c18 column Applications

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Determination of Additives in Beverages using Ascentis Express Columns

by Sigma-Aldrich Co., LLC     based in Bellefonte, PENNSYLVANIA (USA)

Beverages, such as sodas and energy drinks, can include a number of polar ingredients, which are easily soluble in the water matrix of the drinks. These ingredients include sweeteners (sugars and sugar substitutes), caffeine, vitamin supplements, amino acids, organic acids, and plant extracts. Because the analytes are already in solution, there is no need for extensive sample preparation. Dilution followed by direct injection into an HPLC is typically suitable. In this article we present two beverage applications using Ascentis Express HPLC columns. Ascentis Express columns offer faster HPLC on any system. One benefit is their ability to produce the resolution, efficiency, and speed on conventional HPLC systems that is associated with the use of sub-2 micron columns on a UHPLC system, without generating high backpressure. Column chemistries (RP-Amide and HILIC) were selected for this article based on their enhanced performance with polar compounds in comparison to C18.

Increased Pigment Removal with Analysis of Pesticides in Oranges

by Sigma-Aldrich Co., LLC     based in Bellefonte, PENNSYLVANIA (USA)

An application was developed to demonstrate increased pigment removal for the analysis of pesticides, using Supel™ QuE Z-Sep/C18 QuEChERS and an Ascentis® Express C18 HPLC Column. The improved cleanup can decrease column and instrument fouling, leading to extended LC column lifetime and reduced instrument downtime.

Analysis of Isocyanates Using the ASSET™ EZ4-NCO Dry Sampler

by Sigma-Aldrich Co., LLC     based in Bellefonte, PENNSYLVANIA (USA)

Isocyanates are used as a raw material to produce a number of products . Personal exposure can occur while the products made with isocyanates are being applied, or when the materials are removed by grinding or thermal degradation. Workers who are exposed to these compounds are at risk for respiratory disorders and asthma. The highly reactive nature of the isocyanate compounds and the low occupational exposure limits put high demands on both sampling and analytical techniques for monitoring of isocyanates in air. We investigated the performance of the LC-MS and LC-MS-MS methods in the analysis of isocyanates using the new ASSET™ EZ4-NCO Dry Sampler. We found that the analytical method can successfully reach the quantitation limit for most isocyanates of 5 ng/mL in the final sample when LC-MS-MS analysis was used and the quantitation limit of 10 ng/mL when LC-MS analysis was used. All 11 compounds were well-resolved chromatographically using a 15 cm Ascentis Express C18 column.

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