Duration of extraction

Fig 2, where the observed amount of the naphthylamine generated from the reacted film is plotted against duration of extraction. 

This advantage permits an important decrease in the duration of extraction as opposed to that of other liquid extraction. 

Tempunit TU-16A heater, outlet restrictor solvent mixture. hexane-MTBE temperature of the ultrasonic bath. 70°C duration of extraction. ... 

Since only PDMS coating is available as an extraction phase, SBSE has been used predominantly for low-polarity analytes, but the problems of extraction of polar compounds may be solved by in situ derivatiziation. It is clear that further developments in stir bar coatings and designs could extend the applicability of the method. The main drawback of this method is the duration of extraction, typically 30-150 min. For this reason SBSE may be impractical for routine high-throughput laboratories. 

Unlike the other techniques, SPME has a considerable concentration capacity and is very simple because it does not require especial equipment. The principle involves exposing a silica fibre covered with a thin layer of adsorbent in the HS of the sample in order to trap the volatile components onto the fibre. The adsorbed compounds are desorbed by heating and introduced into the detection system A SPME sampler consists of a fused silica fiber that is coated by a suitable polymer (e.g. PDMS, PDMS/divinylbenzene, carboxen/PDMS) and housed inside a needle. The fiber is exposed to headspace volatile and after sampling is complete, it is retracted into the needle. Apart from the nature of the adsorbent deposited on the fiber, the main parameters to optimize are the equilibration time, the sample temperature and the duration of extraction. Compared with other sampling methods, SPME is simple to use and reasonably sensitive, so it is a user-friendly pre-concentration method. 

However, according to CEN EN 12697-1 (2012), Annex D, great attention should be given on the selection of the appropriate solvent, the duration of extraction and the separation of the fine mineral matter. 

Anions of another group were derivatized with formation of gaseous chemiluminescing species. Chemical reaction - gas extraction has been used with chemiluminescence detection in the stream of canier gas in on-line mode. Rate of a number of reactions has been studied as well as kinetic curves of extraction of gaseous products. Highly sensitive and rapid hybrid procedures have been developed for the determination of lO, BrO, CIO, CIO, NO,, N03, CrO, CIO, Br, T, S, 803 with detection limits at the level of pg/L, duration of analysis 3 min. 

Microbial over-growth was controlled with carbon dioxide passed through the bed. There was a maximum 30% increase in the beads diameter at the lower part of column, where the glucose concentration was maximum. The void volume was measured by passing sterilised water. In addition to the carbon source, the feeding media consisted of 1 g l 1 yeast extract pumped from the bottom of the reactor, while the flow rate was constant for a minimum duration of 24 hours. 

Sample solution instability or incomplete extraction/separation would show up if several aliquots from the same sample work-up were put in a series of vials that would be run in sequence that would cover at least the duration of the longest sequence that could be accommodated on the autosample/instrument configuration. For example, if an individual chromatogram is acquired for 5.5 minutes, postrun reequilibration and injection take another 2.75 minutes, and 10 repeat injections are performed for each sample vial in the autosampler, then at least 15 60/(5.5 -I- 2.75)/10 = 11 vials would have to be prepared for a 5 P.M. to 8 A.M. (=15 hour) overnight run. If there is any appreciable trend, then the method will have to be modified or the allowable standing time limited. 

The aim of the present investigation is to study the influence of microwave pretreatment of fresh orange peels on the extraction time of orange pectin and the influence of the intensity and duration of microwave heating on pectin yield. 

The extraction time has been observed to vary linearly with polymer density and decreases with smaller particle size [78,79]. The extraction time varies considerably for different solvents and additives. Small particle sizes are often essential to complete the extraction in reasonable times, and the solvents must be carefully selected to swell the polymer to dissolve the additives quantitatively. By powdering PP to 50 mesh size, 98 % extraction of BHT can be achieved by shaking at room temperature for 30 min with carbon disulfide. With isooctane the same recovery requires 125 min Santonox is extractable quantitatively with iso-octane only after 2000mm. The choice of solvent significantly influences the duration of the extraction. For example talc filled PP can be extracted in 72 h with chloroform, but needs only 24 h with THF [80]. pH plays a role in extracting weakly acidic and basic organic solutes, but is rarely addressed explicitly as a parameter. 

To examine the effect of ultrasound on the decomposition of Zn-dithizone complex, 0.2264 g Zn metal was treated with 10 ml of 5 M NaOH and sonicated for 30 min for maximum dissolution of Zn metal. After treating with ultrasound, 0.5 ml of 1 % dithizone was added to form Zn-dithizone red coloured complex. This red colour Zn-dithizone complex was extracted in chloroform and made upto to the mark in 50 ml volumetric flask with chloroform. 10 ml of this complex was sonicated for different duration of time (10, 20 and 30 min) and UV-vis spectro-photometric analysis was carried out. 

However for several of the molecules shown in Figures 1 and 2, DNA has only a small effect on the observed fluorescence lifetime. These molecules include trans-7,8-dihydroxy-7,8-dihydro-BP (15,18,19), trans-4,5-dihydroxy-4,5-dihydro-BP (15,18), BPT (7,18), 1,2,3,4-tetrahydro-BA (12), 8,9,10,11-tetrahydro-BA (14), 5,6-dihydro-BA (12), anthracene (12) and DMA (14). Typical decay profiles obtained in fluorescence lifetime measurements of trans-7,8-dihydroxy-7,8-dihydro-BP and of 8,9,10,11-tetrahydro-BA are shown in Figure 6. The lifetimes extracted from the decay profiles shown here have been obtained by using a least-squares de-convolution procedure which corrects for the finite duration of the excitation lamp pulse (77). 

A baseline potential pulse followed each current pulse in order to strip extracted ions from the membrane phase and, therefore, regenerated the membrane, making it ready for the next measurement pulse. This made sure that the potentials are sampled at discrete times within a pulse that correspond to a 6m that is reproducible from pulse to pulse. This made it possible to yield a reproducible sensor on the basis of a chemically irreversible reaction. It was shown that the duration of the stripping period has to be at least ten times longer than the current pulse [53], Moreover the value of the baseline (stripping) potential must be equal to the equilibrium open-circuit potential of the membrane electrode, as demonstrated in [52], This open-circuit potential can be measured prior to the experiment with respect to the reference electrode. 

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