Evaporative flame ionization detector

Two types of evaporative flame ionization detectors (FID) are the moving wire (100,101) and the rotating disk detectors (102-104). These convey the eluant along a wire or quartz disk into an evaporation chamber, where the volatile carrier solvent is removed. The nonvolatile sample is then passed through an FID. Any unbumed sample is removed in an ashing chamber before the wire or disk returns to its eluant-collecting position. 

DEC and the internal standard (Istd), 1-diethylcar-bamyl-4-ethyl piperazine HC1 (E-DEC), were extracted from human plasma - that has been alkalised with carbonate buffer - after loading onto a conditioned Cl8 solid phase extraction cartridge, rinsed with water and eluted with methanol. After evaporation under a stream of nitrogen and reconstitution in methanol, 3 il. were injected into the GC system and detected using a flame ionization detector (FID). The retention time for DEC was 5.5 min and for the internal standard (E-DEC) it was 7.28 min. 

Although tocopherols and tocotrienols can be detected by UV absorbance at 280 nm, fluorescence detection (excitation 294 nm and emission 326 nm), as shown in Figure 11.3, has proven to be a much more sensitive method. Electrochemical detection such as pulsed amperometric and coulometric (Uspitasari-Nienaber, 2002) has also proven to be sensitive and potentially valuable for the quantitative analysis of tocopherols and Tocotrienols (Abidi, 2000), especially for tocol analysis in blood and serum samples. HPLC mass detectors such as flame-ionization detectors, evaporative light-scattering detectors, and charged aerosol detectors have proven to be valuable for the quantitative analysis of many types of lipids, but because tocols have... 

Using gas chromatography, the arsines are rapidly evaporated by immersing the trap in hot water, and detected by a flame ionization detector, or an electron capture detector, or an atomic absorption detector. 

The products were analyzed with a Shimadzu organic acid analyzer (LC-IOAD type) and an Okura SSC-1 steam chromatograph with a flame ionization detector and a Porapak R column. The products were found both in the solution and within the coated film. The samples for these analyses were the distillate that was prepared by evaporating 20 cm of the catholyte until 2 cm under reduced pressure. The products adsorbed on the coated film were released into 25 cm of distilled water under ultrasonic irradiation for 5 min. The identification of lactic acid (product) was performed by liquid chromatograph / electrospray mass spectrometry (LC/MS) examining negative ions. The apparatus used was a Hitachi M-1200 LC/MS. 

Perrier and Lear converted theophylline to its butyl derivative by means of tetrabutyl-anrnonium hydroxide and on-column alkylation in connection with a rapid extraction procedure. Samples of 100 yl plasma were extracted with chloroform-isopropanol (95 5) containing the internal standard, amobarbital. The solvent was evaporated and the residue dissolved in 1 ml toluene. With the aid of 10 yl of an aqueous solution of tetrabutylammonium hydroxide, theophylline and amobarbital were quantitatively extracted from the toluene, and by injection of an aliquot of this solution into the gas chromatograph, alkylation took place in the injector, and quantitation of theophylline in concentrations in 100 ul plasma was possible with a flame ionization detector, using a packed column with 3 OV-17 on Chromosorb G at 250°C. 

The NMR spectra were recorded on Bruker AC200 (200 MHz) and AC300 (300 MHz) spectrometers at ambient temperature in NMR solvents obtained from ISOTEC Inc.. G.C. analysis were performed on Unicam PU4600 and PU610 apparatus with 30 m J W Scientific DB-1, DB-17 and AT-SILAR capillary columns and flame ionization detectors. Product yields were determined by peak area analysis response factors for selected substrates and products were foimd to be virtually identical. Internal standards were used in the initial stage of this study, but were found to influence the catalyst characteristics. G.C.M.S. was performed on a Unicam Automass apparatus combined with 610 series G.C. apparatus equipped with 30 m J W Scientific DB-1 and DB-17 columns. TEM-EDAX was performed on a Phillips CM 200 microscope equipped with a field emission gun. TEM-EDAX samples were prepared by application of a few droplets of a suspension of the catalyst in ethanol onto a holey carbon film which was supported by a nickel grid after which the ethanol was allowed to evaporate. 

Another instrument called the transport detector, used for detection of lipids, proteins or carbohydrates, requires the transport of the column eluent by a moving wire disc, chain or helix. The solvent is evaporated in a furnace and the nonvolatile sample passes into a flame ionization detector (FID) which is detailed later under gas chromatography (GC) wherein FID counts amongst the major detectors. 

The catalytic reactions were carried out in a catalytic flow microreactor at atmosheric pressure and various temperatures. The catal ic bed (Ig) was covered by silica. TTie reaction conditions were the following the oil (40(wt%) in cyclohexane) was introduced with a flow of 0.12 mkmin l simultaneoulsy with hydrogen (flow = 20 mIxmin H. After evaporation of the solvant, the products were successively treated by sodium methoxide, methanol and sulfuric acid to obtain the free-esters before analysis. The final products were analysed by gas chromatography with a flame ionization detector and AT-FILAR (Altech) capillary column (30m, I.d = 0.32 pm, film thickness = 0.25 pm) at 140 C. 

Mass detector. The liquid chromatographer s demand for a universal detector which overcomes some of the problems encountered with the RI detector, (such as poor sensitivity and temperature instability) led to the development about ten years ago of the mass detector described here. The transport detectors of the 1960s detected the solute by means of a flame ionization detector after removal of the solvent from the eluent stream. They were abandoned, owing to lack of sensitivity and mechanical problems associated with the moving belt or wire. The new mass detector is similar in principle, but here the eluent leaves the column and is pumped into a nebulizer, assisted by an air supply. The atomized liquid is passed into a heated evaporation column where all the solutes less volatile than the solvent are carried down the column as a cloud of fine particles. A light source and photomultiplier arranged at the bottom of the column, perpendicular to the flow, detect the cloud of particles. The output from the photomultiplier, which is proportional to the concentration, can be amplified and directed to a recorder or data system. 

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