Ultra-purity water

Fluid handling systems and ultra-purity water (UPW) systems are flushed with UPW, acids, or bases to extract ions and remove the loose particles from surfaces. Diluted hydrofluoric acid is effective in leaching out metals from fluoroplastics. Ultra pure water removes anions and particles. It is not unusual to flush a system with several hundred liters of water. 

The oil that remains is only slightly dark. Definitely translucent which is always lovely. One can then add some water to take up the unreacted salts and separate the oil from this. If an emulsion forms it can be busted up with some 10% HCl. That isosafrole is clean enough to proceed with but it can of course be distilled for ultra purity. 

Semi-conductors Ultra-high purity water Total organic carbon (TOC) reduction... 

The solid polymer electrolyte cells are viewed as being particularly appropriate for the treatment of high purity water systems, including the provision of ultra pure water for the pharmaceutical industry, cf. Ref. [205], The process is often coupled with UV radiation which serves to decompose unwanted, residual ozone [133],... 

More recently, ozone has been found to be particularly suitable as a sterilant in bottled water and ultra-high purity water production. 

The following procedures are provided for application as necessary in determining compliance with the vendor s declared representations for enzyme activity. For all of the procedures use filtered, ultra-high purity water with a resistivity of 16 to 18 megohms. 

Wikol MJ, Kobayashi M, and Hardwick SJ, Application of PTFE membrane contactors to the infusion of ozone into ultra-high purity water. The ICCS 14th International Symposium on Contamination Control, Phoenix, AZ, April 26-May 1, 1998. 

Bulk production of hydrogen via electrolysis appears improbable until renewable or nuclear electricity becomes widely available and considerably cheaper than at present. The principal attribute of electrolytic hydrogen is its ultra-purity, which is an important requirement for proton-exchange membrane fuel cells. Nevertheless, the use of valuable electricity to electrolyze water and then feeding the resultant hydrogen to a fuel cell is intrinsically wasteful by virtue of the combined inefficiencies of the two devices involved. This really only makes sense in situations where there is more electricity than can be consumed as such, or where there are reasons for wanting hydrogen that transcend considerations of efficiency and cost. 

All chemicals were purchased in the highest available purity from Merek (Darmstadt, Germany). Ultra pure water (at least 18.2 MQ) was obtained from a Milli-Q-Gradient-System (Millipore GmbH, Sehwalbaeh, Germany) and used for the preparation of all solutions and suspensions. 

The candidate technologies for purification are many. Distillation, the work-horse of the chemical processes, leads the pack. Most of the synthesis effort to date has concentrated on the product purification step. This step is often the last step for liquid products especially in the chemical and petrochemical industries. The biochemical industry utilizes membrane and chromatographic processes more than the other industries due to the thermal stability and purity requirements. In the electronic industry, membrane processes are more prevalent due the ultra-purities necessary. Supercritical fractionation of alcohol water systems with the aid of a dense gas is an example of a purification step. 

Waters Associates Bulletin H 81 Ultra Purity in Gram Quantities Liquid Crystal Formulations. ... 

Blank values. Ihe overall blank values of the analytical method, from weighing of the specimen to the prepeuation of the sample, are mainly caused by the added reagents, Le., the buffer solution, acids and bases, the dithiodicarbamate and, last but not least, the ultra-pure water if used instead of seawater for dilution or for the determination of the blank values. If no water of sufficient purity (ultra-pure water) is available, seawater extracted with Na-DBDTC is an accetable substitute. The use of reference seawater is another option (c.g., NASS and CASS reference material see Section 12.1.6). The blanks are derived firom the difference between the certified and the measmed values and should result in the same (similar) blank values from different reference materials. Typical blank values for Fe have been found to be between 100 and 150ng/L, for Zn between 60 and 90 ng/L, and for Cd and Pb below 10 ng/L. Variations depend on the stocks of chemicals employed. In particular the... 

Figure 9-77 illustrates the required valve switching for this technique. In the first step (Fig. 9-77A), the injection loop (5 mL) is filled with the solvent sample. Sample delivery is carried out with a simple isocratic pump at a flow rate of 1.5 mL/min for seven minutes out of a reservoir with a small head pressure, so that the loop is rinsed several times with sample. After loading the loop, the sample is transferred with ultra-high purity water to the concentrator column, in which the anions or cations are retained (Fig. 9-77B). The remaining solvent is rinsed off with ultra-high purity water (flow rate 1.7 mL/min rinse time 10 minutes). Afterwards, the concentrator column is put inline with the analytical separator column. The pre-concentrated ions are then eluted from the concentrator column in opposite directions and separated on the analytical separator...

In practice, such ozone celts are extensively automated to control the process cycle (Fig. 5< 14(b)) and may incorporate ultraviolet facilities. Current applications include those sectors of the pharmaceutical and fineultra-pure water for critical synthetic steps or to meet stringent purity limits. In such applications, the electrolytic route to ultra-pure water, via ozone generationf is competing against the more traditional methods of sterile filtration (e.g. ultra-filtration), ultraviolet irradiation and the use of conventional air-phase corona-discharge ozonizers. 

Table 15.15 gives the metal extraction data for a filter cartridge that is a common device in the chemical distribution and ultra-pure water systems in fabs. The filter media is a PTFE membrane and the hardware is made of high-purity PFAt ] Two eonsecutive extractions were conducted in high-purity hydrochloric acid, each for the duration of 16 hours, followed by ICP-MS measurement of the metal eontent of the acid. The second extraction shows a decrease in the metal contamination, which is typical of most devices. Fluid handling components are flushed with relatively large volumes of acids and/or UPW to remove most of the extractable contaminants. 

Table 15.10. Detection Limit of Purity Tests for Extraction by Ultra-pure Water ...

Takaku,Y., Masuda, K.,Takahashi,T, and Shimamura,T. (1994). Determination of trace silicon in ultra-high-purity water by inductively coupled plasma mass spectrometry.J.Atud. At. Spectrom. 9(12), 1385. 

The critical applications in the electronics industry are the production of ultra-pure water for the washing of semi-conductor material (silicon chips), and the cleaning of the chemical fluids (liquid and gaseous) used in their manufacture. The object of an ultra-pure water plant for semi-conductor manufacture is to produce water as close to the theoretical purity as possible. Users of ultra-pure water should take all steps possible to ensure that the filters selected meet the highest standards of quality and performance. Every fluid that comes into contact with integrated circuit surfaces is a potential sonrce of the contamination that will affect yields. For this reason, filtration of these fluids at the point of use is essential to obtain high yields. All chemicals that contact microcircuits should be filtered to a level of at least 0.2 pm. 

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