The Washing Step

1987) patent dealing exclusively with the washing step. 

Parameters to consider are the purity, the temperature, the amount, and the flow regime of the washing liquid. An optimization of all these parameters is a current research project in the author s laboratory (cf. e.g., Poschmann and Ulrich 1993 Wang- 

The efficiency of a washing operation depends, of course, on the quality, which means purity as well as smoothness, of the crystal layer. 

Finally, it should be stated that improvements in product purity are achieved by a contamination of the washing liquid. In most cases the washing liquid is purified melt which contaminates through the washing step and has to be purified again afterwards. 

In order to enable the prediction of the purification effect of the rinsing step, Wangnick (1994) introduces a characteristic dimensionless number won from a dimension analysis of all influencing parameters 

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Extra.ction St ige. The washing step after the chlorination stage removes the chlorine. In alkaline extraction, about 1.5—3.5% NaOH based on pulp is used. This typically amounts to about 55% of the CI2 demand used in the chlorination stage (% NaOH = 0.55 x % CI2 ). The target pH exiting the... 

After the chromatographic run the column can be stored in 20% ethanol at 3-8°C. Ethanol has to be removed before the next run by rinsing with several volumes (at least five) of buffer. The removal of ethanol during the washing step is demonstrated in Fig. 7.16. 

Wash the cartridge with 1.0 mL of a solution of 0.8% formic acid in water followed by 1.0 mL of acetonitrile-water (3 7, v/v, at a rate of approximately one drop every 2 s). Do not allow the cartridge to dry out until the end of the washing step. Then dry the cartridge for 2 min using vacuum or positive nitrogen pressure. 

In the case that TER values below 5 kf2 are measured for surfactants or neutral organics, an assessment of dye (sulforhodamine B) penetration can be carried out to determine false-positive results [150], Preparation of the skin discs and the washing steps are known to be the critical steps. 

A separation of conjugated AP from unbound enzyme in EIA is not necessary, because free AP is removed during the washing steps. 

All further procedures are performed at room temperature and samples are handled in mesh-buckets with a 12-well plate unless otherwise specified see Fig. 2). Wear gloves when moving mesh-buckets manually. All the wash steps are conducted with a defined incubation time indicated by moving up and down the buckets softly but occasionally to ensure thorough mixing. To facilitate the transfer of individual embryos, use a pipette fitted with a 200 pi or a 1,000 pi tip that was cut to make a wide opening, but avoid excessive agitation. 

At the end of the washing step, the liquid is drained to the operative tank by the pump, and through the button filter, FB, then the gas-recovery step takes place to recover most of the vapour or gaseous CO2 from the chamber. As the gas-recovery can be assumed to be like an adiabatic process, the fluid in the chamber is pre-heated by an electric resistance heat exchanger, HE2, to contain the reduction in temperature. The CO2 vapour is compressed by the oil-free compressor CV and fed to HE1 to condense before being stored in the operative tank. Finally, the chamber is vented and the door can be opened to recover the cleaned garments. 

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