Colorimetric determination of some sulphonamides with phenothiazine

Two simple and sensitive calorimetric procedures for determination of some sulphonamides with phenothiazine (thiodiphenylamine) are presented. One is based on reaction in aqueous alcohol solution in presence of hypochlorite, with direct measurement at 515 nm. The other is based on reaction in presence of copper(II) acetate at 70 degrees , extraction with chloroform and measurement at 515 nm. The method is applied to the determination of sulphonamides in pure and tablet form, with a coefficient of variation less than 2%.     

Derivative spectrophotometric determination of sulphonamides by the Bratton-Marshall reaction

A modified method for the determination of sulphonamides, based on the Bratton-Marshall reaction with derivative spectrophotometry, is proposed. Diverse sulphonamides are determined with excellent precision by using first- to fourth-order derivative spectra. The method was applied for the determination of sulphonamides in urine, honey and pharmaceutical formulations without pretreatment of the samples.     

Liquid chromatographic-tandem mass spectrometric determination of selected sulphonamides in milk

Liquid chromatography–tandem mass spectrometry is used for the quantitative analysis of selected sulphonamides in milk. Ultrafiltration is the only sample pre-treatment technique which is required. Consequently, sample throughput is much higher than with conventional procedures, and analyte recoveries are high. As for quantification, both external standard and isotope dilution calibration yield satisfactory results. The method is fully validated for five sulphonamides with a maximum residue limit of 100 μg/kg, and which are included in the Dutch control programme on residues. Furthermore, results are presented on the applicability of the method to detect compounds at a much lower concentration level exemplified by a banned sulphonamide, dapsone, which has a provisional action limit of 5 μg/kg. The main conclusion is that the present, novel approach to the trace-level determination of veterinary drugs is simple and straightforward and has a wide-ranging application potential which is briefly exemplified by the analysis of selected benzimidazoles in milk by essentially the same procedure.     

Rapid determination of sulphonamides in milk using liquid chromatographic separation and fluorescamine derivatization.

A simple and selective method is presented for the multiple residue determination of eight sulphonamides in consumers' milk. The drugs are sulphisomidine (ID), sulphadiazine (DZ), sulphamerazine, sulphadimidine, sulphamonomethoxine, sulphamethoxazole, sulphadimethoxine and sulphaquinoxaline (SQ). The milk sample was deproteinized with the same volume of 2 M hydrochloric acid and filtered. A 1-ml volume of the filtrate was mixed with 1 ml each of 1.25 M sodium acetate solution and a buffer (pH 3.0) for derivatization with 0.6 ml of 0.02% fluorescamine solution in acetone. A high-performance liquid chromatographic analysis was carried out on a C18 column with a mobile phase of acetonitrile-2% acetic acid (3:5) at 55 degrees C using a fluorescence detector at an excitation wavelength of 405 nm and an emission wavelength of 495 nm. Average recoveries at fortification levels of 2, 5 and 10 ng/ml were 114%, 109% and 106%, respectively. Relative standard deviations were 1-4% at 10 ng/ml for ID, 5 ng/ml for DZ and SQ and 2.5 ng/ml for the other five sulphonamides. The method was applied to 25 milk samples and all appeared to be free from the drugs.     

Separation of sulphonamides and determination of the active ingredients in tablets by micellar electrokinetic capillary chromatography.

The separation and determination of seven sulphonamides and trimethoprim by micellar electrokinetic capillary chromatography were successfully achieved, employing sodium dodecyl sulphate (SDS) as a micellar phase and tetrabutylammonium bromide as additive. The effects of surfactant and modifier concentrations, pH and applied voltage on the retention behaviour of the solutes and the column efficiency were studied. The migration time of sulponamides increase with increasing SDS concentration and decreasing the applied voltage, but varies only slightly with pH. There is an optimum applied voltage at which a higher theoretical plate number is achieved, in contrast to the sulphonamides, the retention behaviour of trimethoprim gave a more obvious response to changes in the experimental conditions. The determination of three active ingredients in tablets was performed using sulphathiazole as an internal standard with good results. The theoretical plate number ranged between 2.0 x 10(5) and 2.8 x 10(5) with a 50-cm capillary.     

Report by the Analytical Methods Committee. Nitrogen factors for chicken meat

Recent studies have raised doubts about the relevance of the nitrogen factors for chicken meat recommended by the Analytical Methods Committee in 1963 when applied to the chicken meat currently being processed. The Nitrogen Factors Sub-Committee was asked to carry out a reappraisal of the chemical composition of chicken meat. It was informed that the majority of meat produced in the UK came from either of the breeds Ross or Cobb and one or other of the categories broilers (male or female, killed at 5 weeks), heavy broilers (male, killed at 7/8 weeks) and hens. Selected birds from these categories were dissected into samples representing breast, leg, thigh, other meats and skin and these were analysed for fat, moisture, nitrogen, ash and hydroxyproline content. The separate results for breast, leg, thigh, skin and other meats were combined mathematically to give figures for whole birds. From these results it was possible to recommend nitrogen factors for the individual joints and for the entire carcases, with and without skin, for broilers and hens. These factors are lower than those recommended in 1963.     

Report by the Analytical Methods Committee. Nitrogen factors for turkey meat

There are uncertainties about the relevance of the nitrogen factors for turkey meat recommended by the Analytical Methods Committee in 1965 when applied to current strains of turkey reared under modern systems of management. As a result, the Nitrogen Factors Sub-Committee has carried out a reappraisal of the chemical composition of turkey meat using two strains of turkey currently used in the UK and Europe. Turkeys representing both sexes at two typical ages for processing were obtained from UK producers. Each bird was dissected to give five samples representing breast, drumstick, thigh, other meat and skin (with associated fat), which were then analysed for fat, moisture, nitrogen, ash and hydroxyproline content. The separate results for each portion were combined mathematically to give figures for whole birds. From these results it was possible to recommend fat-free nitrogen factors for the individual joints and for the entire carcase, with and without skin, for males and females and for type of turkey where known.     

Isotachophoretic determination of creatinine in meat and meat products

A capillary isotachophoretic method (CITP) to determine the creatinine concentration in meat and meat products is described. A clear separation of the creatinine from other components of an acidic extract of sample was achieved within 20 min. Method characteristics (linearity, accuracy, precision and detection limit) were determined. The developed method was successfully applied to analyze real samples and to determine creatinine and creatine content (indirect determination after acidic hot extraction) in meat and meat products.     

Methods for the determination of water in polymers

Water may be “weakly” or “strongly” bound to other substances by physical or chemical forces. Knowledge of the amount of water and the type of bonding in polymeric materials is very important in control of many polymerization processes and in the physical behavior of the polymer. Hundreds of methods have been proposed for the determination of water in concentrations ranging from p.p.b. to high percentages. Some are direct; others require preliminary concentration or chemical reaction. The most useful methods of analysis for water in polymers are based on chemical, spectroscopic, gravimetric, thermal, electrical, and physical techniques. Chemical methods are represented by Karl Fischer titration, acylation, and nitride reactions. Infrared, nuclear magnetic resonance, and mass spectrometry are the principal spectroscopic approaches. Other useful methods include direct weight loss, thermogravimetry, differential thermal analysis, thermal evolution analysis, dielectric constant, conductance, coulometry, chromatography, azeotropic distillation, piezoelectric, manometric, and volumetric procedures. Recent developments are described with emphasis on applications of these techniques.     

Kinetic determination of sulphonamides at the millimolar level by the continuous addition of reagent technique

A kinetic method for the determination of sulphonamides by the continuous addition of reagent (CAR) technique is reported. The method involves the formation of an azo dye between 1-naphthol and a diazonium salt, which is in turn obtained on reaction between the free primary aryl amine of the sulphonamide and sodium nitrite in a weak acid medium. The reaction is monitored via the initial rate of change of the absorbance of the azo dye formed at 470 nm, which is proportional to the sulphonamide concentration. Practical problems associated with this type of reaction for the determination of sulphonamides were readily avoided by using the CAR technique. Sulphonamides can be determined in the range 3 × 10^?6 ?3 × 10^?5 M with a relative standard deviation of about 1% and a sampling frequency of 25 h^?1 (triplicate runs). The proposed method is simple and rapid and insensitive to the presence of excipients; it proved useful for the determination of sulphonamides in pharmaceutical samples.     

A micro method for the determination of protein and screening of added water in meat and meat products

Summary The automatic Dumas method is feasible for determining the protein and screening for added water in meats and meat products. It is rapid, convenient, and requires less laboratory space and cost for routine operation. Homogeniety of the meat sample is important. Samples identified as positive for added water should be confirmed and quantified by the official macro-Kjeldahl method.

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Zusammenfassung Die automatisierte Dumas-Methode eignet sich für die Proteinbestimmung in Fleisch und Fleischwaren zwecks Ermittlung von Wasserzusätzen. Das Verfahren ist rasch durchzuführen, beansprucht wenig Platz im Labor und verursacht im Routinebetrieb nur geringe Kosten. Die Fleischproben müssen homogen sein. Gegebenenfalls festgestellter Wasserzusatz soll mit der offiziellen Makro-Kjeldahlmethode verifiziert werden.

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This paper was persented at the Sixth Middle Atlantic Regional Meeting of the American Chemical Society, February 3–5, 1971, Baltimore, Md.     

Methods for the determination of anionic surfactants

Methods for the determination of synthetic anionic surfactants published in the past two decades are considered, and their advantages and disadvantages are demonstrated. Spectrophotometric and potentiometric (with the use of ion-selective electrodes) techniques, including flow injection analysis versions, are used for the determination of anionic surfactants. Chromatographic techniques (primarily, high-performance liquid chromatography) are most frequently used for the separation, preconcentration, and determination of anionic surfactants in complex mixtures. Spectrofluorimetry, voltammetry, and immunoassay did not find wide application.     

Colorimetric determination of arylamines and sulphonamides by diazotization and coupling in a micellar solution

The use of a micellar solution as a means for improving the colorimetric determination of arylamines by diazotization and coupling is studied. Sodium dodecylsulphate (SDS), Triton X-100 (TX-100) and N-cetylpyridinium chloride (NCPC), together with the diazotizable substances aniline and sulphanilic acid and the coupling agents 1-naphthylamine and N-(1-naphthyl)ethylenediamine are used as model compounds. The protonation constants of the dyes follow the order SDS>H₂O>TX-100>NCPC. In an SDS micellar solution the coupling rate increases greatly, allowing the rapid formation of the protonated dyes in an acetate buffer. Other advantages are the possibility of analysing very non-polar samples and of using a wider range of diazotizable substances and substrates. A procedure for the determination of 10–100 μg of aniline in an SDS micellar solution is proposed. The procedure is applied to the determination of sulphonamides in pharmaceutical preparations.