Quality control chemical purchasing

QC Experience. When we applied quality controls to purchased catalysts vithin Exxon Chemical Company, ve found... 

Quality control tests or improvement of existing processes. Raw materials from various sources can be used in the manufacture of fine chemicals and pharmaceuticals. The raw materials can contain different impurities at various concentrations. Therefore, before the raw material is purchased and used in a full-scale batch its quality should be tested in a small-scale reactor. Existing full-scale procedures are subject to continuous modifications for troubleshooting and for improving process performance. Laboratory reactors used for tests of these two kinds are usually down-scaled reactors or reactors being a part of the full scale-reactor. 

The laboratories have a quality manager and quality section. The quahty section prepares all of the analytical quality control (AQC) standards for the laboratories, including spiked and duplicate samples. The quality section is a separate laboratory with a separate supply of deionized water, glassware, balances and chemicals. The latter, wherever possible, are purchased from a different source to those for the analytical sections. These actions ensure a more independent approach to quality control. 

In 1984, a standard quality control procedure vas introduced for all purchased fixed bed catalysts and adsorbents, e.g. to be used at the discretion of all Exxon Chemical vorldvide operating plants. 

Specifications. Purchase specifications have to be defined first. Then, quality control of catalyst samples which are representative of the purchased catalyst lots, can be implemented to compare actual chemical and physical properties with the range of values stated in the purchase specifications. 

Standard Quality Control Procedure. A standard quality control procedure vas established in Exxon Chemical Company in 1984. Operating plants were offered in-house assistance for developing appropriate purchase specifications, and for monitoring the quality of lot samples of purchased commercial catalysts and adsorbents. 

Chemical control is the most widely practised method for vector and pest control in the Region. However, appropriate pesticide use is hampered, inter alia, by the lack of capacity, coordinated mechanisms and funding for the registration, purchase, application and quality control of products absence of effective systems for monitoring use and lack of implementation of existing rules and regulations. 

MATERIALS. All chemicals and reagents were either reagent or HPLC grade. o-Bromo-2,3,4,5,6-pentafluorotoluene was purchased from Aldrich Chemical Co., Milwaukee, WI. 13-cis and all trans retinoic acid were obtained from Quality Control, Hoffmann-La Roche Inc., Nutley, NJ. [11,12-3H]-al1 trans retinoic acid, [10,11- C]-13-cis retinoic acid and 13-cis tetradeuterated retinoic acid were obtained from Dr. A. Liebman, Department of Isotope Synthesis, Hoffmann-La Roche Inc., Nutley, NJ. 

If purchased radiopharmaceuticals are used without further processing (e.g. " Tc-radiopharmaceuticals in syringes, F-FDG in syringes or vial, in capsules), their receipt and supply to the nuclear medicine department is an administrative process. On receipt the certificate of analysis is checked under responsibility of the pharmacist and the radiopharmaceuticals are registered. In most situations no physical or chemical quality control is necessary. It is important to purchase only from a certified supplier. However, auditing and qualifying the supplier may be necessary. 

To maintain the production rate, product quality, and plant safety requires a data acquisition and control system. This system consists of temperature, pressure, liquid level, flow rate, and composition sensors. Computers record data and may control the process. Modem chemical plants use program logic controllers (PLC) extensively. According to Valle-Riestra [20], instrumentation cost is about 15% of purchased equipment cost for little automatic control, 30% for full automatic control, and 40% for computer control. 

It is recognized that the value of industrial products is determined more than before by their performance, which cannot always be expressed in terms of their composition. Well known examples of this include products such as motor fuels, lubricants, plastics, fibres, paints, lacquers, adhesives, agricultural chemicals, pharmaceutical products, and photographical chemicals, that is to say almost all chemical end products. These are to distinguished from intermediate chemical products, often called chemicals, the quality of the latter can usually be specified in terms of their composition. The manufacturing industries that convert the chemical end products into consumer products are often faced with strict quality requirements and sometimes even with product liabilities. They are therefore likely to put stringent requirements on the performance of the raw materials, that are the end products of the chemical industry. In such situations both suppliers and purchasers often prefer to make long term contracts that specify, both sales volumes and product performance. For the chemical industry this means that products of very specific properties have to be made and that these properties have to be constant in time. This requires very careful production control, and consequently a very accurate control of the performance of chemical reactors. 

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