Features of a micro-gas chromatograph equipped with enrichment device and microchip plasma emission detection (muPED) for air monitoring

A field portable gas chromatograph (GC) was constructed allowing the enrichment of organic solutes from air samples on a miniaturized chemical trap and the subsequent gas chromatographic analysis on a resistively heated capillary column. The heart of the system is an integrated chip-based plasma emission detector (muPED). As a non-selective detector, the sensitivity is similar to that of a flame ionization detector (FID). The detector shows good selectivity for phosphorus, sulfur and chlorine-containing compounds with relative selectivities of ca. 5 x 10(5) gP gC(-1), 50 gS gC(-1) and 10(2) gCl gC(-1). The lifetime of the plasma chip under air monitoring conditions exceeded 3000 analyses.     

Sensitivity of a planar micro-flame ionization detector

The sensitivity of a MEMS μFID with reduced fuel gas consumption for portable applications like mobile GC or THA is examined. It is shown that sensitivity depends on flame size and type of sample gas supply (either separate supply or premixed with the hydroxygen). In contrast to conventional FIDs, the sensitivity of the μFID increases with decreasing molecule size. The sensitivity to methane can be optimized up to conventional values. Measurements with the μFID as a second detector in a μGC module prove the additional functionality of such a system.     

Universal and discriminative detection using a miniaturized pulsed discharge detector in comprehensive two-dimensional GC

A miniaturized pulsed discharge detector (Mini-PDD) has been successfully demonstrated for comprehensive 2-D GC (GC x GC) analysis of pyrolysis gasoline and the pyrolysis GC x GC analysis of a polyethylene copolymer. The detector cell volume of the Mini-PDD is reduced to 25% of the Valco plug-in PDD D-3. An n-C11 peak width at base is 96 ms for the Mini-PDD, about 23% larger than a peak width of 78 ms detected by a flame ionization detector (FID). The Mini-PDD has sufficient response time for most GC x GC applications. When Mini-PDD is operated in helium photoionization mode (Mini He-PDD), it is a universal detector for both inorganic and organic compounds. This is especially useful when detection of water is needed in GC x GC applications. When krypton is doped in the helium discharge gas (Mini Kr-PDD), it can suppress signals of compounds having higher ionization potentials and enhance relative signal intensities of aromatic compounds. The determination of aliphatic to aromatic hydrocarbon ratios is essential to the operation of petroleum crackers. Comparison of the signal from two modes of the Mini-PDD is a simple and fast way to verify the location of aromatics in comprehensive 2-D gas chromatograms.     

Novel on-column and inverted operating modes of a microcounter-current flame ionization detector

Improved operating modes of a microcounter-current flame ionization detector (microFID) are demonstrated. By operating the flame inside the end of a capillary gas chromatography (GC) column, the effective cell volume enclosing the flame is considerably reduced and results in significantly lower gas flows being required to produce optimal sensitivity from the stable flame. For instance, in this mode the tiny counter-current flame is situated "upside down" inside the column on the end of a stainless steel capillary delivering 4mL/min of oxygen and is stabilized by a counter flow of only 10mL/min of hydrogen carrier gas. Under these approximately fourfold reduced gas flow conditions, the microFID carbon response is linear over almost 5 orders of magnitude and yields a detection limit of 6x10(-10)gC/s. These figures agree well with those reported for the original microFID, which also similarly operated under hydrogen-rich conditions. To better simulate the oxygen-rich environment of a conventional FID flame, a novel "inverted" counter-current flow mode was also investigated. In this post-column microFID arrangement, a very lean flame is now situated on the end of a stainless steel capillary delivering 10mL/min of hydrogen, which is opposed by a counter-current flow of only 20mL/min of oxygen. The microFID detection limit obtained in this stable, oxygen-rich counter-current flame mode is 7x10(-11)gC/s with a response that is linear over almost 6 orders of magnitude. These findings are more comparable to those of a conventional FID. Overall, the low-flow sensitive microFID operating modes presented demonstrate that this detector may be potentially useful for adaptation to portable devices and related GC applications.     

Analysis of sludge extracts by high resolution GC with selective detectors

Combination of various GC detectors by using a Varian effluent splitter with glass capillary columns has been found to be a rapid procedure for profiling organics extracted from sludges and river sediments. The selectivity and the increased sensitivity of the thermionic nitrogen-phosphorus detector (TSD), the electron capture detector (ECD), and the flame photometric detector (FPD) over the flame ionization detectors (FID) or mass spectrometers allow the detection of compounds present at trace levels without need for extensive sample cleanup. Furthermore, the combination of two selective detectors may supplement the information with regard to the chemical functionalities required for structure elucidation.     

Determination of Atenolol in Pharmaceutical Preparations by Gas Chromatography with Flame Ionization and Mass Spectrometric Detection

The present work describes the methodology and validation of gas chromatography with flame ionization (FID) and mass spectrometric (MS) detection after derivatization with N-Methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) for determination of atenolol with an internal standard (metoprolol) in pharmaceutical preparations. The linearity was established over the concentration range of 0.5–20 μg/mL for GC/FID and 12.5–500 ng/mL for GC/MS method. The intra- and inter-day relative standard deviation was less than 4.72 and 5.80%, respectively. Limit of quantification was determined as 500 ng/mL and 12.5 ng/mL for GC/FID and GC/MS, respectively. No interference was found from tablet excipients at the selected assay conditions. Developed GC/FID and GC/MS methods in this study are accurate, sensitive, and precise and can be easily applied to Tensinor tablet as pharmaceutical preparation.     

Pulsed discharge detector: theory and applications

The pulsed discharge detector (PDD) is a significant advancement in gas chromatography (GC) detector design which can be operated in three different modes: pulsed discharge helium ionization (He-PDPID), pulsed discharge electron capture (PDECD) and helium ionization emission (PDED). The He-PDPID can detect permanent gases, volatile inorganics and other compounds which give little or no response with the flame ionization detector (FID) and has significantly better limits of detection (minimum detectable quantities (MDQs) in low picogram range) than can be achieved with a thermal conductivity detector (typically not lower than 1 ng). The PDECD has similar or better sensitivity (MDQs of 10(-15) to 10(-12) g) than radioactive source ECD but does not require licensing, wipe tests and other administrative or safety requirements which have increased over security concerns. The PDED shows promise as an extremely selective and sensitive elemental detector but a commercial unit is not presently available. In this report, the theory of operation, applications of the PDD and the practical aspects of using this novel detector are presented.     

衍生化气相色谱法测定盐酸芬氟拉明片的纯度

 应用衍生化气相色谱法测定盐酸芬氟拉明片的纯度。样品溶解后经碱化乙酸乙酯提取 ,以盐酸美西律作内标 ,提取液用三氟乙酸酐进行酰化衍生化 ,衍生化产物在 5 %SE 30的色谱柱上分析 ,用氢火焰离子化检测器 (FID)检测。实验结果表明 ,芬氟拉明的质量浓度在 0 1g/L～ 0 5 g/L范围内线性良好 (r =0 9996 ) ;芬氟拉明与内标美西律的分离度大于 4;理论塔板数以芬氟拉明峰计大于 2 0 0 0 ;方法的精密度好 ,相对标准偏差 (RSD)为 1 4% (n=7) ;平均回收率为 (10 0 2± 2 2 ) % (n =6 ) ;检测限为 8ng。用该方法得到的结果灵敏、准确、重复性好。     

Analysis of Polar Thermally Labile Pesticides using Different Solid-Phase Extraction (SPE) Materials with GC and HPLC Techniques

Abstract

In the present study, an efficient method for extraction, separation and determination of a limited number (30) of polar pesticides in aqueous matrices has been developed. Pesticides were extracted with high recoveries (usually >85%) from 1 L water samples, using the solid-phase extraction (SPE) technique. Affinities to different SPE materials (C-18 and XAD resins) have been studied for all pesticides. Special attention has been paid to the following 5 pesticides (which have classified by the EC as compounds which are particularly difficult to analyse): benazolia, bromofenoxim, ethofumesate, fenamiphos and phenmediphain. Thermally labile compounds have been determined with high pressure liquid chromatography (HPLC) and UV detection in comparison to TSP-LC-MS. Absolute limits of detection (LODs) for the HPLC technique are usually below 1 ng at 220 nm. Thermospray LC-MS determination shows usually limits of detection of 1-10 ng (SCAN) and 60-800 pg (SIM). All pesticides, which are amenable to GC have been detected in a comparative study with the following detectors: flame ionization detector (FID), nitrogen-phosphorus detector (NPD), electron capture detector (ECD) and atomic emission detector (AED). Element-specific detection of various functional groups of these pesticides has been achieved using GC-AED. Thus, while the FID has the lowest specificity, the AED is the most specific detector. LODs are usually < 300 pg (FID < 20 pg, NPD < 1 pg, ECD < 1 pg, AED < 300 pg). Spiked river water samples (from the River Leine and River Weser in Lower Saxony, Germany) have been used to test the employed method. With the spiked surface water samples recoveries were usually >80%.     

tability Indicating Method for the Analysis of Nicotine in Transdermal Drug Delivery Systems by Means of Gas Chromatography

The delivery of drugs through human skin using transdermal drug delivery (TDD) systems has become an established technology. A popular drug with that dosage form is nicotine for smoking cessation. A stability indicating method for the analysis of nicotine TDDs using gas chromatography (GC) with post-column effluent splitting to a flame ionization detector (FID) and a nitrogen-phosphorus detector (NPD) is described. FID detection gave reliable results with low day-to-day variability. The detector is relatively simple to operate. NPD detection offered enhanced sensitivity and specificity. The combination of both detectors resulted in a rugged method for content analysis with high sensitivity for detection of degradation products at low concentration levels. Despite a relatively simple sample preparation procedure no matrix interferences were observed.     

Miniaturized dielectric barrier discharge induced chemiluminescence for detection of volatile chlorinated hydrocarbons separated by gas chromatography

A new analytical method was proposed for the detection of volatile chlorinated hydrocarbons (VCHCs) including dichloromethane, 1,2-dichloroethane, chloroform, tetrachloromethane, perfluoromethane and bromoform after gas chromatographic (GC) separation. Atmospheric pressure dielectric barrier discharge (DBD) was miniaturized and used as a GC detector by using chemiluminescence (CL) emission from the reaction of DBD-split VCHCs with luminol solution. The miniaturized DBD-CL detector possessed the advantages of simple construction, very low power consumption, and high sensitivity to many volatile halocarbons, especially VCHCs. The parameters of the detector were optimized by using dichloromethane as a typical analyte. Under the optimized experimental conditions, the limit of detection (LOD) down to sub-nmol can be achieved.     

On-line coupling of immunoaffinity-based solid-phase extraction and gas chromatography for the determination of s-triazines in aqueous samples

The potential of immunoaffinity-based solid-phase extraction (IASPE) coupled on-line to gas chromatography (GC) for the determination of micropollutants was studied with emphasis on the interfacing of the immunoaffinity-based SPE and GC parts of the system. The cartridge containing the immobilized antibodies was coupled to the gas chromatograph via a reversed-phase cartridge (copolymer sorbent). After trace enrichment of the analytes on the immunoaffinity cartridge, they were desorbed and recollected on the reversed-phase cartridge by means of an acidic buffer. After clean-up and drying with nitrogen, desorption and transfer to the GC was done with ethyl acetate via an on-column interface in the partially concurrent solvent evaporation mode. The antibodies used in the immunoaffinity cartridge were raised against atrazine; several s-triazines were used as test compounds. Triazines that were structurally similar to atrazine, showed quantitative recovery. As an application, immunoaffinity SPE–GC was used for the analysis of river and waste water and orange juice. The selectivity of the system was such that non-selective flame ionization detection (FID) could be used to detect the analytes of interest in these complex matrices. The detection limits for 10-ml water samples were 15–25 ng/l for FID and about 1.5 ng/l for the nitrogen–phosphorus detection.     

烟用香精的气相色谱法质量控制研究

采用配有氢焰检测器或催燃检测器的气相色谱仪,对烟用香精进行了快速分析。方法操作简便,结果可靠,可作为烟用香精原料、产品质量监控的有效手段。     

Metal selective flame ionization detection after supercritical fluid chromatography

This work describes the construction and operation of a flame ionization detector for the selective detection of metal-containing compounds after capillary supercritical fluid chromatography. Using optimal conditions for achieving metal sensitive flame ionization responses which have been established for the detector after capillary gas chromatography, initial evaluation of the detector after SFC proved promising. Like the carbon sensitive FID, it appears that the metal sensitive FID is compatible with SFC when pure carbon dioxide is used as the mobile phase. Response characteristics were found to be similar to those observed when the detector is used in gas chromatography.     

HPLC and GC Methods for Determination of Lubricants and Their Evaluation in Analysis of Real Samples of Polyethylene

High performance liquid chromatography (HPLC) and gas chromatography (GC) are introduced for analysis of polymer lubricants (stearamide, oleamide and erucamide). In the HPLC method, a reverse phase octadecylsilane (ODS) column along with acetonitrile/methanol (60:40) as a mobile phase were used. Detection of analytes was performed by a UV detector at 202 nm. The analysis time was less than 8 min. In the GC method, polar capillary column and flame ionization detector (FID) were used for separations and detection, respectively. The analysis time by GC was longer than HPLC and was about 30 min. Limits of detection, linear range and repeatability of both methods are similar, but determination of oleamide in real samples by HPLC method is difficult due to complexity of the initial part of HPLC chromatogram in polyethylene samples. That problem is not observed in the GC method. Detection limits in both methods for all analytes are lower than 0.003% which are much lower than the amount of lubricants in commercial polymers (0.05–0.2%).     

Utilizing two detectors in the measurement of trichloroacetic acid in human urine by reaction headspace gas chromatography

A reaction headspace gas chromatography (HS‐GC) technique was investigated for quantitatively analyzing trichloroacetic acid in human urine. This method is based on the decomposition reaction of trichloroacetic acid under high‐temperature conditions. The carbon dioxide and chloroform formed from the decomposition reaction can be respectively detected by the thermal conductivity detection HS‐GC and flame ionization detection HS‐GC. The reaction can be completed in 60 min at 90°C. This method was used to quantify 25 different human urine samples, which had a range of trichloroacetic acid from 0.52 to 3.47 mg/L. It also utilized two different detectors, the thermal conductivity detector and the flame ionization detector. The present reaction HS‐GC method is accurate, reliable and well suitable for batch detection of trichloroacetic acid in human urine.     

气相色谱/氢火焰离子化检测法分析烷基化物料中的C4氟代烃

以实验室合成的氟代叔丁烷、氟代仲丁烷、氟代正丁烷为参考,建立了烷基化物料中C4氟代烃的气相色谱/氢火焰离子化检测(GC/FID)分析方法。提出了利用气相色谱/原子发射光谱(GC/AED)按元素响应的特点求算C4氟代烃在GC/FID上相对校正因子的方法。方法采用OV-225(50 m×0.25 mm i.d.×0.25 μm)和SE-54(44 m×0.22 mm i.d.×0.25 μm)串联柱为分析柱,FID为检测器,校正归一化或间接外标方法进行定量,具有重复性好、应用移植便利、操作简单等特点,对氟代叔     

Highly sensitive determination of haloperidol in human serum by capillary gas chromatography using a surface ionization detector

A method has been developed for highly sensitive determination of haloperidol in human serum involving a simple extraction procedure followed by gas chromatographic separation. Target components were separated from the extracting solvents with a Van den Berg type solventless sample injector before introduction Into a DB-1 capillary separation column. A surface ionization detector (SID), which has highly selective sensitivity for Substituted amines, was employed for quantitation using bromperidol as an internal standard. Chloroform proved to be the best extracting solvent, yielding a quantitative detection limit of 5 ng/ml (S/N = 2). Comparison of the response to target compounds obtained by the SID, FTD (flame thermionic detector), and FID (flame ionization detector) showed the SID to be superior.     

衍生化气相色谱法测定早强剂中三乙醇胺含量

建立了衍生化气相色谱法定量分析水泥早强剂中三乙醇胺含量的方法。以丙三醇作为内标,采用HP-5毛细管柱分离样品,氢火焰离子化检测器(FID)测定三乙醇胺含量。三乙醇胺在0.2～5.0mg/mL范围内与三乙醇胺/内标的乙酰化物色谱峰面积的比值呈线性关系,相关系数r=0.9996。方法检出限为42.6μg/mL,平均回收率为96.6%,相对标准偏差(RSD)为0.759%。该方法具有操作简便、快速、准确等优点,可用于测定水泥早强剂中三乙醇胺的含量。     

Organic fuelled flames in selective ionization detectors for chromatography

Summary The selectivities of two flame-based ionization detectors identified as a Remote FID (RFID) and a Flame Thermionic Ionization Detector (FTID) have been improved by introducing methane as a fuel for the flame. Both the RFID and FTID feature a detector struture in which the ionization polarizer and collector are located several centimeters downstream of an oxygen-rich flame, rather than immediately adjacent to the flame as in a flame ionization detector. The RFID detects long-lived negative ions produced in the flame by the combustion of lead, tin, phosphorus, or silicon compounds. The FTID re-ionizes and detects neutral electronegative products generated by combustion of nitrogen, halogen, or phosphorus compounds. An organic-fuelled RFID can detect 1 pg Pb (Sn, P)/sec with a selectivity of the order of 10⁶ versus hydrocarbons. An organic fuelled FTID is applicable to detection of compounds at nanogram and higher levels. FTID selectivity for PCB compounds in a transformer oil matrix is of the order of 10⁵1. The improved selectivity achieved by using an organic-fuelled flame is also applicable to the detection of phospholipid and other non-volatile N, P, or Cl compounds using an FID/FTID detector accessory for a TLC/FID analyser.