The technique of gravimetric water sorption was used to identify samples which appear to interact with water as a chemical
reagent. These were distinguished from those which take up moisture purely physically. In the latter case water acts as a
probe which aids the characterization of the sample surfaces and their hydration states. After identifying the features in
the sorption behavior which allow this distinction to be made, we drew the following conclusions:
1. Few if any of the samples investigated interact chemically with water.
2. The demonstration of chemical interaction of a sample with water and other vapors by sorption studies alone is not always
3. Chemical interaction of water with samples appears to be relatively rare. The major problems associated with high humidity
in the production, storage and handling of samples therefore seem to be due to physical rather than chemical degradation.
A simple, selective, precise, and stability-indicating high-performance thin-layer chromatographic method for analysis of rivastigmine in the bulk drug and in a capsule formulation has been established and validated. Chromatographic separation was achieved on aluminum-backed silica gel 60F
HPTLC plates with chloroform-methanol 4:6 (
) as mobile phase. Densitometric analysis of rivastigmine was performed in absorbance mode at 210 nm. The method gave a compact spot for rivastigmine (
0.53 ± 0.02) and was shown to enable excellent separation of a degradation product of rivastigmine (
0.32 ± 0.02). The method was validated for accuracy, precision, linearity, recovery, limits of detection and quantitation, and robustness. Good linearity was observed in the concentration range 200–1600 ng per spot; the correlation coefficient was 0.9916 ± 0.008. The limits of detection and quantitation were 30 and 100 ng per spot, respectively. Rivastigmine was subjected to alkaline hydrolysis and high humidity and found to degrade under these conditions. Statistical analysis proved the method was reproducible, specific, and accurate. The method is stability indicating; because it is economical it can be used for routine analysis of the bulk drug and pharmaceutical formulations.
Authors:Young Cho, Wanno Lee, Kun Chung, Geun Choi, and Chang Lee
The seasonal variation of the 7Be activities in air and the size distribution of the 7Be aerosols were studied by using a continuous air sampler and a five stage cascade impactor. The mean monthly activity level
of 7Be at the Korea Atomic Energy Research Institute (KAERI) site varied from 0.5 to 4.8 Bq·m−3 and revealed a seasonal variation, in which the 7Be activity levels were high in winter and low in summer. The mass size distribution showed a bi-modal distribution with a
higher peak around 0.49 μm and a smaller peak between 3 μm and 7.2 μm. The activity median aerodynamic diameter (AMAD) decreased
with increasing ambient 7Be concentrations. The mean residence times by using a mean growth rate of 0.004 μm·h−1 were estimated to be 2.5–6.4 days. The AMAD has an increasing tendency with higher relative humidity. It seemed that the
high humidity condition facilitated the growth of the aerosol, resulting in increased deposition rates of the aerosols and
the low 7Be content in the surface air. The AMAD of the 7Be aerosols increased with an increasing temperature, but the temperature dependency of AMAD should be explained with geological
and meteorological conditions.
Authors:K. Tanoi, J. Hojo, M. Nishioka, T. M. Nakanishi, and K. Suzuki
We present a new trial to measure real time water movement in a living plant using the positron emitting radionuclide, 15O. 15O was prepared by 14N(d,n)15O reaction and 10 ml of 15O labeled water (2 GBq) was supplied from the root of a soybean plant. To detect activity, an imaging plate (IP) as well as a BGO detector system were used. Since the half-life of 15O is extremely short, (T1/2= 122 s), water uptake measurement was performed only for 20 minutes. In order to get [15O]waterimage, an IP was exposed to the plant for 1 minute for two times. Since the exposure to an IP requires dark condition, a BGO detector system was developed to measure [15O]waterunder light condition. A couple of BGO probes was set at the lowest stem and the gamma-rays (0.511 MeV) emitted from the radionuclide were measured through coincidence counting and compared with the radioactivity measured from an IP image. Using this system, we have found that the water uptake activity of the plant was drastically reduced under high humidity (99%) and dark condition.
Authors:D. Giron, M. Draghi, C. Goldbronn, S. Pfeffer, and P. Piechon
The local anesthetic drug tetracaine hydrochloride is described in the Europ. Pharmacopea with a melting point of 148°C or
with a range of 134 to 147°C due to the melting points of two other forms. The polymorphic behaviour of tetracaine hydrochloride
has been studied by using thermal treatments, storage at 92% r.h., crystallizations and equilibrations with saturated solutions.
Samples were characterized by X-ray diffraction, IR, thermal analysis and elemental analysis. Since some findings were difficult
to interpret, temperature resolved X-ray diffraction was used additionally for the understanding of the thermal behaviour
of tetracaine hydrochloride. In this study the polymorphic behaviour of some other local anesthetic drugs is compared.
Ten different forms of tetracaine hydrochloride: six anhydrous crystalline forms, an amorphous form, a hemihydrate, a monohydrate
and a tetrahydrate were identified. The relationships between all forms are given.
The heating curve of the commercial form 1 is very dependent on the heating rate. This anhydrous form 1 is the thermodynamic
stable modification at ambient temperature. The form 2 is reversibly enantiotrope to form 1. The four other modifications
called 3, 4, 5 and 6 are monotropes of form 1.
Only forms 1 and 5 are stable at ambient temperature. Form 1 is hygroscopic only at high humidity level of 92% r.h., form
5 is hygroscopic at 61% r.h. Both transform into the monohy-drate.
No polymorphic forms of tetracaine base, dibucaine hydrochloride, procaine hydrochloride or prilocaine hydrochloride were
The commercial form of bupivacaine hydrochloride is a monohydrate. Thermal treatment at 200°C gives one anhydrous form. As
demonstrated by temperature resolved X-ray diffraction two other forms are detected by heating and cooling processes between
100 and 170°C. Equilibrations and crystallization experiments show that solvates are easily obtained in different solvents.
Temperature resolved X-ray diffraction is a very efficient tool as a support to DSC for the identification of the transition
processes and interpretation of thermal events and thermodynamic relationships. Equilibration experiments are very adequate
to find out the thermodynamically stable form at ambient temperature (solvent mediated transitions).
Authors:Ian Harvey J. Arellano, Jeiel G. Guarino, Fiona U. Paredes, and Susan D. Arco
, the ILs immediately absorbed moisture upon exposure to high-humidity environment. However, as the test progresses, a saturation moisture level is achieved via desorption. This behavior fortuitously fits into the Henderson–Pabis model represented by the
Authors:Tamás Zsom, Viktória Zsom-Muha, Lien Phuong Le Nguyen, Dávid Nagy, Géza Hitka, Petra Polgári, and László Baranyai
providing relatively highhumidity around the samples. Shelf-life conditions decreased these differences to a significant difference only between at 2.5 and 10 °C stored samples concerning overall texture. Fig. 2 clearly represents the close relation
Authors:Miha Vivoda, Robert Roškar, and Vojko Kmetec
a miniature humidity vessel, using 50 μL of water and tested at 25 °C. Because of the highhumidity in the vessel, the data acquisition began soon after the vessel was closed and loaded into the measuring position; therefore some disturbances were
as proper fuel for pyrotechnic applications. Also, toxicity problems tend to be minimal with these fuels [ 6 , 7 ].
Lactose has two forms α, β in crystalline structure, its moisture contents is about 5% and increase to about 7% at high