Maximum reportable concentration measurement

Maximum reportable concentration. The upper limit of measurement for a method is usually defined as the concentration at which the curve shows a certain deviation from linearity. 

Confidence bands are direct precision data, and the maximum reportable concentration can be defined as the maximum concentration at which the method yields adequate precision ( ) (excluding measurements near the minimum reportable concentration, where poor precision is unavoidable). Table III shows RCB for the determination of iron in water by AAS. The analyst may consider a RCB of say, 15% to be adequate. The maximum reportable concentration would be 15 pg/ml from a single, weighted least-squares curve, and 20 pg/ml by the multiple-curve method. Samples containing > 20 pg/ml should be diluted to 1-10 pg/ml and analyzed using standards containing 0.05 - 15 pg/mL. (Note that it is always better to include a standard above the maximum desired concentration. The precision of this standard measurement will be poor, but poor data at this level are better than none.)... 

Braun and Frank (1980) reported diazinon residues in three fish species collected from a creek in southern Ontario, Canada, contaminated from a point source discharge. Tissue residues for the three edible fish species were 18 ppb in the brown bullhead (Ictalurus nebulosus), 17 ppb in the black crappie (Pomoxis nigromaculatus), and 92 ppb in the gizzard shad (Dorosoma cepedianum). The maximum diazinon concentrations measured in the contaminated creek water for 1975-76 and 1976-77 were 140 ppb (5.75 ppb mean) and 26 ppb (1.02 ppb mean), respectively. 

NCRP (1953). National Committee on Radiation Protection and Measurements, Maximum Permissible Amounts of Radioisotopes in the Human Body and Maximum Permissible Concentrations in Air and Water, NCRP Report No. 11, published as National Bureau of Standards Handbook No. 52, Superseded by NCRP Report No. 22 (National Council on Radiation Protection and Measurements, Washington). 

As informed Dr. A.I. Korableva from Institute for Environmental Management and Ecology under the National Academy of Sciences of Ukraine in the report "Environmental impact of automobile transport by example of Dnepropetrovsk", Dnepropetrovsk with its annual discharge of air pollutants of 177,000 t (as of 1996) is among the worst affected cities in Ukraine. In these, the automobile transport was found to be responsible for at least 30 % of the total emissions which are 15 times the maximum permissible level. Aside from the dust, chemical, photochemical and noise pollution, there is the aspect of street washout of automobile-related pollutants into the River Dnieper. The measured annual receipts of lead, particulates and petroleum derivatives via rainwater and thaw water to the river are 0.45, 80,000+ and 1.8+ t respectively. The actual levels of petroleum derivatives in storm water sometimes were 206 times the maximum permissible concentration (MPC) for the fishery basins. At 34 km downstream from the city, the estimated levels of petroleum derivatives and particulates are 61 and 10.8 times the respective MPCs. The airborne lead is mainly accumulated in the soil of housing areas. 

In a study of pesticide levels in ambient suburban air, diazinon was detected in 80, 80, and 40% of samples collected in three cities (Miami, Florida Jackson, Mississippi and Fort Collins, Colorado), respectively. The maximum diazinon concentration detected in each city was 3.9, 2.0, and 2.2 ng/m3 for Miami, Florida Jackson, Mississippi and Fort Collins, Colorado, respectively (Kutz et al. 1976). During 1973-1974, diazinon concentrations in air were measured in urban Miami, Florida, and in the adjacent Everglades National Park. Urban diazinon levels ranged from not detectable to 3.3 ng/m3 (1.5 ng/m3 mean) corresponding levels in Everglades National Park ranged from not detectable to 1.9 ng/m3 (0.6 ng/m3 mean) (Lewis and Lee 1976). Nationwide, diazinon was detected in 48% of 123 urban air samples collected in ten U S. cities during 1980. The maximum diazinon concentration reported was 23 ng/m3 (mean 2.1 ng/m3) (Carey and Kutz 1985). 

Further acid site strength and concentration measurements were reported by Morita et al. (164), who related the acidity measurements to various catalytic reactions. Using Y zeolite (Linde SK-40, 90% H form) activated at 450°C, they observed no acid sites stronger than an H0 of -8.2, although the total acid site concentration was almost twice that of the former investigations (Fig. 21, curve 4). They also measured acid site concentration as a function of decomposition temperature for NH4Y, and found that n-butylamine titration values paralleled results obtained from pyridine adsorption studies (41,151). The maximum total acidity occurred... 

In the case of metoprolol succinate and metoprolol fumarate, the maximum drug concentration in the plasma( max) and the area under the plasma drug concentration-time curve were statistically equivalent, based on a 90% conLdence interval (Sandberg et al., 1993). With fenoprdffcQmthe following administration of its calcium salt was reached somewhat later thaCmjpassociated with the sodium form (Rubin et al., 1971). This was attributed to the slower dissolution rate for the calcium salt in acidic pH. Bioavailability and the measured distribution and elimination parameters, however, were reported to be similar. 

Solubility constraints define the maximum concentrations of radionuclides at the point of release from the waste. In the second section, radionuclide solubilities in natural waters are reported as measured values and estimated values from thermodynamic data. In addition, information is given concerning the chemical species of radionuclides that could be present in natural waters. 

Five depth profiles of NO and the corresponding NO production rates have been measured in the ETNP (Ward and Zafiriou, 1988) NO concentrations were in the range from 0 up to 65 pmol At four stations located in the open ocean, maximum NO concentrations were observed at the upper boundary of the oxygen minimum zone (OMZ, O2<10 pmol L ), whereas one coastal station showed an increase of NO from Opmol at the surface to about 20 pmol at the bottom in about 250m. Maximum NO production rates were found at the upper boundary of the OMZ at the open ocean stations. However, Ward and Zafiriou (1988) could not unambiguously identify the NO formation process because NO production rates and nitrification rates (i.e., NH oxidation rates) were not correlated. NO accumulation appeared when O2 concentrations were lower than 100 pmol L , whereas in the core of the OMZ with O2 concentrations close to 0 pmol denitrification seemed to cause a rapid turnover of NO. Highest ever-reported concentrations of dissolved NO were found off Peru ranging from 0 up to 400 pmol (Zafiriou, personal communication in Ward and Zafiriou (1988)). 

Thus, there are only a few data of dissolved oceanic NH3 available. (Reports on oceanic NH4 measurements are not considered here because without the knowledge of pH, water temperature, and salinity, the true concentration of dissolved NH3 remains speculative). Because the NH3/NH4 equihbrium strongly depends on the temperature, maximum NH3 concentrations are expected to occur in surface waters and should rapidly decrease with depth in association with temperature profiles in the subsurface and deep ocean. (Exceptions should occur in the few cases where subsurface NH4 maxima have been observed (Brzezinski, 1988 Gibb et al., 1999b)). Oceanic NH3 concentrations discussed in the fohowing paragraph are exclusively from the oceanic mixed layer. 

It is clear from the above discussion that there are large variations and some uncertainty in the reported maximum concentrations of mono-and dicarboxylic acid anions in formation waters. The use of these maximum values leads to erroneous results and conclusions. Maximum reported values together with more reasonable and likely maximum values are listed in Table 5. Only measured concentrations of organic and inorganic species from petroleum wells should be used in rigorous geochemical simulations (Kharaka et al., 1987). If field data are not available, then more reasonable conclusions are obtained by using the likely maximum values of Table 5. 

Current practice becomes less obvious when tar data are to be compared, for instance when comparing the performance of biomass gasifiers or apparatuses for gas cleaning, or when setting or working with tolerances (maximum allowable concentrations) for tar in gas cleaning devices or prime movers. The value of the comparison will depend on definition of tar and on the ability to measure tar according to the definition. A recent report on parallel measurements with different tar measurement methods at the same location 6 shows that comparison of tar data can be a difficult task. 

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