Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Sampling”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources
PubMed2005

The dependence of the counting efficiency of Marinelli beakers for environmental samples on the density of the samples.

The effect of the density of the radioactive material packed in a Marinelli beaker on the counting efficiency was studied. It was found that for all densities (0.4-1.7 g/cm(3)) studied the counting efficiency (epsilon) fits the linear log-log dependence on the photon energy (E) above 200 keV, i.e. obeying the equation epsilon=alphaE(beta) (alpha, beta-parameters). It was found that for each photon energy the counting efficiency is linearly dependent on the density (rho) of the matrix. epsilon=a-brho (a, b-parameters). The parameters of the linear dependence are energy dependent (linear log-log dependence), leading to a final equation for the counting efficiency of Marinelli beaker involving both density of the matrix and the photon energy: epsilon=alpha(1) x Ebeta1 - alpha2Ebeta2rho.

Environmental Monitoring↗
PubMed2006

Application of sample disruption methods in the extraction of anthocyanins from solid or semi-solid vegetable samples.

Cassis, a commercial powder obtained from blackcurrant juice (Ribes nigrum L.), was used to optimize the anthocyanin extraction by matrix solid-phase dispersion (MSPD) and by sea sand disruption method (SSDM). The optimum eluent conditions were 5.0 mL of MeOH/H2O (1:1, v/v) at pH 2. The extracts were analyzed by HPLC with diode-array detection (DAD) and the extraction efficiency was evaluated by statistical comparison (analysis of variance, ANOVA-single factor) of the compounds peak areas. The extraction efficiency for the MSPD procedure was dependent on the chemical nature of the C18 material but the optimized procedure yielded results similar to those obtained by the inexpensive sea sand disruption method (SSDM). This procedure also compared favorably to a previously published liquid-liquid extraction method. The optimized sea sand method was then used in the anthocyanin extraction from red grapes (Vitis vinifera L.) and strawberries (Fragaria ananassa D.) yielding chromatographic profiles similar to those reported in the literature for these products.

Anthocyanins↗
PubMed1981

Sample extraction detector for the liquid chromatographic determination of secoverine in biological samples.

A simple detection system for liquid chromatography based on post-column ion-pair extraction in a solvent-segmented stream is described. The fluorescent ion-pairing reagent 9,10-dimethoxyanthracene-2-sulphonate is added to the aqueous mobile phase prior to the column. An organic solvent, used for extraction of the ion pairs and for segmentation purposes, is added to the column effluent by gravity; about 70% of this phase is drawn through the detector cell using the siphon principle. The noise is significantly less than that of system with a pulsating peristaltic pump. The system has been used for the detection of the prospective drug secoverine. Under optimized conditions, band broadening due to the extraction detection system is sigma t = 7 sec. The detection limit of secoverine is ca. 20 pg, the repeatability in the nanogram range is 2% (relative standard deviation) (n = 6) and the linear range is at least 4 decades. The use of pre-column containing a 1--2-mm layer of stationary phase for clean-up and trace enrichment allows the direct injection of 200--1000 microliters of plasma or serum. In this way, secoverine can be determined in the parts per 10(12) range.

Chromatography, Liquid↗
PubMed1986

Quantitative cytospectrophotometric studies on protein thiols and reactive protein disulphides in samples of normal human uterine cervix and on samples obtained from patients with dysplasia or carcinoma-in-situ.

Quantitative microspectophotometric studies have been made on sections of human cervix after staining for reactive protein thiol-groups (PSHr), and the sum of protein thiols with so-called reactive protein disulphides (together abbreviated as TRPS). Measurements were made on normal epithelium, apparently normal epithelium adjacent to a pathological lesion, dysplastic epithelium, carcinoma-in-situ, and adjoining stroma. The numbers of cases studied were: normal healthy controls (53); patients with dysplasias (34) and patients with carcinoma-in-situ (29). In the normal control sections the ratio of PSHr in epithelium:stroma was approximately 2.7 and this ratio was strongly decreased in dysplasias (1.6) and carcinoma-in-situ (1.5); the 3 populations of values had sufficient overlap to prevent this measurement being an effective discriminator. No significant variations were observed with TRPS-values except with changes in the stroma adjacent to apparently normal epithelium. However, the ratio of PSHr:TRPS was effectively discriminatory when this double-staining ratio was calculated for epithelial values:stromal values. These results are discussed in relation to the importance of thiol-groups in cell division and cancer, and the biological implications of similar changes observed in neighbouring apparently normal epithelium.

Carcinoma in Situ↗