Effect Of Sampling Technique Research Articles

Effects of sampling technique, storage, cocktails, sources of variation, and extraction on the liquid scintillation technique for radon in water

Sampling and analytical procedures used in the liquid scintillation counting technique to determine radon in water were examined in a series of experiments. Factors evaluated included the following: sample collection, length of storage, sources of variability, choice of scintillation cocktail, and extraction procedure. Collection using the direct syringe technique yielded the highest radon activities, but its widespread use may be limited by cost and problems with distribution of syringes. Storage in VOA bottles was primarily affected by radioactive decay; however, leakage also led to decreases in radon activity. Sample preparation and instrumentation caused the majority of the variability observed in this study. An Opti-Fluor O scintillation cocktail yielded significantly higher count rates and was less expensive than toluene and mineral oil based cocktails. The data suggested that while the extraction procedure should not be considered in calculating the efficiency factor, samples should be shaken to maximize the rate of transfer of radon to the cocktail phase.

Electron microscopic characterization of neonatal platelet ultrastructure: Effects of sampling techniques

Detailed ultrastructure of 720 neonatal platelets was systematically examined in 200–300 ul cord blood samples from four normal term infants. There were no differences in platelet organelles between samples collected into standard sodium citrate anticoagulant and minimally heparinized samples collected into sodium citrate. Samples collected into EDTA showed significant differences from the other two solutions. There were also differences in organelle characteristics within a solution group, as time from sample collection to EM fixation varied. These results verify utilization of small minimally heparinized blood samples for examination of platelet ultrastructure. This system can now be expanded to the premature infant, where small blood sample requirements are essential, and minimally heparinized blood may be more readily available.

Effect of Sampling Technique on Specimen Size in Fine Needle Aspiration Biopsy

The effect of the sampling technique in fine needle aspiration biopsy for cytology (FNAC) on the specimen size obtained was studied in vitro. The specimen size increased rapidly and linearly (P less than .001) with the number of needle passes, if the needle was angled between the passes into different directions in a fan-like fashion. However, if the needle was stroking repeatedly into the same channel, less and less tissue was detached per pass. The effect of the amplitude of needle passes (needle excursion) on the specimen weight was linear (P less than .001) after an initial plateau; when needle excursion was less than 3 to 4 mm, no tissue was detached. The specimen weight was significantly larger when a few passes with long needle excursions were used compared with a large number of passes with small needle excursions. Given an equal number of needle passes, the time interval (frequency) between these passes was less important. The sampling technique is important in determining the size of the specimen. The high incidences of unsatisfactory specimens reported and the wide variation in the accuracy rates of FNAC could be explained partly by differences in sampling techniques.

A phytoecological study of the mire Northern Kisselbergmosen, SE Norway. II. Identification of gradients by detrended (canonical) correspondence analysis

The vegetation of a poor mire is sampled by two procedures; 800 randomly placed sample plots made up the R data set, 765 subjectively selected plots in 153 sample plot series made up the S data set. DCA ordination and constrained ordination by DCCA of the data sets and subsets showed the existence of three coenoclines in the material: (1) the coenocline along the mire expanse: low to high median depth to the water table—mire margin gradient, (2) the poor‐rich coenocline, dependent on a complex‐gradient in substrate chemistry, and (3) a coenocline attributed to variation in peat productivity. Thus the assumption of Fennoscandian mire scientists embedded in numerous systems for classifying mire vegetation, that three gradients are the most important in the mire ecosystem, is partly confirmed. In the investigated area, two of the gradients normally considered make up one complex coenocline (1), and a fourth coenocline (3) has to be added. The effects of sampling techniques on correlations between coenoclines and on ordination results are discussed, and an improved sampling technique is suggested. The major faults of DCA: (1) the tongue effect, and (2) the instability, are described and discussed. It is concluded that if due attention is taken to reveal effects of the faults of the method, DCA is among the best ordination methods currently available.

T4: T8-lymphocyte ratios in human bone marrow: the effect of sampling technique.

Marrow aspirate and trephine biopsy T4 : T8-lymphocyte ratios were compared with peripheral blood values. To do this, a new technique for harvesting marrow cells from trephine biopsies is described. Results show that blood and trephine ratios did not overlap. Marrow aspirate ratios were intermediate suggesting that peripheral blood contamination was causing aspirate T4 : T8 ratios to be falsely elevated.

The assessment of the mutagenic potential of vehicle engine exhaust in the Ames Salmonella assay using a direct exposure method

A method for the assessment of the mutagenic activity of vehicle engine exhaust in the Ames assay is described in which the bacterial strains used (TA98 and TA98/DNP) are exposed to the freshly produced engine exhaust using a ‘Cassella’ slit sampler. The method is found to be effective both in the presence and absence of metabolic activation, using Aroclor-1254-induced rat liver S9 fractions. A comparison is made between the direct exposure method and the standard methods involving the collection of particulate samples on glass fibre filters and the testing of various extracts of these samples. Possible uses of the direct exposure testing method are suggested and the effect of sampling techniques on the results obtained in the Ames assay is also discussed.

Effects of sampling technique on measurements of porewater constituents in salt marsh sediments1

We examined the effect of three methods of porewater extraction on the measured concentrations of seven porewater constituents in vegetated salt marsh sediments. Porewater extraction by standard core sectioning followed by squeezing or centrifuging was compared with two less destructive methods of water collection. The core sectioning technique significantly increased the concentration of total dissolved organic carbon and dimethylsulfide presumably due to root damage by cutting. Sampling technique did not appear to influence interstitial salinity or concentrations of dissolved inorganic carbon, dissolved ammonium, soluble sulfides, and dissolved sulfate as long as proper precautions were taken to prevent the loss of reduced compounds.

Evaluation of Selected Procedures for the Rapid Analysis of Fresh Concrete

Abstract Presented in this paper are results of a program to evaluate procedures for the rapid determination of both cement and water contents of fresh concrete. Three generations of a general method were considered. The abilities of the current (Generation II-Construction Engineering Research Laboratory/Kelly Vail [CERL/KV]) and recently evolved (Generation III-Construction Engineering Research Laboratory/Concrete Quality Monitor [CERL/CQM]) procedures to aid in predicting cement and water contents of a variety of concrete mixtures were determined in an extensive series of side-by-side laboratory tests. Evaluated in the tests were effects of sampling techniques and aggregate type. Analysis of variance techniques were used as aids in establishing accuracy statements and comparing the two procedures. Results demonstrated that accuracies of the CERL/KV and CERL/CQM methods were equivalent for identical test conditions. Further, it was determined that aggregate characteristics affect results of both cement-content tests and both water-content tests.

Blood Plasma and Milk Prolactin, and Effects of Sampling Technique on Composition of Milk from Suckled Ewes

Relations of techniques of sampling milk to its composition and concentrations of prolactin in blood plasma and milk from 59 suckled ewes were compared. Prolactin in milk and blood samples 0 to 2h (hour 0) after removal of lambs did not differ significantly within autumn or summer, but both were doubled in summer. After the hour 0 sampling (summer only), one side of the udder of each of 12 ewes (group 1) was milked hourly for 4h, and the opposite side was milked only at 0 and 4h. Group 2 ewes were milked only at 0 and 4h and blood was collected from both groups at 0h and 4h. Concentrations of prolactin were correlated in pairs of milk or blood samples from the same ewe and in plasma and milk of ewes in group 2 but not in group 1. Prolactin in milk increased between 0h and 4h in groups 1 and 2. Although milk lactose and prolactin concentrations differed among hourly samples, their average was similar to that of milk accumulated in the contralateral side for 4h (group 1). Variations among ewes in progesterone of plasma indicated luteal activity during autumn and none during summer. Prolactin was unchanged in milk stored at −23C for 30 days. The hour-0 milk-sampling technique was satisfactory to compare among individuals the concentrations of prolactin, total protein, or somatic cells in milk but not percentage fat and lactose, or milk yield due to variable time from last suckling to milking at hour 0.

The effect of sampling technique on acid-base balance and other blood parameters in the sheep

The effect of 4 sampling routines--venipuncture, intravenous cannula, intravenous cannula following the administration of a tranquiliser (xylidino dihydrothiazine hydrochloride), intravenous cannula following exercise--were compared. Blood pH and base excess values were similar after venipuncture and cannula sampling, but higher (P less than 0 with 05) after the administration of the tranquiliser and lower (P less than 3 with 05) following exercise. Blood haemoglobin, haematocrit and lactate levels followed this pattern, while plasma protein levels were similar for all treatments except after exercise, where they were higher (P less than 0 with 05). The recovery of various blood parameters to normal values after a period of exercise was also studied: acid-base balance had returned to near normal within 60 min, while haemoglobin and haematocrit levels had returned to normal within 10 min.

The effect of sampling technique on some blood parameters in the rat

When used to restrain rats while obtaining cardiac blood, there was little difference between the effects of ether, pentobarbitone sodium, and fentanyl plus droperidol on acid-base balance, haemoglobin, haematocrit, plasma protein, calcium and magnesium. The use of manual restraint increased blood acidity, plasma protein, calcium and magnesium, but decreased blood glucose. Haemoglobin and haematocrit values were higher for tail blood than for blood removed from the heart or abdominal aorta.

Some observations on the effect of sampling technique under different conditions on numbers of some freshwater planktonic Entomostraca and Rotifera caught by a water-bottle

Summary 1. The effect of variations in sampling technique on numbers of freshwater planktonic Entomostraca taken in a 51. water-bottle has been investigated. 2. All samples were taken at 4 m below the surface in deep water of a lake. The tests were aimed to find out more about the effect on the larger planktonic animals of (1) leaving the sampling device open for different intervals of time, in light and in dark (2) lowering the sampling device at different rates and (3) the opacity and the direction of approach of the sampling device. 3. Species differed in their response to lengthening intervals of time before closure of the water-sampler. In daytime, at intervals of more than 5 sec, numbers of the cladoceran Daphnia hyalina fell by up to 50% but the response of other species was less pronounced. In the dark, there was no loss of D. hyalina: in moonlight, there was some loss but not as great as in daylight. Loss of Daphnia thus appears to be associated with a visual response. 4. Rate of lowering of the ...

A method for estimation of Krebs cycle and related intermediates in animal tissues by gas chromatography

1. 1. A method is described for the separation and estimation by gasliquid chromatography of pyruvate, lactate, β-hydroxybutyrate, and some Krebs cycle intermediates in rat tissues. The use of a 14C internal standard for each acid permits corrections for losses. After a simple extraction and purification procedure the intermediates are chromatographed as their methyl esters, the effluent peaks are collected, and their 14C content is measured to enable correction for losses of the individual acids during extraction and chromatography. The mean coefficient of variation of replicate estimations of the individual acids in pooled tissue sample ranged from 3 to 7.1%. Combined gas chromatography-mass spectrometry has been used to confirm the identity of the peaks in tissue chromatograms. 2. 2. Observations on the effect of sampling technique on the concentrations of the intermediates suggest that the combination of ether anesthesia with in situ freezing of tissue is the most satisfactory method when studying these intermediates in rat liver. 3. 3. The method described is also suitable for the simultaneous determination of the concentration and specific activity of tissue intermediates after injection of labeled precursors.

Effect of sampling technique on the determination of PaO2, during oxygen breathing.

Effect of sampling technique on the determination of PaO2, during oxygen breathing.