Trace gas chromatographic analysis by use of large sample on-column injection with bonded phase capillary columns

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Short Communications t 066811 0669respond very strongly to methanol (Figure 1 b). The only solvent interference observed was a slight negative response. The first peakwas due to MEK, and this was followed by the elution of THF, acetone, benzene, TCE, and MIBK. Only the THF peak was affected by this negative perturbation. With a thick-film Carbowax column the methanol coeluted with both MEK and THF and obscured both peaks.All components of the test mixture with the exception of acetone could be determined atthe 1 -ppm level using on-column injection of methanol solutions and a PID. Acetone could be determined in methanol at the 10-ppm level. Figure 1 Chromatograms for methanol solutions of volatile polar organics obtainedusinganFlD(a)anda PID(b).Thesamplecontained 1 ppmeach of acetone, MEK, THF, benzene, TCE, and MIBK. One-microliter aliquots were injected into a 50 m X 0.32 mm 0.2 pm Carbowax bonded-phase fused silica capillary column. Results and DiscussionSince the FID responds to methanol, a broad tailing solvent peak was obtained using that detector (Figure la). In contrast, good chromatograms were obtained using the PID because it does not

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Use of a retention gap for the trace analysis of volatile polar organics at the ppb level by direct aqueous injection

Sung

Shanfield

Zlatkis

et al. 1987

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“…A Hewlett Packard 5890A gas chromatograph was equipped with an on-column injector of our own design [3], a 50 m X 0.32 mm 0.2 pm Carbowax bonded-phase fused silica capillary column (Chrompack, Raritan, NJ, USA), a photoionization detector, electrometer, and power supply (Model PI-52-02) purchased from HNU Systems, Inc. (Newton, MA, USA), and a Hewlett Packard 3393 A microprocessor-controlled integrator. A boron nitride washer was installed in the ion chamber of the PID to reduce the dead volume of the detector.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Capillary gas chromatographic trace analysis of volatile polar organics using a photoionization detector

Sung

Batten

Zlatkis

et al. 1987

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not with cyclohexane. From these results, the desired properties of suitable secondary solvent seem to be the following: (i) the secondary solvent should have good affinity for the solutes of interest; (ii) a solvent having no affinity for the solutes is also effective if the latter have a good affinity for stationary phase.The secondary solvent technique is a very useful method for overcoming peak distortion. It is applicable to polar solutions and even for water-containing solutions.

“…Several methods have been used for the isolation and trace enrichment of organic compounds from aqueous samples prior to GC analysis, including adsorption on XAD resins or polyurethane foams 11-31, large-bore coated metal columns with subsequent thermal desorption onto a Tenax or charcoal precolumn [4], uncoated capillary columns of various materials such as polyethylene [5], and direct aqueous injection onto bonded phase fused silica capillary columns [6,7]. Mostly, however, liquid-liquid extraction [8- In the present study, a modified form of a previously designed LC micro-precolumn [14] packed with a reversedphase sorbent (C8) has been coupled on-line to a gas chromatograph ttirough an interface consisting of an on-column injector and a retention gap.…”

Section: Introductionmentioning

confidence: 99%

Liquid chromatographic trace enrichment with on‐line capillary gas chromatography for the determination of organic pollutants in aqueous samples

Noroozian¹,

Maris²,

Nielen³

et al. 1987

109

SummaryTrace enrichment for the GC analysis of a series of chlorinated pesticides and polychlorinated biphenyls (PCBs) in aqueous samples has been achieved through a simple on-line technique involving sorption on an LC micro-precolumn followed by direct elution into a gas chromatograph with hexane. A 5-m retention gap coupled to the capillary GC column served as the recipient of a relatively large sample volume (ca. 100 pl) introduced into the GC. Partially concurrent solvent evaporation during sample introduction allowed a large sample capacity.Recoveries of more than 95 YO were observed for the majority of the compounds studied. Using 1.0 ml aqueous samples, detection limits of less than 1 ppt were found. The applicability of the developed method was demonstrated for a river water sample.