gas chromatography (GC)

b) Separation based on boiling point.

d) Analyzing the composition of pharmaceutical products.

c) It has high sensitivity and precision for detecting pollutants.

a) By combining GC with a mass spectrometer, the technique can identify the chemical composition of each separated component.

c) Volatile organic compounds (VOCs)

**1. Steps Involved in Sample Preparation and Analysis:** * **Sample Collection:** Collect groundwater samples from the suspected contamination area, ensuring proper sampling techniques and containers. * **Sample Preparation:** * Pre-treat the samples to remove potential interfering substances (e.g., particulate matter, suspended solids) using filtration or extraction techniques. * Depending on the nature of the pesticides, the sample may need further concentration using techniques like solvent extraction or solid-phase extraction. * **GC Analysis:** * Inject a known volume of the prepared sample into the GC system. * The sample is vaporized and transported by a carrier gas through the column. Different pesticides will separate based on their boiling points. * The separated components are detected by a suitable detector, such as a flame ionization detector (FID) or a mass spectrometer (MS). * **Data Analysis:** * The GC produces a chromatogram with peaks corresponding to different components in the sample. * Compare the retention times and peak areas of the identified components to known standards of pesticides to identify the specific pesticides present and quantify their concentrations. **2. Determining Pesticide Presence and Identification:** * If the chromatogram exhibits peaks matching known pesticide standards, it confirms the presence of pesticides in the groundwater. * The retention times and peak areas can be used to identify the specific types of pesticides present. * Comparison with known standards allows for accurate identification and quantification of pesticides. **3. Significance of Findings and Addressing Contamination:** * The findings provide evidence of the extent and nature of the contamination. * The specific pesticide types and concentrations are critical information for assessing the environmental and health risks associated with the contamination. * This information can be used to: * Identify the source of the contamination. * Develop remediation strategies to remove or mitigate the pesticides from the groundwater. * Implement preventative measures to avoid future contamination. * Inform regulatory agencies and local communities about the situation and necessary actions.