OBJECTIVE: To evaluate the influence of temperature and humidity on the drug stability by initial average rate experiment, and to obtained the kinetic parameters. METHODS: The effect of concentration error, drug degradation extent, humidity and temperature numbers, humidity and temperature range, and average humidity and temperature on the accuracy and precision of kinetic parameters in the initial average rate experiment was explored. The stability of vitamin C, as a solid state model, was investigated by an initial average rate experiment. RESULTS: Under the same experimental conditions, the kinetic parameters obtained from this proposed method were comparable to those from classical isothermal experiment at constant humidity. The estimates were more accurate and precise by controlling the extent of drug degradation, changing humidity and temperature range, or by setting the average temperature closer to room temperature. CONCLUSION Compared with isothermal experiments at constant humidity, our proposed method saves time, labor, and materials.
Ascorbic Acid ; chemistry ; Drug Stability ; Humidity ; Kinetics ; Temperature

Glycerin containing carrageenan as a non-aqueous carrier for vitamin C (Vc) was prepared in this study. The stabilities of Vc at room temperature and after high temperature accelerating treatment were investigated. The effects of Vc as well as carrageenan on rheological properties were analyzed. The results showed that, with the increases of Vc, the viscosity of the non-aqueous system decreased and the shear-thinning phenomenon disappeared. Furthermore, the stability of Vc was kept well in this non-aqueous system, and the retention rate maintained at a high level-over 99% a month later in room temperature, and over 97% after high temperature accelerating treatment for 20 days. The retention rate of Vc was improved with the increasing of carrageenan. It was proved that this non-aqueous system was an ideal drug delivery system for Vc.
Ascorbic Acid ; chemistry ; Carrageenan ; Drug Carriers ; chemistry ; Drug Stability ; Glycerol ; chemistry ; Oxidation-Reduction ; Solutions

Study on NO(2) absorption aimed at seeking a better NO(2) absorption chemical at pH 4.5 approximately 7.0 for application to existing wet flue gas desulfurization (FGD). The results from the double-stirred reactor indicated that ascorbic acid has very high absorption rate at this pH range. The rate constant of ascorbic acid reaction with NO(2) (0 approximately 1,000 x 10(-6) mol/mol) is about 3.54 x 10(6) mol/(Ls) at pH 5.4 approximately 6.5 at 55 degrees C.
Absorption ; Air Pollutants ; chemistry ; isolation & purification ; Ascorbic Acid ; chemistry ; Nitric Oxide ; chemistry ; isolation & purification

OBJECTIVETo study the different and the variety of four organic acids in leaves of Isatis indigotica among different cultivated populations in water stress condition and healthy plant.

METHODFour kinds of organic acids, such as oxalic acid, malic acid, ascorbic acid and citric acid from the leaves, were detected by HPLC.

RESULTSignificant differences of four organic acids in the leaves of Beijing, Mongolia, Hebei and Shanxi cultivated populations. Compared with the healthy plant, the content of oxalic acid, malic acid and citric acid in water stress were increased, while the content of ascorbic acid was decreased.

CONCLUSIONContents of four organic acids can act as the guideline factor in I. indigotica because they were related with the water stress condition.

Ascorbic Acid ; chemistry ; metabolism ; China ; Chromatography, High Pressure Liquid ; Citric Acid ; chemistry ; metabolism ; Dehydration ; Isatis ; chemistry ; metabolism ; Malates ; chemistry ; metabolism ; Oxalic Acid ; chemistry ; metabolism ; Plant Leaves ; chemistry ; metabolism

No abstract available.
Ascorbic Acid/*chemistry ; Blood Chemical Analysis/instrumentation/*methods ; Blood Glucose/*analysis ; Maltose/*chemistry

Biological synthesis of L-Ascorbyl Palmitate in organic system were studied in this text. The contradiction between conversion of vitamin C and concentration of L-Ascorbyl Palmitate were resolved. High conversion of vitamin C and concentration of L-Ascorbyl Palmitate were obtained by Novo435. A series of solvents(log P from -0.24 to 3.5 )were investigated for the reaction,and acetone was found to be the most suitable from the standpoint of the enzyme activity and solubility of L-ascorbic. And the equilibrium of the reaction was affected by the addition of the molecular sieves and temperature. Reaction carried out at 60 degrees C and with 20% 0.4nm molecular sieves is good for the enzyme to keep its activity and for making the equilibrium go to the product. With 1.094 g palmitic acid, 0.107 g vitamin C and 0.020 g Novo435, rotate rate of 200 r/min, the conversion of ascorbic reached 80% and the concentration of L-ascorbyl palmitate is 20 g/L after 48 h. Furthermore, reaction batch of Novo435 and substrates recycle were observed, the result indicated that Novo435 may used 4-5 times continuously with high conversion. And 6-O-unsaturated acyl L-ascorbates were synthesized through Novo435 condensation of ascorbic acid and various unsaturated fatty acids with high conversion in this text.
Ascorbic Acid ; analogs & derivatives ; biosynthesis ; Catalysis ; Enzymes, Immobilized ; chemistry ; metabolism ; Lipase ; chemistry ; metabolism

OBJECTIVETo evaluate the 8 main quality characteristic indexes of fruit-using Chaenomeles speciosa and C. sinensis fruits produced in Chongqing and explore the comprehensive assessment for the fresh eating-quality of the samples based on the theory of fuzzy comprehensive.

METHODThe total sugar content, titratable acid content, ascorbic acid content and superoxide dismutase (SOD) activity of fresh samples were determined, and the oleanolic acid, ursolic acid, total flavones and total saponins content of dried sample were determined by HPLC and colorimetry method. The fuzzy probability method was used to comprehensively evaluate their fresh eating-quality of the fruit-using C. speciosa and C. sinensis fruits produced in Chongqing.

RESULTThe mean SOD activity of C. speciosa and C. sinensis fresh fruits separately was 15.99 U x mg(-1) and 27.40 U x mg(-1), respectively. And the fresh fruit titratable acid content, total sugar content, ascorbic acid content separately was 0.357 g x L(-1), 0.854 mg x L(-1), 1.118 mg x L(-1) and 0.252 g x L(-1), 0.845 mg x L(-1), 1.260 mg x L(-1), respectively. The oleanolic acid, ursolic acid, total flavones and total saponins content was 0.320%, 0.461%, 43.90 mg x g(-1), 23.11 mg x g(-1) and 0.255%, 0.176%, 41.24 mg x g(-1), 15.01 mg x g(-1), respectively. The Chaenomeles speciosa and C. sinensis sample quality mean comprehensive evaluation value was 0.599 and 0.367 based on the fuzzy probability method.

CONCLUSIONThe edible quality of fruit-using C. speciosa fruits are better than C. sinensis fruits produced in Chongqing. And the fuzzy probability method could be used to quality comprehensive evaluation of samples containing many trait paramaters.

Ascorbic Acid ; China ; Chromatography, High Pressure Liquid ; Colorimetry ; Fruit ; chemistry ; Rosaceae ; chemistry ; Superoxide Dismutase ; metabolism

OBJECTIVETo establish a method to determine Vitamin C in the Vc Yinqiao Tablets.

METHODDiffuse Reflectance in FTIR was used to determination of Vitamin C in the Vc Yinqiao tablets.

RESULTThe content of Vitamin C could be obtained directly, and the relationship between the absorbance and the concen tration was linear. The average recovery rate of Vitamin C was 98.69%, and RSD was 0.33%.

CONCLUSIONThe method is simple, accurate and reliable, which may well be used for the determination of Vitamin C in the Vc Yinqiao Tablet.

Ascorbic Acid ; analysis ; Drug Combinations ; Flowers ; chemistry ; Lonicera ; chemistry ; Plants, Medicinal ; chemistry ; Spectroscopy, Fourier Transform Infrared ; Tablets ; chemistry

BACKGROUND: Intravenous administration of high doses of ascorbic acid (AA) for certain clinical conditions can cause high levels of blood AA to interfere with the measurement of blood glucose. In this study, we evaluated the potential interference by high concentrations of blood AA with glucose measurement in different instruments. METHODS: Using Hitachi 7600 chemistry autoanalyzer (Hitachi 7600) and Accu-Chek Active monitor glucometer (Accu-Check), glucose was measured in serum specimens in which AA had been added in vitro at concentrations ranging from 0 to 28, 388 micromol/L. To assess the effect of pharmacokinetics of AA on glucose concentrations, blood AA and glucose were measured serially in healthy subjects after 10 g of IV Vitamin C supplement was administered. RESULTS: Beginning at the concentration of 227 micromol/L, the blood AA interfered with glucose measurement negatively in Hitachi 7600, but positively in Accu-Chek. The extent of interference was proportional to AA concentrations in both directions. The in vivo study showed that, although both instruments were affected by high blood AA at 1 hour of IV administration, blood glucose levels were normalized at 5 hours in Hitachi 7600 and at 3 hours in Accu-Chek. CONCLUSIONS: When considering that IV high dose AA supplement is becoming more popular and the extent of its interference with blood glucose measurement is significantly high in commercial systems, it would be important for the clinical laboratory to be informed of the prescription informations of patients and the time of blood collection, and to choose a correct system for an accurate blood glucose measurement.
Administration, Intravenous ; Ascorbic Acid* ; Blood Glucose* ; Chemistry ; Glucose ; Humans ; Pharmacokinetics ; Prescriptions

BACKGROUND: To understand causes of abnormal reaction for the urinalysis, we analyze the interfering substances of clinical urine samples. We focused the effect of urinary vitamin C and fluorescein sodium to the urine chemistry especially glucose, hemoglobin, and leukocyte esterase. METHODS: Incidence of urinary vitamin C was determined for patients and people underwent a medical check–up. We decided dipstick results of glucose, hemoglobin, and leukocyte esterase as false negative based on urine sediment and serum glucose results. Dipstick urinalysis was tested by URiSCAN Pro III with URiSCAN 11 strip (YD Diagnostics, Korea). Urine sediments tests were performed by manual microscopic analysis or Sysmex UF–1000i (Sysmex Co., Japan). RESULTS: The incidence of vitamin C was 20.4% for all subjects. The positive rate of the medical check-up group (34.6%) was higher than others. When vitamin C was detected in clinical urine samples, 42.3%, 10.6%, and 8.2% were defined as false negative for glucose, hemoglobin, and leukocyte esterase dipstick tests, respectively. Fluorescein sodium also interfered on the results of hemoglobin and leukocyte esterase of the dipstick reagents. CONCLUSIONS: Vitamin C was frequently found in the clinical urine samples, and its incidence was higher in the people who underwent medical check-up. The urinary vitamin C and fluorescein sodium can cause interferences in urine dipstick results. Thus, it is expected that present study will give useful information to predict false negative rates of urine dipstick tests by vitamin C and fluorescein sodium.
Ascorbic Acid ; Blood Glucose ; Chemistry ; Fluorescein ; Glucose ; Humans ; Incidence ; Indicators and Reagents ; Leukocytes ; Urinalysis*