База знаний

In introductory liquid chromatography training, almost every beginner has heard the following statement: “In reversed-phase chromatography, more polar compounds elute first, while less polar compounds elute later.” But chromatography is not that simple. In this article, we discuss factors beyond polarity that determines elution order.

Cereulide is an emetic toxin found in grains and dairy products that requires prevention and control. In this article, we present a method that quantifies cereulide in infant formula and rice cereal, using solid-phase extraction, UHPLC, and mass spectrometry.

In HPLC, temperature is an often overlooked factor. Without temperature control, methods may suffer from many abnormalities. In this article, we discuss how temperature influences chromatographic behavior and how column ovens play a role in performance.

In modern analytical chemistry, UHPLC offers significant benefits, including increased throughput, superior resolution, and reduced solvent consumption. However, transferring methods from HPLC to UHPLC is more than simply swapping columns. In this article, we explore the essentials in transferring a method, from mathematical calculation to method validation.

HPLC has been one of the most widely used analytical chromatographic techniques, yet it is not fast enough to meet every laboratory analysis. In this article, we explore UHPLC, the faster version of liquid chromatography, compare the differences between UHPLC and HPLC, and discuss the limitations and application fields of UHPLC.

Chromatographic analysis for peptide drugs are important for ensuring product quality and safety. In this article, we introduce our solutions for peptide drug analysis, including the chiral analysis of protected amino acids, the determination of peptide related substances, the analysis of peptide aggregates by SEC, and the evaluation of amino acid ratios using the Welch Ultisil Amino Acid Method Kit.

The existence of hydrogen bonding in acetonitrile-water solutions is a fundamental question. In this article, we will discuss the question in details, including the physicochemical properties of acetonitrile and water, the interaction that takes place when acetonitrile is dissolved in water, and the abnormalities that may occur when using acetonitrile-water solutions as mobile phase or for sample extraction.

Chocolate is one of the most consumed sweet on Earth, and its quality and safety is a major consideration. However, chocolate's component greatly interfere with chromatographic analysis. In this article, we present an HPLC method with trichloromethane pretreatment to analyze Disodium EDTA in chocolate.

In this article, we present solutions for the chromatographic analysis of biological samples from Welch Materials, covering SEC, RPLC, HIC, and ion exchange chromatography, with multiple applications of peptides, nucleic acids, antibodies, and proteins.

Poor resolution is challenging, but elution order reversal is even perplexing. In this article, the author discusses three primary factors that cause peaks to elute inversed when mobile phase changes: pH, organic modifier, and buffer salt.

Reproducibility issues are an unavoidable topic in HPLC. In this article, we break down easily overlooked, application-level factors that cause reproducibility failures into four aspects: reagents, samples, instruments, and columns, and provide a practical troubleshooting framework to help chromatographers isolate issues and achieve robust, consistent separation results in daily laboratory practice.

Unexplained peak fronting and split peaks often compromise HPLC data quality. Among all possible culprits, solvent effect is the one often overlooked. This article explores the mechanisms of this hidden killer and provides actionable strategies to restore peak symmetry.