Method for Analysis of Polar Volatile Trace Components in Aqueous Samples by Gas Chromatography

Abstract

A new method has been developed for direct analysis of volatile polar trace compounds in aqueous samples by gas chromatography. Water samples are injected onto a short packed precolumn containing anhydrous lithium chloride. A capillary column is coupled in series with the prefractionation column for final separation of the analytes. The enrichment principle of the salt precolumn is reverse to the principles employed in conventional methods such as SPE or SPME in which a sorbent or adsorbent is utilized to trap or concentrate the analytes. Such methods are not efficient for highly polar compounds. In the LiCl precolumn concept, the water matrix is strongly retained on the hygroscopic salt, whereas polar as well as nonpolar volatile organic compounds show very low retention and are eluted ahead of the water. After transfer of the analytes to the capillary column, the retained bulk water is removed by backflushing the precolumn at elevated temperature. For direct injections of 120 microL of aqueous samples, the combined time for injection and preseparation is only 3.5 min. With this procedure, direct repetitive automated analyses of highly volatile polar compounds such as methanol or tetrahydrofuran can be performed, and a limit of quantification in the low parts-per-billion region utilizing a flame ionization detector is demonstrated.

Suda Uçucu Aromatik Hidrokarbonların (UAH’lar) Hassas ve Doğru Analizi için Gaz Kromatografisi Yöntemi Doğrulama Çalışması

“…The objective of this work was to develop the simultaneous determination of sixteen water soluble VAHs, including highly toxic substances such as benzene, toluene, xylenes, styrene with PT method in the drinking water, seawater and wastewater samples. This paper describes the following validation parameters for simultaneous analysis of VAHs: selectivity, calibration curve linearity, limits of detection and quantification (LOD and LOQ), precision studies of the method and instrument according to [10,11,14,15,20,21]. The recovery studies of each analytes from drinking water, seawater and wastewater samples was also examined.…”

“…For solving this problem, important works have been done in this area and many methods have been reached to the present day. A substantial majority of these methods contains one or more intermediate steps in which the desired analytes are isolated from water environment and intensified prior to GC analysis [10][11][12]. Some special equipments such as passive badges, canisters and sorbent traps are used for the determination of volatile compounds and separation process have been carried out with gas chromatography with flame ionization detection (GC-FID) or with GC-MS in general [13].…”

“…At the present time, PT method is the most valuable and applicable method for preparing water samples for volatile compound analysis and in addition to this, critical quantification for several volatile compounds in water has been performed by the automatization of PT process fully with GC-MS systems [14][15][16]. The advantage of this system is that it picks up only the volatile analytes of interest by eliminating non-volatile compounds and provides the measurement of low detection limits [10]. The analysis of volatile compounds in the PT-GC-MS was performed at first purging of volatile compounds from water samples by using a stream of gases and then, they were adsorbed a trap which is made of porous solid sorbent and were desorbed into GC system for separation and quantitation processes.…”

Full automatic determination of chlorophenols in water using solid‐phase microextraction/on‐fiber derivatization and gas chromatography‐mass spectrometry

“…CPs in water samples are usually analyzed using high performance liquid chromatography (HPLC) [] and gas chromatography (GC) []. For the simultaneous determination of isomeric CPs, it is very likely to interfere or co‐elute peaks when using HPLC.…”

Optimizing capillary column backflush to improve cycle time and reduce column contamination

“…Published reports of capillary column backflushing implementations usually involve isothermal and/or portable, dedicated instrumentation, or involve backflushing of packed precolumns [1][2][3][4]. Some commercial laboratory instruments (e.g., from Siemens and IBM Instruments) were developed for flexible implementation of multidimensional separations including backflush [5], but they were difficult to use and not widely accepted for routine use [6].…”