Concentration parts per million

FEED WATER CONCENTRATION PARTS PER MILLION AS NaCI... 

The presence of A-nitrosamines in the atmosphere, workplace, food, and articles of common use should be monitored and later eliminated. Checking the presence of nitrosamines is particularly important for products intended for direct contact with food and the human body. This applies especially to rubber articles intended for infants and children (e.g., pacifiers and toys) and products used in the food industry (e.g., hoses, belts, machine parts). Despite the fact that nitrosamines in rubber products are present in very low concentrations (parts per million and lower), these compounds can threaten health. 

In trace gas analysis, it is required to monitor compounds, frequently organics, in atmosphere at low concentrations (parts per million (mol) or lower). Mass spectrometry offers versatile instrumentation for this, particularly when sensitivity and selectivity are enhanced by special inlet techniques or ionization processes. 

The same conclusions can be drawn regarding electrochemical sensors (Korotcenkov et al. 2011, etc). Electrochemical sensors are suitable only for low-concentration, parts-per-million ranges. In addition, their life expectancy is only 2-5 years. Moreover, depending on the application, life expectancy may be much shorter. However, the electrochemical gas sensors have very low power consumption, respond quickly to gas, and are not affected by humidity. These sensors can also be exposed to gas periodically, which maximizes sensor life. Therefore, one can conclude that electrochemical sensors are a good choice for portable instruments and alarm/dosimeter systems, including Ughtweight, personal monitor/alarm devices, rather than for continuous monitors. 

Country Time period Maximum SO2+SO3 (SOJ concentration (parts per million) ... 

Compound, concentration Parts per million in juice with spike of ... 

A microbe employs a focused beams of energetic ions, to provide infomiation on the spatial distribution of elements at concentration levels that range from major elements to a few parts per million [27]. The range of teclmiques available that allowed depth infomiation plus elemental composition to be obtained could all be used in exactly the same way it simply became possible to obtain lateral infomiation simultaneously. 

Elements in the slope matrix A are proportional to absorptivities and concentrations are in parts per million. We shall take this as the true slope matrix. 

Parts per million (ppm) and parts per billion (ppb) are mass ratios of grams of solute to one million or one billion grams of sample, respectively. For example, a steel that is 450 ppm in Mn contains 450 pg of Mn for every gram of steel. If we approximate the density of an aqueous solution as 1.00 g/mL, then solution concentrations can be expressed in parts per million or parts per billion using the following relationships. 

For gases a part per million usually is a volume ratio. Thus, a helium concentration of 6.3 ppm means that one liter of air contains 6.3 pL of He. 

The units of concentration most frequently encountered in analytical chemistry are molarity, weight percent, volume percent, weight-to-volume percent, parts per million, and parts per billion. By recognizing the general definition of concentration given in equation 2.1, it is easy to convert between concentration units. 

Concentration methods frequently have both lower and upper limits for the amount of analyte that can be determined. The lower limit is dictated by the smallest concentration of analyte producing a useful signal and typically is in the parts per million or parts per billion concentration range. Upper concentration limits exist when the sensitivity of the analysis decreases at higher concentrations. 

A standard solution of Mn + was prepared by dissolving 0.250 g of Mn in 10 ml of concentrated HNO3 (measured with a graduated cylinder). The resulting solution was quantitatively transferred to a 100-mL volumetric flask and diluted to volume with distilled water. A 10-mL aliquot of the solution was pipeted into a 500-mL volumetric flask and diluted to volume, (a) Express the concentration of Mn in parts per million, and estimate uncertainty by a propagation of uncertainty calculation, (b) Would the uncertainty in the solution s concentration be improved... 

Ten laboratories were asked to determine the concentration of an analyte A in three standard test samples. Eollowing are the results, in parts per million. ... 

Description of the Method. The operational definition of water hardness is the total concentration of cations in a sample capable of forming insoluble complexes with soap. Although most divalent and trivalent metal ions contribute to hardness, the most important are Ca + and Mg +. Hardness is determined by titrating with EDTA at a buffered pH of 10. Eriochrome Black T or calmagite is used as a visual indicator. Hardness is reported in parts per million CaCOs. 

The concentration of Ch in a 100.0-mL sample of water drawn from a fresh water acquifer suffering from encroachment of sea water, was determined by titrating with 0.0516 M Hg(N03)2. The sample was acidified and titrated to the diphenylcarbazone end point, requiring 6.18 mb of the titrant. Report the concentration of Cb in parts per million. 

Eor each of the following, determine the forms of alkalinity (OH , HC03, C03 ) that are present, and their respective concentrations in parts per million. In each case, a 25.00-mL sample is titrated with 0.1198 M HCl to the bromocresol green and phenolphthalein end points. 

The concentration of cyanide, CN, in a copper electroplating bath can be determined by a complexometric titration with Ag+, forming the soluble Ag(CN)2 complex. In a typical analysis a 5.00-mL sample from an electroplating bath is transferred to a 250-mL Erlenmeyer flask, and treated with 100 mL of H2O, 5 mL of 20% w/v NaOH, and 5 mL of 10% w/v Kl. The sample is titrated with 0.1012 M AgN03, requiring 27.36 mL to reach the end point as signaled by the formation of a yellow precipitate of Agl. Report the concentration of cyanide as parts per million of NaCN. 

Selectivity Due to the narrow width of absorption lines, atomic absorption provides excellent selectivity. Atomic absorption can be used for the analysis of over 60 elements at concentrations at or below the level of parts per million. 

A sample of Crystal Pepsi, analyzed as described here, yields an absorbance of 0.565. What is the concentration of phosphorus, reported as parts per million of P, in the original sample of Crystal Pepsi ... 

What is the concentration of iron in parts per million for a sample with an absorbance of 0.100 ... 

After adding p-rosaniline and formaldehyde, the colored solution was diluted to 25 ml in a volumetric flask. The absorbance was measured at 569 nm in a 1-cm cell, yielding a value of 0.485. A standard sample was prepared by substituting a 1.00-mL sample of a standard solution containing the equivalent of 15.00 ppm SO2 for the air sample. The absorbance of the standard was found to be 0.181. Report the concentration of SO2 in the air in parts per million. The density of air maybe taken as 1.18 g/L. 

The concentration of copper in a sample of sea water is determined by anodic stripping voltammetry using the method of standard additions. When a 50.0-mL sample is analyzed, the peak current is 0.886 )J,A. A 5.00-)J,L spike of 10.0-ppm Cu + is added, giving a peak current of 2.52 )J,A. Calculate the parts per million of copper in the sample of sea water. 

Scale of Operation Voltammetry is routinely used to analyze samples at the parts-per-million level and, in some cases, can be used to detect analytes at the parts-per-billion or parts-per-trillion level. Most analyses are carried out in conventional electrochemical cells using macro samples however, microcells are available that require as little as 50 pL of sample. Microelectrodes, with diameters as small as 2 pm, allow voltammetric measurements to be made on even smaller samples. For example, the concentration of glucose in 200-pm pond snail neurons has been successfully monitored using a 2-pm amperometric glucose electrode. ... 

Accuracy The accuracy of a voltammetric analysis often is limited by the ability to correct for residual currents, particularly those due to charging. For analytes at the parts-per-million level, accuracies of+1-3% are easily obtained. As expected, a decrease in accuracy is experienced when analyzing samples with significantly smaller concentrations of analyte. 

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