Capillary gas chromatography of some metal acetylacetonates

Summary The retention and resolution of simple mixture of Al(III), Cr(III), Co(III), and Fe(III) acetylacetonates were investigated on capillary columns coated with methyl and methyl phenyl silicones (OV-1 or OV-17) used as the stationary phase, at different column temperatures and carrier gas flow rates. Successful elution and good resolution were obtained only for the Al(III) and Cr(III) complexes, both under isothermal and programmed-temperature conditions; better resolution was observed on the column coated with OV 17.     

Capillary reaction gas chromatography

Summary Thermal decomposition of C₆ hydrocarbons (hexane, cyclohexane, 2-methylpentane, 2,2-dimethylbutane and trans-2-hexene) on a nickel catalyst and on alumina was studied by reaction gas chromatography. The products were analyzed on two capillary columns containing squalane and Citroflex and were identified on the basis of their retention indices. The degree of conversion of the initial substances and the relative contents of the products were determined. On the basis of the results obtained, the probable course of the catalytic decomposition is discussed.     

Capillary gas chromatography of some metal chelates of dipropyl- and dibutyldithiocarbamic acids

Summary The thermal behaviour of some metal chelates of dipropyl- and dibutyldithiocarbamic acids has been investigated to determine their suitability for gas-chromatographic determination of trace metals. Good determinations can be achieved within the range 50–1000 ng and perhaps even lower, on carefully constructed, short glass capillary columns.

---

Kapillare Gaschromatographie einiger Metallchelate der Dipropyl- und der Dibutyldithiocarbamin-Säure

Zusammenfassung Das thermische Verhalten einiger Metallchelate der Dipropyl- und der Dibutyldithiocarbaminsäure wurde untersucht, um deren Eignung für die gaschromatographische Bestimmung von Metallspuren zu bestimmen. Zwischen 50 und 1000 ng und vielleicht auch etwas weniger lassen sich in sorgsam hergestellten, kurzen Glaskapillar-Säulen bestimmen.

     

Capillary gas chromatography of amines with ammonia as carrier gas

The use of ammonia as a carrier gas for the chromatography of aliphatic and aromatic amines has been investigated. As compared to nitrogen, ammonia gave drastically improved peak symmetry and lower capacity factors (k′) for primary and secondary amines on polar (Polyethylene glycol) and medium Polar (methylphenylcyanopropylsilicone) stationary Phases. The effect of ammonia was more Pronounced at low column temperatures. Considerably better detection limits of primary and secondary amines were obtained with ammonia as carrier gas than with nitrogen. No detrimental effects of using ammonia were observed on the gas chromatograph or on the columns over a period of about one year.     

氯代苯甲酸异构体的毛细管气相色谱分析

氯代苯甲酸是一种重要的精细化工产品,用途广泛,如用于合成临床治疗精神抑郁症的吗氯贝胺[1]及有机颜料中间体N (3 氨基 4 氯代苯甲酰基) 2 甲基 3 氯代苯胺[2]。但是氯代苯甲酸各异构体的性质差异极大,用途也不尽相同[3,4]。工业产品或多或少都会含有位置异构体,因此测定[5 7]氯代苯甲酸中各异构体含量就显得相当重要。已有报道的分析方法,或对仪器性能要求高,或操作繁琐,或分离效果不甚理想,因而在实际应用中受到一定的限制。考虑到氯代苯甲酸具有强极性、低挥发性等特点,本文采用甲酯化衍生物法对氯代苯甲酸异构体进行了气相色谱分…     

Capillary complexation gas chromatography in analysis of halohydrocarbons

Summary Investigations were carried out on capillary columns coated with liquid stationary phases possessing cyano (3-cyanopropylmethylpolysiloxane) and thiol (3-mercaptopropylmethylpolysiloxane) groups. These phases were modified by bonding CuCl₂ and CoCl₂ to cyano groups or NiCl₂ and CoCl₂ to thiol groups. The modified phases were examined in order to assess their usefulness for the analysis of aliphatic and aromatic halohydrocarbons. A number of retention parameters (I, ΔMe, Vg), which allow characterisation of the specific interactions between the bonded metal and the halohydrocarbon molecule, were determined for the columns both with and without the metal. The separations performed show that the columns with bonded metals are applicable for the practical analysis of the halohydrocarbons.     

Capillary gas chromatography of monosubstituted cyclopentenes and cyclohexenes

Summary Regularities in the variation of retention indices (I) and index increments (δI/°C, H, ΔI) of monosubstituted cyclopentenes and cyclohexenes with molecular structure on various liquid phases are discussed. An equation for the linear dependence of I on the carbon number is given. Differences in gas chromatographic characteristics between 1- and 3-isomers are more pronounced in the n-alkylcyclopentene series. In the n-alkylcyclohexene series extension of the side chain and increase of column temperature lead to the inversion of the elution order of 1-and 3-isomers. The temperature increments of I for cyclenes are markedly greater than those for open chain hydrocarbons (n-alkenes, n-alkynes).     

Capillary gas chromatography of metal chelates of diethyl dithiocarbamates

Summary Capillary GC of metal chelates of diethyl dithiocarbamate (DDTC) was examined on a methylsilicone DB-1 column, (25 meter, 0.2 mm. i.d) with a film thickness of 0.25 μm. Elution was carried out at the initial column temperature of 180°C and programmed at 5°C min⁻¹ to 260°C. Detection was by FID or ECD. Symmetrical peaks with base line separation were obtained with the metal chelates of copper(II), nickel(II), cobalt(III), manganese(II) and chromium(III). The ECD gave better sensitivity than the FID with a linear calibration range of 5–50 μg mL⁻¹ and detection limits 2.0–6.0 μg mL⁻¹, corresponding to 111–333 pg of metal ion reaching the detector. The method was applied to the determination of metal ions in water and pharmaceutical preparations with a coefficient of variation (CV) within 4.0%. When compared with a standard flame AAS method the results revealed no significant difference.     

Capillary column gas chromatography of environmental polycyclic aromatic compounds

The methodologies are described for isolating clean fractions of polycyclic aromatic compounds from diverse environmental samples such as air particulate matter, sediments, and fish tissue. The common step in all procedures is the separation of the polycyclic aromatic compound fraction into well-defined chemical classes by adsorption chromatography on an alumina column. These procedures greatly facilitate the detailed characterization of the polycyclic aromatic hydrocarbons, sulfur heterocycles, and nitrogen heterocycles by capillary column gas chromatography.     

Capillary gas chromatography of tert-butyldimethlysilylamino acids with PTV injection

The programmable temperature vaporizing injector (PTV) has been used to study the effects of injection temperature and initial heating period on the FID response factors of TBDMS derivatives of 17 protein amino acids. The relative response factors were calculated for injection temperatures of 50°C, 90°C, 160°C, 220°C, and 260°C with different initial heating periods (1 s, 5 s, and 10 s) and the results compared with the values obtained for the calculated response factors obtained under classical split injection conditions (300°C, continuous). Except for expected peak broadening effects, the initial heating period does not seem to have significative effects on relative peak areas. The response to the derivatives of alanine, glycine, α-aminobutyric acid, valine, proline, methionine, cysteine, phenylalanine, asparagine, and arginine was only slightly affected by increasing the injection temperature whereas the response factors for the derivatives of serine, threonine, glutamic acid, lysine, histidine, tyrosine, and tryptophan were strongly dependent upon initial injection temperatures, decreasing rapidly at temperatures above 160°C. The cold split-splitless injection is clearly advantageous over the classical hot injection techniques for the analysis of this type of aminoacid derivative.     

Capillary gas chromatography of polychlorinated benzonitriles (PCBN)

Polychlorinated benzonitriles (PCBN) are products of combustion chemistry and can be emitted from municipal waste incinerators. Their possible relevance to environmental chemistry has not previously been described, with the exception of the herbicide 2,6-dichlorobenzonitrile. The isomer-specific separation and detection of the 19 PCBN congeners is performed by HRGC-ECD and HRGC-MSD. Commercially unavailable congeners were synthesized from chlorinated anilines and benzaldehydes. Retention data on three different stationary phases are given. Structure-retention relationships are discussed. A structure-specific systematic numbering of the 19 PCBN congeners is suggested.     

Capillary gas chromatography of urinary steroids of terbutaline-treated asthmatic children

Summary Steroid metabolites have been measured by capillary gas chromatography in the urine of 38 children aged 3–6 years. The children comprised three groups: those with asthma being treated with Terbutaline (13), children with asthma but not undergoing treatment (17), and control children in hospital but free from endocrine diseases (8). There were significant (P<0.05) differences between the amounts of steroids excreted by the different groups of children. Terbutaline therapy led to elevated levels of tetrahydrocortisone, androstenediol, 11-ketopregnanetriol and a reduced ratio of androgen to cortisol metabolites compared with those for untreated asthmatic children. We assume that Terbutaline does not have a steroid-like mechanism of action but acts by modification of the activity of several adrenocortical enzymes. We suggest a hypothesis whereby the antiasthmatic effect of Terbutaline could not only be a connected with its well-known mechanism of action, but it might be explained as a result of the modification of the production of certain glucocorticoids and androgen hormones. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997.