Relative standard deviation RSDs

The obtained analytical forms are used for quantitative determination of both Diclofenac natrium and Ibuprofen content in medicinal forms as well as for the testing uniformity of batching of the basic substance in tableted forms. The relative standard deviation (RSD) were 3,7-4,6 % (n = 5 P = 0,95). 

The accuracy and precision of the determinations were investigated. Recovery was found to be 101 2.0% for a range of volumetrically mixed samples and the relative standard deviation (RSD), for a standard injected 23 times over a period of 4.5 months, was found to be 1.1%. It should be noted that the performance of a method for samples based on standard materials may not be attainable when real samples are being determined and further method development may be required. 

The relative standard deviation RSD (also known as the coefficient of variation, c.o.v., or CV), which is frequently used to compare reproducibilities, is calculated as... 

The relative standard deviation RSD (or c.o.v. = coefficient of variation ) is constant over the whole range, such as in many GC methods, that is, the standard deviation Sy is proportional to y. 

An interlaboratory study using mixed vegetable reference material showed average relative standard deviations (RSDs) of 23% ranging from 11% for lutein and a-carotene to 40% for lycopene." Triplicate HPLC injections of the same extract showed RSD values of 0% for P-carotene and 6.8% for lutein. ... 

If the variability (a) depends on concentration, prior knowledge of concentration may be required to use these formulas. If the relative standard deviation (RSD) is constant with respect to concentration, then the formulas can be applied by interpreting a and E as relative standard deviation and relative error, respectively. A common case in which RSD is constant with respect to concentration is when analytical results are lognormally distributed. For example, suppose it is desirable to estimate the average concentration with 95% confidence that the estimate will be within 10% of the true value if the relative standard deviation is 25%. Then... 

The limit of detection (LOD) is an important criterion of the efficiency of an analytical method. It is characterized by the smallest value of the concentration of a compound in the analytical sample. The detectable amount of anilide compounds is in the range 0.01-0.5 ng by GC and 0.1 ng by HPLC. The limit of quantitation (LOQ) ranges from 0.005 to 0.01 mg kg for vegetables, fruits and crops. The recoveries from untreated plant matrices with fortification levels between 10 and 50 times the LOD and the LOQ are 70-120%. The relative standard deviation (RSD) at 10-50 times the level of the LOD and LOQ are <10 % and <20%, respectively. 

Prior to use, the linearity of the GC system should be verified by analyzing at least four standards of different concentrations. The linearity standards should range in concentration from 0.1 to 2.0 j.gmL for crops and soils and from 0.05 to 1.0 lagmL for water. The response of each standard is normalized to response per 1.0 lagniL by dividing the response of each standard by its concentration. The relative standard deviation (RSD) of these normalized responses should be < 10%. 

The acceptable method recoveries using untreated plant matrices at fortification levels between 10 and 50 times the LOD must be from 70 to 120%. The relative standard deviation (RSD) must be within the range 10-20% (according to the analytical method of the Ministry of the Environment, Japan). 

The recoveries from untreated control samples fortified with fluthiacet-methyl at 0.2mgkg were 96% [relative standard deviation (RSD) 3.1%] for corn and 74% (RSD 8.0%) for green corn. The limit of detection was 0.01 mg kg 7 The recoveries from untreated control soils fortified with fluthiacet-methyl at 0.1 and 0.2mgkg were 85-103% and 87-103%, respectively. The limit of detection was 0.01 mgkg 7... 

Content uniformity is a USP test is designed to establish the homogeneity of a batch. Ten tablets are assayed individually after which the arithmetic mean and relative standard deviation (RSD) are calculated. USP criteria are met if the content uniformity lies within 85-115% of the label claim and the RSD is not greater than 6%. Provision is included in the compendium for additional testing if one or more units fail to meet the standards. 

Fig. 7.3. The so-called Horwitz trumpet Dependency of the relative standard deviation, rsd(x) on the concentration (x)...

Another form of expression can also derived as CV (%) is another term for % relative standard deviation (%RSD) as equation 71-6 (reference [6]). 

Statistical analysis One hundred microspores were analysed per slide. Counting was done in four or five replicates (the number of Petri dishes per treatment). Results were expressed as mean SEM (SEM shown graphically in figures). The relative standard deviation (RSD) was 5-6% (n = 400-500 microspores per one variant P =0.95). 

Precision FIA measurements typically show low relative standard deviations (RSD) on replicate measurements, mainly due to the definite and reproducible way of sample introduction. This is a very important feature especially for CL, which is very sensitive to several environmental factors and sensitivity relies greatly on the rate of the reaction. 

Relative measures of the spread of data are often used, particularly where, for example, the spread of results seems to increase with analyte concentration. The relative standard deviation (RSD) is a measure of the spread of data in comparison to the mean of the data ... 

Figure 6.18 presents example chromatograms obtained during the evaluation of retention time and peak area reproducibility across the 24 columns (within a single composite run). Table 6.1 lists the average retention time reproducibility and peak area reproducibility values obtained across 24 columns for a total of 24 composite runs (column to column within run). Reproducibility values are expressed as percentage relative standard deviation (%RSD). 

Relative standard deviation. One final deviation parameter is the relative standard deviation (RSD). It is calculated by dividing the standard deviation by the mean and then multiplying by 100 or 1000 ... 

According to the dissolution method, precision is determined by testing at least six aliquots of a homogenous sample for each dosage strength. The precision should be assessed at each specification interval for the dosage form. The precision can be determined by calculating the relative standard deviation (RSD) of the multiple aliquots from each solution. 

Another HPTLC method has been developed for the separation of kaempferol and quercetin in the extract of Ginkgo biloba leaves showing beneficial effect in brain diseases. Leaves were refluxed with methanol for 30 min then filtered. The filtrate was refluxed with 25 per cent HC1 for 60 min then neutralized with ammonia and the clear supernatant was applied for HPTLC. Silica plates were predeveloped in chloroform-methanol (1 1, v/v). Separation was performed with toluene-acetone-methanol-formic acid (46 8 5 1, v/v) as the mobile phase using incremental multiple development. A densitogram illustrating the good separation charactersitics of the system is shown in Fig. 2.42. The relative standard deviation (RSD) of the method was low (1.37 and 1.40 for kaempferol and quercetin,... 

The CE method was validated in terms of accuracy, precision, linearity, range, limit of detection, limit of quantitation, specificity, system suitability, and robustness. Improved reproducibility of the CZE method was obtained using area normalization to determine the purity and levels of potential impurities and degradation products of IB-367 drug substance. The internal standard compensated mainly for injection variability. Through the use of the internal standard, selected for its close mobility to IB-367, the method achieved reproducibility in relative migration time of 0.13% relative standard deviation (RSD), and relative peak area of 2.75% RSD. 

Abstract A preconcentration method using Amberlite XAD-16 column for the enrichment of aluminum was proposed. The optimization process was carried out using fractional factorial design. The factors involved were pH, resin amount, reagent/metal mole ratio, elution volume and samphng flow rate. The absorbance was used as analytical response. Using the optimised experimental conditions, the proposed procedure allowed determination of aluminum with a detection limit (3o/s) of 6.1 ig L and a quantification limit (lOa/s) of 20.2 pg L, and a precision which was calculated as relative standard deviation (RSD) of 2.4% for aluminum concentration of 30 pg L . The preconcentration factor of 100 was obtained. These results demonstrated that this procedure could be applied for separation and preconcentration of aluminum in the presence of several matrix. 

The precision of the method calculated as the relative standard deviation (RSD) for five replicates was 2.4% for the level of 30 pg L of aluminum in water. 

Whereas precision (Section 6.5) measures the reproducibility of data from replicate analyses, the accuracy (Section 6.4) of a test estimates how accurate the data are, that is, how close the data would represent probable true values or how accurate the analytical procedure is to giving results that may be close to true values. Precision and accuracy are both measured on one or more samples selected at random for analysis from a given batch of samples. The precision of analysis is usually determined by running duplicate or replicate tests on one of the samples in a given batch of samples. It is expressed statistically as standard deviation, relative standard deviation (RSD), coefficient of variance (CV), standard error of the mean (M), and relative percent difference (RPD). 

This 2D-method was validated for the concentration range between 0.005 and 0.5 pmol for D-amino acids and 0.05-5 pmol for L-amino acids. Within-day and interday precisions were always better than 8% relative standard deviation (RSD) and the accuracies for spiked rat plasma samples were between 95.5% and 100.2%. Limit of detections (LCDs) and limit of quantitations (LOQs) were reported to be as low as 3 fmol (S/N = 3-5 corresponding to 0.15 nmolg wet tissue) and 5 fmol (corresponding to 0.25 nmolg wet tissue). It was concluded that this assay is supposed to be one of the most sensitive analysis method for amino acid enantiomers in mammalian samples. 

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