Injection method

More specific methods involve chromatographic separation of the retinoids and carotenoids followed by an appropriate detection method. This subject has been reviewed (57). Typically, hplc techniques are used and are coupled with detection by uv. For the retinoids, fluorescent detection is possible and picogram quantities of retinol in plasma have been measured (58—62). These techniques are particularly powerful for the separation of isomers. Owing to the thermal lability of these compounds, gc methods have also been used but to a lesser extent. Recently, the utiUty of cool-on-column injection methods for these materials has been demonstrated (63). 

DFA is one of the main tools and techniques prescribed by the PIM process. Other tools and techniques currently specified include QFD, FMEA and DOE. Significant benefits have been obtained through the use of the tools and techniques in a team-based concurrent engineering environment. They inject method, objectivity... 

Two techniques conceptually related to classical continuous flow make use of different injection methods. In one of these a reactant solution formed into a highspeed jet is injected through a sheet or film of the second solution. The jet speed is 40 ms , and the mixing time is 1 p.s. 

E. A. Hogendoorn, C. Verscliraagen, U. A. Th Brinkman and van P. Zoonen Coupled column liquid chr omatography for the tr ace determination of polar pesticides in water using dhect large-volume injection method development strategy applied to methyl isothiocyanate , Awn/. Chim. Acm 268 205-215 (1992). 

In the gas plant, corrosive agents (H,S, HCN, and NHj) are r concentrated at high-pressure points. Water is usually injected into the first and second-stage compressor discharges. The water contacts the hoi gas and scrubs these agents. There are two common injection methods forward cascading and reverse cascading. 

Slower introduction of the dinitrogen tetroxide, by either dropwise addition of an ether solution or entrainment in a slow stream of nitrogen, gave similar results. The direct injection method was found to be easiest. The checkers distilled dinitrogen tetroxide at atmospheric pressure (b.p. 21°) prior to use. 

In the salt injection method(3l) a pulse of salt solution is injected into the line and the time is measured for it to travel between two electrode pairs situated a known distance apart, downstream from the injection point. 

In a recent study of the transport of coarse solids in a horizontal pipeline of 38 mrrt diameter, pressure drop, as a function not only of mixture velocity (determined by an electromagnetic flowmeter) but also of in-line concentration of solids and liquid velocity. The solids concentration was determined using a y-ray absorption technique, which depends on the difference in the attenuation of y-rays by solid and liquid. The liquid velocity was determined by a sail injection method,1"1 in which a pulse of salt solution was injected into the flowing mixture, and the time taken for the pulse to travel between two electrode pairs a fixed distance apart was measured, It was then possible, using equation 5.17, to calculate the relative velocity of the liquid to the solids. This relative velocity was found to increase with particle size and to be of the same order as the terminal falling velocity of the particles in the liquid. 

Pirie. R. L., Davies, T., Khan, A. R. and Richardson, J. F. 2nd International Coni, on Flow Measurement — BHRA, London (1988) Paper F3, 187. Measurement of liquid velocity in multiphase flow by salt injection method. 

Advantage was taken of these solubility differences in refining mixtures of the chlorinated dibenzodioxins. Digestion with boiling chloroform was effective in removing trichlorodibenzodioxin while recrystallization from anisole reduced the penta-substituted isomer content. In a typical purification (Table II) these two procedures were alternated through four cycles. The assays were made by mass spectroscopy using the batch injection method to introduce the sample into the spectrometer. X-ray studies 14) confirmed the structure. 

A disadvantage of the ethanol injection method to produce SUV is the need to use a low lipid concentration, resulting in a low encapsulation efficiency of the aqueous phase. The dispersions can be concentrated by ultracentrifugation, ultrafiltration, or removal of water by evaporation. 

P. H. (1977). Vesicles of variable diameter prepared by a modified injection method. Biochemistry, 16, 3932-3935. 

Clusters of C oN and MePH were prepared by dissolving C oNand MePH in TH F-H2O (2 1) mixed solvent using first injection methods [50]. CfioNand MePH form optically transparent clusters. The formation of nanoclusters of CfioN " "-MePH (diameter about 100 nm) was verified from absorption measurements and AFM. 

Conditions apparatus, Hewlett-Packard HP5890 equipped with an HP5972 mass-selective ion detector (quadruple) column, PTE-5 (30 m x 0.25-mm i.d.) with 0.25- am film thickness column temperature, 50 °C (1 min), increased at 20 °C min to 150 °C(5 min) and then at 4 °Cmin to 280 °C (30 min) inlet and detector (GC/MS transfer line) temperature, 250 and 280 °C, respectively gas flow rate, He carrier gas ImLmin" injection method, splitless mode solvent delay, 3 min electron ionization voltage, 70eV scan rate, 1.5 scanss scanned-mass range, m/z 50-550. The retention times of benfluralin, pendimethalin and trifluralin are 15.2, 25.1 and... 

Chlornitrofen and nitrofen conditions for GC/MS column, cross-linked methyl silicone capillary (12 m x 0.22-mm i.d., 0.33- am film thickness) column temperature, 60 °C (1 min), 18 °C min to 265 °C inlet, transfer line and ion source temperature, 260, 200 and 200 °C, respectively He gas column head pressure, 7.5 psi injection method, splitless mode solvent delay, 3 min electron ionization voltage, 70 eV scan rate, 0.62 s per scan cycle scanned mass range, m/z 100-400. The retention times for chlornitrofen and nitrofen were 11.8 and 11.3 min, respectively. The main ions of the mass spectrum of chlornitrofen were at m/z 317, 319 and 236. Nitrofen presented a fragmentation pattern with the main ions at m/z 283, 202 and 285. ... 

The residue levels of 46 pesticides, including oxyfluorfen in soil, were determined using GC/ITDMS as described in S ection 3.2.1. The conditions for GC/ITDMS were as follows column, fused-silica capillary (30 m x 0.25-mm-i.d.) with a0.25- am bonded phase ofDB-5 column temperature, 50 °C (1 min), 30 °Cmin to 130 °C, 5 °C min to 270 °C inlet and transfer temperature, 270 and 220 °C, respectively He gas with column head pressure, 12psi injection method, splitless mode. The retention time and quantitation ion of oxyfluorfen were 23.9 min and mjz 252, respectively. ... 

In the above-mentioned method by Hodgeson el acifluorfen was determined by GC/ECD after the extraction with a 47-mm PS-DVB disk and derivatization with diazomethane. The conditions for GC/ECD were as follows column, DB-5 fused silica (30 m X 0.32-mm i.d., 0.25-p.m film thickness) He carrier gas velocity, 25 cm s (210°C), detector makeup gas, methane-argon (5 95), 30mLmin column temperature, 50 °C (5 min), 10°Cmin to 210 °C (5 min) and to 230 °C (10 min) injection port and detector temperature, 220 and 300 °C, respectively injection method, splitless mode. The recovery of acifluorfen from purified water, dechlorinated tap water and high humic content surface water fortified at 0.5-2.0 ug was 59-150% and the LOD was 25 ngL Acifluorfen after derivatization with various chlorofor-mates was also determined by GC/MS using an SE-54 column (25 m x 0.20-mm i.d., 0.32- um Aim thickness), and the average recovery of acifluorfen fortified between 0.05 and 0.2 ugL was 78%. ... 

Injection of a small aliquot of aqueous phase into surfactant-containing organic solvent (injection method, INJ). 

Table 4.17 Characteristics of various syringe injection methods...

Of course, to be able to use the direct injection method of sample introduction, the analyte or the polymer system must be soluble in a solvent. Other methods of sample introduction need to be considered in order to eliminate the involatile material from the chromatographic separation. These have become extremely effective in the analysis of matrices such as polymers. 

The chromatographic and mass spectrometric choices facing the analyst in coupling SFC and MS successfully, namely injection method column type of flow restrictor and mass spectrometer ionisation method and type of vacuum system, have been described [398]. In SFC-MS coupling, the restrictor plays a major role, as the expansion behaviour to a large extent determines the overall performance of the SFC-MS system and defines the range of applications. 

A similar technique, the so-called spontaneous emulsification solvent diffusion method, is derived from the solvent injection method to prepare liposomes [161]. Kawashima et al. [162] used a mixed-solvent system of methylene chloride and acetone to prepare PLGA nanoparticles. The addition of the water-miscible solvent acetone results in nanoparticles in the submicrometer range this is not possible with only the water-immiscible organic solvent. The addition of acetone decreases the interfacial tension between the organic and the aqueous phase and, in addition, results in the perturbation of the droplet interface because of the rapid diffusion of acetone into the aqueous phase. 

The earliest injection method in hplc used a technique borrowed from gc in which a microlitre syringe was employed to inject the sample through a self-sealing rubber septum held in an injection unit at the top of the column. In another method, (stopped flow), the flow of mobile phase through the column was halted and when... 

Recently, a flow-injection method has been reported in which pKa values are measured by UV absorbance after injection into a flowing phosphoric acid buffer [40],... 

Couto et al. [11] developed a flow injection system with potentiometric detection for determination of TC, OTC, and CTC in pharmaceutical products. A homogeneous crystalline CuS/Ag2S double membrane tubular electrode was used to monitor the Cu(II) decrease due to its complexation with OTC. The system allows OTC determination within a 49.1 1.9 x 103 ppm and a precision better than 0.4%. A flow injection method for the assay of OTC, TC, and CTC in pharmaceutical formulations was also developed by Wangfuengkanagul et al. [12] using electrochemical detection at anodized boron-doped diamond thin-film electrode. The detection limit was found to be 10 nM (signal-to-noise ratio = 3). 

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