Pentafluorophenylhydrazone Derivatization

A sensitive and selective GC analysis of lower aliphatic carbonyl compounds as their penta-fluorophenylhydrazones was described by Hoshika and Muto.

The general procedure for the preparation of the pentafluorophenylhydrazone derivatives was as follows: 0.5x10~3mol of lower aliphatic carbonyl compound was added, using a 100 |L microsyringe, to 1 mL methanol containing 1.01 x 10 3 mol pen-tafluorophenylhydrazine (PFPH). The mixture was allowed to stand overnight at room temperature. A 1 |L volume of the solution was injected into the GC. The acetone, acrolein and propionaldehyde derivatives were separated on a 30 mx 0.25 mm i.d. glass capillary column coated with polyethylene glycol 20 M at 130°C with an FID. This temperature compares favourably with the 200°C column temperature necessary with DNPH derivatives.

A procedure for the GC determination of low molecular weight carbonyl compounds in aqueous solution as their pentafluorophenylhydrazones and its application to such compounds produced by photolysis of a-amino acids were reported by Kobayashi et al. (Figure 3). The calibration graphs for formaldehyde, acetaldehyde and isobutyraldehyde showed good linearity in the range 10-40 |g. Solutions of DL-alanine, DL-valine, DL-leucine or DL-isoleucine in phosphate buffer containing mercury (II) chloride were irradiated in a quartz vessel with a 20 W blacklight lamp (300-400 nm) as a light source for 300 h and the mixtures were measured by this method. Two peaks corresponding to formaldehyde and acetaldehyde were observed for valine.

Time (min)

Figure 3 Chromatogram of some carbonyl compounds as their pentafluorophenylhydrazones. Conditions: 3% XE-60, 2.0 m glass column, temperature-programmed from 105 to 130°C at 2°Cmin~1, FID. 1, Formaldehyde; 2, acetaldehyde; 3, acetone; 4, isobutyraldehyde; 5, diethyl ketone; IS, p-xylylene dichloride; 6, methyl isobutyl ketone. (Reproduced with permission from Kobayashi K etal. (1979) Gas chromatographic determination of low-molecular-weight carbonyl compounds in aqueous solution as their pentafluorophenylhydrazones. Journal of Chromatography 176:118.)

Time (min)

Figure 3 Chromatogram of some carbonyl compounds as their pentafluorophenylhydrazones. Conditions: 3% XE-60, 2.0 m glass column, temperature-programmed from 105 to 130°C at 2°Cmin~1, FID. 1, Formaldehyde; 2, acetaldehyde; 3, acetone; 4, isobutyraldehyde; 5, diethyl ketone; IS, p-xylylene dichloride; 6, methyl isobutyl ketone. (Reproduced with permission from Kobayashi K etal. (1979) Gas chromatographic determination of low-molecular-weight carbonyl compounds in aqueous solution as their pentafluorophenylhydrazones. Journal of Chromatography 176:118.)

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook


Post a comment