Determination of strontium-90 in urine by extraction without ashing

Preconditions for reasonable detection sensitivity and for zone symmetry in electrophoretic separations of cluster borane anions

Single-cage boron cluster anions with at least 11 cluster atoms, free of bonded functional groups that strongly absorb UV light, and their cobalt complexes have been the investigated compounds. Their UV-absorption spectra have absolute maxima between 200 and 215 nm. Corresponding molar extinction coefficients that are of the order of 10(3)-10(4) L mol(-1) cm(-1) indicate medium detection sensitivity. Its reaching requires elimination of background electrolytes that weaken the UV-light beam in any way. Frequently used carboxylic acids and zwitterionic Good's buffers cannot be used as buffering compounds from this reason. Freshly prepared 1 mM solutions of boron cluster compounds in aqueous sodium chloride, chosen as indifferent electrolyte, which contain 20-30% (v/v) of methanol or acetonitrile, give zones free of tailing. After storing in the fridge, zones of the compounds became pronouncedly tailed even if their solutions remain clear and free of precipitation, turbidity or opalescence. The tailing usually disappeared if the acetonitrile or the methanol concentration in samples was 40-60% (v/v) depending on the dissolved compound hydrophobicity. Solutions of extremely hydrophobic compounds, stored in the fridge, require mild heating to 30-40 degrees C for half an hour for the avoiding of the tailing. Permanent slow decrease in effective mobilites of boron cluster anions was found if background electrolytes contained acetonitrile and beta-cyclodextrin. Analogous decrease was not observed with organic anions. Constant mobilities of boron cluster anions have been reached if acetonitrile was replaced with methanol. Analyte zones were more symmetrical in background electrolytes buffered with sodium borate of pH 9 than in background electrolytes buffered with sodium phosphate of pH 7.

Biological activities of phthalocyanines--XV. Radiolabeling of the differently sulfonated 67Ga-phthalocyanines for photodynamic therapy and tumor imaging

Phthalocyanines have been advanced as photosensitizers for the photodynamic therapy of cancer and selectively sulfonated derivatives have shown promise as tumor imaging agents. In order to study the effect of the degree of sulfonation on their biodistribution pattern, we prepared a series of sulfophthalocyanines (PcS) labeled with 67Ga. Direct chelation of metal free phthalocyanines with 67Ga gave chelates which demetallated on further purification whereas condensation of 67Ga with phthalic acid precursors, following purification and fractionation on Sep-Pak C18 cartridges, gave stable products. The distribution pattern of the [67Ga]GaPcS among human plasma proteins was strongly affected by the degree of sulfonation of the PcS. The lower sulfonated GaPcS showed significant binding to the various lipoprotein fractions whereas increased sulfonation favored association to albumin. The use of the 67Ga allowed for the validation of spectrophotometric quantification of GaPcS in biological samples and confirmed the in vivo stability of the radiolabeled complex.