Nelson method

The Wagner-Nelson method of calculation does not require a model assumption concerning the absorption process. It does require the assumption that (a) the body behaves as a single homogeneous compartment and (b) drug elimination obeys first-order kinetics. The working equations for this calculation are developed next. 

In the development of equations for the Wagner-Nelson method of calculation, the following equation was derived [see Eq. (42)] ... 

Martinelli and Nelson (M7) developed a procedure for calculating the pressure drop in tubular systems with forced-circulation boiling. The procedure, which includes the accelerative effects due to phase change while assuming each phase is an incompressible fluid, is an extrapolation of the Lockhart and Martinelli x parameter correlation. Other pressure drop calculation procedures have been proposed for forced-circulation phase-change systems however, these suffer severe shortcomings, and have not proved more accurate than the Martinelli and Nelson method. 

Alternate Protocol 1 Determination of Reducing Sugars Using the Somogyi-Nelson Method... 

DETERMINATION OF REDUCING SUGARS USING THE SOMOGYI-NELSON METHOD... 

The reference describes the analysis of reducing sugars using the Somogyi-Nelson method. It contains no experiments, but it is one of the first compilations explaining the method currently in use today. 

The Chi in the hairy roots and parent plant organs was extracted with a mixture of 80% acetone and 20% phosphate buffer (2.5 mol m 3,pH 7.8), and analyzed according to the method described by Porra et al. [17]. The activities of SOD and POD in the hairy roots and parent plant organs were spectrophoto-metrically determined using ferricytochrome C [18] and o-aminophenol [19], respectively. Fructose in the medium was analyzed by the Somogyi-Nelson method [20] or was determined using an HPLC with a refractive index detector. Light intensity was measured with a thermopile on the outer walls of flasks at the level of the medium surface or at the top of the Petri dish, and expressed as the mean of values determined at several positions. 

Even in its simplified form, the Nelson protocol will deter the most enthusiast natural-product chemist. Unsurprisingly, alternative protocols have been described in the proprietary literature, and their sheer number testify to the ingenuity and commitment of chemists to solve what is still today a daunting task. Some modern modifications to the Nelson method from the proprietary literature include the use of supercritical carbon dioxide to reduce the extraction of pigments in the preparation of the oleoresin [54], and the recourse to macroporous adsorption resins [55] or to repeated extraction with aqueous silver nitrate to trap capsaicinoids and reduce the number of partition steps [56]. 

Flydroxyzine may cause falsely elevated urinary concentrations of 17-hydroxycorticosteroids in certain lab tests (e.g., Porter-Silber reaction, Glenn-Nelson method)... 

Obtained from the QCM method in 20 mM acetate buffer, pH 5.2, 150 mM NaCl, 25 °C Obtained from Somogyi-Nelson method in the bulk solution at 20 mM acetate buffer. 

As the clearance of rhG-CSF is known to decrease with a rise in dose and is known to be saturable, the average clearance after i.v. administration will be lower than that after s.c. administration. Therefore, the apparent absolute bioavailability with subcutaneous administration calculated from the AUC ratio is expected to be a conservative estimate. In a second study by Flayashi et al., the estimation of rhG-CSF absorption kinetics after s.c. administration with a nonlinear elimination pharmacokinetic model using a modified Wagner-Nelson method was studied... 

Hayashi N, Aso H, Higashida M, et al. (2001). Estimation of rhG-CSF absorption kinetics after subcutaneous administration using a modified Wagner-Nelson method with a nonlinear elimination model. Eur. J. Pharmaceu. Sci. 13 151-158. 

The absorption rate constant obtained by the feathering, or residual, method could be erroneous under the conditions stated above. Should that be the case, it is advisable to employ some other methods (Wagner and Nelson method, statistical moment analysis, Loo-Rigelman method for a two-compartment model, just to mention a few) of determining the absorption rate constant. Though these methods tend to be highly... 

Percentage absorbed plot (Wagner-Nelson method) from plasma or urinary data... 

We remain cognizant that this edition of the textbook includes some references that may be considered by some viewers not to be the most current. We, however, believe that the chosen references are classic ones best suited to illustrate a particular point. Additionally, we fully recognize that this edition omits topics such as the Wagner and Nelson method for the determination of the absorption rate constant, urinary data analysis following the administration of a drug by an extravascular route, two-compartment model pharmacokinetics for an extravascularly administered dmg, and metabolite kinetics. 

The enzyme reactions were carried out in 0.2 M acetate buffer at pjj 5.2 and 37 0 by adding the enzyme solution to the substrate solution in a test tube with a micropipette. At appropriate intervals 0.2 ml samples of the hydrolysate were taken and the reducing values were measured by the Somogyi-Nelson method (14). 

S. Frankel and E. Nelson, Methods of Treatment of Displacement Integral Equations, A CD-3497, September, 1953. 

NACE The Corrosion Data Survey Handbook, has two sections metals and non-metals. There are more than 50000 points of data (Nelson method) on the performance of metallic and non-metallic construction materials in corrosive environments. 

---