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Displaying 1-5 of 9 results for Tag: Postcolumn reaction

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TN26: Determination of Cr(VI) in Water, Wastewater, and Solid Waste Extracts

Instrument Type: IC

The method presented here overcomes analyte interference by separating the two chromium using a detection method specific for Cr(VI) that is capable of handling the high-ionic-strength sample matrices generated in many leaching, and digestion procedures. Cr(VI) is separated as the divalent anion on the IonPac AS7 column using ammonium sulfate, ammonium hydroxide eluent. After the separation, Cr(VI) reacts with the color reagent diphenylcarbohydrazide (DPC) and detected by UV absorbance at 520 nm. This method is consistent with U.S. EPA Method 218.6. Please refer to AU179 for an updated method.

TN24: Determination of Chromium by Ion Chromatography

Instrument Type: IC

Three methods are presented here for the determination of Chromium in various matrices. Method A utilizes a postcolumn reaction (PCR) with a color reagent. It is a very selective and sensitive method, allowing determination of Cr(III) & Cr(VI) at ppb levels. Method B also utilizes a PCR, but determines Cr (VI) only. It is used for industrial waste waters, analyzing samples that have undergone standard oxidation. Method C allows the determination of inorganic anions in addition to chromate by chemically suppressed conductivity. Please refer to AN1116, AU144, AU165 and AU179 for updated methods.

AU179: Sensitive Determination of Hexavalent Chromium in Drinking Water

Instrument Type: IC

The work shown here describes modification of the conditions described in EPA Method 218.6, including use of the column in the 2 mm format and a smaller reaction coil to increase method sensitivity. The modified method uses Dionex IonPac AS7 column (2 × 250 mm), a 1000 μL injection volume, and post column reaction (using a 125 μL reaction coil) followed by visible absorbance detection at 530 nm. This method permits an MDL for chromate of 0.001 μg/L. This results in a quantitation limit of 0.003 μg/L, which is more than sufficient for analysis at the proposed California PHG level of 0.02 μg/L.

AN 136: Determination of Inorganic Oxyhalide Disinfection Byproduct Anions in Drinking Water Using IC with the Addition of a Postcolumn Reagent for Trace Bromate Analysis

Instrument Type: IC

This application note describes an improved IC method to quantify low levels of oxyhalide DBP anions and bromide in reagent water, bottled water, and finished drinking water. The method uses a Dionex IonPac AS9-HC column and suppressed conductivity detection, followed by postcolumn addition of o-dianisidine (ODA) to enhance visible absorbance detection of the bromate ion. This method allows quantification of all the key oxyhalide anions and bromide at low µg/L levels by using conductivity detection, and the postcolumn addition of ODA. Also refer to AN168 for updated method.

AB107: Determination of Hexavalent Chromium in Dyes

Instrument Type: IC

Hexavalent chromium [Cr(VI)] is the most toxic form of the metal chromium. Leather products colored with dyes containing trivalent chromium, and sweat can transfer the chromium from the leather to the skin. It is possible that some of the Cr(III) oxidizes to Cr(VI). Leather gloves were found to contain Cr(VI). Here, we analyze two dyes for Cr(VI) using a sensitive ion chromatography (IC) method with postcolumn reaction to produce a colored complex detected by visible absorbance. Also refer to AU 179 for an updated method for Cr(VI) analysis.