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