Regulatory acceptable concentration

With the acceptable concentrations of herbicides in drinking water being taken to very low levels by some regulatory authorities (e.g., the EC), there has been interest in very low levels of atrazine present in some samples of groundwater and in drinking water. This finding illustrates the point that mobility of pesticides becomes increasingly evident as sensitivity of analysis improves. 

When sampling in the enviromnent, it is often impossible to determine which chemical mixtures are causing a total petroleum hydrocarbons reading, which is one of the major weaknesses of the method. At minimum, before using contaminants data from diverse somces, efforts should be made to determine that field collection methods, detection limits, and quality control techniques were acceptable and comparable. This will help the analysts compare the analysis in the concentration range with the benchmark or regulatory criteria concentrations should be very precise and accmate. 

Nitrite ion is an undesirable by-product of radiolysis in waters containing high nitrate concentrations, and regulatory limits exist regarding its acceptable concentration. The presence of nitrate does not preclude radiolytic water treatment. One approach that compensates for nitrite generation in high nitrate waters is ozone addition, discussed later. 

Alpha-tocopherol is a highly lipophilic compound, and is an excellent solvent for many poorly soluble drugs.Of widespread regulatory acceptability, tocopherols are of value in oil- or fat-based pharmaceutical products and are normally used in the concentration range 0.001-0.05% v/v. There is frequently an optimum concentration thus the autoxidation of linoleic acid and methyl linolenate is reduced at low concentrations of alpha tocopherol, and is accelerated by higher concentrations. Antioxidant effectiveness can be increased by the addition of oil-soluble synergists such as lecithin and ascorbyl palmitate. " ... 

There are two general principles or options that are used to manage both radioactive and nonradioactive wastes. These are (1) to concentrate and isolate wastes (i.e., concentrate-and-contain) and, (2) to dilute to regulatory-accepted levels and then discharge the wastes to the environment (i.e., dilute-and-disperse). 

Principles and Characteristics On-line thermal desorption (TD) is the use of heat with a flow of inert gas to extract volatile chemicals from a solid matrix transfer (often followed by transfer to GC). TD was originally developed as an off-line sampling method with pre-concentration of workplace atmosphere by pumping air through a solid adsorbent material, such as charcoal or Tenax. In this field thermal desorption has gained regulatory acceptance. For a 10 L gas sample a typical detection limit is ca. 10 /u.gm . ... 

In general, nonconventional protein foods must be competitive with conventional plant and animal protein sources on the bases of cost delivered to the consumer, nutritional value to humans or animals, functional value in foods, sensory quality, and social and cultural acceptability. Also, requirements of regulatory agencies in different countries for freedom from toxins or toxic residues in single-cell protein products, toxic glycosides in leaf protein products, pathogenic microorganisms, heavy metals and toxins in fish protein concentrates, or inhibitory or toxic peptide components in synthetic peptides must be met before new nonconventional food or feed protein products can be marketed. 

There are two significant reasons why water contamination needs to be considered. The first is that aqueous effluent must comply with environmental regulations before discharge. The concentration, and perhaps load, of contamination of various specified contaminants must be less than the regulatory requirements. The second reason is that contaminant levels will affect the feasibility of reuse and recycling of water, as shown in Figure 26.2. If water is to be reused or recycled, then the level of inlet contamination to the operation receiving reused or recycled water must be acceptable. What types of contamination need to be considered ... 

An initial calibration verification standard should be measured after calibration and before measuring any sample. A calibration verification standard is a standard solution or set of solutions used to check calibration standard levels. The concentration of the analyte should be near either the regulatory level of concern or approximately at the midpoint of the calibration range. These standards must be independent of the calibration solutions and be prepared from a stock solution with a different manufacturer or manufacturer lot identification than the calibration standards. An acceptance criterion is set, usually as a maximum allowable percentage variation (e.g., 5%, 10%). The calibration can be continually verified using either a calibration standard or the initial calibration verification standard. Acceptance criteria must be set and action taken when results fall outside the limits (i.e., stop the analysis, investigate, correct the problem and rerun samples run between the verification standards that were not limits). 

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