Infrared (IR) spectrometry and mass spectrometry are two powerful analytical tools widely applied in environmental chemistry for the identification, quantification, and structural elucidation of chemical substances. Both techniques are based on different scientific principles but complement each other in environmental analysis. Their ability to provide highly sensitive, specific, and reliable data makes them essential in monitoring pollutants, studying chemical transformations, and evaluating the overall impact of chemical substances on the environment. The principle of infrared spectrometry lies in the interaction between infrared radiation and molecular vibrations. Molecules absorb infrared light at specific wavelengths corresponding to the vibrational frequencies of chemical bonds. Each molecule produces a unique absorption pattern, known as an IR spectrum, which serves as a molecular fingerprint. Functional groups such as hydroxyl, carbonyl, nitro, or aromatic rings can be identified through their characteristic absorption bands. In environmental chemistry, this principle allows for the detection and identification of organic pollutants in air, water, and soil samples. For example, hydrocarbons, pesticides, and volatile organic compounds exhibit distinctive absorption features that can be monitored using IR spectrometry. The instrumentation of IR spectrometry includes several key components. The source of infrared radiation typically involves a Globar (silicon carbide rod) or Nernst glower that emits a broad range of IR radiation when heated. The sample can be analyzed in solid, liquid, or gaseous form, often prepared as pellets, thin films, or contained within gas cells. The monochromator or interferometer separates the incident radiation into distinct frequencies, and detectors such as thermocouples, bolometers, or more advanced pyroelectric detectors measure the transmitted or absorbed radiation. Fourier Transform Infrared (FTIR) spectrometers have largely replaced dispersive instruments because they allow simultaneous collection of a full spectrum with improved resolution, sensitivity, and rapid data acquisition. The resulting spectrum displays peaks corresponding to absorption at specific frequencies, which can be compared to spectral libraries for compound identification. Environmental applications of IR spectrometry are extensive. In atmospheric studies, IR techniques are used to monitor greenhouse gases like carbon dioxide, methane, and nitrous oxide due to their strong IR absorption bands. Remote sensing through satellite-based IR spectrometers provides large-scale monitoring of atmospheric pollutants. In water quality analysis, IR spectrometry helps identify oil spills, surfactants, and organic contaminants. For soil and sediment studies, IR techniques allow characterization of organic matter and detection of hazardous compounds like polychlorinated biphenyls (PCBs). Moreover, FTIR microscopy allows analysis of microplastics in environmental samples, providing insights into the growing problem of plastic pollution. These applications demonstrate the versatility of IR spectrometry as a non-destructive, rapid, and highly informative technique in environmental monitoring. Mass spectrometry operates on a fundamentally different principle, focusing on the