| What are the main sources of anthropogenic contaminants? |
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| Agriculture, industry and households |
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| Natural Contaminant sources |
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| Animals, Plants, Minerals |
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| By-products of imcomplete burning in boilers |
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| Fly ash, bottom ash, boiler slag |
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| Five main conditions for formation of photochemical smog |
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| Heavy traffic, sunlight, high temp, ozone, quiet weather |
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| Natural sources of aerosols |
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| Deserts, oceans, forests, fires, volcanoes |
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| Chemical species which affects the outcome of a measurement. |
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| How do you eliminate interferences? |
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| Separating analyte from sample matrix. Part of sample pretreatment step. |
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| Seven steps of quantitative analysis |
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| Method selection, Sampling, Solution Preparation, sample pretreatment, analytical measurement, calculating result, statistical evaluation |
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| When is a sample representative of the bulk of a material? |
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| If its composition is identical to the average composition of the bulk material |
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| Collection of a gross sampleReduction of gross sample to homogeneous laboratory sample |
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| Three methods for calculating the analytical result |
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| Calibration curve method, internal standards method, standard addition method |
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| What is the calibration equation? |
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| Describe the standard addition method. |
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| Known amounts of analyte are added to the sample with unknown analyte conc.
The analytical signal is measured before starting the additions, and after each addition. |
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| Equation for multipoint standard addition of varying volumes |
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| When should varying volume multipoint addition be used? |
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| When there could be changes to the sample matrix |
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| Equation for determining concentrating using multipoint constant volume |
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| When is the internal standards method used? |
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| Instrument response varies slightly in time; Sample loss can occur during pretreatment |
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| Equation for the internal standards method |
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| C = [(1/F)*(C(internal)/Z(internal)] * Z(analyte) |
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| What are the three main types of experimental error? |
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| Systematic, random, gross |
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| How do you correct instrumental errors? |
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| What is a gross error, and how do we determine a gross error? |
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| Large outlier. Identified using statistical evaluation. |
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| Can we identify and quantify the source of random error? |
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| No, as the error introduced is usually very small. |
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| How do we characterize precision and accuracy? |
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| Precision – variance, standard deviation, RSDAccuracy – Absolute or relative error |
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| What are the two main types of columns used in chromatography? |
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| Packed columns and open tubular columns |
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| Three types of GC detectors |
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| Flame-ionisation (hydrocarbons), Thermal conductivity, Electron capture detector (halogens) |
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| Gas tank – Pressure regulator – Sample port – Oven – Detector |
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| What are the requirements of the partition coefficient such that there is separation and preconcentration of the analyte? |
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| K >> 1 ; [Sample] >> [Extractant] |
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| What is column resolution? |
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| Quantitative measure of its ability to separate 2 analytes. R = 2[(tb – ta)/(Wa + Wb)] |
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The difference between the titrant volume to equivalence, and the actual titrant volume used.Error = V(equiv.
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) – V(end) |
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| Light source – Premix Burner (Sample, fuel, air) – Monochromator – Detector |
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| What are releasing agents and protective agents? |
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| Releasing agents react preferentially. Protective agents form stable, non-volatile compound with the analyte. |
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| Why is the analysis of phosphoric compounds important? |
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| Orthophosphate supports eutrophication, which leads to anoxic conditions. |
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| What are the main sources of ammonium salts as water comtaminants? |
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| Decomposition of proteins, Atmospheric nitrogen, agriculture, cleaning products |
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| What are the main sources of anions as water comtaminants? |
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| Erosion, sedimentary release, agriculture, soaps, sewage treatment |
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| What are the main organic derivatives as water comtaminants? |
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| Organic decay, algae, oils, pesticides, detergents |
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| List aerosol control devices in order of increasing particulate size. |
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| Electrostatic precipitators, Fabric filter separator, Scrubber, Cyclone, Settling chamber |
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| What are the effects of water hardness? |
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| Interfering with cleaning tasks, Formation of mineral deposits in pipes, Flocculation of colloidal particles in soil. |
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| What are the parameters of water hardness? |
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| < 60 mg/L - soft >270 mg/L – hard |
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| Formula for the student t-test |
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| mean – true > ts/sqrt(n) : no difference |
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| F =variance 1/variance 2 : compared with critical f value |
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