High-performance liquid chromatographic determination of the antitumor agent mitomycin c in human blood plasma

A high-performance liquid chromatographic method for the determination of the antitumor drug mitomycin C in blood plasma samples of cancer patients is described. The drug is extracted from the plasma with chloroform–2-propanol (1+1, $\text{w}\text{w}$) and chromatographed on a reversed-phase column with u.v. detection at 365 nm. The detection limit of the determination is 1 ng ml^-1 for 0.2–1.0 ml plasma samples. Preliminary results of a pharmacokinetic study show that the sensitivity and selectivity of the assay are adequate for drug monitoring in clinical practice. The results obtained from multiwavelength detection suggest the existence of metabolites.     

The Effect of Alkane Chain Length on the Liquid–Liquid Critical Temperatures of Oligostyrene/Linear-Alkane Mixtures

Summary. Upper critical solution temperatures (UCSTs) for liquid–liquid demixing in a set of mixtures of linear alkanes (pentane (N ₁=5) to pentacontane (N ₁=50)) with an oligostyrene (1241amu, N ₂=12) are reported. We find strong correlation between the Hildebrand solubility parameters of the alkanes and the UCST. Correlations are developed which enable predictions concerning the miscibility of mixtures of compounds with longer chains.     

Vibrational analysis of chlorinated methylphosphonic acids: Part 2. Vibrational analysis of CHCl2PO3H2 and its anions

The vibrational spectra (IR and Raman) of CHCl₂PO₃H₂ and its anions in H₂O and D₂O solutions are reported. The IR spectra of the solid dibasic sodium and potassium salts, the solid normal and O-deuterated monobasic sodium and potassium salt and the solid normal and O-deuterated acid are discussed. The principal results of the normal coordinate analysis of the compounds are tabulated.     

Chemical studies of carbohydrates. Part I. Conversion of derivatives of glucose and allose into pyrazoles and pyridazines

On reaction of 1,2:5,6-di-O-isopropylidenc-3-O-(p-tolylsulfonyl)-α-D-glueofuranose ( 1 ) with hydrazine hydrate at 140° besides formation of 3-deoxy-3-hydrazino-1,2:5,6-di-O-isopropylidene-α-D-allofuranose ( 2 ) and 3-dcoxy-1,2:5,6-di-O-isopropylidene-α-D-erythro-hex-3-enofuranose ( 3 ), ring transformation into 3-[4′-(2′,2′-dimethyl-1′,3′-dioxolanyl)]pyridazine ( 4 ) takes place. At 170°, however, only 2 and 4 are formed, indicating that 3 is the precursor of 4. Treatment of 3 with hydrazine hydrate at 170° indeed gives a nearly quantitative ring expansion into 4. Treatment of 3-dcoxy-3-hydrazino-1,2:5,6-di-O-isopropylidenc-α-D-glucofuranose ( 8 ) as well as the stereoisomeric allofuranose 2 with concentrated hydrochloric acid gives a nearly quantitative ring interconversion into 3-(D-erythro-trihydroxypropyl)pyrazole ( 9 ).     

Application of the FCP-activation procedure to the synthesis of a biospecific adsorbent for trypsin

The synthesis of a biospecific adsorbent for trypsin was chosen as a model to investigate the applicability of FCP activation in affinity chromatography.p-Aminobenzamidine was chosen as a ligand, directly suitable for immobilization. The nonspecific binding properties of the first series of synthesized agarose derivatives were obviated either by FCP activation of the ligand instead of the matrix, or by modifying the initial FCP-activation procedure. The adsorbents prepared in this way, however, demonstrated no selectivity between trypsin and chymotrypsin. The introduction ofe-aminocaproic acid as a spacer was ineffectual. These problems were solved by the application of glycylglycine as a spacer. The final affinity matrices had a degree of substitution of approximately 4 μ.mol of ligand per gram gel (100 μmol ligand per gram dry adsorbent). The specific activity of a current trypsin preparation was increased by 58% in a single cycle. The biospecificity of these adsorbents was demonstrated.     

Development of a quality control method for the characterization of oligonucleotides by capillary zone electrophoresis-electrospray ionization-quadrupole time of flight-mass spectrometry

A capillary zone electrophoresis-negative electrospray ionization-quadrupole time of flight-mass spectrometric method was developed for the characterization of oligonucleotides after synthesis, using model compounds. The major difficulty is the adduction of metal cations to the polyanionic backbone of the oligonucleotide sample, resulting in complex spectra and decreased sensitivity. Several approaches were investigated to circumvent this problem. Separation was performed in an ammonium carbonate buffer. During separation, the interfering metal ions were exchanged for ammonium ions, which are less tightly bound to the oligonucleotide when ionized. The influence of the addition of piperidine and imidazole or trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CDTA) to the running buffer for further reduction of cation adduction was investigated. Addition of CDTA to the buffer system resulted in a deconvoluted spectrum with very little adducts. On-line sample stacking proved vital to preconcentrate the samples. The pH and the concentration of the ammonium carbonate buffer as well as the electrophoresis voltage were optimized to achieve the best signal response for the oligonucleotides and a maximum reduction of the cation adducts as well as a short analysis time. Finally, the sheath liquid composition was examined for further improvement of the signal. The developed method was used to analyze different oligonucleotides (5000-9200 Da) in light of its use as a final quality control method for oligonucleotides in terms of purity and sequence homogeneity of the synthesized products. In all cases, very little adducts were observed in the deconvoluted spectra, and the relative errors of the measured molecular masses ranged from 3 to 35 ppm.     

Analysis of unknown compounds in azithromycin bulk samples with liquid chromatography coupled to ion trap mass spectrometry

A selective reversed-phase liquid chromatography/mass spectrometry (LC/MS(n)) method is described for the identification of azithromycin impurities and related substances in commercial azithromycin samples. Mass spectral data are acquired on an LCQ ion trap mass spectrometer equipped with an atmospheric pressure chemical ionization interface operated in positive ion mode. The LCQ provides on-line LC/MS(n) capability, making it ideally suited for identification purposes. In comparison with UV detection, this hyphenated technique provides as its main advantage efficient identification of novel substances without time-consuming isolation and purification procedures. Using this technique, six novel related substances detected in commercial azithromycin samples have been studied.     

Evaluation of a high-performance thin-layer chromatographic technique for the determination of salbutamol serum levels in clinical trials.

Salbutamol concentrations were determined by high-performance thin-layer chromatography in the sera of two sets of ten volunteers at hourly intervals for 6 h after taking one 8-mg slow-release tablet. The influence of time lapse in processing of serum samples, i.e. centrifugation, extraction and chromatography, was studied. A statistical significant instability of salbutamol in the sera of patients was found which was not present in standard drug-free serum samples spiked with salbutamol and used for construction of standard curves.     

Polarography of disodium pentacyanonitrosylferrate(II): Part 2. Determination at Therapeutic Levels in Serum,Plasma, and Whole Blood

Disodium pentacyanonitrosylferrat(II) (sodium nitroprusside) is determined at therapeutic (ng ml^?1) levels in plasma, serum and blood with conventional and high-performance differential pulse polarography (d.p.p. and h.p.d.p.p.) at a dropping mercury electrode or a static mercury drop electrode. Serum or plasma (3 ml) is treated with perchloric acid containing 1 mg ml^?1 potassium hexacyanoferrate(II), centrifuged for 10 min and subjected to polarography. For spiked serum, calibration graphs are linear over the range 30–1000 ng ml^?1 sodium nitroprusside, regardless of the polarographic technique; the estimated detection limit is 15 ng ml^?1 (5 × 10^?8 M). Calculated therapeutic levels range from 100 to 1000 ng ml^?1. Similar results were obtained for spiked plasma. A similar procedure is suitable for whole blood and was used to study the in-vitro degradation of sodium nitroprusside (200 ng ml^?1) on incubation at 37°C. The in-vitro loss is rapid (t_{$\text{1}\text{2}$} ≈ 6 min) but meaningful in-vivo levels can be obtained when the blood is collected in a 0.9% sodium chloride solution at 0°C. Thiocyanate, the main metabolite of nitroprusside, and thiosulphate, which is a potential antidote for cyanide, do not interfere.