Polarography
SAMPLE PREPARATION METHODS FOR LIQUID SAMPLES
Table of Contents
SAMPLE PREPARATON
Analytical procedures consist of numerous stages, the most important of which is the collection of a sample and its preparation for analysis as samples are usually not in a suitable form for direct introduction into analytical instruments (Tankiewicz et al., 2011). Sample preparation can be thought of as any treatment that the sample is subjected to following its collection, prior to its analysis. Often this involves conversion of the sample to its most appropriate form for measurement (Cajka et al., 2012). Sample preparation is also used for the following reasons:
For degradation and solubilisation of the matrix
For the release of the analyte of interest
Extraction of the analyte from its matrix into a suitable solvent
For dilution of the analyte and/or matrix
Selection of the method of sample preparation is dependent on four factors. These being type of analyte, type of matrix the analyte exists in, expected concentration range of the analyte as well as the analytical method to be used for analysis (de Koning et al., 2009).
SAMPLE PREPARATION METHODS FOR THE ANALYSIS OF PESTICIDES
Over the years, the use of organic synthetic pesticides has become a widespread practise. These have been used for the prevention, control and/or destruction of pests in an endeavour to increase agricultural production. Extensive use of pesticides however, can cause environmental contamination as well as presence of pesticide residues in food, hence posing a threat to the health of consumers (Stoytcheva, 2011). Thus, reliable and accurate analytical methods are essential in the quantification of pesticide residues in food.
Pesticides present several challenges in their analysis. In an aquatic environment, for example, pesticides often exist in low concentrations due to their high solubility. Therefore they require preparation methods which offer isolation
Table of Contents
SAMPLE PREPARATON
Analytical procedures consist of numerous stages, the most important of which is the collection of a sample and its preparation for analysis as samples are usually not in a suitable form for direct introduction into analytical instruments (Tankiewicz et al., 2011). Sample preparation can be thought of as any treatment that the sample is subjected to following its collection, prior to its analysis. Often this involves conversion of the sample to its most appropriate form for measurement (Cajka et al., 2012). Sample preparation is also used for the following reasons:
For degradation and solubilisation of the matrix
For the release of the analyte of interest
Extraction of the analyte from its matrix into a suitable solvent
For dilution of the analyte and/or matrix
Selection of the method of sample preparation is dependent on four factors. These being type of analyte, type of matrix the analyte exists in, expected concentration range of the analyte as well as the analytical method to be used for analysis (de Koning et al., 2009).
SAMPLE PREPARATION METHODS FOR THE ANALYSIS OF PESTICIDES
Over the years, the use of organic synthetic pesticides has become a widespread practise. These have been used for the prevention, control and/or destruction of pests in an endeavour to increase agricultural production. Extensive use of pesticides however, can cause environmental contamination as well as presence of pesticide residues in food, hence posing a threat to the health of consumers (Stoytcheva, 2011). Thus, reliable and accurate analytical methods are essential in the quantification of pesticide residues in food.
Pesticides present several challenges in their analysis. In an aquatic environment, for example, pesticides often exist in low concentrations due to their high solubility. Therefore they require preparation methods which offer isolation
References: 1. Andreu, V., and Pico, Y., Determination of pesticides and their degradation products in soil: critical review and comparison of methods, Trends in Analytical Chemistry, 23 (10-11), pp 772-789. 2004. 2. Bhadekar, R., Pote, S., Tale, V., and Nirichan, B., Developments in analytical methods for detection of pesticides in environmental samples, American Journal of Analytical Chemistry, 2, pp 1-15, 2011. 3. Bhadra, M., and Mitra, S., Carbon nanotube immobilized polar membranes for enhanced extraction of polar analytes, Analyst, 137, pp 4464-4468, 2012. 6. de Koning, S., Janssen, H.G., and Brinkman, U.A.T., Modern methods of sample preparation for GC analysis, Chromatographia Supplement, 69, pp 33-78, 2009. 8. Jin, B., Xie, L., Guo, Y., and Pang, G., Multi-residue detection of pesticides in juice and fruit wine: A review of extraction and detection methods, Food Research International, 46, pp 399-409, 2012. 10. Lambropoulou, D.A., and Albanis, T.A., Liquid-phase micro-extraction techniques in pesticide residue analysis: a review, Journal of Biochemical and biophysical methods, 70, pp 195-228, 2007. 12. Marczak, M., Wolska, L., Charzanowski, W., and Namiesnik, J., Microanalysis of Volatile Organic Compounds (VOCs) in water samples – Methods and Instruments, Microchimica Acta, 155, pp 331-348, 2006. 15. Sanchez-Rojas, F., Bosch-Ojeda, C., and Cano-Pavon, J.M., A review of stir bar sorptive extraction, Chromatographia Supplement, 69, pp 79-94, 2009. 17. Tankiewicz, M., Fenik, J., and Biziuk, M., Solventless and solvent-minimized sample preparation techniques for determining currently used pesticides in water samples: a review, Talanta, 86, pp 8-22, 2011. 18. Wolska, L., Wiergowski, M., Galer, K., Gorecki, T., and Namiesnik, J., Sample preparation for GC analysis of selected pesticides in surface water, Chemosphere, 39(9), pp 1477-1486, 1999. 19. Zwi-Ferenc, A., and Biziuk, M., Solid phase extraction technique – trends, opportunities and applications: Review, Polish Journal of Environmental Studies, 15 (5), pp 677-690, 2006.