Temperature programmed quantitative analysi

Although cSFC shows relatively poor figures of merit (speed, sensitivity, detection dynamic range and sample capacity) as well as a limited application area, its applications tend to be unique. These include solutes that can be solvated with pure SCCO2 and quantified with FID. Linear density programs typical in cSFC are ideal for homologous series found in surfactants, many prepolymers, etc. Selectivity in cSFC, which can be achieved by mobile phase density and temperature programming, relies on selective interactions with the stationary phase. Quantitative analysis in cSFC may be rendered difficult by small injected volumes the use of internal standards is recommended. 

Gas Chromatographic Analysis. We used temperature programmed glass capillary gas chromatography to separate PCB residues. Use of an electron capture detector required an efficaceous sample cleanup for isomer quantitation (27). These combined techniques offered enhanced separations and enabled us to identify and quantitate individual PCB constituents (jL> 27). Schwartz (27) separated more than 100 constituents from a 1 1 1 1 mixture of Aroclors 1242, 1248, 1254, and 1260. 

Elemental composition Ni 34.38%, C 28.13%, O 37.48%. The compound may be identified and measured quantitatively by GC/MS. An appropriately diluted solution in benzene, acetone, or a suitable organic solvent may be analyzed. Alternatively, nickel tetracarbonyl may be decomposed thermally at 200°C, the liberated carbon monoxide purged with an inert gas, and transported onto the cryogenically cooled injector port of a GC followed by analysis with GC-TCD on a temperature-programmed column. Nickel may be analyzed by various instrumental techniques following digestion of the compound with nitric acid and diluting appropriately (See Nickel). 

Culea et al. reported a quantitative GC-MS analysis of procaine and some neurotransmitters in rat brain tissue [94], Procaine was extracted fi om brain homogenates by the ultrasonication method of Sundlof et al. [95], and was determined in its underivatized form on a 24 m glass capillary column coated with Silar IOC (temperature programmed from 120°C to 225°C at 12°C/min with pyrene as the internal standard). It was found necessary to wash the injector liner and the GC-MS interface stainless steel tubing with 1 1 0.1 M KOH-methanol so that the interface tubing could be coated with a film of OV-17 (from acetone solution), and to condition the apparatus by injecting bis-(trimethylsilyl)-acetamide and triethylamine. 

Temperature-programmed desorption (or decomposition) with quantitative analysis of gas-phase products (usually by mass spectrometry) has been used to help identify the ligands bonded to a metal in a supported complex. Complications such as reaction of desorbed ligands (e.g., CO) with support groups (e.g., OH) may complicate interpretation of the data (Brenner, 1986). 

Mixtures of dihydropyridine derivatives (including nimodipine) were qualitatively and quantitatively determined by GC MS [15]. Methanolic samples were injected into a HP column (12 m x 0.2 mm i.d.), operated with temperature programming to 280°C at 2°C/min, and then to 300°C at 10°C/min. Helium was used as the carrier gas (flow rate of 4.5 mL/ min), and 70 eV EMIS was used for detection. The analysis time was 45-60 min. The recoveries were better than 99%, and the relative standard deviations were 2.11-2.46%. 

Instrumental Analysis. A Hewlett-packard Model 5880 A GC, equipped with thermionic specific detector and a 50 m x 0.23 mm i.d. fused silica capillary column coated with Carbowax 20m, was used for quantitative analysis of thiazolidine and 2-acetylthiazolidine derived from formaldehyde and methyl glyoxal, respectively. GC peak areas were calculated with a HP 5880 A series GC integrator. The oven temperature was programmed from 70 to 180°C at 2 C/min. A Finnigan Model 3200 combination GC/MS equipped with an INCOS MS data system was used for mass spectral identification of thiazolidine derivatives. 

The quantitative analysis of the liquid products (collected once at the end of the experiment) was performed using a gas chromatograph equipped with a flame ionization detector (FID YANACO G6800 column, 100% methyl silicone 50 m x 0.25 mm x 0.25 p,m temperature program, 40°C, hold 15 min 280°C, rate 5°C/min hold 37 min) to obtain... 

The injection should transfer the sample quantitatively or at least reprodu-cibly to the capillary column. On-column and splitless injectors are suitable for ultratrace analysis. The capillary column should enable a complete separation of all components by selection of a suitable stationary phase and optimization of other parameters such as column length, diameter, film thickness, carrier gas flow and temperature program. The detector should have a sufficient sensitivity... 

The apparatus which has been described In detail previously (ref 2), allows both temperature programnad desorption (TPO) and tenderature programmed reaction (TFRn) studies to be effected. The quantitative analysis of the gas stream eluting from the reactor was accomplished by mass spectrometry. 

In conclusion, this chapter shows the potential of temperature-programmed techniques. Qualitative information on structure is obtained, which allows efficient exploratory research in optimizing pretreatment procedures. Moreover, quantitative kinetic analysis allows optimal process design for catalyst pretreatment, both as a separate step in catalyst manufacture and in the start-up of the reactor. 

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