Substituted benzeneboronic acids for the gas chromatographic determination of bifunctional compounds with electron-capture detection

Sensitive method for the determination of 1,3-dichloropropan-2-ol and 3-chloropropane-1,2-diol in soy sauce by capillary gas chromatography with mass spectrometric detection

This paper reports the development of a highly selective and sensitive method for the determination of parts-per-billion level of 1,3-dichloropropan-2-ol (1,3-DCP) and 3-chloropropane-1,2-diol (3-MCPD) in soy sauce using capillary gas chromatography with mass spectrometric detection. Samples were homogenised, mixed with sodium chloride solution and then adsorbed on silica gel. The loaded silica gel was packed into a chromatographic column, from which chloropropanols were extracted by elution with ethyl acetate. Heptafluorobutyric acid anhydride was added to the concentrated eluant to derivatise the chloropropanols and the derivatised analytes were separated by gas chromatography, identified and quantified by mass spectrometry. A linear relationship between the concentration of the two chloropropanols and the detector response was obtained over the concentration range of 10-1000 microg/kg. Precision of the method was satisfactory at about 5%, and recoveries of 1,3-DCP and 3-MCPD from soy sauce samples spiked at 25 microg/kg were 77 and 98%, respectively. The limit of quantitation of the method was found to be about 5 microg/kg for 1,3-DCP and 3-MCPD, respectively meeting the requirements of tolerance limits adopted by different international institutions and governments around the world. This paper is the first of its kind in reporting an analytical procedure for the simultaneous separation and determination of 3-MCPD and 1,3-DCP, a more potent contaminant, at low microg/kg level.

Analytical methods for the determination of 3-chloro-1,2-propandiol and 2-chloro-1,3-propandiol in hydrolysed vegetable protein, seasonings and food products using gas chromatography/ion trap tandem mass spectrometry

The EC Scientific Committee for Foods and more recently the Food Advisory Committee in the UK have proposed that levels of 3-chloro-1,2-propanediol (3-MCPD) in foods and ingredients should be reduced to the lowest possible. This paper reports on the development of methods for the determination of parts-per-billion (microgram/kg) levels of 3-MCPD in hydrolysed vegetable protein (HVP), flour, bread, meat and starch products using gas chromatography/ion-trap tandem mass spectrometry (GC/ITMS/MS). Mass spectrometer conditions for detecting 3-MCPD and the stable isotope internal standard (3-chloro-1,2-propandiol-d7) were established. Candidate extraction methods were initially evaluated for recovery and repeatability by spiking selected commodities at a level of 100 micrograms/kg. Extracts of ingredients and foods prepared by the candidate extraction methods were examined by GC/ITMS/MS using samples spiked at a level of 25 micrograms/kg. The results showed that detection limits of between 3 and 5 micrograms/kg could be achieved for all commodities.

15 beta-hydroxysteroids (Part III). Steroids of the human perinatal period: the synthesis of 3 beta, 15 beta, 17 alpha-trihydroxy-5-pregnen-20-one. Application of n-butyl boronic acid protection of a 17,20-glycol

We report the synthesis of 3 beta,15 beta,17 alpha-trihydroxy-5-pregnen-20- one (1) from 3 beta,15 beta-dihydroxy-5,16-pregnadien-20-one (11) in 7 steps using boronate derivatives as a means of protecting the 17,20-glycol side-chain of steroid intermediates. 16 alpha,17 alpha-Epoxy-3 beta,15 beta-dihydroxy-5- pregnen-20-one (12), an intermediate in the synthesis was prepared by epoxidation of 11 using a mixture of sodium hydroxide and hydrogen peroxide. Reduction of 12 with lithium aluminium hydride gave the two isomers of 5-pregnene-3 beta, 15 beta,17 alpha,20 (S+R)-tetrol (13a and 13b) which on subsequent reaction with n-butyl boronic acid gave 5-pregnene-3 beta,15 beta,17 alpha, 20(S+R)-tetrol 17 alpha,20-butyl boronate (15a and 15b). Acetylation with acetic anhydride and pyridine yielded 3 beta,15 beta-diacetoxy-5-pregnene-17 alpha,20(S+R)-diol 17 alpha,20(S+R)-butyl boronate (15c and 15d). Oxidative cleavage of the boronic ester using sodium hydroxide and hydrogen peroxide gave 3 beta,15 beta-diacetoxy-5-pregnene-17 alpha,20(S+R)-diol (13c and 13d). After isolation of these latter two products, dibromide protection of the C-5,6 olefin of 13d and oxidation with N-bromosuccinimide gave 3 beta,15 beta-diacetoxy-17 alpha-hydroxy-5-pregnen-20-one (16) which on deacetylation gave in good yield (35%) the desired product 3 beta,15 beta,17 alpha-trihydroxy-5-pregnen-20-one (1) in an overall yield of 24% from 11.

Gas chromatographic-mass spectrometric identification and quantitation of ethylene glycol in serum after derivatization with perfluorooctanoyl chloride: a novel derivative

Ethylene glycol poisoning is a common clinical problem and identification as well as quantitation of ethylene glycol in serum is important for medical and legal purposes. Most investigators described determination of ethylene glycol by gas chromatography without derivatization or derivatives forming a molecular ion < 200. We describe a novel derivatization technique of ethylene glycol using perfluorooctanoyl chloride, after extraction from serum using acetone. This derivative has a molecular mass of 854 and produces a base peak at m/z 441 and other diagnostic strong peaks for unambiguous identification. Moreover, this derivative is less volatile and is free from interferences from endogenous serum components. Quantitation can be achieved by using 1,4-butanediol as an internal standard. The assay showed within-run and between-run precision of 7.2% and 8.0%, respectively, and linearity over the serum ethylene glycol concentration range 70-2240 micrograms/ml with a detection limit of 5 micrograms/ml.

Identification and quantification of ethylene glycol and diethylene glycol in plasma using gas chromatography-mass spectrometry

A method for the gas chromatographic-mass spectrometric identification and quantification of ethylene glycol and diethylene glycol in plasma is described. Such a method is necessary in clinical and forensic toxicology to diagnose probable intoxication and to control the efficacy of detoxification. For sample preparation, the glycols were isolated using acetone after the addition of 1,3-propylene glycol as internal standard. The glycols were then esterified by pivalic acid (pivalic acid anhydride, triethylamine and methanol, 70 degrees C, 15 min) to improve their gas chromatographic characteristics. The glycols were first identified by a comparison of the full mass spectra with reference spectra and then quantified. Therefore, the peak area ratio in the total ion chromatogram (ethylene glycol or diethylene glycol/1,3-propanediol) of the sample was compared with the calibration curve in which the peak area ratios of the standards (0.05, 0.1, 0.5, 1 and 2 g/l), prepared in the same way, were plotted versus their concentrations. The method was linear at least from 0.05 to 2 g/l, with a detection limit of less than 0.01 g/l. The analytical recoveries were 99.2-102.9% for the different concentrations. Precision studies show coefficients of variation of 3.0-6.3% for the different concentrations.

Determination of the alpha, beta-adrenoceptor blocker YM-09538 in urine by gas chromatography with a nitrogen-sensitive detector

A gas chromatographic method for the quantitative determination of the alpha, beta-adrenoceptor blocker YM-09538 in urine is described. YM-09538 was extracted from alkalinized urine with ethyl acetate and converted to its cyclic methylboronate derivative. Analysis by gas chromatography using a nitrogen-sensitive detector allowed quantitation of the drug over a concentration range of 0.2-5.0 micrograms/ml. Urinary excretion of YM-09538 was determined in humans after oral administration of 50 mg.

Electron-capture, capillary column gas chromatographic determination of low-molecular-weight diols in serum

Research on alcoholism has revealed that concentrations of 1,2-propanediol, d,1-2,3-butanediol and meso-2,3-butanediol may be greater in the serum of chronic alcoholics than in the serum of social drinkers and nondrinkers. In connection with one of these studies, we developed methodology to determine these diols at the micromolar levels in 500 serum samples. The procedure consisted primarily of extraction of the serum with acetonitrile containing internal standard. The extract was then concentrated to dryness and reacted with p-bromophenylboric acid. The reaction mixture was injected into a gas chromatograph fitted with a capillary column and an electron-capture detector. The total coefficients of variation were best for 1,2-propanediol, 6.82 and 10.00%, and worst for d,1-2,3-butanediol, 13.64 and 19.22%. The observed means for the analytes were all within 10% of the spiked level.

The determination of steroids with and without natural electrophores by gas chromatography and electron-capture detection

The response of the electron-capture detector to organic compounds is poorly defined, and the steroids are no exception to this observation. For those steroids which are naturally electron-capturing, the structures of the electrophores will be defined. Other steroids can be made electron-capturing by the formation of appropriate derivatives. Some new or infrequently used reagents for this purpose (flophemesyl ethers, t-bulflophemesyl ethers, pentafluorophenylhydrazone derivatives and halogen-substituted aromatic boronic acids) are described.

Formation of electron-capturing derivatives of alprenolol by transboronation: application to the determination of alprenolol in plasma

The reaction between 2,4-dichlorobenzeneboronic acid, 3,5-bis(trifluoromethyl)benzeneboronic acid or the 1,3-propanediamine derivatives of the boronic acids and the 3-isopropylaminopropan-2-ol side chain of the beta-blocking drugs occurs essentially as an on-column thermal reaction in the gas phase. Derivatization of the side chain of the beta-blocking drugs by transboronation is shown to be the method of choice for general application as it affects the detector background signal very little compared to the use of the boronic acid itself. The transboronation reaction can be used for the determination of alprenolol in plasma extracts with a detection limit of 2.5 ng ml-1 using the electron-capture detector. The ultimate sensitivity of the method is limited by the detector background signal resulting from some column decomposition of the transboronation reagent.