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hplc analysis Applications

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    Improved Reproducibility and Reduced Sample Preparation Time for the HPLC Analysis of Aflatoxins in Raw Peanut Paste

    The US FDA and international regulatory agencies have set contamination levels for aflatoxins in animal feedstuffs. Since Aspergillus may infect commodities pre-harvest, during storage or during processing, monitoring for aflatoxins in associated agricultural commodities at all stages of production is requisite. Field screening methods exist that are adequate to estimate contamination levels for aflatoxins. When additional confirmation or quantification is desired, chromatographic laboratory analysis is often necessary. Preparation of matrix samples prior to chromatographic analysis typically requires extraction and purification. Commonly, immunoaffinity columns (IAC), which employ a multi-step bind and elute mechanism to concentrate and purify aflatoxins, are used to purify matrix samples for subsequent analysis. Solid phase extraction (SPE), an alternate method which may use interference removal, can also be employed.

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

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    Increased Pigment Removal with Analysis of Pesticides in Oranges

    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.

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

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    Analysis of Herbicides in Drinking Water

    Herbicides are used throughout the world to combat the growth of unwanted plant life. These polar compounds are hydrophilic, so they may find their way into drinking water sources. While gas chromatography has historically been the preferred technique for analysis of herbicides in water samples, the use of LC-MS/MS for this application is gaining acceptance. This is due to the power of MS/MS to provide detailed identification of multiple analytes, but also in part due to the variety of HPLC stationary phases that are available. In particular, several HPLC phases are available that provide great retention and peak shapes for polar analytes, such as herbicides, even under mostly aqueous mobile phase conditions. The combination of these factors may possibly eliminate need for time-consuming sample preparation.

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

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    Analysis of Methylimidazoles in Caramel Colored Carbonated Beverages

    Caramel colorings are used as additives in a broad range of food and beverage products to impart a desired color, but have no nutritional or preservative function. Recently, the potential hazard to humans of ammonia- and ammonia-sulfite-process caramel colorings was raised, because they contain the by-product 4-methylimidazole, which is a potential carcinogen.1 The methylimidazole compounds are difficult to analyze due to their polar nature and low molecular weight. Traditional reversed phase techniques are unsuccessful in retaining these small polar compounds. Therefore, most HPLC methods utilize ion-exchange resins for analysis. Another common method involves GC analysis after the analytes first undergo a derivatization step. The purpose of the work shown in this article was to develop a simple and fast analytical method to determine the levels of 2-methylimidazole and 4-methylimidazole in caramel colored carbonated beverages.

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

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    Formaldehyde and Acetaldehyde Determination in Air Using Fully Automated On-Line Desorption and Analysis of DNPH Cartridges

    Airborne aldehydes and ketones are collected by passing air through a cartridge containing 2,4-dinitrophenylhydrazine (DNPH). Carbonyl compounds react with the DNPH to form hydrazones, which are immobilized on the cartridge. These compounds can be easily eluted from the cartridge with acetonitrile and analyzed by HPLC with UV detection. Traditionally, this analysis including the workup contains a series of manual steps, which can become time-consuming and could incur experimental error. Automating the extraction of LpDNPH S10 cartridges and putting it in-line with the HPLC analysis will significantly reduce manual labor using this technique and this will improve reproducibility of the method by reducing potential experimental errors by the operator. The automation and unattended operation of the method leads to high throughput for determining airborne formaldehyde and acetaldehyde.

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

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