investigated by means of non-isothermal differential scanning calorimetry (DSC), thermogravimetery (TG), and chemiluminescence (CL). This temperature enabled to evaluate the interpretation of slow degradation reaction at lower temperatures and accelerated
The decomposition in HTPB bonded HMX was characterized with two highly sensitive methods: heat flow microcalorimetry (HFMC)
and Chemiluminescence (CL). The material is stabilized with a phenolic antioxidant. The heat generation (HFMC) rate was determined
from 120 to 150 °C using a TAM™ microcalorimeter and the oxidation of the substance was followed by the CL emission between
100 and 140 °C directly from the solid state sample. The end of antioxidant activity results in both measurements sets in
characteristic changes in the curves. Kinetic parameters were calculated applying Arrhenius parameterization for the times
to the end of antioxidant activity and by applying modelling with an autocatalytic model extended by a side reaction, which
is assigned to the antioxidant consumption. The evaluation with the characteristic times gives good agreement between the
two methods; the modelling represents the different but supplementing probing of the two measurement methods.
A 2D-separation of 16 polyaromatic hydrocarbons (PAHs) according to the Environmental Protecting Agency (EPA) standard was introduced. Separation took place on a TLC RP-18 plate (Merck, 1.05559). In the first direction, the plate was developed twice using n-pentane at −20°C as the mobile phase. The mixture acetonitrile-methanol-acetone-water (12:8:3:3, v/v) was used for developing the plate in the second direction. Both developments were carried out over a distance of 43 mm. Further on in this publication, a specific and very sensitive indication method for benzo[a]pyrene and perylene was presented. The method can detect these hazardous compounds even in complicated PAH mixtures. These compounds can be quantified by a simple chemiluminescent reaction with a limit of detection (LOD) of 48 pg per band for perylene and 95 pg per band for benzo[a]pyrene. Although these compounds were separated from all other PAHs in the standard, a separation of both compounds was not possible from one another. The method is suitable for tracing benzo[a]pyrene and/or perylene. The proposed chemiluminescence screening test on PAHs is extremely sensitive but may indicate a false positive result for benzo[a]pyrene.
Authors:András Németh, Krisztián Stadler, Judit Jakus, and Tamás Vidóczy
Luminol (LH,5-amino-2,3-dihydro-1,4-phthalazinedione) induced chemiluminescence (LCL) is one of the most frequently applied methodologies for peroxynitrite (ONOO − ) detection [ 1 , 2 ]. It has a high selectivity
A DSC instrument modified to incorporate a chemiluminescence (CL) detector has been used to make simultaneous measurements
of heat flow and light emission for oxidising polymer samples. Comparison of heat flow and light emission from unstabilised
polypropylene shows a linear relation between heat flow and square root of intensity, giving indirect confirmation of the
Russell mechanism for CL emission. Measurements of oxidation induction times (OIT) for stabilised samples show excellent correlation of the two techniques. The advantage of the CL method in being insensitive
to thermal transitions in the sample is illustrated by a study of poly(ethylene terephthalate), whilst the very high sensitivity
of CL detection is illustrated by its ability to detect peroxides at levels which are not detected by DSC. Finally, the limitations
of the OIT approach in lifetime prediction by Arrhenius extrapolation are emphasised.
A common scepticism towards the application of many product formulations results from the fact that their long-term stability
is difficult to predict. In the present study we report on a new approach of kinetic analysis of the oxidation reactions of
natural rubbers with and without stabiliser in an oxygen atmosphere at moderate temperatures using CL measurements carried
out on a newly-developed instrumentation. The kinetic parameters of the oxidation process, calculated from the chemiluminescence’s
signals by means of the differential isoconversional method of Friedman, were subsequently applied for the simulation of the
rubber aging under different temperature profiles. The presented results are the first stage of research by using the chemiluminescence
method to measure the oxidative aging of rubber and predicting the life time of rubber items.
An ultrasensitive and rapid method for the determination of epicatechin, rutin, and quercetin was developed using capillary zone electrophoresis with on-line chemiluminescence detection. Under the optimal conditions, the analytes were baseline separated within 12 min. The limits of detection in turn were 0.60 pg mL−1 for epicatechin, 0.50 pg mL−1 for rutin, and 1.0 pg mL−1 for quercetin. The developed method was an easy and reliable method of determining these analytes concentrations in tea, extract Ginkgo biloba, and rutin tablet, demonstrating the feasibility and reliability of the proposed method.
The aim of this study was to evaluate a Chemiluminescence Enzyme Immunoassay (CLIA) developed for the detection of E. coli O157:H7, using different E. coli O157 serotypes. The sensitivity and specificity of the kit were determined from the tenfold dilutions of the 24-hour broth cultures of the test strains. According to the results obtained in this trial, the sensitivity of the kit is 103–104 cells ml−1, and it is specific for E. coli O157. Twenty-five g ground raw beef samples were prepared and inoculated with E. coli O157:H7 at different CFU g−1. The samples were incubated in 225 ml of modified E. coli broth with novobiocin (mEC + n) at 42 °C for 4 h and the immunoassays were performed following the instructions of the manufacturer. According to the results obtained by the CLIA test 101–102E. coli O157 g−1 can be detected from the sample. So this kit seems to be suitable for screening the samples before selective cultivation of E. coli O157:H7.