The area of clinical pathology , that is concerned with analysis of urine, blood (whole blood, serum, plasma), body fluids for screening, diagnosis and monitoring of different diseases. Clinical tests are taken to identify the changes when compared to the biological reference interval of human beings. A wide range of techniques like chemiluminescence , Immunoassays , radioimmunoassay , Biochemical methods like colorimetry , enzymatic reactions , spectrophotometry , nephelometry , electrophoresis , enzyme linked flourescence, Analytical chemistry methods like high performance liquid chromatography, atomic absorption , mass spectrometry , infrared spectrometry , etc are used by Clinical pathologists and biochemists to detect and control diseases. Specialists in Forensic chemistry identify materials in a crime scene through a wide array of methods and using instruments such as Fourier transform infrared spectroscopy , thin layer chromatography, gas chromatography -mass spectrometry, high-performance liquid chromatography and atomic absorption spectroscopy . To preserve evidence and to determine which destructive methods will produce the best results, Forensic chemists prefer using nondestructive methods first. A set of standards are followed by Forensic chemists that have been proposed by various agencies and governing bodies, including the Scientific Working Group on the Analysis of Seized Drugs. Forensic chemists routinely check and verify their instruments, to ensure the accuracy of what they are reporting.