Micelle formation in concentrated sulfuric acid solutions by long-chain fatty acids (which form cationic bisulfates) was studied by means of surface tension and light scattering measurements. It was found that micelle formation in 95% sulfuric acid took place at a higher concentration than in water, that 5 M potassium bisulfate had a small or negligible effect, and that water (presumably present as hydronium bisulfate) had a very marked effect, lowering the c.m.c.

Two methods for the determination of N-acetyl-p-aminophenol (APAP) in plasma that differ in principle from the diazotization procedure of Brodie and Axelrod (1) are described. One method based on the differential absorption peak of APAP at 266 mµ, which corresponds to the isosbestic point of common drugs such as acetylsalicylic and salicylic acids, is simple and most specific for APAP. The other method employs a free-radical dye diphenylpicrylhydrazyl which extracts a hydrogen atom from the APAP molecule and is progressively decolorized. The dye method is the least complex and most sensitive. All three methods exhibited satisfactory replication, recovery of added APAP, and comparable plasma levels of the drug.

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trol amplifier with the high current booster switched in, the working electrode potential was measured, with the control amplifier damping set at 0.01 pf. The electrode potential follows the imposed square wave well, but the same system with the control amplifier damping at 0.00033 pf and an imposed 20 cps square wave yields a wave whose shape is distorted by ringing. Fast scan work is possible, but requires careful adjustment of the damping capacitance.The circuit diagram in Figure 1 is not necessarily the ultimate design, but it illustrates an approach that provides a useful and convenient instrument with considerable versatility. A number of alternatives in terms of construction are possible. For example, the cost of the instrument, which for parts is about $1800, can be reduced by the use of utility grade operational amplifiers; this will not impair the performance noticeably at ambient temperatures. Also, if the performance of the integrator-sweep generator is not crucial, a Philbrick P-75AU amplifier can be employed in place of the P-25A. On the other hand, if the performance of the integrator-sweep generator holds top priority, a Philbrick P-2A operational amplifier should be used for this component.