Analytical colorimetric method

Analytical and Test Methods. Colorimetric quaUtative tests for diketene are known but seldom used (131). Identification is by spectrometric methods. Diketene has typical ir absorption bands at - ISSO, 1855, and 1685 cm , and signals at 3.92 (t), 4.51 (m), and 4.87 (m) ppm in the H-nmr spectmm (CDCl ). Purity is routinely monitored by gc. Alternatively, diketene is quantitatively converted to acetoacetic derivatives which are assayed by standard methods. 

There are a variety of analytical methods commonly used for the characterization of neat soap and bar soaps. Many of these methods have been pubUshed as official methods by the American Oil Chemists Society (29). Additionally, many analysts choose United States Pharmacopoeia (USP), British Pharmacopoeia (BP), or Pood Chemical Codex (FCC) methods. These methods tend to be colorimetric, potentiometric, or titrametric procedures. However, a variety of instmmental techniques are also frequendy utilized, eg, gas chromatography, high performance Hquid chromatography, nuclear magnetic resonance spectroscopy, infrared spectroscopy, and mass spectrometry. 

L C Thomas and G J Chamberlin (revised by G Shute), Colorimetric Chemical Analytical Methods, 9th edn, Tintometer Ltd, Salisbury, 1970... 

A Handbook of Colorimetric Chemical Analytical Methods, 6th edn, The Tintometer Ltd. 

The aforementioned series of reactions provides a basis for a colorimetric analytical method for Compound 118 in which the commonly used agricultural chemicals do not interfere. The procedure described herein permits the estimation of as little as 10 micrograms of Compound 118, and has been successfully applied to the analysis of this insect toxicant in insecticidal dusts, in film residues on glass and paper, in human and animal urine, and in mixture with other insecticides. Application of this procedure to the determination of Compound 118 in milk and in spray and dust residues on plants appears promising. 

Colorimetric methods (3, 6-10), some of which are specific, have been developed for the determination of DDT in small amounts. For benzene hexachloride (hexachloro-cyclohexane), chlordan, and toxaphene, however, specific analytical methods have not been developed, and their residues have been evaluated by the determination of organically bound chlorine. The procedure comprises extraction of the insecticide residue from the sample with benzene or other suitable organic solvent, evaporation of the solvent, treatment of the residue with isopropyl alcohol and metallic sodium, and finally determination by standard methods of the amount of chloride ion formed. 

Water for injection (WFI) is the most widely used solvent for parenteral preparations. The USP requirements for WFI and purified water have been recently updated to replace the traditional wet and colorimetric analytical methods with the more modern and cost-effective methods of conductivity and total organic carbon. Water for injection must be prepared and stored in a manner to ensure purity and freedom from pyrogens. The most common means of obtaining WFI is by the distillation of deionized water. This is the only method of preparation permitted by the European Pharmacopoeia (EP). In contrast, the USP and the Japanese Pharmacopeias also permit reverse osmosis to be used. The USP has also recently broadened its definition of source water to include not only the U.S. Environmental Protection Agency National Primary Drinking Water Standards, but also comparable regulations of the European Union or Japan. 

The methods most commonly used to detect hydrogen sulfide in environmental samples include GC/FPD, gas chromatography with electrochemical detection (GC/ECD), iodometric methods, the methylene blue colorimetric or spectrophotometric method, the spot method using paper or tiles impregnated with lead acetate or mercuric chloride, ion chromatography with conductivity, and potentiometric titration with a sulfide ion-selective electrode. Details of commonly used analytical methods for several types of environmental samples are presented in Table 6-2. 

Determination in Biological Fluids and Tissues All the advances in pharmacokinetics and drug metabolism described in Sections 7 and 8 would not have been possible without the availability of the proper analytical methods. The following is a tabulation of publications in this field, most of which have already been discussed in Section 5. It should be mentioned that a few publications talk about aspirin blood levels, but really mean salicylate levels. The following tabulation covers only those papers where aspirin was differentiated from other salicylates by chromatography or other means. It seems that the "workhorse" for serum salicylate levels is still the colorimetric (ferric-nitrate) method of Brodie, Udenfriend and Coburn153 published in 1944, or modifications thereof. Simplified versions (cf. 206) may lead to erroneous results under certain conditions.207 The method is also applicable for urinary metabolites after proper hydrolysis (cf. 208). For other methods restricted to salicylic acid, see Section 5.61. 

Thomas LC and GJ Chamberlain, Colorimetric Chemical Analytical Methods, 9th ed., Wiley-Interscience, New York, 1980. 

Part—I has three chapters that exclusively deal with General Aspects of pharmaceutical analysis. Chapter 1 focuses on the pharmaceutical chemicals and their respective purity and management. Critical information with regard to description of the finished product, sampling procedures, bioavailability, identification tests, physical constants and miscellaneous characteristics, such as ash values, loss on drying, clarity and color of solution, specific tests, limit tests of metallic and non-metallic impurities, limits of moisture content, volatile and non-volatile matter and lastly residue on ignition have also been dealt with. Each section provides adequate procedural details supported by ample typical examples from the Official Compendia. Chapter 2 embraces the theory and technique of quantitative analysis with specific emphasis on volumetric analysis, volumetric apparatus, their specifications, standardization and utility. It also includes biomedical analytical chemistry, colorimetric assays, theory and assay of biochemicals, such as urea, bilirubin, cholesterol and enzymatic assays, such as alkaline phosphatase, lactate dehydrogenase, salient features of radioimmunoassay and automated methods of chemical analysis. Chapter 3 provides special emphasis on errors in pharmaceutical analysis and their statistical validation. The first aspect is related to errors in pharmaceutical analysis and embodies classification of errors, accuracy, precision and makes... 

Rozet, E., Wascotte, V., Lecouturier, N., Preat, V., Dewe, W., Boulanger, B., Hubert, P. Improvement of the decision efficiency of the accuracy profile by means of a desirability function for analytical methods validation application to a diacetyl-monoxime colorimetric assay used for the... 

If analytical methods are at the heart of biopharmaceutical development and manufacturing, then protein concentration methods are the workhorse assays. A time and motion study of the discovery, development, and manufacture of a protein-based product would probably confirm the most frequently performed assay to be protein concentration. In the 1940s Oliver H. Lowry developed the Lowry method while attempting to detect miniscule amounts of substances in blood. In 1951 his method was published in the Journal of Biological Chemistry. In 1996 the Institute for Scientific Information (ISI) reported that this article had been cited almost a quarter of a million times, making it the most cited research article in history. This statistic reveals the ubiquity of protein measurement assays and the resilience of an assay developed over 60 years ago. The Lowry method remains one of the most popular colorimetric protein assays in biopharmaceutical development, although many alternative assays now exist. 

In Figure 5.1, the fraction of iron whose concentration is being reported is identified as the total dissolved iron concentration. In practice, this fraction is operationally defined by the analytical method used in its measurement. For the data in Figure 5.1, the total dissolved iron concentration was determined by filtration to remove the solid iron, followed by colorimetric analysis to quantify the solutes. Another analytical technique, such as filtration followed by atomic absorption spectrophotometry, might yield a different total dissolved concentration, so it is important to be aware of the analytical methods used. To address this issue, marine chemists engage in intercalibration experiments to assess differences in results from various analytical methods. 

The reasonably well-established dithiophosphate complexes are listed in Table 1. Complexes alleged to be involved in colorimetric analytical methods, solvent extraction and flotation procedures are generally omitted unless they have also been characterized in the solid state. 

A colorimetric method based on the violet color produced by ferrous sulfate in sulfuric acid in the presence of N03 was announced by English in 1947 (Ref 9) and applied to the determination of NA and nltrosylsulfuric acid (NSA) in spent mixed acid. Since then a number of papers (Refs 13, 14, 15, 16 and 17) have extended the method to NOa, organic nitrates and RDX -HMX mixtures Analytical Methods The visual determination of the endpoint (appearance of a permanent brown color) in the dead-stop titrimetric method is reported accurate to 0.03ml (Ref 3) and was used recently by Frejacques and LeClercq (Ref 12) for analysis of Pentolites, Tetryls, NGu, NG prepns, and Nitroethane-EGDN expls. The endpoint has been criticized as difficult to see, and if problems arise, electrometric methods are available for detection (Refs 6,... 

Analytical methods employed in soil chemistry include the standard quantitative methods for the analysis of gases, solutions, and solids, including colorimetric, titrimetric, gravimetric, and instrumental methods. The flame emission spectrophotometric method is widely employed for potassium, sodium, calcium, and magnesium barium, copper and other elements are determined in cation exchange studies. Occasionally arc and spark spectrographic methods are employed. 

W.Keyser, "Colorimetric Analysis , Chapman Sc Hall, London (1957) 7)D.F.Boltz, "Colorimetric Determination of Nonmetals , Wiley (1958) 8)E.B.Sandell, "Colorimetric Determination of Traces of Metals , Wiley, NY (1959 ) 9)Tintometer Ltd "Colormetric Chemical Analytical Methods , The Author, Salisbury, England (1959) 10)Vogel, InorgAnalysis (1961) 738-837 (Colorimetric and spectrophotometric analysis description of various colorimeters) ll)Pamphlets and catalogs of A.H.Thomas,... 

Traditional methods for analyzing proanthocyanidins have relied on general colorimetric methods. The main drawback for using these analytical methods is that they are not specific for proanthocyanidins. This can be said for chromatographic methods that analyze intact proanthocyanidins. The selectivity of the... 

Wet chemical methods involve sophisticated sample preparation and standardization with National Bureau of Standards reference materials but are not difficult for the analytical chemist nor necessarily time consuming (Figure 1). The time from sample preparation to final results for various analytical methods, such as GFAA (graphite furnace atomic absorption), ICP (inductively coupled plasma spectroscopy), ICP-MS (ICP-mass spectrometry), and colorimetry, ranges from 0.5 to 5.0 h, depending on the technique used. Colorimetry is the method of choice because of its extreme accuracy. Typical results of the colorimetric analysis of doped oxides are shown in Tables I and II, which show the accuracy and precision of the measurements. 

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