Daniel P. Schwartz

Liquid-liquid partition chromatography : Separation of the 2,4-dinitrophenylhydrazones of saturated aldehydes, methyl ketones, 2-enals and 2,4-dienals

Abstract Two similar partition chromatographic systems are described. Acetonitrile or 2-chloroethanol is used as the stationary phase on a celite column and hexane saturated with acetonitrile or 2-chloroethanol is the mobile phase. Both are suitable for the separation of the 2,4-dinitrophenylhydrazones of saturated aldehydes, saturated methyl ketones, 2-enals, and 2,4-dienals. Details of column preparation and operation are given. Graphs indicating the separations to be expected from each of the four homologous series are included.

Methods for the isolation and characterization of constituents of natural products: X. New and improved methods for the analysis of carbonyl 2,4-dinitrophenylhydrazones and 2,4-dinitrophenylosazones

Abstract New and improved thin-layer and column adsorption and partition chromatographic systems are described for classifying and separating series of 2,4-dinitrophenylhydrazone and bis(2,4-dinitrophenylhydrazones). Improved and simplified thin-layer adsorption chromatographic methods for separating classes of monocarbonyls (methyl ketones, saturated aldehydes, 2-enals, and 2,4-dienals) and dicarbonyls (α-diketones, α-ketoaldehydes, and glyoxal) are outlined. Partition systems employing a neutral and a basic stationary phase are presented.

Analytical13C NMR: Detection, quantitation, and positional analysis of butyrate in butter oil

The amount of butyrate contained in a complex mixture of butter oil triglycerides was 10.3 mole % as determined by natural abundance13C Fourier transform pulse nuclear magnetic resonance (NMR) spectroscopy. This NMR technique also demonstrated the primary isomeric positioning (>97%) of the butyrl group without the need for altering or fractionating the fat mixture.

Trace constituents in milk fat: Isolation and identification of oxofatty acids

Ca. 1% of the glycerides of milk fat contain oxofatty acids. The isolation, fractionation, and characterization of oxofatty acids were accomplished using the following sequence of steps: (A) transmethylation, (B) conversion into 2,4-dinitrophenylhydrazones, (C) adsorption of the 2,4-dinitrophenylhydrazones on magnesium oxide to eliminate the colorless lipid, (D) fractionation of the 2,4-dinitrophenylhydrazones into non-oxofatty acid and oxofatty acid fractions on alumina, (E) separation of the oxofatty acid 2,4-dinitrophenylhydrazones into saturated and unsaturated classes by argentation column chromatography, (F) separation of these classes by chain length using liquid-liquid column and thin layer partition chromatography, (G) resolution of positional isomers by thin layer chromatography, (H) regeneration of the positional isomer 2,4-dinitrophenylhydrazones, and (I) analysis of the parent oxofatty acids by gas liquid chromatographymass spectrometry. In this manner, 36 saturated and 11 unsaturated oxofatty acids were identified tentatively or positively. The saturated oxofatty acids ranged in chain length from C10–C24, predominantly C18 and C16, and generally contained an even number of carbon atoms. The unsaturated oxofatty acids ranged from C14–C18, with C18 predominating.

Solid-phase extraction of sulfamethazine in milk with quantitation at low ppb levels using thin-layer chromatography.

Abstract A method for the solid-phase extraction and thin-layer chromatographic (TLC) quantitation of sulfamethazine (SMZ) residues in milk is presented. Sulfabromomethazine was added as an internal standard to homogenized milk samples which were then diluted and passed through C 18 solid-phase extraction columns. The C 18 columns were eluted with methanol, and interfering components in the methanol were removed by passing eluate over an acidic alumina column. The analyte was then concentrated on a small ion-exchange resin. SMZ was eluted and applied to a silica gel TLC plate. Fluorescence detection was induced with fluorescamine and quantitated with a scanning densitometer. Recoveries were 88.36–103.15% in the analysis range [0.51–15.34 ppb (μg/l)]. The average recovery over the analysis range was 96.07%, with a coefficient of variation of 12.52%.

Thin-layer chromatography of carbonyl compounds separation of aliphatic carbonyl 2,4-dinitrophenylhydrazones into classes

Abstract A procedure is described for the separation of the 2,4-dinitrophenyldrazine derivatives of aliphatic carbonyl compounds into classes by thin-layer chromatography on magnesia-Celite plates. The four classes examined were the methyl ketones, saturated aldehydes, 2-enals, and 2,4-dienals. Each class produces a characteristic color to the plate which aids in its classification. The procedure, which takes about 1 hour, will readily permit the classification of as little as 9 × 10 −4 μmoles of any of the classes studied.

A column procedure for the esterification of organic acids with diazomethane at the microgram level

Abstract A simple procedure is described in which micro- and submicrogram amounts of organic acids can be converted to methyl esters with diazomethane. The gas, generated in only micromole amounts, contacts the acids which have been applied to a column of Celite contained in a capillary. The resultant esters are then eluted for chromatographic analysis. The entire procedure can be done in less than 5 min.

Separation of homologous series of 2,4-dinitrophenylosazones by column partition chromatography

Abstract Ethanolamine-benzene systems are described for the partition chromatography of the 2,4-dinitrophenylosazone derivatives of homologous series of α-keto-aldehydes and 2,3-diketones. Each class produces a different vivid color on the chromatogram facilitating differentiation and permitting very small amounts of derivative to be followed visually down the column. A special system is also described for the chromatography of the 2,4-dinitrophenylosazone of glyoxal, the only saturated vicinal dialdehyde.

Quantitative studies on methyl ketone formation in butteroil: Effect of temperature

A quantitative study of the effect of various heat treatments on methyl ketone formation in butteroil was conducted. Methyl ketone formation was found to follow first-order reaction kinetics. The energy of activation was calculated to be approximately 26.55 kcal/mole. The ketones were formed in a fairly constant molar ratio approximating to the following C15,2∶C13,1∶C11,1∶C9,1∶C7,2∶C5,1. The temperature-time conditions had little or no effect on the ratio.

Methods for the isolation and characterization of constituents of natural products: IV. Amide derivatives of amines with pyruvyl chloride 2,6-dinitrophenylhydrazone

Abstract Preparation of a new acid chloride, pyruvyl chloride 2,6-dinitrophenylhydrazone, and esters of it with primary, secondary and tertiary alcohols is described. The esters form readily in benzene solution in the presence of triethylenediamine in good yield within 20 minutes at room temperature. The derivatives are bright yellow to yellow-orange, have sharp and relatively high-melting points, and have an absorption maximum near 400 mμ in benzene. The esters have a molar extinction coefficient near 5950 in benzene. They possess properties which lend themselves well to direct isolation from lipids. Reference to certain products or companies does not imply an endorsement by the Department over others not mentioned.