Near infrared reflectance spectroscopy for the fast identification of PVC-based films

Near infrared (NIR) reflectance spectroscopy was used to develop a non-destructive and rapid qualitative method for the analysis of plastic films used by the pharmaceutical industry for blistering. Three types of films were investigated: 250 microm PVC [poly(vinyl chloride)] films, 250 microm PVC films coated with 40 g m(-2) of PVDC [poly(vinylidene dichloride)] and 250 microm PVC films coated with 5 g m(-2) of TE (Thermoelast) and 90 g m(-2) of PVDC. Three analyses were carried out using different pre-treatment options and a PLS (partial least squares) algorithm. Each analysis was aimed at identifying one type of film and rejecting all types of false sample (different thickness, colour or layer). True and false samples from four plastics manufacturers were included in the calibration sets in order to obtain robust methods that were suitable regardless of the supplier. Specificity was demonstrated by testing validation sets against the methods. The tests showed 0% of type I (false negative identification) and 1% of type II errors (false positive identification) for the PVC method, 13 and 3%, respectively, for the PVC-PVDC method and no error for the PVC-TE-PVDC method. Type II errors, mostly due to the slight sensitivity of the methods to film thickness, are easily corrected by simple thickness measurements. This study demonstrates that NIR spectroscopy is an excellent tool for the identification of PVC-based films. The three methods can be used by the pharmaceutical industry or plastics manufacturers for the quality control of films used in blister packaging.     

Investigation of trifluoroacetolysis of some 2-bromoethanol arylsulfonates

Conclusions By PMR spectroscopy the kinetics of trifluoroacetolysis of 2-bromoethyl-2,2-d₂-toluene and 2-bromoethyl-2,2-d₂-anisole sulfonates, the dependence of rate constant on the presence of lithium perchlorate and on salts with a common ion were investigated. The trifluoroacetolysis of 2-bromoethyl-2,2-d₂-toluene-d₇-sulfonate in the presence of the lithium salt of nondeuterated toluenesulfonic acid was investigated. It was shown that reaction is accompanied by isomerization of the initial sulfonate (1,2-migration of bromine) and occurs by an ion pair mechanism.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 371–375, February, 1987.     

Occurrence of synergism between phospholipids and prostaglandins in extracts of some tissues of commercial squid

The phospholipid compositions, prostaglandin-like activities, and ratios of prostaglandins of groups of E, F and A in prostaglandin extracts of some organs of two species of commercial squid have been investigated.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Division of the Russian Academy of Sciences, Russia, 69022, Vladivostok, Prosp. Stoletiya Vladivostoka, 159. Translated from Khimiya Priodnykh Soedinenii, No. 5,pp.693–696, September–October, 1996. Original articel submitted June 19, 1995     

Interaction of diquat and paraquat with humic acid and the influence of salt concentration and pH on the strength of interaction

Summary The interaction of the herbicides diquat and paraquat with humic acid and the influence of various salts and pH on the strength of interaction was studied by charge-transfer chromatography. Interactions between humic acids and both herbicides, probably by complex formation, were confirmed; they were stronger with paraquat than with diquat. The complex formation makes the herbicides more hydrophilic, facilitating their movement on cellulose surface. Salts in the environment significantly decreased the strength of interaction, indicating the hydrophilic character of the interactive forces. The charge of the cation also influenced the strength of interaction whereas the effect of ion radii was negligible. The effect of pH was lower than that of salt concentration.     

A spectrometric,separation and voltammetric study of the complexation reactions of bromazepam with iron(ii),copper(ii) and cobalt(ii)

Bromazepam, in the form of a cationic iron(II) chelate, can be determined spectrophotometrically at 588 nm with a limit of detection of ca. 10^-6 M. When this chelate is ion-paired with perchlorate, it can be extracted into organic solvents such as 1,2-dichloroethane and 4-methyl-2-pentanone, and determined by atomic absorption spectrometry with a limit of detection of 1.5 × 10^-5 M bromazepam at the iron resonance 248.3-nm line. Ion-pairs involving the Fe(II), Cu(II) and Co(II) chelates and perchlorate can be separated by h.p.l.c. using a C₁₈ reverse-phase column and a mobile phase of 4:1 water—methanol, with a u.v. detector at 242 nm. This approach allowed for the determination of iron(II) ions in aqueous solution with a limit of detection of 10^-8 M. The h.p.l.c. method could also be used to quantify bromazepam spiked in plasma in the concentration range 1–10 μg ml^-1, following extraction of bromazepam from plasma and subsequent formation of the iron(II) ion-pair. Copper(II) forms a labile chelate with bromazepam in pH 4.8 acetate buffer which, when subjected to differential pulse voltammetry at the hanging mercury drop electrode, gives rise to a catalytic phenomenon which can be utilised for the determination of bromazepam in the concentration range 10^-5–10^-9 M.     

Determination of d-glucose in undiluted whole blood using chemically modified electrodes and segmented sample injection in a flow system

A flow system for the determination of d-glucose in undiluted whole blood, in which segmented sample injection and on-line dialysis are used to decrease the red cell volume fraction (haematrocrit) dependence, is described. Glucose is degraded enzymatically by means of immobilized glucose dehydrogenase. The nicotinamide coenzyme (NAD⁺) that is present in the solution is reduced in the enzymatic reaction and is reoxidized amperometically at 0 mV vs. Ag/AgCl on a graphite electrode, modified with phenoxazinium ion. The potential use of the system for clinical analysis is evaluated.     

L3/L2 white-line intensity ratios in the electron energy-loss spectra of 3d transition-metal oxides

The L₃/L₂ white-line intensity ratio in transition-metal oxides deviates widely from the statistical value of 2 : 1 but shows interesting systematics. In a series of oxides of a given metal, the ratio reaches a maximum for the d⁵ configuration (e.g. MnO) and a minimum for the d⁰ configuration (e.g. KMnO₄). In a series of monoxides, sesquioxides and dioxides of different metals, the ratio is again a maximum at the d⁵ configuration and decreases as the configuration changes towards d⁰ or d¹⁰. Our results, obtained by electron energy-loss spectroscopy, carried out in an electron microscope, are interpreted on an atomic mechanism involving spin-spin coupling. According to this model, the L₂ transition probability decreases in the progression d⁰ to d⁵ whereas the L₃ transition probability decreases beyond d⁵.     

Lime,soda and selenium: An early example of chemical process automation

The automatic control of certain physical phenomena, such as temperature and speed of rotation, has long been commonplace. However, the means by which this form of control can be applied to a chemical process are not so obvious. A sensing system must be found to monitor the status of the particular chemical system.     

The arylation of nitroalkanes and nitronate salts with aryllead triacetates

Nitroalkanes and their nitronate salts undergo α-arylation in good yield when treated with an aryllead triacetate in dimethyl sulfoxide.