Fab(nimotuzumab)-HYNIC-99mTc: Antibody Fragmentation for Molecular Imaging Agents.

Finally, fast blood clearance nimotuzumab is a humanized monoclonal antibody that recognise, with high specific affinity, the epidermal growth factor receptor (EGF-R) which play an important role in the growth process associated with many solid tumors. In this work, the whole antibody was digested with papain in order to generate a Fab fragment, derivatized with NHS-HYNIC-Tfa and radiolabel with technetium-99m (99mTc) as a potential agent of molecular imaging of cancer. Both, whole and fragment radiolabels were in-vivo and in-vitro characterized. Radiolabeling conditions with Tricine as coligand and quality controls were assessed to confirm the integrity of the labeled fragment. Biodistribution and imaging studies in normal and spontaneous adenocarcinoma mice were performed at different times to determine the in-vivo characteristics of the radiolabel fragment. Tumor localization was visualized by conventional gamma camera imaging studies, and the results were compared with the whole antibody. Also, an immunoreactivity assay was carried out for both. The results showed clearly the integrity of the nimotuzumab fragment and the affinity by the receptor was verified. Fab(nimotuzumab)-HYNIC was obtained with high purity and a simple strategy of radiolabeling was performed. Finally, a fast blood clearance was observed in the biodistribution studies increasing the tumor uptake of Fab(nimotuzumab)- HYNIC-99mTc over time, with tumor/muscle ratios of 3.81 ± 0.50, 5.16 ± 1.97 and 6.32 ± 1.98 at 1 h, 4 h and 24 h post injection. Urinary excretion resulted in 32.89 ± 3.91 %ID eliminated at 24 h. Scintigraphy images showed uptake in the tumor and the activity in non-target organs was consistent with the biodistribution data at the same time points. Hence, these preliminary results showed important further characteristic of Fab(nimotuzumab)-HYNIC-99mTc as a molecular imaging agent of cancer.

A method for determination of imazapic and imazethapyr residues in soil using an ultrasonic assisted extraction and LC-MS/MS.

At least 52 % of the planted rice area in Rio Grande do Sul, a major rice producing state in Brazil, employs Clearfield(®) production system, corresponding to 580,000 ha of cultivated area. To grow rice with Clearfield(®) technology, producers combine imazethapyr and imazapic herbicides. However, these herbicides leave residual activity in soil; consequently, the repeated application of imazethapyr and imazapic on Brazilian Clearfield(®) rice fields has increased these herbicides persistence in treated soils. In this study, a method has been developed for removal and quantification of imazethapyr and imazapic residues in soil through ultrasonic assisted extraction using methanol-phosphoric acid aqueous solution (pH 2.0). The detected response was linear for both herbicides within the range of 0.25-5 ng mL(-1) with correlations coefficients >0.99. The quantification limit was limit of quantification 0.2 µg Kg(-1) for both pesticides. The good recovery rate from all pesticides, which ranges between 70 % and 120 %, demonstrates the method's validity.

Determination of neonicotinoid insecticides in environmental samples by micellar electrokinetic chromatography using solid-phase treatments.

A sensitive and reliable method based on MEKC has been developed and validated for trace determination of neonicotinoid insecticides (thiamethoxam, acetamiprid, and imidacloprid) and the metabolite 6-chloronicotinic acid in water and soil matrices. Optimum separation of the neonicotinoid insecticides was obtained on a 58 cm long capillary (75 µm id) using as the running electrolyte 40 mM SDS, 5 mM borate (pH 10.4), and 5% (v/v) methanol at a temperature of 25°C, a voltage of 25 kV and with hydrodynamic injection (10 s). The analysis time was less than 7 min. Prior to MEKC determination, the samples were purified and enriched by carrying out extraction-preconcentration steps. For aqueous samples, off-line SPE with a sorptive material such as Strata-X (polymeric hydrophobic sorbent) and octadecylsilane (C18) was carried out to clean up and preconcentrate the insecticides. However, for soil samples, matrix solid-phase dispersion (MSPD) was applied with C18 used as the dispersant. Good linearity, accuracy, and precision were obtained and the detection limits were in the range between 0.01 and 0.07 µg mL⁻¹ for river water and 0.17 and 0.37 µg g⁻¹ for soil samples. Recovery levels reached greater than 92% for all of the assayed neonicotinoids in river water samples with Strata-X. In soil matrices, the best recoveries (63-99%) were obtained with MSPD.

Application of high performance liquid chromatography to the analysis of some non-volatile coffee components.

High performance liquid chromatography (HPLC) was applied to the analysis of caffeine, trigonelline, nicotinic acid and sucrose in Arabica and Robusta coffee. Green and roasted coffee samples were used in this study and the degradation of sucrose and trigonelline, with the formation of nicotinic acid, was followed during roasting. Caffeine did not undergo significant degradation with only 5.4% being lost under severe roasting. Sucrose was degraded rapidly during processing with light roasting producing a 97% loss and dark roasting degrading it completely. Loss of trigonelline was strongly dependent on the degree of roasting, being higher in the Robusta coffee. Trigonelline degradation was associated with nicotinic acid formation both in the Arabica and Robusta coffees as a consequence of the roasting process. Trigonelline and sucrose were determined simultaneously by partition chromatography and detection with the mass detector. Determination of caffeine was carried out using reversed phase chromatography and nicotinic acid by ion-pair reversed phase chromatography. Detection in both cases was achieved using an ultraviolet detector at 272 nm or 254 nm, respectively. HPLC showed adequate precision and accuracy for routine analyses. In addition, the methods used were more rapid and simple than traditional procedures. HPLC appears to be a suitable technique for quality control in the coffee industry, and for fundamental investigation on the mechanisms involved in the roasting process.