Xiaodong Liu | Authors

Dionex Corporation


Fast Separation of Dinitrophenylhydrazine Derivatives of Aldehydes and Ketones Determined by CARB Method 1004 and EPA Method TO-11

Carbonyl compounds, including low molecular weight aldehydes and ketones, have environmental and health concerns; for example, short-term exposure to aldehydes can irritate the eyes, skin, and upper respiratory tract. Motor vehicles emit reactive hydrocarbons that undergo photochemical oxidation in the atmosphere, which generates formaldehyde and other carbonyls. In addition, formaldehyde contributes to the formation of photochemical ozone. California Air Resources Board (CARB) Method 1004 (1) provides an analytical method for the automotive industry to monitor 13 carbonyl compounds in engine exhaust. US EPA Method TO-11A (2) and Method 8315 (3) monitor atmospheric formaldehyde and 14 other carbonyl compounds and are used for a variety of environmental and occupational health purposes. In these methods, carbonyl compounds are trapped as the dinitrophenylhydrazine (DNPH) derivatives before analysis by HPLC.

Simultaneous Separation of an Acidic Drug Substance and its Counterion on a Weak Cation-Exchange/Reversed-Phase Mixed-Mode HPLC Column

The separation and quantitation of drug substances and counterions are two important determinations in the pharmaceutical industry (1). Drug substances and counterions are determined by HPLC (often on reversed-phase columns) and by ion chromatography (IC), respectively. IC is the preferred method for selective and sensitive screening of both cationic and anionic pharmaceutical counterions (2). To increase the analysis throughput, it is desirable that for analysis of drug formulation both drug substance and counterions can be determined within a single run. Naproxen is a non-steroidal anti-inflammatory drug commonly used for treating moderate to severe pain, fever, inflammation, and stiffness. Naproxen sodium was approved by the U.S. Food and Drug Administration (FDA) as an over-the-counter drug. No reports were found describing one technique for the simultaneous determinations of both naproxen and the counterion (Na+).

Fast Analysis of Vanilla Extracts on the Acclaim RSLC 2-mm C18 Column

The recent development of ultra-HPLC (UHPLC) has provided a great potential for high throughput analysis achieved using small (sub-2 μm) particle size columns at increased linear velocities. The advantage of UHPLC over conventional HPLC is increased throughput without sacrificing resolution. Despite their popularity, sub-2 μm particle columns impose practical difficulties, such as high backpressure (which often requires a UHPLC system) and susceptibility to column fouling. Thus difficulty can be overcome using 2.0 to 2.5 μm particles. This study describes an example (analysis of vanilla extract) of transferring a conventional LC method to a high-throughput method using newly developed Acclaim® RSLC 2-μm columns that are based on spherical, porous, high-purity silica particles (dp = 2 μm, pore size = 120 Å, surface area = 320 m2/g).