Search Results

You are looking at 11 - 20 of 862 items for :

  • "Quality control" x
  • All content x
Clear All

Abstract  

This work reports the radioiodination of human thyrotropin (hTSH) in our laboratory (IPEN) and evaluates its quality in comparison with a commercial product. The radioiodination yield obtained in 20 experiments ranged from 18.5 to 56.3%, while the purification recovery ranged from 75.5 to 124.0% and the specific activity ranged from 1.01 to 3.10 MBq g–1. The values for the distribution coefficient revealed in the purification of radioiodinated hTSH ranged from 0.232 to 0.371. When tested concomitantly in the same radioimmunoassay system, the IPEN and the commercial tracer presented parallel standard curves. A highly significant correlation ion was observed between the quality control samples estimated through both curves (p<0.001). These results confirm the quality of the hTSH radioiodinated at IPEN and suggest the acquirement of self-sufficiency in this in vitro nuclear technology.

Restricted access
Acta Alimentaria
Authors: Zs. Hajdu, L. Lorántfy, N. Jedlinszki, K. Boros, J. Hohmann, and D. Csupor

The radish-like hypocotyls of Maca (Lepidium meyenii Walp., Brassicaceae) are widely consumed as common vegetable in the Andean highlands. It is considered as healthy food, rich in carbohydrates and protein, a herbal medicine with a general invigorating reputation and fertility and sexual performance enhancer. The latter is the most popular contemporary application of the plant in Europe. The number and variety of industrial products on the market is increasing. Here we report the development of a simple and reliable analytical protocol for the qualitative and quantitative analysis of maca content of preparations and for the detection of synthetic phosphodiesterase inhibitors. Fourteen products were analysed by the method based on TLC and HPLC-DAD analysis developed by us. Our experiments revealed that beside good-quality products, the majority of the multicomponent preparations did not contain the declared herbal component or the quantity of the measured macamide was very low. Furthermore, one preparation is adulterated with a synthetic phosphodiesterase inhibitor. The presented method is suitable for quality control of L. meyenii products.

Restricted access

Abstract  

Twenty laboratories from 17 countries around the world participated in two analytical quality control exercises, coded NAT-5 and NAT-6, on determining trace and minor elements in plant bioindicator samples. 1398 laboratory mean values for 51 elements were submitted for two lichen and two moss materials. The submitted measurement results were evaluated as interlaboratory comparison (IC) exercises and as proficiency tests (PT) following standard procedures developed by the International Atomic Energy Agency (IAEA). The evaluations confirmed good performance of the participating laboratories for many elements. Furthermore, the laboratories performance based on IC criteria improved from the first exercise to the second one. Subsequent NAT-5 evaluation revealed systematic differences between the analytical values obtained non-destructively or after the total sample dissolution and the measurements following nitric acid sample dissolution (without the use of hydrofluoric acid) for some elements. The most critical elements for this kind of discrepancies appeared to be Al, Ca, Cr, Fe, Na, Ni, and Pb. After changing analytical methodologies in the concerned laboratories, more consistent values for those elements were obtained in NAT-6.

Restricted access
Acta Chromatographica
Authors: R.-R. Durón, L. C. Almaguer, A. De J. Garza-Juárez, Ma. De La Luz, Salazar Cavazos, and N. Waksman-De-Torres

Summary

Use of thin-layer chromatography (TLC) for quality control of herbal medicinal products (HMPs) is very useful for determining and comparing the compositions of such products. In Mexico, HMPs are sold as herbal dietary supplements, and there is no legislation regarding their quality control. Heterotheca inuloides, Citrus aurantium, Peumus boldus, Equisetum arvense, Eucalyptus globulus, Ginkgo biloba, Mentha piperita, Aloe vera, Salvia officinalis, and Cassia senna are some of the major commercial products obtained from plants in this region. In this paper we describe the effectiveness of TLC methods for quality control of several commercial products containing plants and their extracts. We used one or several specific markers for each type of plant. In only 20% of the 40 commercial products that were analysed did the chromatographic characteristics of the respective plants match those of the specific respective marker compounds. These results highlighted a problem arising from the lack of regulation of these products. The proposed TLC methods are simple, sensitive, and specific, and can be used for routine quality control of raw herbal products and formulations of the plants tested. The results obtained emphasize the need to develop simple and reliable analytical methods that can be performed in any laboratory for the purpose of quality control of dietary supplements or commercial herbal products sold in Mexico.

Restricted access

Abstract  

Biological and radiochemical quality control of indigenous (Pinscan) diagnostic cold kits of Methylene Diphosphonate (MDP), Tin-colloid and Diethylene Triamine Pentaacetic Acid (DTPA) was performed in parallel with imported Amersham's kits (Amerscan). The results of radiochemical purity, sterility, apyrogenicity and biodistribution of indigenous (Pinscan) kits were good and quantitatively and qualitatively comparable to those obtained with Amersham's (Amerscan) imported kits.

Restricted access

Abstract  

High specific activity radiotracers, used in studies related to trace elements and human health, must be characterized by the following specific requirements: (i) high specific activity (activity/mass of isotopic carrier), (ii) high activity concentration (activity/volume or mass of substrate), (iii) radionuclidic, radiochemical and chemical purities, (iv) biological compatibility (physiological pH, sterility and physiological values). For this purpose, selective radiochemical separations and quality control procedures have been developed and tested at our laboratories for the production of several NCA radiotracers.

Restricted access

Abstract  

Radiochemical quality control using high performance high pressure liquid chromatography and, to some extent, gas chromatography is described for a variety of carrier-free11C-,18F-and123I-labelled compounds and radiopharmaceuticals. The particular problems associated with the handling of carrier-free compounds labelled with short-lived radionuclides are outlined, and chromatographic data are given for the separation and purification of such products.

Restricted access

Abstract  

A data reduction system for the routine instrumental activation analysis of samples is described, with particular emphasis on interactive graphics capabilities for evaluating analytical quality. Graphics procedures have been developed to interactively control the analysis of selected photopeaks during spectral analysis, and to evaluate detector performance during a given counting cycle. Graphics algorithms are also used to compare the data on reference samples with accepted values, to prepare quality control charts to evaluate long term precision and to search for systematic variations in data on reference samples as a function of time.

Restricted access

Abstract  

One novel styrylpyridine derivatives(AV-45) coupled with 99mTc complex was synthesized. 99mTc-BAT-AV-45 was prepared by a ligand exchange reaction employing sodium glucoheptonate, and effects of the amount of ligand, stannous chloride, sodium glucoheptonate and pH value of reaction mixture on the radiolabeling yield were studied in details. Quality control was performed by thin layer chromatography and high performance liquid chromatography. Besides the stability, partition coefficient and electrophoresis of 99mTc-BAT-AV-45 were also investigated. The results showed that the average radiolabeling yield was (95 ± 1%) and 99mTc-BAT-AV-45 with suitable lipophilicity was stable and uncharged at physiological pH.

Restricted access