Microfluidic Deans switch for comprehensive two-dimensional gas chromatography
Microfluidic Deans switch for comprehensive two-dimensional gas chromatography
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DOI：
10.1021/ac061881g
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发表时间：
2007-03-01
影响因子：
7.4
通讯作者：
McCurry, James D.
中科院分区：
文献类型：
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作者：
Seeley, John V.;Micyus, Nicole J.;McCurry, James D.
采用微流控Deans开关作为全二维气相色谱(GCxGC)调制器。迪恩斯开关的简单性和宽温度范围使其成为现有调制技术的一种有前途的替代方案。然而，Deans开关是一种低占空比的调制器；也就是说，它只对一次柱流出物的一小部分进行采样。与所有低占空比调制器一样，如果主峰值采样不足，Deans开关会产生从主列到副列的不一致的分量传输。理论模拟和实验研究表明，当调制比大于2.5时，从主塔转移到副塔的物料分数的相对标准偏差(RSD)小于1%。但当调制比降至2.5时，RSD迅速增大。通过对汽油芳烃含量的分析，验证了Deans开关GCxGC的有效性。快速分析(<；10分钟)产生窄的主峰和1.7的调制比。定量结果与差动流量调制GC和GC/MS结果吻合较好，但单组分水平的相对标准偏差约为3倍。Deans Switch调制器还用于较慢的汽油分析(运行时间33min)，得到的调制比接近5。在这种情况下，定量结果和RSD与差流GCxGC和GC/MS结果非常一致。这些研究表明，只要采用大于2.5的调制比，Deans开关就可以成为有效的调制器。
A microfluidic Deans switch was used as a comprehensive two-dimensional gas chromatography (GCxGC) modulator. The simplicity and wide temperature range of the Deans switch make it a promising alternative to existing modulation techniques. However, the Deans switch is a low duty cycle modulator; that is, it samples only a small portion of the primary column effluent. Like all low duty cycle modulators, the Deans switch produces inconsistent transfer of components from the primary to the secondary column if the primary peaks are undersampled. Theoretical simulations and experimental studies show that the relative standard deviation (RSD) of the fraction of material transferred from the primary column to the secondary column is less than 1% if the modulation ratio is greater than 2.5. But the RSDs increase rapidly as the modulation ratio is decreased below 2.5. Deans switch GCxGC was validated by analyzing the aromatic content of gasoline. A fast analysis (< 10 min) produced narrow primary peaks and a modulation ratio of 1.7. The quantitative results were in good agreement with results obtained with differential flow modulation GCxGC and GC/MS, but the RSDs of single-component levels were approximately three times greater. The Deans switch modulator was also used for a slower gasoline analysis (33 min run time) that produced modulation ratios near 5. In this case, the quantitative results and RSDs were in excellent agreement with the differential flow GCxGC and GC/MS results. These studies demonstrate that a Deans switch can be an effective modulator provided that modulation ratios greater than similar to 2.5 are employed.