Turbidimetric method

HTSol assays employing DMSO stock solutions vary in the nature of the analysis of aqueous samples. Two approaches are commonly observed (1) turbidimetric methods, where the formation or loss of precipitate is monitored against concentration, and (2) direct quantification of compound in solution by UV absorption spectroscopy following removal of precipitate by filtration. 

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Analysis of zinc solutions at the purification stage before electrolysis is critical and several metals present in low concentrations are monitored carefully. Methods vary from plant to plant but are highly specific and usually capable of detecting 0.1 ppm or less. Colorimetric process-control methods are used for cobalt, antimony, and germanium, turbidimetric methods for cadmium and copper. Alternatively, cadmium, cobalt, and copper are determined polarographicaHy, arsenic and antimony by a modified Gutzeit test, and nickel with a dimethylglyoxime spot test. 

Sulphate in Waters, Effluents and Solids (2nd Edition) [including Sulphate in Waters, Effluents and Some Solids by Barium Sulphate Gravimetry, Sulphate in waters and effluents by direct Barium Titrimetry, Sulphate in waters by Inductively Coupled Plasma Emission Spectrometry, Sulphate in waters and effluents by a Continuous Elow Indirect Spectrophotometric Method Using 2-Aminoperimidine, Sulphate in waters by Elow Injection Analysis Using a Turbidimetric Method, Sulphate in waters by Ion Chromatography, Sulphate in waters by Air-Segmented Continuous Elow Colorimetry using Methylthymol Blue], 1988... 

Turbidimetric methods for particle size analysis (Refs 10, 16 27) are used in conjunction with sedimentation procedures to determine the concn of particles at given distances below the surface at successive time intervals. From these data, and Stokes law, particle size distribution can be calculated... 

Physical methods for endpoint detection have been suggested. Hellsten [226] proposed an instrumental turbidimetric method to determine the endpoint, which does not need indicators. Since chloroform is emulsified by the anionic surfactant, changes in the optical density can be followed by a colorimeter thus detecting the endpoint when the emulsion breaks. Another turbidimetric method based on commercially available automatic titrators has also been proposed [227],... 

Vogel, W. C. and Zieve, L. A rapid and sensitive turbidimetric method for serum lipase based upon differences between lipases of normal and pancreatitis serum. Clin. Chem. (1963), , 168-181. 

TITRATIONS FOR COMPARISON OF METHODS. The automated photometric and turbidimetric methods were compared using 30 cm3 samples of surfactant solution containing a nominal 20 mol SDBS to give an equivalence volume of 5 cm3. The effect of salinity on the titrations was studied using samples prepared containing sodium chloride concentrations of 0.0, 0.14, 0.70 and 1.46 wt%. The influence of the choice of filter (580 or 620 nm) was also investigated. 

Avigad and Milner224 used a turbidimetric method based on the measurement of residual turbidity caused by complexing the acid polysaccharide with such quaternary ammonium detergents as cetyl-pyridinium bromide. The activity unit was expressed as the amount of enzyme bringing about a decrease of absorbance at 400 nm of 0.01/min. 

The microbiological methods used for the determination of CTC potency in body tissues and fluids, bulk products, and pharmaceutical formulations can be separated into two testing procedures (1) agar diffusion plate method (cylinder-plate) and (2) turbidimetric method. 

This method is used in lieu of the diffusion plate method for human and animal pharmaceutical formulations and bulk products. The turbidimetric method is described in the Code of Federal Regulations (77). 

Microbiological assays are the primary assay method for antibiotics. They provide sensitive but non-selective methods. A variety of microbiological methods have been described for the assay of gramicidin. The official method in the United States is the turbidimetric method described in the Code of Federal Regulations127 12 . 

The application of a turbidimetric method to the examination of serum samples has been reported by Felsenfeld - - ... 

Similar problems occur for the nephelometric and turbidimetric methods, where the sizes of the IgG-Lp(a) complexes depend upon that of apo(a) itself (L2, W4). Furthermore, problems due to interferences from elevated plasma triglyceride are commonly encountered in the precipitation techniques (C3). As Lp(a) can be redistributed among the Lp(a) fraction and the triglyceride-rich lipoproteins, especially in patients after a fatty meal (B11), these methods are not appropriate for monitoring Lp(a) levels and distribution in plasma. 

Brooker, P.J. and Ellison, M. The determination of the water solubility of organic compounds by a rapid turbidimetric method, Chem. Ind., (October 1974), pp. 785-787. 

Walstra, P. 1967. Turbidimetric method for milk fat determination. J. Dairy Sci. 50, 1839-1840. 

Fig. 21. Molecular weight distribution obtained by the turbidimetric method, as a function of the degree of conversion. Degree of conversion (mole/1) a —1.5 b —3.0 c —5.2 d —9.5 (74)...

Klipp, R. W. Determination of Trace Sulfur in Leaded Gasoline by Modified Lamp-Turbidimetric Method. Anal. Chem. 33, 1912 (1961). 

A turbidimetric method has been described for the determination of water-soluble and acid-soluble sulfate in hydrochloric acid extracts of soils [62]. Spectrophotometry has also been employed to carry out the determination of total water-soluble sulfate in soil [63,64],... 

Turbidimetric method is applicable when the S042- concentrations is between 5 and 50 mg/L. For concentrations above 50 mg/L, dilute the sample and analyze. 

In Table II are summarized representative results for the light scattering on a latex that was presumed to be capable of expansion at high pH. An independent estimate by the turbidimetric method gave a core diameter of 0.43 ym. 

K9. Kyhse-Andersen, J., Schmidt, C., Nordin, G., Andersson, B., Nilsson-Ehle, P., et al., Serum cystatin C, determined by a rapid, automated particle-enhanced turbidimetric method, is a better marker than serum creatinine for glomerular filttation rate. Clin. Chem. 40(10), 1921—1926 (1994). 

Platelet aggregation was measured according to the turbidimetric method with an... 

Turbidimetric methods are often used to estimate the relative mass of suspended solids generated in laboratory column studies or present in surface- and ground-water samples.717-29 38 47-50 In fact, turbidity is commonly used as an indicator when the chemistry within a monitoring well has stabilized during pumping so that a representative groundwater sample can be taken. 

Like crystallization, US also successfully assists the formation of extremely finely divided and uniform particles, which can be termed sonoprecipitation. This effect, which has not yet been used in analytical chemistry and might facilitate sample preparation in nephelometric or turbidimetric methods, has been widely exploited by the pharmaceutical industry to prepare liquid dispersions of drugs for oral or subcutaneous administration where extremely small particle sizes ensure stable suspensions of the drug and faster assimilation into the body. On a laboratory scale, US-assisted precipitation of magnesium carbonate in a model system has been studied [65]. 

Although extended reaction time was also used by Selsted and Martinez (1980) in their turbidimetric method, they did not stress the importance of the kinetic order of cell lysis. McKenzie and White (1986) showed that, while the reaction is biphasic, simple kinetics are obeyed over a sufficiently long period that this property can be exploited in the determination. The kinetic order must be considered in the quantitative treatment of the results. The limit of detection was found to be 100 pg ml of reaction mixture, equivalent in the case of bovine milk lysozyme to 6 ng ml of skim milk, for a 50-/xl sample. 

The fecal marker (PEG) was analyzed by the turbidimetric method of Malaware and Powell ( ). Total recoveries of ingested PEG in feces ranged from 20% to 99 7%. Three subjects excreted less than 60% of the ingested PEG, whereas the rest had an average recovery of 85.3% (range 73%-99.7%). 

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