William C. Purdy

The residual current in orthophosphate medium

The residual current in orthophosphate medium exhibits as many as three waves in addition to the normal mercury dissolution wave. The first of these waves is diffusion controlled while the others are adsorption controlled. At pH values below 4.2, the half-wave potential of the diffusion-controlled wave corresponds well with the potential for the mercury—mercurous phosphate half-cell. No simple potential relationship appears to hold for pH values greater than 4.7. Iodide ion at concentrations of 10−3M destroys the adsorption waves but has no effect on the diffusion wave.

The determination of chromium in biological materials by atomic absorption spectroscopy.

Abstract Biological samples were mineralized with a mixture of nitric, sulfuric, and perchloric acids. The chromium was oxidized to chromium(VI) followed by extraction into methyl isobutyl ketone in the cold. The ketone extract was aspirated into a fuel-rich hydrogen-air flame, and the absorption recorded using the 357.9 nm line of chromium. The limit of detection for chromium was found to be 10 p.p.b. Tissue chromium levels of normal albino rats were determined. Increased chromium values were observed for animals maintained on a high chromium diet compared to those fed a deficient diet.

Simplex optimization of the separation of phospholipids by high-pressure liquid chromatography

Abstract A simplex procedure is shown to be an efficient approach for solving separation problems. The best solvent ratio for the separation of phosphatidylcholine and sphingomyelin has been found by means of a two-dimensional simplex capable of expansion and contraction. A successful high-pressure liquid chromatography separation of lysophosphatidylcholine, phoaphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidylcholine, sphingomyelin and phosphatidic acid was achieved with a 180-cm column packed with Corasil II and a solvent mixture of chloroform—methanol—ammonia (50.0:35.9:7.0, v/v/v).

The atomic absorption spectroscopy of chromium

Abstract Conditions were studied for the determination of trace amounts of chromium by atomic absorption spectroscopy. Solution matrix, flame composition, and extraction procedures were the variables studied. A detection limit of 0.006 p.p.m. of chromium was observed with an air-hydrogen flame and methyl isobutyl ketone as the solvent.

Determination of di-(2-ethylhexyl)-phthalate (DEHP) in human plasma.

Abstract A method for the determination of di-(2-ethylhexyl)-phthalate in human plasma is reported, based on the column Chromatographic separation of the plasticizer from the plasma, followed by gas chromatography. Selection of the best gas Chromatographic conditions results in a lower limit of detection of 50 nanograms. Recoveries of DEHP added to serum ranged from 94 to 106%.

Polarographic study of copper complexes with radiation protective drugs correlation of instability constant with radiation prophylaxis

Abstract A correlation has been demonstrated between the instability constant of the copper-agent complex and the protective capacity of the agent against ionizing radiation. The instability constants for the complexes formed between copper and 8 agents have been. reported in a Michaelis phosphate buffer of pH 7–4.

The determination of manganese in urine by atomic absorption spectrometry

Abstract Urine samples were digested with a mixture of nitric, sulfuric, and perchloric acids containing molybdate as catalyst. A two-point standard addition technique involved extracts of buffered, digested aliquots containing 10- and 20-p.p.b. manganese(II) in the aqueous phase. The extraction system was MIBK-cupferron. Of the substances tested only bismuth, antimony, and thallium interfered. From the same subject, five morning urine samples averaged 3.0 p.p.b. of manganese with a range of 2.0–4.2 p.p.b.; the average deviation was 0.6 p.p.b.

Extraction of vanadium into isobutyl methyl ketone.

Because of its advantages in atomic-absorption spectroscopy, isobutyl methyl ketone was chosen as organic solvent for an extraction study on vanadium. Of eight chelating agents which were evaluated for completeness of extraction, ease of use, working pH range, and freedom from interference, cupferron was judged best.

Analysis of the phospholipid composition of Plasmodium knowlesi and rhesus erythrocyte membranes.

Abstract Methods for the separation and analysis of the phospholipid classes have been studied. The lipid extracts of normal and Plasmodium knowlesi- infected rhesus erythrocytes and of the parasite itself have been examined for phospholipid composition on an animal-to-animal basis. Several differences were apparent between the phospholipids of parasites and infected host cells. Phosphatidylinositol, phosphatidylcholine, and phosphatidylethanolamine represented larger percentages in the parasite than in the host; the average phosphatidylinositol content was 1.8 % in infected host cells and 4.3 % in parasites. Sphingomyelin and phosphatidylserine were also strikingly different in the two membranes; in the parasite they averaged less than 20 % and 33 % respectively of their level in the infected red blood cell.

The coulometric titration of barbiturates

Abstract Constant-current coulometry has been applied to the titration of barbituric acid derivatives, i.e., sodium phenobarbital, sodium, seconal, sodium barbital, and sodium sandoptal. The titrant is generated mercury (II). The titration may be performed in aqueous potassium nitrate-acetone, or aqueous sodium perchlorateacetone solutions. The most sensitive systems are the partially nonaqueous ones, with both supporting electrolytes giving similar results. Comparable results also were obtained at room temperature and at 37°. Considerable evidence has been obtained to support the theory that mercury(II) is not generated directly in these media, but is formed from the disproportionation of mercury (I) into the element and mercury(II). Qualitative tests proved the presence of all three species in the titration medium. Structural analysis of the compound formed in the coulometry cell was performed, and with sodium phenobarbital the evidence indicates that a polymeric compound containing continuous Hg-N linkages is formed. The evidence for the other compounds is less conclusive, probably because a mixture of products is formed in the titration cell.