The CHROMacademy technical team was recently posed with the question of the causes of baseline drift in gradient HPLC.
The CHROMacademy technical team was recently posed with the question of the causes of baseline drift in gradient high performance liquid chromatography (HPLC) (Figure 1).
The primary cause of baseline drift in gradient HPLC is due to changes in the refractive index of the eluent. During gradient elution the composition of the eluent will change and, hence, so will its refractive index. This usually manifests itself as a gradual increase in response during the gradient time. To compensate for the change in refractive index properties a reference wavelength should always be set otherwise drifting baselines will occur.
Positive baseline drift is commonly seen in gradient elution and is often caused by differences in the absorbance properties of the A and B solvents. In the case of reversed phase HPLC gradient elution the eluent composition will change from a high percent of A (aqueous) to a high percent B (organic solvent). The common organic solvents used in reversed phase HPLC have a greater UV absorbance (Table 1) than aqueous (water) which results in the rising baseline when monitoring at low wavelengths (~200 nm). The problem of baseline drift caused by the disparity in UV absorbance can be remedied in three ways.
The complete article is available to CHROMacademy Lite and Premier members here >>
CHROMacademy Lite Membership is FREE and it only takes two minutes to register.
With a Lite Membership you are given access to:
∙ This month's webcast & tutorial
∙ Selected eLearning modules
∙ Featured CHROMacademy Content
∙ The CHROMacademy forum
Test drive CHROMacademy and Check out more great content available FREE to our Lite members »
Characterization and Assessment of Effects of Drying Temperature on Edible Mushrooms with HS-GC–MS
September 6th 2024To gain insight into the effect of drying temperature on its composition, headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC–MS) was used for the identification of volatile organic compounds (VOCs) of 86 mushroom samples that were divided into five groups and dried at different temperatures.
Modern HPLC Strategies: Improving Retention and Peak Shape for Basic Analytes
August 16th 2024In high-performance liquid chromatography (HPLC), it is common for bases and unreacted ionized silanols on silica-based columns to cause irreproducible retention, broad peaks, and peak tailing when working with basic analytes. David S. Bell, Lead Consultant at ASKkPrime LLC offers innovative HPLC strategies that can help mitigate such issues.
Real-Time Measurement of EPA Regulated HON Compounds and Environmental Pollutants Using SIFT-MS
September 6th 2024This application note describes the determination of method detection limits (MDLs) for the newly regulated HON (Hazardous Organic NESHAP) compounds, which validate SIFT-MS as an effective solution for measuring these toxic VOCs and other environmental pollutants in ambient air, whether at the fence line or in a mobile setting.