SERS investigation and high sensitive detection of carbenicillin disodium drug on the Ag substrate.

The reliable and ultrasensitive detection of antibiotic drug residue is of great interest for environmental protection and human health. Herein, we propose a simple SERS strategy based on Ag nanoparticles (NPs) as substrate with the assistance of aggregation agent (MgSO4) for the SERS investigation and the high sensitive detection of antibiotic drug carbenicillin disodium (CBDM). The density functional theory calculation was performed for the assignment and identification of Raman bands of the CBDM molecule. The results indicate that the CBDM molecule is close to the Ag NP substrate surface through the carboxyl group. The CBDM molecules on Ag NP substrate exhibit the largest SERS enhancement, when the concentration of MgSO4 is 1 × 10-2 mol/L and the pH value of CBDM solution is 6. By this SERS method, the limit of detection of CBDM is 0.63 × 10-8 mol/L, which is lower than the standard of European Union for the maximum residue limit of antibiotic drug (1.2 × 10-8 mol/L). And, a quantitative detection method of CBDM can be established. There is a good linear relationship (R2 = 0.9908) in the concentration range of 1.0 × 10-8-1.0 × 10-3 mol/L. It proves that the proposed SERS method is a simple, rapid (within 6 min), reliable and highly sensitive scheme with a good reproducibility for the detection of CBDM. And, the proposed SERS strategy can also be applied for the high sensitive detection and identification of other antibiotic drug (penicillin).

A polythiophene-derived ratiometric fluorescent sensor for highly sensitive determination of carbenicillin in aqueous solution.

A new ratiometric fluorescent sensor based on a quaternized quinine substituted 3-phenylpolythiophene derivative (PTQ1) was designed and developed for facile and reliable detection of carbenicillin with high sensitivity and selectivity.

Infrared and Raman microspectroscopy of foreign materials in tissue specimens.

Infrared and Raman spectra of materials found in tissue specimens submitted for histopathologic diagnosis have been recorded. These foreign materials range in size from approximately 5 to 50 microm, and the vibrational spectra have been used to identify them. Examples include cholesterol and polytetrafluoroethylene (PTFE) in an implant case, polyethylene terephthalate (PET) and polyacrylonitrile (PAN) in a pilonidal cyst, and carbenicillin in a skin biopsy. In some instances, either the infrared or Raman spectra were sufficient to make a definitive identification, while in other cases both were necessary. Because some of the samples fluoresced with visible excitation at 532 nm, FT-Raman spectra with 1064-nm excitation were also recorded. The flexibility of sampling for vibrational microspectroscopy and the value of the recorded data in assisting pathologists render medical diagnoses in the examples cited and other cases are discussed.

Calorimetric analysis of cephalosporins using an immobilized TEM-1 beta-lactamase on Ni2+ chelating sepharose fast flow.

Two beta-lactamases, penicillinase type I from Bacillus cereus and TEM-1 beta-lactamase from Haemophilus ducreyi, were immobilized on a Chelating Sepharose Fast Flow column loaded with Ni2+ in an active form. Flow-injection analysis of beta-lactams was performed by using an enzyme column reactor fitted into the enzyme thermistor. With both enzymes it was possible to monitor both penicillins and cephalosporins. Moreover, Michaelis constants of the TEM-1 beta-lactamase were markedly increased upon immobilization for all substrates, especially carbenicillin, cephaloridine, and cefoperazone.

Polarographic determination of some penicillins through nitrosation.

Direct current and differential pulse polarography DPP were used for the determination of three penicillins, namely, ampicillin, benzylpenicillin and carbenicillin, in pure form and in their dosage forms. The method is based upon treatment of penicillins with nitrous acid followed by polarographic measurement of the produced derivatives polarographically. The nitroso derivatives formed exhibited reduction waves over the whole pH range in Britton-Robinson buffers. The waves were characterized as being diffusion-controlled and free from adsorption phenomena. The current-concentration plots were rectilinear over the concentration range 8-200 and 2-160 micrograms ml-1 for DCt and DPP, respectively, for all the studied compounds. The proposed method was further applied to determine penicillins in pharmaceutical preparations, and the results obtained were in good agreement with those given by the companies.

Development and validation of an LC method for the quantitation of carbenicillin in human serum.

An LC method for the quantitation of carbenicillin in human serum has been developed and validated. After protein precipitation with acetonitrile and evaporation, the residue was taken up by citric acid at pH 1.9. Carbenicillin and the internal standard (I.S.), piperacillin, were extracted with ethyl acetate, evaporated to dryness and reconstituted with a buffer solution. The separation of carbenicillin,, the I.S., and matrix peaks was achieved on a Microsorb C18, 3 microns column with a mobile phase of acetonitrile-tetrabutylammonium-phosphate buffer (pH* 6.6). The detection was by UV at 208 nm. The run time was 8 min. The established linearity range was 0.25-20 microgram ml-1 (r2 > 0.99) with a limit of quantitation of 0.25 microgram ml-1. Interday precision (RSD) and bias over the entire range were 1.1-6.9% and -1.83 to +2.80%, respectively. The interday precision (RSD) and bias for the QC samples at 0.75, 3.0 and 12 micrograms ml-1 were 5.9-7.9% and -2.80 to +2.30%, respectively. Stabilities of on-system, bench top, freeze-thaw cycles and sample storage were established.

Determination of carbenicillin epimers in plasma and urine with high-performance liquid chromatography.

A high-performance liquid chromatographic method was developed for determining the concentrations of carbenicillin (CBPC) epimers in plasma and urine. Samples were prepared for HPLC analysis by solid-phase extraction and the concentrations of CBPC epimers were determined using reversed-phase HPLC with a mixture of 0.05 M ammonium acetate and methanol as a mobile phase. Baseline separation of the two epimers was observed for both plasma and urine samples with a detection limit of ca. 10 micrograms/ml. No peaks interfering with either of the CBPC epimers were observed on the HPLC chromatograms for blank plasma and urine. The presented method was used to determine the protein binding of CBPC epimers in vitro in human and rabbit plasma. The stereoselectivity of the binding of CBPC appeared to be reversed in human and rabbit plasma.

Epimerization kinetics of moxalactam, its derivatives, and carbenicillin in aqueous solution.

The mechanism of the epimerization of moxalactam was studied by measuring the rate of epimerization after deuteration of the C-7 side-chain chiral carbon, introduction of different substituents on the side chain, and variation of the ring system. Deuteration slowed the epimerization rate considerably. The rate was also influenced by the choice of the ring system and the substituent on the C-7 side-chain chiral carbon. When the penicillin ring system with the 2-carboxy-2-phenyl-acetamide was studied, the epimerization rate decreased indicating that the same ring system needed to be used throughout the epimerization studies. Thus, experiments were conducted with different substituents replacing the phenolic group at the C-7 side-chain chiral carbon of moxalactam. The epimerization rate decreased in the substituent order thienyl, phenyl, 4-hydroxyphenyl, the ionized form of 4-hydroxyphenyl, and ethyl. These results showed that dehydrogenation of the chiral carbon seems to be the rate-determining step and that the stronger the electron-donating effect of the substituent, the slower the epimerization rate becomes.

Tobramycin inactivation by carbenicillin, ticarcillin, and piperacillin.

The in vitro and in vivo inactivation of tobramycin by carbenicillin, ticarcillin, or piperacillin was investigated by the enzyme immunoassay method in clinically employed dosages. After the addition of an 80-mg dose of tobramycin to 4- to 5-g doses of a penicillin in 100 ml of 0.9% saline or distilled water, the degradation profile of tobramycin appeared to follow a biexponential pattern of decay. Remarkable losses (30 to 40%) of tobramycin combined with carbenicillin or ticarcillin were observed within 1 h, as compared with the later decline. The combination of tobramycin with piperacillin was least inactivating. When the admixture of tobramycin with carbenicillin or piperacillin used in the in vitro study was infused to six volunteers over 1 h, the observed maximum concentrations of tobramycin were on the average 66 and 74% for carbenicillin and piperacillin, respectively, of that observed after tobramycin alone was given. In contrast, the value obtained for tobramycin in combination with piperacillin was close to 90% of the control value. The elimination half-lives of tobramycin combined with the penicillins were slightly shorter than those of tobramycin alone, indicating that the interaction occurs even in patients with normal renal function.

Ion chromatographic determination of the principal inorganic ion in bulk antibiotic salts.

Two ion-chromatographic procedures were developed for determining the principal inorganic ions in bulk antibiotic salts. The anion system enables sulfate determination in sulfate salts of polymyxin, neomycin, streptomycin, and dihydrostreptomycin, with typical analysis times of 8 min/sample and a relative precision of +/- 2% (95% confidence interval). The cation system is applicable to sodium or potassium analysis in the respective penicillin salts in 9--16 min with a relative precision of +/- 2.5%. These methods offer speed, specificity, and easy sample preparation compared with traditional assays.

Quantitation of carbenicillin disodium, cefazolin sodium, cephalothin sodium, nafcillin sodium, and ticarcillin disodium by high-pressure liquid chromatography.

High-pressure liquid chromatographic (HPLC) methods for the quantitation of carbenicillin, cefazolin, cephalothin, nafcillin, and ticarcillin were developed. The stability of 2% solutions of the antibiotics in normal saline and in 5% dextrose in water were studied at 24 and 5 degrees. The assays were conducted using a previously reported colorimetric method, and some assays also were performed using HPLC. For discolored solutions of cephalothin, the colorimetric method was not stability indicating. The percent relative standard deviations by HPLC based on six injections were 1.69, 0.94, 1.30, 1.59, and 1.6 for carbenicillin, cefazolin, cephalothin, nafcillin, and ticarcillin, respectively. Both carbenicillin and ticarcillin apparently may be mixtures of two isomers at equilibrium with each other. The shelflives recommended by the manufacturers at 5 degrees may be too conservative.

Antibiotic bioassay by flow microcalorimetry.

A rapid, sensitive microcalorimetric bioassay of good reproducibility has been developed for the antibiotics penicillin-G, carbenicillin, ampicillin and cefoxitin. The use of growing organisms as responding agents allows discussion of the results for systems which may involve biological fluids.