Analytical procedure range

Type of Analytical Procedure Range, at Minimum, to Be Covered... 

Integration of the whole analytical procedure ranging from sample pretreatment procedures to the analytical signals leads to true analytical labs-on-chips. 

The objective ia any analytical procedure is to determine the composition of the sample (speciation) and the amounts of different species present (quantification). Spectroscopic techniques can both identify and quantify ia a single measurement. A wide range of compounds can be detected with high specificity, even ia multicomponent mixtures. Many spectroscopic methods are noninvasive, involving no sample collection, pretreatment, or contamination (see Nondestructive evaluation). Because only optical access to the sample is needed, instmments can be remotely situated for environmental and process monitoring (see Analytical METHODS Process control). Spectroscopy provides rapid real-time results, and is easily adaptable to continuous long-term monitoring. Spectra also carry information on sample conditions such as temperature and pressure. 

Ultrafiltration utilizes membrane filters with small pore sizes ranging from O.OlS t to in order to collect small particles, to separate small particle sizes, or to obtain particle-free solutions for a variety of applications. Membrane filters are characterized by a smallness and uniformity of pore size difficult to achieve with cellulosic filters. They are further characterized by thinness, strength, flexibility, low absorption and adsorption, and a flat surface texture. These properties are useful for a variety of analytical procedures. In the analytical laboratory, ultrafiltration is especially useful for gravimetric analysis, optical microscopy, and X-ray fluorescence studies. 

Electrodriven Separation Techniques encompass a wide range of analytical procedures based on several distinct physical and chemical principles, usually acting together to perform the requh ed separation. Example of electrophoretic-based techniques includes capillary zone electrophoresis (CZE), capillary isotachophoresis (CITP), and capillary gel electrophoresis (CGE) (45-47). Some other electrodriven separation techniques are based not only on electrophoretic principles but rather on chromatographic principles as well. Examples of the latter are micellar... 

Moisture, Analytical Procedures. Various quantitative procedures have been developed ranging from simple oven drying thru sophisticated instrumental methods (Expls Refs 31,33,42,47, 52, 56, 57,60 62 Proplnts Refs 25,28,29,... 

Peroxomonosulphate and peroxodisulphate have also been used to oxidize sulphoxides to sulphones in good yields at room temperature. Potassium persulphate (KHS05) readily oxidizes a range of sulphoxides to sulphones at 0°C in yields greater than 90%, in the presence of hydroxy, keto and alkene groups82-84. The mechanism is similar to that observed for other peroxy species, as discussed above. Peroxomonosulphate oxidation has been used as an analytical procedure for the estimation of dimethyl sulphoxide84. 

The linearity of an analytical procedure is its ability (within a given range) to obtain test results, which are directly proportional to the concentration (amount) of analyte in the sample. 

The range of an analytical procedure is the interval between the upper and lower concentration (amounts) of analyte in the sample (including these concentrations) for which it has been demonstrated that the analytical procedure has a suitable level of precision, accuracy and linearity. 

Thompson, M., Robust Statistics and Functional Relationship Estimation for Comparing the Bias of Analytical Procedures over Extended Concentration Ranges, Anal. Chem. 61, 1989, 1942-1945. 

Because of the special regulatory position occupied by foods and beverages, a great deal of attention has been given to development and application of analytical procedures for them. Improved procedures have resulted in quantitation and confirmation levels in the range of 1 to 10 ppb with sample amounts of 10 to 250 g. Detection limits for foods are in the 0.1 to 1 ppb range. Detection limits of 0.1 to 1 ppm appear adequate for pesticide formulations (1, > while sensitivity of 0.01,... 

INAA is well suited to study homogeneity of small samples because of its dynamic range of elemental sensitivity. The technique allows for the use of small solid samples, with the smallest usable sample size in the range of 0.5 mg to i mg as determined by handling and blank considerations. The INAA analytical procedure is well understood and characterized with mathematical relationships. Its analytical uncertainties can be sufficiently controlled and can be well determined for a particular procedure. This allows the calculation of the contribution of material heterogeneity to the uncertainty budget based on experimental data. 

A form of this approach has long been followed by RT Corporation in the USA. In their certification of soils, sediments and waste materials they give a certified value, a normal confidence interval and a prediction interval . A rigorous statistical process is employed, based on that first described by Kadafar (1982,), to produce the two intervals the prediction interval (PI) and the confidence interval (Cl). The prediction interval is a wider range than the confidence interval. The analyst should expect results to fall 19 times out of 20 into the prediction interval. In real-world QC procedures, the PI value is of value where Shewhart (1931) charts are used and batch, daily, or weekly QC values are recorded see Section 4.1. Provided the recorded value falls inside the PI 95 % of the time, the method can be considered to be in control. So occasional abnormal results, where the accumulated uncertainty of the analytical procedure cause an outher value, need no longer cause concern. 

If this range overlaps the stated confidence interval of the certified value, then the analytical procedure may be assumed to be under satisfactory statistical control. Discussion about the accepted degree of overlap may inevitably occur so when reporting results it is good practice that the certified value of the CRM should be within the experimentally determined confidence interval. 

Different analytical procedures have been developed for direct atomic spectrometry of solids applicable to inorganic and organic materials in the form of powders, granulate, fibres, foils or sheets. For sample introduction without prior dissolution, a sample can also be suspended in a suitable solvent. Slurry techniques have not been used in relation to polymer/additive analysis. The required amount of sample taken for analysis typically ranges from 0.1 to 10 mg for analyte concentrations in the ppm and ppb range. In direct solid sampling method development, the mass of sample to be used is determined by the sensitivity of the available analytical lines. Physical methods are direct and relative instrumental methods, subjected to matrix-dependent physical and nonspectral interferences. Standard reference samples may be used to compensate for systematic errors. The minimum difficulties cause INAA, SNMS, XRF (for thin samples), TXRF and PIXE. 

Dyed aniline is spectrophotometrically indistinguishable from dyed parathion, within the visible range. However, when purified cyclohexylamine (7.6 X 10 5 M) is subjected to the analytical procedure there is no color development. 

The nature and the relative amounts in which the components of materials have to be detected in different analytical studies varies greatly from the identification and determination of the few major elements that make up a material, to the wide range, often in almost vanishing concentrations, of impurities. From a practical point of view and regardless of the objective of, or the type of information required from an analysis, most analytical procedures entail a sequence of three main operations ... 

The problem is illustrated in a simplified way in Fig. 7.6. The quantities sel(A,B,..., N) and spec(A,B,..., N) not only define absolute characteristics but also a certain degree of selectivity and specificity of an analytical procedure. The measures can take values from 1 for fully selective or totally specific procedures, respectively. The range of selectivity R sel and the range of specificity R spec are given by... 

The robustness of an analytical procedure for the determination of the analyte A in presence of some accompanying species i = B,...,N under influence of various factors fj(j = l,...,m) according to Eq. (4.30) is in reciprocal proportion to the sum of all their cross sensitivities, SA multiplied by the actual amounts, x and the specific influencing strengths, hjy of the factors multiplied by their actual values (in relation to xA) see Danzer (2004). Because of the way measurements are obtained, the range of their values is range = (0... oo), so it makes sense to calculate the relative robustness which includes the analyte sensitivity and amount itself, SAA xA, as follows ... 

The range of relative ruggedness is range rug = (0... 1), too. According to Burns et al. [2005], the relative ruggedness of an analytical procedure is given by the ratio of the ideal signal for an uninfluenced method corn-... 

Many analytical procedures based on GC/MS have been described for the analysis of a wide range of lipid materials in samples from art and historical objects [2,3,7,11,17,21,26], Wet chemical pretreatments are generally needed before GC/MS analysis, in order to ... 

---