Environmental occurrence of nitrotriphenylene observed in airborne particulate matter.

1- and 2-Nitrotriphenylenes were found in the airborne particulate matter extracts collected in central Tokyo between the winter of 1998 and the winter of 1999. In particular, we have identified and quantified nitrotriphenylenes in the airborne particulate matter extracts collected over four consecutive 6-h periods on 2 December 1999. The concentrations of 1- and 2-nitrotriphenylene ranged from 0.04 to 0.44 and from 0.02 to 0.47 ng/m3, respectively, and the concentrations in the airborne particulate matter extracts collected during the 18:00-24:00 h time period were the highest of the four collection periods. 1-Nitropyrene and 2-nitrofluoranthene were also identified and quantified in the four 6-h samples. Although the concentrations of 1- and 2-nitrotriphenylenes were not higher than that of 2-nitrofluoranthene except during the 18:00-24:00 h time period, the concentrations were much higher than that of 1-nitropyrene during the four collection periods. The higher concentrations of 1- and 2-nitrotriphenylenes during the 18:00-24:00 h time period are presumably responsible for the high reactivity of parent triphenylene with NO2/NO3/N2O5, and high stability of 1- and 2-nitrotriphenylenes toward O3 + O2. In addition, the observed isomer distribution of nitrotriphenylenes suggested that direct emission of nitrotriphenylenes is also a source as well as their atmospheric formation.

Mutagenic nitrated benzo[a]pyrene derivatives in the reaction product of benzo[a]pyrene in NO2-air in the presence of O3 or under photoirradiation.

In order to clarify the contribution of nitrated products to the direct-mutagenic activity of products of the reactions of benzo[a]pyrene in NO2-air under various conditions, heterogeneous reactions of BaP deposited on filter in the air containing 10 ppm of NO2 have been conducted in dark or under photoirradiation. The reaction products have been analyzed by gas chromatography and mutagenicity of the products fractionated by preparative HPLC was assayed for Salmonella typhimurium strains TA98 and YG1024 in the absence of S9 mix. 3,6-dinitrobenzo[a]pyrene and 1,3-dinitrobenzo[a]pyrene, which are strong direct-acting mutagens, largely contributed to the total direct-acting mutagenicity of the dark reaction products in NO2-air. On the other hand, both the dark reaction in the presence of O3 and the photoreaction in NO2-air resulted in the formation of much smaller amounts of nitrobenzo[a]pyrenes than that observed in the dark reaction in the absence of O3. These results show that the contribution of other direct-acting mutagens to the total direct-acting mutagenicity of the products in these reactions should be considered. Benzo[a]pyrene lactones were identified in a highly mutagenic fraction of the products of the dark reaction in the presence of O3 and photoreaction and a nitrobenzo[a]pyrene lactone was also identified in a highly mutagenic fraction of the dark reaction products in the presence of O3. Nitrated oxygenated benzo[a]pyrene derivatives such as nitrobenzo[a]pyrene lactone were considered to largely contribute to direct-acting mutagenicity of the products of the dark reaction in the presence of O3 and photoreaction.

Freeze-drying of cephalothin sodium: granularly agglomerated crystallization during freezing. I.

Optimal conditions for the crystallization and subsequent freeze-drying of an aqueous cephalothin sodium (CET-Na) solution of supersaturated concentrations to obtain granular crystalline CET-Na have been discussed, as have the qualities of the product thus obtained. In general, CET-Na in supersaturated aqueous solution is barely recrystallized, even when in its frozen stage. Our previous report revealed that when the solution is kept at low temperatures for a long duration, the molecules begin to change structurally to as condensed a state as that of liquid crystals, and such change facilitates a spontaneous nucleation and seed-independent crystal growth in the frozen solution. These findings prompted the authors to investigate optimal CET-Na concentrations and thermal histories during the crystallization and subsequent freeze-drying process without seeding. It has subsequently been found out that optimization of the latter conditions gives granular agglomerated crystalline CET-Na contaminated with neither the amorphous nor the quasi-crystalline form. The optimized conditions are: 25-28% CET-Na concentrations; storage before the freezing process at 0 degrees C for 2 h, and subsequent storage at 20-25 degrees C for 1 h; cooling in the freezing process at a rate not faster than 0.5 degrees C/min; warming of the solution for facilitating crystallization prior to vacuum application for drying at -4 degrees C. Under these conditions, the freeze-dried product of CET-Na in granular form has been successfully obtained in a shorter freeze-drying cycle, exhibiting a faster reconstitution time than those of CET-Na prepared according to seeded crystallization followed by a conventional freeze-drying.

Freeze-drying of cephalothin sodium: granularly agglomerated crystallization during freezing. II.

The mechanism of granularly agglomerated crystallization during freezing of cephalothin sodium (CET-Na) in aqueous solution has been discussed. Our previous report noted that strict control of the following is important in order to obtain crystalline granular agglomerates of CET-Na: (1) thermal history of the solution before receiving freezing, (2) cooling rate in freezing, and (3) aging temperature level in the crystal growth step. In order to clarify the physico/chemical meanings of the individual controls, further investigations have been made: 1) with varying thermal history, aqueous 30-% CET-Na solutions were prepared for storage, first at 0 degrees C with its supersaturation and secondly at 25 degrees C, in an unsaturated state for observing any structural changes by viscosimetry, refractometry, and surface tensiometry; 2) morphological changes in ice crystals during freezing at varying cooling rates, as well as those during the crystal growth step, were observed by polarized-light cryomicroscopy and scanning electron microscopy; 3) melting, as well as crystal growth, at several aging temperature levels were observed by electrical conductometry and also by the above-mentioned techniques.(ABSTRACT TRUNCATED AT 250 WORDS)

Freeze-drying and quality evaluation of protein drugs.

Gamma interferon from genetic recombination (IFN) has been found to have an optimal pH at about 7. An increase in IFN concentration may cause a decrease in solution clarity. A proper selection of isotonizing agent, as well as the addition of sugars, is effective in improving the clarity. The amount of IFN adsorbed on filter membranes varies with the membrane materials: cellulose acetate adsorbs much IFN, 2-fluorovinylidene is the next, followed by polysulfon, and polycarbonate adsorbs it least of all materials tested. Stainless steel adsorbs little IFN, and the level can be lowered even more by electropolishing. Silicone coating can decrease the amount adsorbed to about 1 microgram per vial of 10 ml. The effect of pressure given to the IFN solution during filtration is negligible. Transfer of IFN solution through pipings of conventional shape may result in partial deactivation by bubbling. At around pH 7, a lower pH of IFN solution causes a higher moisture level of the freeze-dried product. Moisture levels up to 3% have no effect on IFN stability. Upon reconstitution of freeze-dried IFN by vigorous shaking with distilled water, filtration of the solution may become difficult because polymers might have been formed during vigorous shaking. The addition of L-cysteine, maltose, and human serum albumin, has been found to be as effective in preventing such unfavorable reactions. Fatty acids in human serum albumin, which is effective in stabilizing IFN, has been found to participate in preventing denaturation of human serum albumin upon freezing and freeze-drying; however, the denaturation prevention mechanisms are not clear yet.

[Non-crystallinity determination by thermal analysis of freeze-dried cephalothin sodium].

Cephalothin sodium (CET-Na) prepared according to the conventional freeze-drying methods is known to easily develop color during storage. Since amorphous CET-Na has been reported to be markedly unstable, the color development is thought to be due to the presence of traces of CET-Na in an amorphous state observed with scanning electron microscopy. Quantitation by use of the powder X-ray diffractometry of such traces of amorphous CET-Na has proved to be of little use. Thermogravimetry (TG) and differential scanning calorimetry (DSC) have demonstrated that the freeze-dried CET-Na by the conventional methods contains three types of CET-Na: amorphous (unstable phase), quasi-crystalline (metastable phase) and crystalline (stable phase). Pyrolysis initiation temperatures of these three types of CET-Na have been demonstrated to become higher in this order. A new parameter for the evaluation of non-crystallinity of CET-Na has been introduced, in which the ratio is calculated from the data of the total weight loss observed through the pyrolysis of both amorphous and quasi-crystalline CET-Na against the total weight loss of all components during the pyrolysis of sample specimen. The ratio thus calculated is defined as "non-crystallinity". This new parameter has successfully been introduced to establish a good correlation to the degree of increasing color intensity with aging of freeze-dried CET-Na.

[Crystallization and subsequent freeze-drying of cephalothin sodium by seeding method].

Cephalothin sodium (CET-Na) in crystals can be obtained by freezing the aqueous solution and subsequent warming at a fixed temperature for facilitating crystallization prior to vacuum application for drying. The product has, however, been found to unavoidably contain traces of the amorphous CET-Na, which causes a rapid color development during storage. By using thermal analysis, differential scanning calorimetry (DSC), electric conductometry, and polarized light cryomicrographic techniques, the solubilities in water, freezing point, eutectic point, and melting behavior of CET-Na in aqueous solution were investigated. The investigation demonstrated that CET-Na in supersaturated aqueous solution is very stable, and that seeding with microcrystalline CET-Na to the supersaturated solution and subsequent cooling of the mixture till its freezing point gives neither any evidence for crystallization nor for growth of the seed crystals. The freeze-drying of CET-Na in the supersaturated solution after seeding has been demonstrated to give crystalline CET-Na containing neither of amorphous nor of quasi-crystalline form.

Total organic carbon as an index for specification of water for injection.

Determination of organic compounds present as contaminants in purified water is of great importance. Total organic carbon (TOC) may be a useful parameter for evaluating the purity of water. This paper describes and compares the analytical results for solutions of 12 model compounds obtained by 3 methods: total organic carbon (TOC) analysis, determination of potassium permanganate consumption, and UV spectroscopy. TOC analysis gave values corresponding to the expected amounts of organic carbon for all the model compounds, whereas the other 2 methods gave highly variable results.