(i) Hydrophobic Interaction : Hydrophobic interaction chromatography (HIC) is a classic purification tool applied in protein and antibody, laboratory and industrial production process. It has been mainly used for the removal of both product-related impurities such as aggregates, as well as process contaminants such as host cell proteins. This review will focus on the recent development of HIC in its applications in the industrial purification processes. The process economy and requirements of high product purity and quality hare driven much of the recent advancement in HIC chromatography in terms of increased throughput and enhanced selectivity or resolution. Meanwhile, high throughput screening (HTS). 

design of experiments (DoE) and platform approach for process development hare been applied to shorten the development time. The throughput improvement has been achieved through new resins with increased binding capacity , using dual salts for load conditioning, and operating in the flow-through mode. In addition, hydrophobic interaction membrane filter chromatography technology reduces bed volumes and buffer usage and potentially improves process throughput by reducing cycle time. Selectirity and/or resolution enhancements have been achieved through optimization of operation parameters such as temperature and efforts such as application of solvent additives .

(ii) Colorimetry: It is based on the use of interaction of light energy with colored solutions of certain molecules as when light passes through a colored solution, some wavelengths are absorbed more than others. The amount of light absorbed is proportional to the intensity of color and hence to the concentration of the compound. 

Applications: 

• Quantitative estimation i.e., concentration in solution. 

• Detect and identification of bio molecules.