Percent recovery

Spike Recoveries One of the most important quality assessment tools is the recovery of a known addition, or spike, of analyte to a method blank, field blank, or sample. To determine a spike recovery, the blank or sample is split into two portions, and a known amount of a standard solution of the analyte is added to one portion. The concentration of the analyte is determined for both the spiked, F, and unspiked portions, I, and the percent recovery, %R, is calculated as... 

A spike recovery for the analysis of chloride in well water was performed by adding 5.00 mb of a 25,000-ppm solution of Ck to a 500-mL volumetric flask and diluting to volume with the sample. Analysis of the sample and the spiked sample resulted in chloride concentrations of 183 ppm and 409 ppm, respectively. Determine the percent recovery of the spike. 

Quantitative mass spectrometry, also used for pharmaceutical appHcations, involves the use of isotopicaHy labeled internal standards for method calibration and the calculation of percent recoveries (9). Maximum sensitivity is obtained when the mass spectrometer is set to monitor only a few ions, which are characteristic of the target compounds to be quantified, a procedure known as the selected ion monitoring mode (sim). When chlorinated species are to be detected, then two ions from the isotopic envelope can be monitored, and confirmation of the target compound can be based not only on the gc retention time and the mass, but on the ratio of the two ion abundances being close to the theoretically expected value. The spectrometer cycles through the ions in the shortest possible time. This avoids compromising the chromatographic resolution of the gc, because even after extraction the sample contains many compounds in addition to the analyte. To increase sensitivity, some methods use sample concentration techniques. 

NOTE Percent recovery = 97.5 percent residue = 1.0 percent loss = 1.5. To convert degrees Fahrenheit to degrees Celsius, = ( F — 32)/1.8. 

Four theoretical plates have been stepped off for the key component (butane) on Fig. 14-9 and are sufficient to give a 75 percent recovery of butane. The operating hues for the other components were drawn in with the same slope and were placed so as to give the same number of theoretical plates insofar as possible. 

The effects of vaiious cationic interferences on percent recovery of Cobalt were studied. The method was successfully applied for the determinations of Cobalt ion from synthetic and water samples. 

Fraction Volume (mL) Total Protein (mg) Total Activity Specific Activity Percent Recovery ... 

The percent recovery of total activity is a measure of the yield of die desired product, xandiine dehydrogenase. 

Figure 2 The percent recovery of the modified polymer from rat small intestine after 1 h (a), and the schematic representation of in situ loop method using rat small intestine (b).

Yn + 1 = Mol fraction VOC component in the incoming fresh air (equals zero for fresh air) yj = Mol fraction solvent component in vapor Ys = Mol fraction steam in vapor YjB = Percent recovery of, i, in the bottoms YiD = Percent recovery of, i, in the distillate Z = Compressibility factor z F = Mol fraction component, i, in feed Zj Fj = Mol fraction component, i, in feed, j z s = Mol fraction component, i, in sidestream Zi sk = Mol fraction component, i, in sidestream, k... 

The composition and quantity of rich oil, and percent recovery of a specified key component are known, also column pressure and temperature. 

Another useful standard Is SRM 1647, priority pollutant polynuclear aromatic hydrocarbons (in acetonitrile). It can be used to calibrate liquid chromatographic Instruments (retention times. Instrument response), to determine percent recoveries, and to fortify aqueous samples with known PAH concentrations. Figure 8 Illustrates the HPLC separation and UV detection (fluorescence is also used extensively) for the 16 priority pollutants. 

Sample matrix Preparation method Analytical method Sample detection limit Percent recovery Reference... 

An alternative for evaluating accuracy is spiking known amounts of standards to a food, as reported in several papers,although percent recoveries of spikes do not truly address the influence of the food matrix complexity on the extraction efficiency. Data evaluation procedures were developed as a manual system to assess the quality of analytical data for carotenoids in foods. ... 

Table II. Percent Recoveries of Polystyrene Using SLS and NaCl...

Calculation of material halances of the polystyrene latexes through these LEG systems showed significant retention of the sample within the column. Percent recoveries of polystyrene latexes calculated at 2 k nm for the columns oj Set II are given in Table IV. The small particle sizes (<1000 A) are completely recovered, while significant loss of sample is seen for the larger particle sizes. 

Percent Recoveries of Polystyrene Latexes Using Column Set II... 

For a known injection of concentration Cq (particles/cc), the number of particles injected is given by CqVs. Therefore the niomber percent recovery, R, is calculated as... 

The minimum detectable level is estimated with the dinifroaniline signal-to-noise ratios (S/N). With fortification levels between 0.2 and 0.5mgkg the recovery of trifluralin from plant matrices is 70-99% with the LOD/LOQ being 0.005 mg kg according to the analytical method of the Ministry of the Environment, Japan. In multiresidue analysis by GC/NPD, the percent recoveries of pendimethalin from each crop with a fortification level of 0.25 mg kg were brown rice 70, potato 70, cabbage 80, letmce 89, carrot 84, cucumber 64, shiitake 74, apple 76, strawberry 99, and banana 99%. The LOD for each sample was 0.01 mg kg for pendimethalin. In residue analysis by GC/ECD, recoveries of the majority of dinifroaniline herbicides from fortified samples of carrot, melon, and tomato at fortification levels of 0.04—0.10 mg kg ranged from 79 to 92%. The LODs were benfluralin 0.001, pendimethalin 0.002 and trifluralin 0.001 mg kg for the GC/ECD method. ... 

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