The difference between flow plus formic acid and no addition

1. Mobile phase basic concept

The mobile phase, usually consisting of solvents, inorganic salts and organic additives, has the primary function of dissolving or carrying the components to be separated while interacting with the stationary phase to effect separation. The nature of the mobile phase determines the efficiency and selectivity of the separation. For example, a polar mobile phase (e. g., methanol) is suitable for separating components of similar polarity, while a non-polar mobile phase (e. g., dichloromethane) is suitable for separating non-polar components.

2. With formic acid and without formic acid mobile phase

In some mobile phase configurations, formic acid is added as a co-solvent or the pH of the mobile phase is adjusted. In this case, the mobile phase can be divided into two types: "with formic acid" and "without formic acid. There are significant differences between the two in practical applications.

2.1 plus formic acid mobile phase

In the mobile phase with formic acid, a certain concentration of formic acid is usually added to enhance the solvent effect of the mobile phase and improve the separation efficiency. Formic acid is a strong acid that can increase the viscosity of the mobile phase while enhancing the solubility of solutes, especially when separating samples with strong acidic and basic components. Formic acid also reacts with the matrix in the stationary phase, for example, with acidic substances such as silica gel, thereby reducing the adsorption of the stationary phase to the sample and increasing the linear range of the separation.

2.2 mobile phase without formic acid

Mobile phases without formic acid are entirely dependent on other solvents and conditioning reagents to achieve separation. This mobile phase typically has low viscosity and low solubility, making it ideal for scenarios that require rapid separation and reduced sample cross-contamination. The mobile phase without formic acid has certain advantages in the service life and cost of the column, but it may also affect the efficiency and selectivity of the separation in some cases.

2.3 with and without formic acid comparative analysis

3. Choose to add formic acid or not to add formic acid

In practice, the choice of whether to add formic acid or not depends on the specific analytical needs and sample characteristics:

• Formic acid mobile phase: suitable for analysis that requires high separation efficiency and high linear range, especially when separating components with strong acidity and alkalinity. This mobile phase can significantly improve the sensitivity and accuracy of the separation.

• No formic acid mobile phase: suitable for rapid analysis, cost control and high sample quality requirements. The mobile phase without formic acid has advantages in terms of column life and cost of use.

4. Conclusion

The mobile phase is a key factor in chromatographic analysis, and there is a significant difference in performance between the mobile phase with and without formic acid. The choice of mobile phase type depends on the specific analytical objectives and sample characteristics. By selecting the mobile phase scientifically and reasonably, the accuracy and consistency of the analysis results can be significantly improved. Chemical industry technicians need to make the best choice based on actual needs, combined with experimental data and experience.

Through the analysis of this article, readers can better understand the difference between flow plus formic acid and no formic acid, so as to make more scientific decisions in practical work.