Development and validation of a capillary electrophoresis method for the determination of phenothiazines in human urine in the low nanogram per milliliter concentration range using field-amplified sample injection

A capillary zone electrophoresis (CZE) method with ultraviolet-visible detection has been established and validated for the determination of five phenothiazines: thiazinamium methylsulfate, promazine hydrochloride, chlorpromazine hydrochloride, thioridazine hydrochloride, and promethazine hydrochloride in human urine. Optimum separation was obtained on a 64.5 cm x 75 microm bubble cell capillary using a buffer containing 150 mM tris(hydroxymethyl)aminomethane and 25% acetonitrile at pH 8.2, with temperature and voltage of 25 degrees C and 20 kV, respectively. Naphazoline hydrochloride was used as an internal standard. Field-amplified sample injection (FASI) has been applied to improve the sensitivity of the detection. Considering the influence of parameters affecting the on-line preconcentration (nature of preinjection plug, sample solvent composition, injection times, and injection voltage) and due to the significant interactions among them, in this paper we propose for the first time the application of a multivariate approach to carry out the study. The optimized conditions were as follows: preinjection plug of water for 7 s at 50 mbar, electrokinetic injection for 40 s at 6.2 kV, and 32 microm of H3PO4 in the sample solvent. Also, a solid-phase extraction (SPE) procedure is developed to obtain low detection limits and an adequate selectivity for urine samples. The combination of SPE and FASI-CZE-UV allows adequate linearities and recoveries, low detection limits (from 2 to 5 ng/mL), and satisfactory precisions (3.0-7.2% for an intermediate RSD %).     

Identification and determination of inorganic anions in real extracts from pre- and post-blast residues by capillary electrophoresis

Fast, selective, and sensitive analysis of inorganic anions is compulsory for the identification of explosives in post-blast or environmental samples. For the last twenty years, capillary electrophoresis (CE) has become a valuable alternative to ion chromatography (IC) for the analysis of inorganic-based explosives because of its low running costs and its simplicity of use. This article focuses on the development and validation of a CE method for the simultaneous analysis of 10 anions (chloride, nitrite, nitrate, thiosulphate, perchlorate, chlorate, thiocyanate, carbonate, sulphate, and phosphate) which can be found in post-blast residues, plus for the first time azide anion, possibly present in the composition of detonators, and the internal standard (formate) in 20 min total runtime. Intermediate precisions were 2.11% for normalized areas and 0.72% for normalized migration times. Limits of detection close to 0.5 ppm for all anions were obtained with the use of preconcentration techniques, thanks to a fast and simple sample preparation allowing the analysis of a large variety of matrices with the developed generic CE method. The matrix effects were statistically studied for the first time in the explosive field for different matrices, containing interfering anions and cations, sometimes at high levels. In fact, no significant matrix effect occurred (tests with blank matrix extracts of soil, cloth, glass, plastic, paper, cotton, and metal). Finally, analyses of real post-blast residues and real detonator extracts were performed. The CE results were compared with those obtained with the IC method used routinely and showed excellent correlation.     

Enantioselective Syntheses of Substituted γ‐Butyrolactones

The previously described chiral 2‐acyloxathianes 5 (Scheme I) are used in two different enantioselective syntheses of γ‐butyrolactones. In one synthesis, Grignard addition, cleavage and reduction to carbinols RR'C(OH)CH₂OH is followed by tosylation, malonate homologation, lactonization, and removal of the carbomethoxy group to give optically active γ‐lactones. A modification of this synthesis (Scheme I) leads to optically active α‐methylene‐γ‐lactones. In the second synthesis, reaction of a bromomagnesium enolate with ketones 5 leads to β‐hydroxyesters, which, by appropriate sequences of reduction and cleavage (Scheme II) are converted to optically active α‐ or β‐hydroxy‐γ‐lactones.     

Triphenylphosphine‐Mediated Reduction of Electron‐Deficient Propargyl Ethers to the Allylic Ethers

Semihydrogenation of α,β‐unsaturated ynoates and ‐ynones bearing a γ‐alkoxy group can be performed using triphenylphosphine and water. α,β‐Unsaturated ynoates were reduced to a mixture of cis and trans α,β‐unsaturated enoates, whereas, ynones were reduced to trans α,β‐unsaturated enones as the only products.     

Studies on the Mass Spectra of N‐Aryl α,β‐Unsaturated γ‐Lactams

The mass spectra of a series of N‐aryl α,β‐unsaturated γ‐lactams were studied. Besides the molecular ion, the three characteristic fragments such as [M⁺‐29], [M⁺‐55], and [M⁺‐82] were commonly found in a series of N‐Aryl α,β‐unsaturated γ‐lactams in EI/MS. Further more the mechanism for the interpretation of these fragments is also de scribed.     

毛细管电泳直接分析与水不互溶溶液中痕量物质的新方法

本文采用在线反萃取-场放大进样方法实现了毛细管电泳与溶剂微萃取的直接联用.     

A Convenient and Versatile Method for the Preparation of α‐Hydroxymethyl Ketone Derivatives from the Corresponding Allyl Silyl Ethers or Allyl Carboxylates

The ozonolysis of 1‐substituted allyl silyl ethers or 1‐substituted allyl carboxylates followed by treatment with bases gave the corresponding α‐silyloxymethyl‐ or α‐acyloxymethyl‐ketones in good yields. It is proposed to proceed via the corresponding α‐silyloxy‐ or α‐acyloxyaldehydes intermediates followed by 1,4‐group migration. The results of theoretical calculations are applicable to explain the experimental results.