in the atmosphere. Quality control and quality assurance. Traceability. Good laboratory practice. Accreditation of laboratories.
Laboratory exercises (1 credit, 8 hours/student). Laboratory practice in a chemical laboratory under contamination control (clean room). Determination of heavy metals (Cd, Pb, Cu) by square wave anodic stripping voltammetry (SWASV) in natural waters and in the atmosphere. Evaluation of accuracy: use of certified reference materials.
Field work (two one-day school trips). Two one-day school trips are expected to be carried out (one in winter, one in summer) dedicated to field activity: sampling of snow and spring water with analyses on site (pH, conductivity, chloride, fluoride, iodide, nitrate), and visit to plants for bottling of mineral water.
Methods for assessing learning outcomes:
The student consigns (on line) his own laboratory reports. The assessment method is an oral examination and subsequent revision/discussion of the script. For the final grade, up to two points maximum will be assigned with reference to the reports of laboratory exercises. The exam is passed when the final score is higher or equal to 18.
Criteria for assessing learning outcomes:
In the oral examination, the student will have to demonstrate to have acquired a sound knowledge of basics and methods (theory and practice) of the chemical analytical methodologies of polarography and fluorimetry. In the laboratory reports, the student will have to demonstrate of having achieved the capacity to apply the acquired knowledge during the course to the execution of laboratory analyses on environmental matrices and the capacity to write critically, in autonomy and/or in-group, a test report.
Criteria for measuring learning outcomes:
The final mark is attributed in thirtieths. Successful completion of the examination will lead to grades ranging from 18 to 30, and 30 with laud.
Criteria for conferring final mark:
The final mark is attributed by summing to the evaluation of the oral examination that of the laboratory report, the latter up to two points. The laud is attributed when the score obtained by the previous sum exceeds the value of 30 and contemporaneously the student demonstrates complete mastery of the matter.
- Lecture notes
- D. A. Skoog, F. J. Holler, S. R. Crouch. Chimica analitica strumentale, 2a ediz., EdiSES, Napoli, 2009.
- K. A. Rubinson, J. F. Rubinson. Chimica analitica strumentale, Zanichelli, Bologna, 2002.
- F. W. Fifield, P. J. Haines (eds.). Environmental analytical chemistry, Blackwell Science, Oxford, 2000