Quality control chemical monitoring

Sampling of limestone may be done for a variety of reasons, ranging from the assessment of a deposit and the evaluation of a product, to quality control and monitoring compliance with a specification. Testing may be of the mechanical, physical, thermal, weathering, chemical, or general characteristics of the limestone. 

Applications of the fibre optics transmittance or ATR probe are in quality control, reaction monitoring, skin analysis, goods-in checking, analysis at high and low temperature, radioactive or sterile conditions, and hazardous environments. Applications of the reflectance probe are for turbid liquids, powders, surface coatings, textiles, etc. By using an on-line remote spectrophotometer, real-time information is gathered about a chemical process stream (liquids, films, polymer melts, etc.), as often as necessary and without the need to collect samples. This determines more reliable process control. Remote spectroscopy costs less to maintain and operate than traditional techniques. Fernando et al. [48] have compared different types of optical fibre sensors to monitor the cure of an epoxy resin system. 

Because temperature control can be so critical to safety and quality, highly trained operators -- "human controllers", so to speak --are often assigned to control chemical processes. But human operators have other responsibilities and thus may not be able to monitor the temperature during the entire process. Even the finest operator may not be able to achieve the kind of temperature control required for certain demanding specialty products. 

DNA analysis, performance of polymerase chain reactions, clinical assays for pH, enzymes, proteins, oxygen etc., trace pollution monitoring and other sorts of biological analyzes are at the focus of recent developments [5]. Another reference lists environmental monitoring (including speciation), clinical monitoring, and quality control in production processes as applications of pTAS equipment in chemical analysis [30]. 

The annual cost of the laboratory analyses required for process monitoring and quality control is a significant item in most modem chemical plants. The costs should be calculated from an estimate of the number of analyses required and the standard charge for each analysis, based on experience with similar processes. 

Chemical analysis finds important applications in the quality control of industrial processes. In an ideal situation a continuous analysis of the process stream is made and some aspects of this are discussed in Chapter 12. However, such continuous analysis is by no means always possible, and it is common to find a process being monitored by the analysis of separate samples taken at regular intervals. The analytical data thus obtained need to be capable of quick and simple interpretation, so that rapid warning is available if a process is going out of control and effective corrective action can be taken. 

The unique appearance of an infrared spectrum has resulted in the extensive use of infrared spectrometry to characterize such materials as natural products, polymers, detergents, lubricants, fats and resins. It is of particular value to the petroleum and polymer industries, to drug manufacturers and to producers of organic chemicals. Quantitative applications include the quality control of additives in fuel and lubricant blends and to assess the extent of chemical changes in various products due to ageing and use. Non-dispersive infrared analysers are used to monitor gas streams in industrial processes and atmospheric pollution. The instruments are generally portable and robust, consisting only of a radiation source, reference and sample cells and a detector filled with the gas which is to be monitored. 

Many facilities already measure the above parameters (and many others) on a regular basis to control plant operations and confirm chemical mixture quality more closely monitoring these parameters may create operational benefits for facilities that extend far beyond security, such as reducing operating costs and chemical usage. Chemical industrial facilities also should thoughtfully monitor customer complaints and improve connections with local public health networks to detect public health anomalies. Customer complaints and public health anomalies are important ways to detect potential contamination problems and other environmental quality concerns. 

The XAD procedure was selected on the basis of the comparison of results of complementary methods as mentioned earlier because it is effective in concentrating toxic as well as mutagenic compounds from Rhine water. The investigation demonstrates the application of short-cut biological methods needed for water quality control and complementary to chemical monitoring techniques. 

Chemical Gas Detection. Spectral identification of gases in industrial processing and atmospheric contamination is becoming an important tool for process control and monitoring of air quality. The present optical method uses the ftir (Fourier transform infrared) interference spectrometer having high resolution (<1 cm-1) capability and excellent sensitivity (few ppb) with the use of cooled MCT (mercury—cadmium—tellutide) (2) detectors. 

We are working with the Food Quality Control Department of the Ministry of Health to study the contamination of OCPs and PCBs in local fish and chickens. This project is in line with our current effort to assess the health risk arising from consumption of food contaminated with POP chemicals. The health risk assessment of POPs through dietary intakes project involved analyses of OCPs and PCBs in various foodstuff, initially raw materials which will be extended to cooked food. Unfortunately, we do not currently have the capability to analyze PCDD/PCDF in our laboratory but there are two high resolution mass spectrometers in the country that are capable of analyzing PCDD/PCDF. National and international collaborations will definitely improve the country capacity to monitor POPs not only those listed in the Stockholm Convention but other toxic chemicals found in the environment. 

---