On-line coupling of in-tube solid phase microextraction (SPME) to HPLC for analysis of carbamates in water samples: Comparison of two commercially available autosamplers * Presented at the Twenty-First International Symposium on Capillary Chromatography and Electrophoresis, Park City, Utah, USA, June 20–24, 1999

Gou, Yanni; Tragas, Charalambos; Lord, Heather; Pawliszyn, Janusz

doi:10.1002/(sici)1520-667x(2000)12:3<125::aid-mcs1>3.3.co;2-0

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“…The extraction process involves agitation by sample flow in and out of the extraction capillary. Successful coupling of in-tube SPME with HPLC as well as HPLC−MS has been achieved for the speciation of organoarsenic compounds and determination of ranitidine, β-blockers, carbamate pesticides, − and aromatic compounds …”

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Sol−Gel Capillary Microextraction

et al. 2002

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Sol-gel capillary microextraction (sol-gel CME) is introduced as a viable solventless extraction technique for the preconcentration of trace analytes. To our knowledge, this is the first report on the use of sol-gel-coated capillaries in analytical microextraction. Sol-gel-coated capillaries were employed for the extraction and preconcentration of a wide variety of polar and nonpolar analytes. Two different types of sol-gel coatings were used for extraction: sol-gel poly(dimethylsiloxane) (PDMS) and sol-gel poly(ethylene glycol) (PEG). An in-house-assembled gravity-fed sample dispensing unit was used to perform the extraction. The analysis of the extracted analytes was performed by gas chromatography (GC). The extracted analytes were transferred to the GC column via thermal desorption. For this, the capillary with the extracted analytes was connected to the inlet end of the GC column using a two-way press-fit fused-silica connector housed inside the GC injection port. Desorption of the analytes from the extraction capillary was performed by rapid temperature programming (at 100 degrees C/min) of the GC injection port. The desorbed analytes were transported down the system by the helium flow and further focused at the inlet end of the GC column maintained at 30 degrees C. Sol-gel PDMS capillaries were used for the extraction of nonpolar and moderately polar compounds (polycyclic aromatic hydrocarbons, aldehydes, ketones), while sol-gel PEG capillaries were used for the extraction of polar compounds (alcohols, phenols, amines). The technique is characterized by excellent reproducibility. For both polar and nonpolar analytes, the run-to-run and capillary-to-capillary RSD values for GC peak areas remained under 6% and 4%, respectively. The technique also demonstrated excellent extraction sensitivity. Parts per quadrillion level detection limits were achieved by coupling sol-gel CME with GC-FID. The use of thicker sol-gel coatings and longer capillary segments of larger diameter (or capillaries with sol-gel monolithic beds) should lead to further enhancement of the extraction sensitivity.

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Sol−Gel Capillary Microextraction

et al. 2002

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“…The 10% (% ACN) initial mobile-phase strength was restricted by the extraction conditions in the on-column focusing studies. The 50% (% ACN) final strength was initially set since it was the optimal isocratic condition used for the in-tube SPME/LC methods described previously. , The value of the retention factor k for each band in isocratic elution is important for controling the HPLC separation. The average value of k in gradient elution, defined as k* , determines the sample resolution and bandwidth.…”

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“…In the conventional in-tube SPME/HPLC method, it was found that preloading of the extraction capillary with methanol can double the extraction efficiency of carbaryl from an aqueous sample. A volume of 4 μL of methanol was selected to preload into the capillary before extraction based on experimental optimization . It was expected that methanol would have the same effect on the extraction of analytes in the capillary LC system.…”

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confidence: 99%

“…The total draw/eject sample volume is determined by the total volume of the needle assembly and the extraction capillary. As described previously, the sample injection volume is determined by the volume of mobile phase required to completeely desorb the analytes . Three different lengths of capillary, (15, 30, and 60 cm) were investigated; the corresponding injection volumes (μL) are listed in Table .…”

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confidence: 99%

“…Automated In-Tube SPME Technique. The Omegawax 250 GC capillary was previously demonstrated as optimal for the extraction of six carbamates from aqueous solutions . In the first step of the in-tube SPME technique, extraction is performed by a dynamic absorption/desorption process where sample is aspirated from and dispensed back to a sample, through the Omegawax extraction capillary.…”

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In-Tube Solid-Phase Microextraction Coupled to Capillary LC for Carbamate Analysis in Water Samples

Gou

Pawliszyn

2000

Anal. Chem.

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Recently, the on-line sample preparation technique, intube solid-phase microextraction (SPME), was successfully implemented with a Hewlett-Packard 1100 HPLC system for analysis of carbamates in water samples. This paper describes the coupling of in-tube SPME to capillary LC and explores its utility as a sample preparation method in that format, relative to conventional LC. The Hewlett-Packard HPLC system was upgraded to a capillary LC system using commercially available accessories from LC Packings. The combination of in-tube SPME with a capillary LC system was expected to build on the merits of both in-tube SPME and the capillary LC to generate a sensitive method with an easy, effective, and efficient sample preparation. Due to the relatively large effective injection volume of the in-tube SPME technique (30-45 microL), on-column focusing was employed in order to achieve good chromatographic efficiency. Excellent sensitivity was achieved with very good method precision. For all carbamates studied, the RSD of retention time was between 0.5 and 0.8% under 4 microL/min microgradient conditions. The RSD of peak area counts was between 1.5 and 4.6%. The detection limits for all carbamates studied were less than 0.3 microg/L and, for carbaryl, just 0.02 microg/L (20 ppt). Compared with the conventional in-tube SPME/LC method, the LODs were lowered for carbaryl, propham, methiocarb, promecarb, chlorpropham, and barban, by factors of 24, 45, 42, 81, 62, and 56, respectively. The optimized method was successfully applied to the analysis of carbamates in surface water samples.

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In-Tube Solid-Phase Microextraction and Liquid Chromatography Using a Monolithic Column for the Selective Determination of Residual Ethylenediamine in Industrial Cationic Polymers

2009

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The selective determination of the diamine ethylenediamine (EDA) in the presence of a higher amount of residual dimethylamine in cationic polymers has been developed. The strategy uses both a solution derivatization with a selective agent of primary amines such as o-phthaldialdehyde-N-acetyl-L-cysteine (OPA-NAC) and an in-tube solid-phase microextraction (IT-SPME) coupled to liquid chromatography (LC). A 70 cm long, 0.32 mm internal diameter, and 3 microm thick commercially available capillary column coated with 95% polydimethylsiloxane and 5% polydiphenylsiloxane was employed to replace the injection loop of a Rheodyne injection valve. A volume of 1 mL of derivatized sample was passed through the capillary, and 100 microL of water was later used for cleaning and filling the capillary. After, the injection was effected and the desorption of the derivative from the capillary was carried out in the dynamic mode using the mobile phase. Chromatographic separation was performed in less than 2 min using a monolithic silica column Onyx (100 mm x 3.0 mm i.d.) under isocratic conditions. The effect of several parameters affecting derivatization and IT-SPME was investigated. The quantification of EDA was realized over the range of 0.07-2 microg/mL with adequate linearity, accuracy, and reproducibility, and the limit of detection was 20 ng/mL. The method is rapid and low in cost, and sample handling and organic solvent consumption have been minimized. Its application to polymeric cationic surfactants used in water treatment allowed the selective quantification of residual EDA at low microgram per milliliter levels of concentration without off-line preconcentration.

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Cited by 4 publications

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Sol−Gel Capillary Microextraction

Sol−Gel Capillary Microextraction

In-Tube Solid-Phase Microextraction Coupled to Capillary LC for Carbamate Analysis in Water Samples

In-Tube Solid-Phase Microextraction and Liquid Chromatography Using a Monolithic Column for the Selective Determination of Residual Ethylenediamine in Industrial Cationic Polymers

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