Determination of parabens in sweeteners by capillary electrochromatography

Parabens, common food preservatives, were analysed by capillary electrochromatography, using a commercial C18 silica (3 µm, 40 cm × 100 µm i. d.) capillary column as separation phase. In order to optimise the separation of these preservatives, the effects of mobile phase composition on the separation were evaluated, as well as the applied voltage and injection conditions. The retention behavior of these analytes was strongly influenced by the level of acetonitrile in the mobile phase. An optimal separation of the parabens was obtained within 18.5 minutes with a pH 8.0 mobile phase composed of 50:50 v/v tris(hydroxymethyl)aminomethane buffer and acetonitrile. The method was successfully applied to the quantitative analysis of paraben preservatives in sweetener samples with direct injection.

Os parabenos, empregados como conservantes em alimentos, foram analisados por eletrocromatografia capilar, empregando uma coluna comercial recheada com partículas de sílica-C18 (3 µm, 40 cm × 100 µm d. i.) como fase estacionária de separação. Para otimizar a separação destes conservantes foram avaliados os efeitos da composição da fase móvel na separação, bem como a voltagem e as condições de injeção. O comportamento de retenção dos analitos foi fortemente influenciado pela proporção de acetonitrila na fase móvel. A separação dos parabenos foi alcançada em 18,5 min com uma fase móvel contendo tampão tris(hidroximetil)aminometano e acetonitrila na proporção 50:50 v/v. O método foi aplicado na análise quantitativa de parabenos em adoçantes empregando a injeção direta das amostras.

Capillary electrophoresis method for the determination of flavonoids / 药学学报

Due to their biological and physiological importance, flavonoids received considerable attention in the literature. This review discusses the widely used analytical method i.e. capillary electrophoresis (CE) including the chiral flavonoids separation and the hyphenation of CE and MS. Techniques used for enhancement of sensitivity such as stacking, sweeping, isotachophoresis etc. were also discussed.

Determination of cytidine and adenosine in cordyceps by monolithiccapillary electrochromatography / 中国中药杂志

<p><b>OBJECTIVE</b>To develop a capillary electrochromatography method for determination of cytidine and adenosine in cordyceps with monolithic column.</p><p><b>METHOD</b>The total length of the home-made ploy-butyl methacrylate (PBMA) monolithic capillary electrochromatographic column was 34.5 cm with the effective length of 26.0 cm. The mobile phase was 20 mmol x L(-1) borax solution (adjusted pH to 3.5 using acetic acid); the operation voltage was 15 kV; sample injection pressure was 6 bar x 0.1 min; column temperature was 30 degrees C and the detection wavelength was set at 214 nm. The internal standard solution was 100 mg x L(-1) trimethoprim solution [ethanol-mobile phase (1 : 1) was used as the solvent].</p><p><b>RESULT</b>The results indicated that the concentrations of cytidine and adenosine within the range of 12.5-125 mg x L(-1) were linearly correlated with the relative peak areas, and the correlative coefficients (r) were 0.999 8 and 0.999 3, respectively. The LOD (S/N = 3) and LOQ (S/N = 10) of cytidine were 2.14 and 7.14 mg x L(-1), and those of adenosine were 1.88 and 6.25 mg x L(-1). The average recoveries of the two nucleosides were from 97.2% to 103.5% with relative standard deviation (RSD) within 0.9%-2.6% in three levels.</p><p><b>CONCLUSION</b>The method is effective and credible. It can be used to determine the contents of cytidine and adenosine in cordyceps.</p>

Determination of tetrandrine and fangchinoline in Radix Stephaniae tetrandrae and its preparation by nonaqueous capillary chromatography / 中国中药杂志

<p><b>OBJECTIVE</b>To establish a new method for the determination of fangchinoline and tetrandrine in Stephania tetrandra and Fengtongan capsule by noanqueous capillary electrophoresis.</p><p><b>METHOD</b>Separation was carried out in an uncoated fused capillary (50 cm x 75 microm i.d.) with a running buffer containing 50 mmol x L(-1) ammonium acetate, 1.0% acetic acid and 20% acetonitrile in methanol. A separation voltage of 20 kV and a UV detector wavelength at 214 nm were adopted. Sample was introduced from the anode.</p><p><b>RESULT</b>The calibration ranges were 1.00, 500 mg x L(-1) for both analytes. Under the optimum conditions, the relative standard deviation (RSD, n = 6) for the migration time of each analyte were 0.09%, 1.9% (intra-day) and 0.63%, 1.9% (inter-day); The RSD for the peak area of each analyte were 0.45%, 5.9% (intra-day) and 2.3%, 5.6% (inter-day), respectively. The contents of the analytes were determined easily with average recoveries 102% for fangchinoline and 105% for tetrandrine in S. tetrandra and 94.6% for fangchinoline and 98.7% for tetrandrine in Fengtongan capsules, respectively.</p><p><b>CONCLUSION</b>The proposed method is simple, rapid, accurate and higher repeatable, and can be used to control of the quality of S. tetrandra and Fengtongan capsules.</p>

Regulations of residual solvents in pharmaceuticals and advances in the research of its analytical methods / 药学学报

If the presence of residual solvents in pharmaceuticals exceeds tolerance limits as suggested by safety data, they may be harmful to the human body or the environment. It is because of this that the determination of residual solvents receives a great deal of attention. This paper reviews in detail the changes in the regulations on residual solvents in pharmaceuticals in leading pharmacopoeias, and the advances in the techniques involved, especially, the recent advances in the analytical techniques are summarized. At the end, the authors introduce the prospect of the expert system for determining residual solvents in pharmaceuticals based on the studies of their research group.

Safety destruction of tetramethylene disulfotetramine and its medical waste / 中华预防医学杂志

<p><b>OBJECTIVE</b>To develop suitable methods for safety destruction of tetramethylene disulfotetramine (TETS) and the medical wastes polluted by TETS.</p><p><b>METHODS</b>The chemical stability of TETS was evaluated under the conditions of acid, alkali and high temperature. TETS was treated with sodium hydroxide, hydrochloric acid, sulfuric acid and nitric acid under various treatment conditions, i.e. concentration, temperature and time, followed by determining remaining TETS using gas chromatograms to estimating the degradation efficiency of TETS. TETS was put into ampoule and heated under the different conditions of temperature and time. After heat treatment, TETS residue was determined. For evaluating the absorption factor of active carbon to TETS in water and blood, active carbon was added into the water and blood with content of TETS, incubated at room temperature for 24 hours, and then determined the remaining TETS in water and blood.</p><p><b>RESULTS</b>The complete degradation of TETS was achieved by one of the following treatments: heating with 6.0 mol/L hydrochloric acid at 100 degrees C for half an hour, heating with 3.0 mol/L hydrochloric acid or 6.0 mol/L sodium hydroxide at 100 degrees C for 3 hours, mixing with concentrated sulfuric acid or nitric acid at room temperature for 24 hours, and dry heating at 300 degrees C for 4.5 hours. Active carbon showed a marked effectiveness in absorbing the TETS in blood and water, with the mean absorption efficiency of over 90%.</p><p><b>CONCLUSIONS</b>The results of this study suggest that TETS powder should be degraded by acid or alkali, and that the solid medical wastes polluted by TETS should be destroyed at high temperature. For the blood and water having contents of TETS, the active carbon should be used as to absorbing the TETS and then be destroyed at high temperature.</p>