Apiezon phases

Above C5 (aliphatic) Apiezon phases carbowax 1500, 1540, 4000, 6000, 20M most of the high-temperature substituted adipates, phthalates, succinates, and sebacates (boiling point separations) methyl silicones... 

Instmmental methods of analysis provide information about the specific composition and purity of the amines. QuaUtative information about the identity of the product (functional groups present) and quantitative analysis (amount of various components such as nitrile, amide, acid, and deterruination of unsaturation) can be obtained by infrared analysis. Gas chromatography (gc), with a Hquid phase of either Apiezon grease or Carbowax, and high performance Hquid chromatography (hplc), using siHca columns and solvent systems such as isooctane, methyl tert-huty ether, tetrahydrofuran, and methanol, are used for quantitative analysis of fatty amine mixtures. Nuclear magnetic resonance spectroscopy (nmr), both proton ( H) and carbon-13 ( C), which can be used for quaHtative and quantitative analysis, is an important method used to analyze fatty amines (8,81). 

Non-polar hydrocarbon-type liquid phases, e.g. paraffin oil(Nujol), squalane, Apiezon L grease and silicone-gum rubber the latter is used for high-temperature work (upper limit 400°C). 

Numerous stationary phases were investigated by Callahan et al. [135] but only OV-101 separated C14 5-sultone from the C14 unsaturated-y/2-chloro-y-sultone combination and also separated these from other components present in the sample. Apiezon L separated all three sultones of interest but other components in the neutral oil interfered with the C14 unsaturated y-sultone. Additional stationary phases were found which will separate these sultones, but again, interfering components preclude their use for neutral oil analysis. 

Commercially available Apiezon greases are usually orange colored prior to cleanup and colorless afterwards. Exhaustive hydrogenation can be used to saturate aromatic and olefinic groups to produce a more stable product, Apiezon MB, having properties more typical of a saturated hydrocar]x>n phase [18].. ... 

Boylan and Tripp [76] determined hydrocarbons in seawater extracts of crude oil and crude oil fractions. Samples of polluted seawater and the aqueous phases of simulated samples (prepared by agitation of oil-kerosene mixtures and unpolluted seawater to various degrees) were extracted with pentane. Each extract was subjected to gas chromatography on a column (8 ft x 0.06 in) packed with 0.2% of Apiezon L on glass beads (80-100 mesh) and temperatures programmed from 60 °C to 220 °C at 4°C per minute. The components were identified by means of ultraviolet and mass spectra. Polar aromatic compounds in the samples were extracted with methanol-dichlorome-thane (1 3). 

The purity of the 1,1-diphenylpentane is attested by vapor-phase chromatography on a 5-ft. column of 10% Apiezon L on Celite at 200°. 

W containing 15% 200M Apiezon silicone oil as the immobile phase. 

The retention index of a compound obtained on a given stationary phase under given experimental conditions constitutes worthwhile information. However, if several indices of the same compound obtained on different stationary phases are available, better identification of this compound can be made. Because of the excellent reproducibility of retention times on modern chromatographs, this method is reliable for known control compounds. While obtaining retention indices does not constitute absolute identification of a compound, this method can be quite useful to identify unknowns if the proper retention indices tables are available on the most common stationary phases (Squalane, Apiezon, SE30, Carbowax 20M). However, the use of retention indices is now of lesser interest because of capillary columns that involve new stationary phases. This limits the information that can be obtained from the retention indices. Hyphenated techniques are currently more popular. They represent excellent methods for compound identification but depend on instruments that are more complex and more expensive. 

Figure 24-10 Comparison of (a) isothermal (constant temperature) and ( >) programmed temperature chromatography. Each sample contains linear alkanes run on a 1.6-mm-diameter x 6-m-long packed column containing 3% Apiezon L (liquid phase) on 100/120 mesh WarAport 30 solid support with He flow rate of 10 mL/min. Detector sensitivity is 16 times greater in panel a than in panel b. [From H. M McNair and E. J. Bonelli, Basic Gas Chromatography (Palo Alto. CA Varian Instrument Division. 1968).]...

Acetylation of amino groups is necessary to promote volatility and trifluoroacetyl derivatives (N-TFA) formed from trifluor-oacetic anhydride or acyl derivatives formed from acetic anhydride have both been used with success (Table 9.3). Excess reagent must be removed with care at this point since the derivatives are highly volatile. Gehrke and co-workers have studied a number of stationary phases in detail as summarized in Figure 9.8 (41). They have suggested the use of Apiezon M and a rapid GLC... 

Alkaloids (includes drugs and vitamins) Apiezon L carbowax 20M di-(2-ethylhexyl) sebacate ethylene glycol adipate ethylene glycol succinate, neopentyl glycol adipate phenyldiethanolamine succinate SE-30 (methyl silicone phases)... 

Nitrogen compounds Apiezon L Armeen SD butanediol succinate (Craig polyester) carbowax 400, 1500, 20M ethylene glycol adipate propylene glycol tetraethylene glycol dimethylether THEED UCON phases... 

Phosphorous compounds Apiezon L carbowax 20M di-n-butyl phthalate diethylene glycol succinate Emulphor-ON-870 ethylene glycol succinate Reoplex-400 methyl silicone phases, including gum viscosities squalane STAP... 

Silanes Sugars Methyl silicone phases STAP Apiezon L butanediol succinate carbowax 4000, Hyprose SP80 mannitol methyl silicone phases... 

Sulfur compounds Apiezon L 7,8-benzoquinoline carbowax 1500, 20M diethylene glycol succinate diisodecyl phthalate methyl silicone phases Reoplex-400 tricresyl phosphate... 

Table 2.6 shows that some stationary phases show exactly the same Rohschneider constants. The fact that these phases also show identical chromatographic selectivity in practice forms an indication for the validity of the Rohrschneider approach. Any of these phases can be selected, but it would be a waste of time to investigate the selective effect of more than one of them. The choice will now be based on secondary considerations, such as stability, temperature range, availability and cost. Indeed, one of the first consequences of the Rohrschneider characterization scheme was for some manufacturers to reconsider the program of available stationary phases and to remove obsolete ones (see e.g. ref. [212], p.62). It is seen that not all non-polar stationary phases are identical, and that minor differences in selectivity may be anticipated from the use of Apiezon L instead of one of the silicone polymers. 

Fatty aldehydes with long chains were separated by Gray [64,65] as dimethylacetals on Apiezon L and Reoplex 400 stationary phases. Aldehydes were converted into their dimethylacetals by refluxing with 2% anhydrous methanolic HC1 (20 1, v/v) for 2 h. 

Dove [74] analysed a complicated mixtuie of aromatic amines after their conversion into TFA derivatives on a mixed stationary phase containing 9.5% of Apiezon L and 3.6% of Carbowax 20M (Fig. 5.5). The derivatization was performed in a 25-ml vial in which the sample of a mixture of amines (0.2 g) and a standard (0.05 g of n-dodecane) were dissolved in 2 ml of tetrahydrofuran and 5 drops of pyridine. The mixture was cooled in an ice-bath and 2 ml of TFA anhydride were added carefully. The contents of the vial were then heated at 50°C for 10 min, cooled and 5 ml of water were added. The mixture was extracted with 8 and 4 ml of dichloromethane. The extract was washed with 5 ml of saturated aqueous NaHC03 and 5 ml of water, dried over anhydrous Na2S04 and a 5-pi portion was chromatographed. 

The advantage of this procedure is that it can be carried out in an aqueous medium, but the residues of the reagent and the derivatives of formic, acetic and propionic acids are poorly separated on the stationary phases used (2.5% sodium dodecyl benzene-sulphonate or 1% Apiezon L or their 1 1 mixture). 

Wood et al. [174] analysed long-chain fatty hydroxy acids. After esterification with diazomethane, hydroxyl groups were silylated with HMDS. DEGS and Apiezon L were used as the stationary phases and even the partial resolution of some diastereoisomers was achieved. TMS esters have similarly been applied to the analysis of resin acids, and retention data have been reported for several of them on SE-30, Apiezon L, QF-1, etc. [175]. 

A number of stationary phases were later applied successfully. Fig. 5.26 shows the separation of glucopyranosides methylated to various extents on 5% Carbowax 20M esterified with 2-nitroterephthalic acid [400]. For the GC of methylxylofuranosides, Anderle and co-workers [401,402] applied several stationary phases (10% Apiezon L,... 

Gas chromatography is a useful adjunct to the schemes previously described. The fractions remaining from Scheme 2 can be examined directly by gas chromatography or, alternatively, the miCTO-extraction method, described below, can be used. The most generally useful system for screening is one using a dimethylsilicone stationary phase such as SE-30, OV-1, or OV-101, Volatile amines elute with a better peak shape on alkaline columns such as Apiezon L coated with potassiiun hy(hoxide. 

Apiezon Z is a hydrocarbon grease which is used for the separation of barbiturates. It has the advantage over the silicone phases that it is stable when coated with alkali to reduce the tailing of strongly basic compounds. The amphetamines may be separated on a column of 10% Apiezon L with 2% potassium hydroxide. 

A chromatogram showing the elution of Yb(thd)3 and the hydrocarbon, tetracosane (n-C24H5o), is illustrated in Figure 2. This column was 15 cm. long, contained an Apiezon liquid phase and was thermostated at 185°C. 

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