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Environmental Health Science · 400 Level
This is the complete lecture note for EVM 414 Experimental pesticide chemistry and residue Analysis, prepared for Environmental Health Science students at 400 Level. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Series 1 Course code: EVM 414 Course title: Experimental Pesticide Chemistry and Residue Analysis Course credit load: 2 Units List of Series: • Series 1: Sampling and Preservation in Pesticide Studies • Series 2: Extraction, Cleanup, and Instrumentation for Residue Analysis • Series 3: Pesticide Formulation and Analytical Quality Assurance • Series 4: Experimental Trials on Crop Growth, Pest Control, and Resistance • Series 5: Herbal Screening, Active Ingredient Characterization, and Instrument Maintenance Series 1: Sampling and Preservation in Pesticide Studies. Series 1 Outline • Part 1 (1.1): Foundations of Environmental Sampling ◦ Sub-Part 1.1.1: Principles and planning of sampling programmes ◦ Sub-Part 1.1.2: Types of sample containers and collection equipment • Part 2 (1.2): Collection of Environmental Samples ◦ Sub-Part 1.2.1: Water, sediment, and soil sample collection ◦ Sub-Part 1.2.2: Biological sample collection vegetation, blood, milk, fish, invertebrates, birds, and mammals • Part 3 (1.3): Air Sampling and Sample Preservation ◦ Sub-Part 1.3.1: Methods of air sample collection ◦ Sub-Part 1.3.2: Techniques and importance of sample preservation • Part 4 (1.4): Quality Assurance in Sampling ◦ Sub-Part 1.4.1: Chain of custody and documentation ◦ Sub-Part 1.4.2: Common sampling errors and how to avoid them
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Introduction Sampling is the foundation of any credible pesticide residue study. Before a laboratory can analyse the presence or concentration of pesticide residues in the environment, reliable samples must first be collected from the relevant media, whether water, soil, vegetation, or biological organisms. The quality of data generated from any analytical investigation is only as good as the quality of the samples on which it is based. This Series introduces you to the principles and practice of sampling and sample preservation in pesticide studies, equipping you with the knowledge needed to plan and execute sound sampling programmes. The aim of this Series is to provide you with a thorough understanding of how to plan sampling programmes, select appropriate containers, collect samples from diverse environmental compartments, preserve them to prevent degradation, and apply basic quality assurance measures during the sampling process. We shall begin this Series by exploring the foundations of environmental sampling, including the principles that guide sampling design and the planning of a sampling programme. Next, we will examine the collection of environmental samples from various matrices such as water, sediments, soil, and biological specimens. We will then move on to air sampling and the techniques used to preserve collected samples. Finally, we will consider quality assurance practices in sampling, including chain of custody procedures and the avoidance of common sampling errors. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1 describe the principles of planning a sampling programme and identify appropriate containers for different sample types, • SLO 1.2 explain procedures for collecting environmental samples from water, sediments, soil, and biological materials,
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS • SLO 1.3 demonstrate knowledge of air sampling methods and the importance of sample preservation techniques, • SLO 1.4 evaluate quality assurance practices in sampling, including chain of custody and error prevention. 1.1 Foundations Of Environmental Sampling 1.1.1 Principles and planning of sampling programmes A sampling programme is a structured plan that defines what will be sampled, where, when, how many samples will be taken, and how they will be processed. The planning of a sampling programme is driven by the objective of the study. For instance, a study investigating pesticide contamination of drinking water sources will require a different sampling strategy compared to one examining pesticide residues in bird populations. Key principles include representativeness, which ensures that samples reflect the true condition of the environment being studied; reproducibility, which allows the programme to be repeated under similar conditions; and statistical adequacy, which ensures that the number of samples collected is sufficient to support valid conclusions. Fill in the blank: The principle that ensures samples reflect the true condition of the environment is called __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Short description: A flowchart illustrating the key steps in planning a pesticide residue sampling programme. Figure 1.1 Key steps in planning a sampling programme for pesticide studies 1.1.2 Types of sample containers and collection equipment The choice of sample container is critical in pesticide residue studies because inappropriate containers can cause contamination or degradation of the sample before analysis. Glass containers are generally preferred for organic pesticide analysis, as they do not leach chemicals into the sample. High-density polyethylene (HDPE) containers may be used for certain aqueous samples. Amber-coloured glass is used when samples are sensitive to light. Containers must be pre-cleaned, sealed, and labelled before use. Collection equipment such as Teflon-coated samplers, stainless steel corers, and syringe samplers must similarly be inert and free of contaminating residues. Fill in the blank: __________ glass containers are preferred for samples that are sensitive to light.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Pilot questions 1.1 1. What is the primary purpose of a sampling programme in pesticide residue studies? 2. State one principle that guides the planning of a sampling programme. 3. Why are glass containers generally preferred over plastic in pesticide residue sampling? 4. What type of container should be used for light-sensitive samples? 5. Fill in the blank: Reproducibility in sampling ensures that a programme can be __________ under similar conditions. 1.2 Collection Of Environmental Samples 1.2.1 Water, sediment, and soil sample collection Water samples for pesticide analysis may be collected from surface water bodies such as rivers, lakes, and irrigation channels, or from groundwater through wells and boreholes. Surface water is collected using grab sampling, where a sample is taken at a single point and time, or composite sampling, which involves combining multiple grab samples to represent an average condition. Sediment samples are collected from the bottom of water bodies using grab samplers or core tubes, since pesticides tend to accumulate in sediments due to their hydrophobic properties. Soil samples are collected using soil corers or augers at defined depths, and multiple sub-samples from a sampling area are typically composited to reduce variability. Fill in the blank: __________ sampling involves combining several individual samples to represent an average environmental condition.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Short description: A photograph or illustration showing field collection of a surface water sample using a grab sampler. Plate 1.1 Surface water grab sampling in a pesticide residue study 1.2.2 Biological sample collection vegetation, blood, milk, fish, invertebrates, birds, and mammals Biological samples encompass a wide range of matrices and require specific collection procedures. Vegetation samples, such as leaves and fruits, are collected by hand or with scissors and placed in labelled bags; they must be representative of the plant tissue most likely to contain residues. Blood samples from mammals and birds are collected by venepuncture and stored in appropriate anticoagulant tubes. Milk samples are collected directly during milking and stored at low temperatures. Fish are collected by netting or electrofishing; relevant tissues such as muscle and liver are dissected for analysis. Invertebrates are collected using sweep nets, pitfall traps, or aquatic nets. Birds and mammals may be sampled through non-lethal methods such as feather collection or faecal sampling, or through legally regulated collection of whole specimens when necessary.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Fill in the blank: Fish used in pesticide residue studies are typically collected using __________ or electrofishing. Pilot questions 1.2 1. Distinguish between grab sampling and composite sampling of water. 2. Why do pesticides tend to accumulate in sediments? 3. Describe one method used to collect soil samples in the field. 4. What anticoagulant tubes are typically used to store blood samples? 5. Fill in the blank: Vegetation samples are collected to represent the plant tissue most likely to contain __________. 1.3 Air Sampling And Sample Preservation 1.3.1 Methods of air sample collection Pesticide residues in air arise from spray drift, volatilisation from treated surfaces, and wind erosion of contaminated soils. Air sampling is therefore an important component of environmental monitoring near agricultural areas. Two principal approaches are used: active sampling and passive sampling. In active sampling, a pump draws air through a collection medium such as a polyurethane foam (PUF) plug or XAD-2 resin trap, which adsorbs the pesticide vapours and particles. In passive sampling, a sorbent material is exposed to the ambient air for a defined period and absorbs pesticides without the use of pumps; this method is simpler and less expensive but yields time-averaged concentrations rather than instantaneous readings. Fill in the blank: __________ air sampling uses a pump to draw air through a collection medium such as polyurethane foam.
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