Are you planning to learn or buy an HPLC (High Performance Liquid Chromatography)? Buying an HPLC can be a tough job especially when you do not have expertise in it. The interesting thing for you is that we are with you. After helping 1000+ buyers buying the right HPLC, we have planned to make the most detailed guide on how to buy an HPLC without having technical knowledge. The guide is easy to read and follow whether you are in your early 20’s or 50+ age. Anyhow, if you still need our help in selecting the right model of HPLC, our technical team is available 24/7 for your help free. Which things you need to need to know before buying a HPLC? A brief knowledge about HPLC and its applications Your careful attention for 15 minutes to read this guide. Yes, only 15 minutes you need to understand, how to buy HPLC and you will pass through the whole steps. In this guide, you will cover. HPLC Overview Working Principle of HPLC Types of HPLC based on Operational Method Main Parts of HPLC Quality Parameters Checking of HPLC Trouble Shooting of Common Problems, which occurs during Operation. HPLC Applications Merits and demerits of HPLC Famous brands of HPLC High Performance Liquid Chromatography (HPLC) In this chapter you are going to learn about chromatography and its types, its major concern is about High performance liquid chromatography (HPLC). Chromatography is a separating technique, in which separation is done on the basis of the structure of the molecule in two-phase (i.e. Mobile phase and Stationary phase)                The stationary phase is a solid or a liquid material packed in a column and a mobile phase is a liquid or a gas that flows through the stationary phase. The mobile phase flows through the stationary phase and carries the components of the mixture with it. The component of a mixture, which shows stronger interactions with the stationary phase, will retain in the stationary phase while the component of the mixture, which dissolves in the mobile phase, will move with it and elute first.                HPLC stands for High performance Liquid chromatography or high-pressure liquid chromatography as it uses a high-pressure liquid mobile phase than gases used in Gas chromatography.                HPLC is an analytical technique used for the separation of components of the organic mixture of compounds when such compounds are nonvolatile, thermally unstable, and have relatively high molecular weights.  Working principle of HPLC                In the previous chapter you learn about the introduction of HPLC, now in this chapter, you will learn about the working principle of HPLC. The working principle of HPLC is based on the distribution of the sample between a mobile phase (eluent) and a stationary phase (packing material of the column). Molecule retarded in stationary phase and separate on the basis of difference in retention time. The component of a mixture which retain in the stationary phase elute later, as compared to that which dissolves in the mobile phase. Types of HPLC This section will help you to learn different types of HPLC. Types of HPLC, Based on mode of separation 1. Normal Phase HPLC In this type of HPLC, components are separated on the basis of polarity.  In the Normal phase HPLC, the polar stationary phase is used with the non-polar mobile phase. The stationary phase is usually silica and the mobile phase is Hexane, Methylene Chloride, Chloroform, Diethyl ether, and mixtures of these. As the Stationary phase is polar in normal phase HPLC therefore, the Retention time of Polar samples on the polar surface of the column is longer and they elute later than less polar materials. 2. Reverse Phase HPLC                In this type of HPLC, the stationary phase is non-polar in nature, while the mobile phase is a polar liquid i.e. mixtures of water and Methanol or Acetonitrile. It works on the principle of hydrophobic interactions hence retention time of non-polar material is longer than polar material. Note: Reverse phase chromatography is more commonly used as drugs are usually Hydrophilic. 3. Size-exclusion HPLC In this type of HPLC, the Column used is filled with a material having control pore size and separate the components on the basis of size. Large size molecules pass through the column while small size molecules penetrate inside the pores of the packing material and due to having large retention time elute later.  4. Ion-Exchange HPLC In this type of HPLC, The stationary phase has a charged surface of opposite charge to the sample ions.  The sample with a strong charge will be attracted to the ionic surface, due to this attraction its retention time will increase and elute later. The mobile phase is an aqueous buffer, where both pH and ionic strength are used to control elution time. (Learn) Types of HPLC Based on Elution technique: Isocratic Elution:                A separation in which the composition of the mobile phase remains the same throughout the procedure. In isocratic elution, peak width increases due to high retention time which directly relates to the number of theoretical plates. This leads to the disadvantage that late eluting peaks become broad and flat. Gradient Elution:                A separation in which the composition of the mobile phase is changed during the procedure. Gradient elution decreases the retention of later-eluting components and gives narrow peaks and also improves the peak shape and height. Main parts of HPLC Now it is the time to learn about some main parts of HPLC. The components of HPLC are following, 1. Solvent Reservoir The mobile phase contained in a glass reservoir. In HPLC, the mobile phase is normally a mixture of polar and non-polar liquid components whose compositions are changed by changing the composition of the sample. 2. Pump A pump sucks the mobile phase from the solvent reservoir and forces it to pass through the system’s column and detector. The pressure of the pump depends on a number of factors including column dimensions, the particle size of the stationary phase, the