Fresh sample

A fresh sample of dimethyl sulphate should be employed an old sample, or one that has been frequently exposed to the air, should be shaken with water, separated, dried over sodium sulphate, and distilled (b.p. 188"). 

Dichloranrine-T (p-toluenesulphondichloramide). Prepare about 200 ml. of a saturated solution of calcium hjrpochlorite by grinding a fresh sample of bleaching powder with water and filtering with shght suction. Dissolve 5 g. of p-toluenesulphonamide in as small a volume of the calcium hypochlorite solution as possible (about 150 ml.) and filter the solution if necessary. Cool in ice, and add about 50 ml. of a mixture of equal volumes of glacial acetic acid and water slowly and with stirring until precipitation is complete. The dichloramine T separates out first as a fine emulsion, which rapidly forms colourless crystals. Filter the latter... 

Pitch. For the solvent analysis of pitch, a number of methods have been proposed. The solvents may be used sequentially or a fresh sample may be used with each solvent. Either the least or the most powerflil solvent may be used first. The ratio of solvent to pitch or pitch fraction and the temperature and time of extraction vary. 

Ammonia.. The most rehable results for ammonia are obtained from fresh samples. Storage of acidified samples at 4°C is the best way to minimi2e losses if prompt analysis is impossible. The sample acidity is neutrali2ed prior to analysis. Ammonia concentrations of 10 -0.5 M can be determined potentiometricaHy with the gas-sensing, ion-selective electrode. Volatile amines are the only known interferents. 

Sodium ethoxide [141-52-6] M 68.1. Hygroscopic powder which should be stored under N2in a cool place. Likely impurity is EtOH which can be removed by warming at 60-80" under high vacuum. Hydrolysed by H2O to yield NaOH and EtOH. Other impurities, if kept in air for long periods are NaOH and Na2C03 In this case the powder cannot be used if these impurities affect the reactivity and a fresh sample should be acquired [IR J Org Chem 21 156 1956]. 

A fresh sample of this 40% peracetic acid contains about 1.54 equivalents, or 0.77 mole, of peroxide per 100 ml. of solution, corresponding to 1.34 equivalents per 100 g. The concentration can be determined by treating the peroxide solution with potassium iodide and titrating the liberated iodine with standard sodium thiosulfate. The concentration of peroxide in peracetic acid decreases somewhat on long standing and should be checked before the peracetic acid is used. The yield of diacetate is lowered if the concentration of the peroxide is less than 1.0 equivalent per 100 g. of peracetic acid. The total amount of peroxide used should be 2.4 moles, or 4.8 equivalents, for each mole of iodo-benzene. 

Fig. 3. EXAFS analysis results for A) oxidic precursors before reduction, B) fresh samples after reduction, and C), D) bulk reference samples.

The data include the fractional content of C in the sample from the shroud, 1.22 X 10. The text states that the fractional content for a fresh sample is 1.33 X 10. To obtain N ] jN, divide the ratio... 

C22-0114. The amount of radioactive carbon in any once-living sample eventually drops too low for accurate dating. This detection limit is about 0.03/g min, whereas fresh samples exhibit a count rate of 15.3/g min. What is the upper limit for age determinations using carbon dating ... 

To distinguish the different actions of different oxygen species over the LiNiLa0x/Al203 on the CO selectivity, the sanq)le was pretreated by 5% H2/Ar flow at 1123K for 0.5 hr. After the pretreatment, the NiO was reduced to the reduced nickel and the surface adsorbed oxygen species was conqrletely consumed, and then the CH4 pulse reaction was performed. The results are different from the results of CH4 pulse reaction on the fresh sample. The... 

Chidwick, K., Winyard, P.G., Zhang, Z., Farrell, A.J. and Blake, D.R, (1991). Inactivation of the elastase inhibitory activity of ai-antitrypsin in fresh samples of synovial fluid from patients with rheumatoid arthritis. Ann. Rheum. Dis. 50, 915-916. 

The concentration of chlorine dioxide, chlorite and total oxidants was determined on site using a portable colorimeter (Palintest Photometer 5000) and a modification of the DPD test in which any chlorine species are complexed with glycine to ensure only chlorine dioxide reacts with DPD. The chlorite and total oxidants are then determined on a fresh sample by acidification and neutralisation in the presence of potassium iodide. The initial dose level was set at 0.3ppm chlorine dioxide injected in the water feed to the cold... 

For consistent, comparable results it is essential that a fresh sample blank be processed and otherwise be treated identically with each current batch of field samples. Whenever possible, this blank specimen should be from the same locality and should have the same previous spray (or other) history as the actual samples. Frequently, fruit and vegetable parts possess benzene-extractable pigments or other substances not removable by the decolorizing treatment utilized. In order to eliminate such background interfer-... 

The Pt dispersion of the fresh samples was measured by dynamic hydrogen chemisorption by using a temperature-programmed desorption (TPD)/R/0 1100 ThermoFisher... 

Instrument. Before the H2 chemisorption, each sample was heated in pure H2 at 300°C for 90 min, subsequently it was heated in He at 290°C for 60 min in order to desorb hydrogen from the sample. The chemisorption measurement was performed at 0°C by several H2 pulses with an Ar purge in between, in order to desorb physisorbed hydrogen. A 1/1 H/Pt ratio was used to estimate the Pt dispersion. Values in the range 50-70% have been obtained on the fresh samples Pt—Ba/ y-Al203 (1/20/100 w/w) catalyst. 

Figure 6.1. Subsequent NO storage runs in NO (1000 ppm) + 02 (3%, v/v), He balance (total flow 200 Ncc/min, catalyst weight 120 mg) at 350°C on a fresh sample of Pt—Ba/Al203 (1/20/100 w/w). NO, H20 and C02 are outlet concentrations, and NO is inlet concentration.

There are several sources of irreproducibility in kinetics experimentation, but two of the most common are individual error and unsuspected contamination of the materials or reaction vessel used in the experiments. An individual may use the wrong reagent, record an instrument reading improperly, make a manipulative error in the use of the apparatus, or plot a point incorrectly on a graph. Any of these mistakes can lead to an erroneous rate constant. The probability of an individual s repeating the same error in two successive independent experiments is small. Consequently, every effort should be made to make sure that the runs are truly independent, by starting with fresh samples, weighing these out individually, etc. Since trace impurity effects also have a tendency to be time-variable, it is wise to check for reproducibility, not only between runs over short time spans, but also between runs performed weeks or months apart. 

Fresh samples reacted slowly with air, but aged and partly decomposed samples... 

Figure 3.3 Comparison of array CGH among DNA extracted from fresh tissue, FFPE tissue by heating protocol or nonheating protocol for two human tissue samples of metastatic carcinoma in lymph node (a-c), and undifferentiated non-small cell carcinoma (d-f). Array CGH hybridization genomic profiles show ratio values representing relative copy number of single BACs. A good result is scored as 1.0 that indicates a low standard deviation for gains (>0.2), normal (0.0), or losses (<-0.2). In these two cases, fresh samples show best score as 2, both FFPE tissue samples show identical score of 3. Each spot represents the average of three replicates. Clones are ordered by chromosomal position as numbers at the bottom (x axis) of each picture. The y axis is the log2 ratio of test reference intensity. Provided by Sandy DeVries from Dr. Frederic Waldman s Lab at UCSF.

Temperature-programmed reduction (TPR) profiles of fresh catalyst samples were obtained using a Zeton Altamira AMI-200 unit. Calcined fresh samples were first heated and purged in flowing argon to remove traces of water. TPR was performed using 30 cc/min 10% H2/Ar mixture referenced to argon. The ramp was 5°C/min from 50 to 1,100°C, and the sample was held at 1,100°C for 30 min. 

The limits of detection for metals in seawater using in situ graphite tube electrodeposition will be governed by the deposition time. Unlike laboratory analyses, there will be no depletion of metals from the solution when lengthy deposition times are used, since fresh sample is being continuously pumped through the electrode. It should therefore be possible to detect the extremely... 

Once you have an idea of the melting point (or looked it up in a handbook, or were told), get a fresh sample, and bring the temperature up quickly at about 5-10°Cper minute to within 20° C of this approximate melting point. Then turn down the voltage control to get a 2°C per minute rise. Patience ... 

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