Restek Corporation

Articles by Restek Corporation

Chromatographic conditions were developed for a fast GC-MS glycol ether analysis on the Rxi®-1301Sil MS column. This cyanobased thin film column provides better resolution and faster run times than the thick film cyanopropylphenyl-type columns commonly used for speciation of the glycol ethers. The glycol ethers are high production volume industrial chemicals that often occur as complex mixtures of isomers. The Rxi®-1301Sil MS column is uniquely matched for the separation of these isomers while still producing narrow and symmetric peaks for the low molecular weight ethylene glycol ethers.

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Semivolatile calibrations on this column dimension often range from 1.0 to over 100 ng/µL; however, a 0.25 mm ID column usually experiences peak overload as the mass on column approaches 10 ng. As shown in Figure 1, isobars that elute close together-such as benzo[b]fluoranthene and benzo[k]fluoranthene-quickly become unquantifiable as mass on column increases. Under split conditions, the resolution requirement (50% valley) is met for all nine calibration standards, and the peak apices shift less than 0.04 min, indicating only minor peak overload. Conversely, under splitless conditions, the three highest concentration calibration standards fail the resolution criterion. The peak fronting and resulting overlap from column overload make it impossible to generate a linear calibration including these points. Additionally, the peak apex of benzo[b]fluoranthene shifts more than 0.2 min, which could result in an erroneous compound identification.

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A rapid, accurate, and reproducible method was developed for high-throughput testing of nicotine, cotinine, trans-3’-hydroxycotinine, nornicotine, norcotinine, and anabasine in urine. Data show that a fast and highly efficient analysis of these basic compounds can be achieved with the Raptor Biphenyl column using standard reversed-phase LC–MS mobile phases that are compatible with a variety of LC–MS instrumentation.

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Concurrent solvent recondensation–large volume splitless injection (CSR-LVSI), an alternative to programmed temperature vaporization (PTV), typically requires a special GC inlet. The technique described here uses an unmodified split/splitless inlet with CSR-LVSI to lower detection limits for the analysis of 1,4-dioxane in drinking water.