Search Results

You are looking at 21 - 30 of 861 items for :

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

Abstract  

Instrumental neutron activation analysis is routinely used at the MURR to quantify selenium in prospectively-collected biologic markers including blood serum and toenails. These specimens are typically collected from well-defined cohort populations participating in investigations assessing selenium intake and incidence of chronic disease endpoints. These epidemiological investigations, whether observational (case-control) or clinical (intervention), typically generate thousands of samples. The purpose of this paper is to assess, through evaluation of quality control results, if the achievable accuracy and precision in the measurement of selenium using NAA is adequate to determine a relative risk of 1.2 at high confidence in epidemiological studies.

Restricted access

Grapefruit (Citrus paradisi) seeds are increasingly applied for medicinal purposes, especially due to their antimicrobial and immunostimulant features, to treat or prevent common cold. However, the scientific background of these uses has not been established. To date, only in vitro studies support the antimicrobial effect of the seeds, and there are no data on the systemic antibiotic or other clinical effects. Moreover, recent data refer to the adulteration of grapefruit seed products with synthetic antiseptics which may be an explanation for the antimicrobial efficacy of some formulations. The aim of our study was to develop a simple thin-layer chromatography- based method for the quality control of grapefruit seed extracts. Besides the analytical procedure, we report a quick and simple method for the isolation of limonoids from grapefruit seeds. Limonoids are characteristic compounds of the seeds; hence, the detection of these marker compounds may be the basis of grapefruit identification. Further, a thin-layer chromatographic screening for synthetic antiseptics (quaternary ammonium salts) is also part of the quality control procedure.

Restricted access

Summary

The ripe fruits of Schisandrae chinensis have a long history of use in traditional Chinese medicine to treat diseases and improve health. There is substantial evidence that lignan constituents are mainly responsible for the beneficial effects of this plant medicine. The amounts of the major bioactive lignans in this plant vary widely with species, habitat, and the collecting time, and as such, establishment of an HPLC fingerprint for quality control of this herbal medicine is of particular importance. To achieve this, ten batches of Fructus schisandrae chinensis were collected from Tieli, in China, and their chemical components were analyzed under optimized HPLC conditions. On the basis of the chromatographic data, a consistent HPLC fingerprint pattern containing 20 common peaks was obtained. Among these common peaks, six were identified as schizandrin, schizandrol B, schisantherin, deoxyschiandrin, γ-schizandrin B, and schizandrin C. On the basis of this HPLC fingerprint and principal-components analysis, the quality of fifteen samples from different producing areas of China was objectively assessed, and the species difference between Fructus schisandrae sphenantherae and Fructus schisandrae chinensis was clearly differentiated. To summarize, the data described in this study offer valuable information for quality control and proper use of Fructus schisandrae chinensis.

Restricted access

Abstract  

Paper chromatography and Gel Chromatography Column Scanning technique (GCS) have been applied for the separation of indium fractions in113mIn-radiopharmaceuticals. By these techniques the percentage of ionic indium,113mIn-colloid and113mIn-compound have been determined. The resolution efficiency of the gels was found to be significantly influenced by the gel type media and the pH of the eluent. The results obtained from the GCS-profiles indicated that the Sephadex G-50 Fine was the best and can be routinely used in the radiochemical quality control of the113mIn-phytate. Good separation of113mIn-colloids,113mIn-microaggregate and113mIn-phytate from carrier-free113mIn-eluate was performed using Whatman No. 3, previously washed with 0.04N HCl and developed either with 0.9% NaCl (for113mIn-colloid), or 85% methanol (for113mIn-phytate), or phosphate-methanol buffer (for113mIn-microaggregate) as rapid and simple procedure for determination of the radiochemical quality control of indium compound in the forms of radiocolloids.

Restricted access

Abstract

Compet-Terra is carrying out QA (Quality Assurance) services for the Hungarian Agriculture and Regional Development Agency. Quality control of the LPIS is one of the important QA duties. The LPIS data set is updated yearly according to the cycles of agricultural subsidies. Compet-Terra elaborated an Open Source Software based checking method that could be adopted by the client without the financial expense of software.

QuantumGIS (as the primary tool), gvSIG, and LibreOffice were used for the quality control of the LPIS. Four primary quality types were checked: (1) the land parcel attributes, (2) the areas of the polygons, (3) the completeness of the content and (4) the topological quality. For these investigations topological GIS functions and database management functions were used. The most important functions were topological difference calculation, polygon area calculation and geometry validity check. Complex procedures were also carried out with proprietary tools to compare the results and the run-time performances.

The result of the adoption of OSS GIS tools for LPIS checking was positive. All the planned procedures could be implemented using OSS GIS. OSS tools proved to be robust, reliable, userfriendly and performed well.

Restricted access

Abstract  

Radio high pressure liquid chromatography (radio-HPLC) is the method of choice for quality control of radiopharmaceuticals labelled with short lived isotopes. Our preparations of “no carrier added”11C-labelled palmitic acid and L-methionine are both designed to end with a HPLC separation on either silica gel or C-18 reversed phase material. Since the crude reaction mixtures contain milligram amounts of inactive substrate materials, both separations must be carried out at preparative scale. Nevertheless they are performed in less than 10 min. The most critical factor for the separation of11C-palmitic acid from the main by-product pentadecane is the solvent composition: while the11C-L-methionine separation is especially sensitive to pH variations.

Restricted access

Abstract  

The radiopharmaceutical201TlCl(thallium-201 chloride) is used in nuclear medicine for myocardial visualization. The solution of201TlCl was prepared using201Tl obtained by irradiating a natural mercury target with protons from the CV-28 cyclotron installed at IPEN-CNEN/SP. This solution was subjected to different quality control processes required for its use in medicine. Some of these controls concerned the determination of the radionuclidic impurities:200Tl,202Tl and203Hg; the chemical identification of201Tl+; the hydrazine concentration, mercury contamination and the presence of phosphate. Furthermore. the biological distribution in Wistar rats and tests for sterility, pyrogenicity and toxicity were carried out. It was verified that the solution obtained was in the form of thallous chloride. This radiopharmaceutical gave good heart images in animals but due to the high levels of200Tl and202Tl its use in humans is not possible unless enriched202Hg is used as target in the irradiation.

Restricted access

In the industrial practice Howard mould count (Howard, 1911) is used for the estimation of mould contamination of foods. It was developed originally for the investigation of mould contamination of tomato purée. It is also used nowadays for quality control purposes for other food products as well. Recently this constitutes the basis of the acceptance of the finished products in international trade. This technique demands experts with a lot of practice and morphological proficiency. The investigation makes use of eyes and so the tiredness of the investigator can cause uncertainties.The possibility of other methods for the determination of mould contamination of tomato purée was investigated to replace the Howard method. The NIR technique — as a rapid, non-destructive, reagentless and accurate method — was anticipated as a suitable method for the mentioned purpose. Canned tomato purée had been allowed to become mouldy then the sample was blended with non-mouldy samples in different ratio, so a series of tomato purées containing known amounts of mouldy purée was prepared. Howard mould counts and ergosterol content — another mould contamination relating value — was used as reference for NIR calibration.At quantitative investigation better results were obtained using ergosterol values. The best correlation coefficient (R=0.93) and the smallest standard error of calibration (SEC=0.008 mg g−1 ergosterol) was achieved with triangular smoothing and second derivation of the spectra. At qualitative investigation Polar Qualification System (PQS) was used. Clusters between samples with low and high ergosterol levels could be separated.

Restricted access

Abstract  

The results of the quality control of 99mTc-DPD produced during five consequtive years are statistically evaluated. Radiochemical purity of the kit determined in 75 batches was 98.3±1.3%. TLC on silica gel with the mixture of acetone and methanole (1:1, v/v) was used to determine the content of free pertechnetate. The labeled complex and 99mTc-hydrolyzate was separated by using ascending paper (Schleicher & Schull) chromatography and lN NaCl as the mobile phase. Reliable results were obtained showing that the content of the impurities 99mTc-pertechnetate and 99mTc-hydrolyzate is 1.7±1.3% and 3.4±2.1%, respectively. The biodistribution depends on the quantity of DPD. For the animal experiments its content should be 70–80 g/kg b.w. The experiments revealed that the mean value of bone distribution was 8.8±1.9%/g and in muscles 0.043± 0.42%/g. The uptake in liver and kidneys was below 3%, i.e., 0.65±0.29 and 1.71±0.68%/organ, respectively. The bone/muscle ratio should be at least 160. The analysis shows that the obtained values are arranged around their, statistically allowed, mean values.

Restricted access

Summary

A liquid chromatographic fingerprinting methodology has been established for identification and quality control of traditional herbal medicines. The methodology was developed from four case studies. Samples of Herba Artemisia annua, Herba Artemisia scoparia, Rhizoma Ligusticum chuanxiong (also called Rhizoma chuanxiong), and Rhizoma Ligusticum jeholense (also called Rhizoma ligustici) were investigated. In each case study, sample preparation and chromatographic conditions (column, organic modifier, column temperature, detection wavelength, and mechanism) were varied to obtain good fingerprints, i.e. with the maximum number of peaks. Further optimization was then performed either by reducing the analysis time or increasing efficiency. The case studies led to the development of a general methodology consisting of sample preparation and HPLC fingerprint development. The fingerprints obtained with the developed methodology were then successfully used to distinguish between the two Artemisia species and between the two Ligusticum species. The methodology also was used to obtain fingerprints for a large number of different Vietnamese Mallotus species, and for Citri reticulatae pericarpium samples collected in different regions of China.

Restricted access