Difference Between HPLC and LCMS

Key Difference – HPLC vs LCMS
 

Let us first look at the meaning of HPLC and LCMS before analyzing the difference between HPLC and LCMS. Chromatography is a separation technique in chemical analysis where sample constituents are separated during passage through a chromatographic medium. It also involves interaction with the sample, stationary phase, and mobile phase. HPLC stands for High Performance Liquid Chromatography, and it is used as a liquid chromatography method in analytical chemistry. The combination of Liquid Chromatography and Mass Spectroscopy (LCMS) has been developed for the quantitative analysis of selected biomolecules and it is a highly sensitive, accurate, and specific assay procedure compared to HPLC. This is the key difference between HPLC and LCMC. This article will introduce you to HPLC and LCMC that deal with chemical analysis and discuss the differences between HPLC and LCMS.

What is HPLC?

High-performance liquid chromatography (HPLC) is a popular separation technique in analytical chemistry. It is mainly used to separate the components, to identify and to quantify each component in a mixture. Earlier, this method was known as high-pressure liquid chromatography because it  depended on pumps to flow a pressurized liquid solvent comprising the sample mixture through a column packed with a solid adsorbent material. Each and every constituent in the sample mixture interacts differently with the solid adsorbent material, which results in different flow rates for different constituents. This can lead to the separation of the constituents as they flow out the HPLC column.

HPLC has been used for various applications such as analysis of vitamin D levels in blood, illegal drug usage of athletes by detecting the drug residues in their urine, sorting out the constituents of a complex biological sample for research purposes and analysis and manufacturing of pharmaceuticals.

What is LCMS?

Liquid chromatography–mass spectrometry (LCMS) is an analytical technique that combines the physical separation abilities of liquid chromatography with the mass analysis abilities of mass spectrometry (MS). Liquid chromatography is a separation technique, and mass spectrometry is used to analyze the mass-to-charge ratio of charged particles. The physical separation is usually achieved by HPLC and alternatively, LCMS also known as HPLC-MS. LCMS is a dominant analytical technique that has a very high accuracy, sensitivity, and specificity compared to HPLC. Thus, it is useful in many applications such as research purposes, drug analysis, food analysis, etc. LCMS is mainly used to separate, to detect, identify and quantify biochemical properties of a particular sample in the presence of complex chemical mixtures.

What is the difference between HPLC and LCMC?

Acronym and definition of HPLC and LCMC

HPLC: HPLC stands for High-Performance Liquid Chromatography. It is a separation technique that is mainly used to separate the components, to identify and to quantify each component in a mixture.

LCMS: LCMS stands for Liquid Chromatography and Mass Spectrometry. It is an analytical technique that combines the physical separation abilities of liquid chromatography with the mass analysis abilities of mass spectrometry (MS).

Characteristics of HPLC and LCMC

Classification

HPLC: This is a Liquid Chromatography method only.

LCMS: This is a combination of Liquid Chromatography method and Mass Spectrometry method.

Efficiency

HPLC: Compared to LCMS, the HPLC analysis is less efficient and slower.

LCMS: Compared to HPLC, the LCMS analysis is efficient and faster.

Sensitivity

HPLC: Compared to LCMS, the HPLC analysis is less sensitive.

LCMS: Compared to HPLC, the LCMS analysis is more sensitive.

Specificity

HPLC: Compared to LCMS, the HPLC analysis is less specific.

LCMS: Compared to HPLC, the LCMS analysis is more specific.

Accuracy

HPLC: HPLC gives less accurate results than LCMS for determination of some chemicals.

LCMS: LCMS gives more accurate results than HPLC for determination of some chemicals.

Component

HPLC: HPLC can be considered as a component of LCMS.

LCMS: LCMS cannot be considered as a component of HPLC.

Ion Source

HPLC: Ion source does not exist in HPLC instrument.

LCMS: Ion source is present in LCMS instrument.

Applications

HPLC: Ions, polymers, organic molecules, and biomolecules can be analyzed using HPLC.

LCMS: Organic molecules and biomolecules can be analyzed. Contrasting to HPLC, LCMS can be used to examine incompletely resolved mixtures.

Operation

HPLC: The diagram of an HPLC instrument is given in figure 1, and it usually includes an autosampler, pumps, and a detector. The sampler introduces the sample mixture into the mobile phase (pressurized mixture of solvents such as water, acetonitrile and/or methanol) which transfers it to the column. The pumps deliver the desired flow and composition of the mobile phase through the column. The column is filled with the adsorbent, which is a grainy solid particle such as silica or polymers. The detector produces a signal proportionate to the amount of sample constituent presence in the column, therefore permitting for quantifiable analysis of the selected sample constituents. The HPLC instrument is controlled, and data analysis is provided by a digital microprocessor and user software.

Figure 1: Diagram of HPLC instrument 

LCMS: The diagram of LCMS instrument is given in figure 2.  The sample extract is inserted into the column consisting of HPLC. This column retains sample metabolites based on physical characters, and different metabolites flow to the mass spectrometer at different time intervals.  Mass spectroscopy is used for assessing masses of particles, for determining the elemental arrangement of a molecule, and for clarifying the molecule structures. However, the sample should be ionized to generate charged molecules in order to determine their mass-to-charge ratios. Therefore, instead of HPLC instruments, LCMS consist additional three modules such as iron source, a mass analyzer, and a detector. An ion source can transform gas phase sample into ions and a mass analyzer grouping the ions by their masses using electromagnetic fields. Finally, a detector quantifies the values and delivers data of each ion present in the sample. The LCMS technique can be used for both qualitative and quantitative applications.

  Figure 2: Diagram of LCMS instrument

In conclusion, HPLC is a liquid chromatography method whereas LCMS is a combination of liquid chromatography and mass spectrometry. Both these analysis techniques have different characteristics, but they can be used to identify and quantify food compositions, pharmaceuticals, and other bioactive molecules.