Koichi Funazo

Gas chromatographic determination of inorganic anions as pentafluorobenzyl derivatives

Abstract Simple and rapid procedures were developed for the determination of cyanide, thiocyanate, nitrite and iodide as their pentafluorobenzyl derivatives. The inorganicanion was dissolved in alkaline or acidic aqueous solution and reacted with pentafluorobenzyl bromide in acetone or ethanol. The derivative formed in the reaction solution was directly analysed by gas chromatography with flame-ionization detection. The effects of added base or acid, amount of pentafluorobenzyl bromide, reaction temperature, solvent and reaction time on the derivatization of each anion are discussed. The derivatives from the anions were identified mainly by direct gas chromatography—mass spectrometry and/or by comparison with authentic samples. The derivatives of cyanide, iodide and nitrite were pentafluorobenzyl cyanide, pentafluorobenzyl iodide and α-nitro-2,3,4,5,6-pentafluorotoluene, respectively. Thiocyanate was not converted into pentafluorobenzyl thiocyanate, but into bis(pentafluorobenzyl) sulphide.

Separation of phenoxy acid herbicides and their enantiomers in the presence of selectively methylated cyclodextrin derivatives by capillary zone electrophoresis

Abstract The chiral and mutual separation of nine phenoxy acid herbicides including seven pairs of phenoxy acid enantiomers was examined by capillary zone electrophoresis using unmodified and selectively methylated α-cyclodextrin (α-CD), β-CD and γ-CD derivatives as separation additives. The selective methylation of the secondary hydroxyl groups on the rim of the CD cavities produced remarkable selectivity changes for the phenoxy acid herbicides. For the chiral separation of seven racemic phenoxy acid herbicides, unmodified and methylated α-CDs exhibited higher enantioselectivities than the β-CD additives and also much higher enantioselectivities than the γ-CD additives. Among the α-CD chiral selectors, hexakis(2,3-di-O-methyl)-α-CD (2,3-DM-α-CD) especially exhibited quite high enantioselectivity at 10 mM for all seven phenoxy acid herbicides. For the nine phenoxy acid herbicides, unmodified α-CD at 5 mM produced their complete mutual separation within 14 min, but could not resolve all (seven) pairs of their enantiomers. The simultaneous (both chiral and mutual) separation of 2-(3-chlorophenoxy)propionic acid, 2-(2,4,5-trichlorophenoxy)propionic acid, (2,4,5-trichlorophenoxy)acetic acid, 2-(2-chlorophenoxy)propionic acid and 2-phenoxypropionic acid could be readily attained, but 2-(2,4-dichlorophenoxy)propionic acid, 2-(4-chloro-2-methylphenoxy)propionic acid, (2,4-dichlorophenoxy)acetic acid (2,4-D) and 2-(4-chlorophenoxy)propionic acid (2,4-CPPA) could not be mutually separated by mixing 5 mM α-CD and 10 mM 2,3-DM-α-CD. However, 2,4-D and 2,4-CPPA could be completely separated with α-CD and 2,3-DM-α-CD at 2.5 mM each, though neither 2-(2,4-dichlorophenoxy)propionic acid nor 2-(4-chloro-2-methylphenoxy)propionic acid could be separated at all.

Pentafluorobenzyl p-toluenesulphonate as a new derivatizing reagent for gas chromatographic determination of anions

A new derivatizing agent, pentafluorobenzyl p-toluenesulphonate, has been synthesized, which is designed to enhance the volatility of analytes and introduce a detector-oriented tag into the molecules for gas chromatography (GC) with electron-capture detection. The derivatization of several inorganic anions was studied, and a new GC method for their simultaneous determination has been developed. Bromide, iodide, cyanide, thiocyanate, nitrite, nitrate and sulphide can be simultaneously derivatized to their pentafluorobenzyl derivatives using tetra-n-amylammonium chloride as the phase transfer catalyst. The derivatives were subsequently determined by GC with flame ionization detection. This method has also been applied to the determination of carboxylic acids or phenols, the derivatives of which were identified using mass spectrometry. The derivatives from bromide, iodide, cyanide, thiocyanate, nitrite, nitrate and sulphide were pentafluorobenzyl bromide, pentafluorobenzyl iodide, pentafluorobenzyl cyanide, pentafluorobenzyl thiocyanate, α-nitro-2,3,4,5,6-pentafluorotoluene, pentafluorobenzyl nitrate and bis(pentafluorobenzyl) sulphide, respectively. The effects of added acid or base, and of the reaction time, on the pentafluorobenzylation are discussed.

Pentafluorobenzyl p-toluenesulphonate as a new derivatizing reagent for electron-capture gas chromatographic determination of trace inorganic anions

Abstract Inorganic anions in water were reacted with pentafluorobenzyl p -toluenesulphonate in dichloromethane, using tetra- n -amylammonium chloride as a phase-transfer catalyst. Bromide, iodide, thiocynate and nitrate at relatively low concentrations can be pentafluorbenzylated, and the resulting derivatives can be detected by electron -capture gas chromatography. The interferences of some anions were examined. The recovery test of bromide, iodide or thiocynate spikes and an intercomparison study for nitrite were performed. This gas chromatographic method has been successfully applied to the determination of bromide and iodide in kelp extract, and thiocyanate and/or nitrate in human urine or saliva.

Electron-capture gas chromatographic determination of cyanide as pentafluorobenzyl cyanide

Abstract A simple, sensitive and specific method was established for the determination of cyanide as pentafluorobenzyl cyanide, based on the derivatization of cyanide anion in an alkaline medium with pentafluorobenzyl bromide. The derivative formed in the reaction solution was injected directly into a gas chromatograph equipped with an electron-capture detector. The detection limit was about 0.2 ng of cyanide anion in 0.1 ml of aqueous sample (2 ppb). The effects of base, amount of pentafluorobenzyl bromide, solvents, reaction temperature and reaction time on the derivatization were investigated, and the optimal derivatization conditions were established. Interferences due to some anions commonly found in wastewater were examined and were found to be minimal except for thiocyanate ion. The proposed method was applied to the determination of cyanide in industrial wastewater and the results agreed well with those obtained using the pyridine—pyrazolone spectrophotometric method.

Double-chain surfactants with two sulfonate groups as micelle-forming reagents in micellar electrokinetic chromatography of naphthalene derivatives

Three surfactants having two sulfonate groups and two lipophilic chains, disodium 5,12-bis(dodecyloxymethyl)-4,7,10,13-tetraoxa-1-16-hexadecanedisulfonate (DBTHX), 5,13-bis(dodecyloxymethyl)-4,7,11,14-tetraoxa-1-17-heptadecanedisulfonate (DBTHP) and 5,13-bis(dodecyloxymethyl)-4,7,11,14-tetraoxa-9,9-dimethyl-1-17-heptadecanedisulfonate (DBTDMHP), were used in micellar electrokinetic chromatography (MEKC) to separate eight naphthalene derivatives as model analytes. Their capacity factors linearly increased as the concentration of each surfactant increased from 1 to 10 mM at pH 7.0. These double-chain surfactants exhibited different selectivity and wider migration time windows when compared with sodium dodecyl sulfate (SDS), which is used widely in MEKC. The eight naphthalene derivatives were baseline separated at 5 mM DBTHX and 2.5 mM DBTHP, respectively, and nearly baseline separated at 2.5 mM DBTDMHP. However, SDS at 60 mM could not completely resolve three of the analytes.

Methylation of inorganic anions for gas chromatographic determination

Abstract Some inorganic anions were converted into their methyl derivatives by reaction with three methylating agents (dimethyl sulphate, methyl p-toluenesulphonate and trimethyl phosphate) at 70°C. The derivatives were extracted with dichloromethane or 1,2-dichloroethane, and determined by gas chromatography with a flame ionization detector. By this method, cyanide, thiocyanate, iodide, bromide and sulphide were determined at concentrations of 0.1–1.0 mg/ml.

Chiral separation of several amino acid derivatives by capillary zone electrophoresis with selectively acetylated β-cyclodextrin derivatives

Abstract The chiral separation of five pairs of several amino acid enantiomers was examined by capillary zone electrophoresis using three selectively acetylated and methylated β-cyclodextrin (β-CD) derivatives. After acetylation of the hydroxyl groups of β-CD, its enantioselectivity completely disappeared for α- and β-naphthalenesulfonylamino acids. For dansylamino acids, several solutes were resolved only with heptakis(2,3-di- O -acetyl and 2,3-di- O -methyl)-β-CDs. The chiral recognition abilities of selectively acetylated and methylated β-CD derivatives were similar for dansylamino acids and α- and β-naphthalenesulfonylamino acids. Heptakis(3-mono- and 3,6-di- O -methyl)-β-CDs exhibited quite high chiral recognition abilities for α-naphthoylamino acids. On the other hand, β-naphthoylamino acids were resolved better in the presence of unmodified β-CD and heptakis(3-mono- and 3,6-di- O -acetyl)-β-CDs. Neither heptakis(2,3-di- O -acetyl nor 2,3-di- O -methyl)-β-CD could resolve α- and β-naphthoylamino acids at all.

Simultaneous gas chromatographic determination of iodide, nitrite, sulphide and thiocyanate anions by derivatization with pentafluorobenzyl bromide

Abstract A gas chromatographic method is described for the simultaneous determination of iodide, nitrite, sulphide and thiocyanate anions as their pentafluorobenzyl derivatives. The method is based on transfer of the anions from the aqueous solution by n-hexadecyltrimethylammonium bromide into the dichloromethane organic phase, where derivatization with pentafluorobenzyl bromide occurs. Several parameters affecting the transfer and/or derivatization of the anions were investigated, including the phase-transfer catalyst, concentration of acid and base added, organic solvent, reaction time and the amount of derivatizing agent needed. Individual and simultaneous determinations of the anions could be achieved at sub-μmol levels initially in the aqueous phase, by use of a flame ionization detector.

Simultaneous gas chromatographic determination of cyanide, iodide, nitrite, sulphide and thiocyanate anions by derivatization with pentafluorobenzyl bromide and using a kryptand as phase-transfer catalyst

Abstract An improved gas chromatographic method has been established for the simultaneous determination of cyanide, iodide, nitrite, sulphide and thiocyanate anions as their volatile pentafluorobenzyl derivatives. The method is based on kryptate formation using Kryptofix 222 B polymer as complexing agent and phase-transfer catalyst to transfer the anions from aqueous alkaline solution to the dichloromethane organic phase for derivatization with pentafluorobenzyl bromide to be effected. Structural identification and correction of the cyanide derivative was studied. The parameters affecting the partition and/or derivatization of the anions were investigated, including the concentrations of acid and base in the aqueous phase. Individual and simultaneous determinations of the anions are attainable at sub-micromole levels with flame ionization detection.