An analysis model to detect and quantify white cells (WBCs) in red cell concentrates (RBCC) drawn from units of blood that are highly depleted of WBCs is described. WBC detection is performed by fluorescence analysis of 50 microL of RBCC labeled with propidium iodide, a DNA/RNA fluorophore. Quantification is performed by regression analysis of standard dilutions of RBCC in substantially WBC-free red cells. This RBCC diluent is obtained by filtration of blood through a new medium. The method proves to be precise (CV = 7%), efficient (+/- 30 min/aliquot), and linear (r = 0.99) to 6 log10 WBC depletion of the native product. The current technique is preferable to those suggested previously, such as ficoll concentration, which requires the sacrifice of the unit of blood for counting purposes, and to earlier fluorescence analysis techniques that do not employ WBC-free red cell diluents. The latter do not monitor extremely low concentrations of WBCs because they lack adequate signal-to-noise discrimination. The sensitivity of the described method allows for monitoring of WBC depletion procedures with greater efficiency than is currently available commercially.
A gas chromatographic method has been developed for the determination of piperonyl butoxide in technical piperonyl butoxide. The sample is dissolved in a solvent containing a definite concentration of dioctyl phthalate as an internal standard, and the piperonyl butoxide is determined by relating the area of the piperonyl butoxide peak to that of dioctyl phthalate. The method is precise and results are slightly lower than those of the AOAC colorimetric method. The procedure is also applicable to common blends of pyrethrins and piperonyl butoxide.Gas chromatographic studies of insecticidal concentrates containing piperonyl butoxide (the butyl carbitol ether of 3,4-methylenedioxy-6-propylbenzyl alcohol) indicated the feasibility of a gas chromatographic method for the determination of this widely used synergist for pyrethrins and related ins.cticides.The AOAC method (1965) is the most common procedure used for determining piperonyl butoxide in the technical grade material, insecticidal concentrates, or finished formulations. Other methods applicable to pyrethrum synergists which contain the methylenedioxyphenyl group have been reported by Beroza (1956) andBlum (1955). The AOAC method was developed by Jones et al. (1952) and is based on the blue color produced by heating piperonyl butoxide with tannic acid in the presence of phosphoric and acetic acids. Interferences which have been reported are pyrethrins, allethrin, alkylated naphthalenes, cyclohexanone, and high-boiling hydrocarbons (Allen et a/., 1962; Jones et al., 1952). Jones et al. (1952),
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