determination of citric acid
Abstract: In this paper weight method of citrate in the Treatment of low concentration of sulfur dioxide system in the determination of citrate were analyzed. Determination results of the impact analysis of major factors such as pH, water volume, aging time, drying temperature were studied. Determination of the better conditions for the selection: testing the process control of solution pH, about 4.6; add water volume to 250mL; aging time select 50min; precipitation to be dried at 140 ℃. The results show that the method is reliable for the determination of high concentrations of citric acid. Number of pages: 3 pages :65-66 range, 46 Keywords: citric acid Gravimetric Determination of low concentrations of sulfur dioxide, citric acid pH, control of the process of drying temperature, aging time Subject Category citrate method: TS275 [Industry Technology] X701.3 [] Related Articles: Topics related references (8) citations (1) coupling the literature (14)

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Current location: China paper Download Center> Medicine> Pharmacy> body thin layer of gold throat citrate tablets identification and determination
Source: China paper Download Center [09-09-06 11:59:00] Editor: studa20
2.2.3 System Suitability Testing precision drawing reference solution, respectively, the test solution, lack of negative control ebony extract solution of 10 μl, high performance liquid chromatograph, record the chromatogram. The results shown in Figure 2. Figure 2 shows the retention time of citric acid is about 15.5 min, citric acid peak and its peak before and after the separation were 1.78,3.61, tailing factor was 1.04, the peak number of theoretical plates to the total, 14,198 of citric acid , citric acid peak purity factor of 997, the peak at the negative control without interfering in the citric acid, that under the experimental conditions complete separation of citric acid and other components.
2.2.4 The linear relationship between the study were drawn precision control solution of citric acid (0.52 mg · ml-1) 2,4,6,8,10,15,20 μl, into the liquid chromatograph, the peak measured by the chromatographic conditions area of the peak area A of the sample volume C (μg) regression, have standard curve equation: A = 1.8162C 0.0325, r = 0.999 9. The results show that the citric acid in the range of 1.04 ~ 10.4 μg, peak area and sample size has a good linear relationship.
2.2.5 precision experiments
Precise amount of reference substance solution preparation under the reference solution 10μl, repeat 5 times injection, citric acid, the average peak area of 9.401 8, RSD was 0.17% (n = 5), showed that good precision instrument.
2.2.6 Stability testing of this product (batch number 051214) of the test solution, room temperature, were measured in 0,2,4,6,8,10,12,24,36 h, citric acid peak area average of 3.867 5, RSD was 0.15% (n = 9), show that the sample solution was stable at 36 h.
2.2.7 repeated experiment with a number of samples taken (batch number 051214), according to the test solution under the method of preparation, the parallel preparation of 5 copies of the test solution were measured, the measured average concentration of citric acid 21.358 0 mg · g -1, RSD was 0.13% (n = 5), showed good reproducibility of this Law.
2.2.8 Weigh the recovery experiments of known precision levels (21.3580 mg · g-1) of the product (batch number 051214) powder 9 copies, each 0.5 g, were divided into 3 groups of 2 were, respectively, to add precision citric acid reference solution (2.68 mg · ml-1) 3,4,5 ml, according to the test solution prepared under preparation for the test solution, determined by the above chromatographic conditions, and calculate the recovery. The results in Table 1. Experimental results show that this law has a good recovery. Table 1 Experimental determination of sample recovery results (omitted)
2.2.9 Determination of the samples were precise amount of reference substance solution and test solution 10μl, determined by the above chromatographic conditions. The results in Table 2. Table 2 gold throat citrate tablets assay results (omitted)
3 Discussion
Ebony in identifying the citric acid extract of 4 when used to start the system, ether - chloroform - formic acid - methanol (5:2:1.5:0.5) [2], butyl acetate - formic acid - water (4:2: 2) [3], butanol - acetic acid - water (4:1:5) [4], isopropyl ether - methanol - formic acid - water (30:4:4:1) [5], the results of the first 3 Expand the system separation are not as good as the first four to start the system. Reagent has compared a 1% ferric chloride ethanol solution, 10% sulfuric acid in ethanol, 0.1% ethanol solution of methyl orange, bromocresol green 0.1% ethanol and 0.1% bromophenol blue ethanol solution. 3 pending the outcome of reagent spots are not obvious, and sprayed with 0.1% ethanol solution of bromocresol green was a blue background yellow spots, 0.1% bromophenol blue ethanol solution was in the blue-violet background of yellow spots. Two reagent effects are good, but the yellow background of blue-violet spots stronger contrast, it is 0.1% of use ethanol as bromophenol blue color agent. As is the use of acid-base indicator color, while the developing agent containing formic acid, so the spray reagent is preferable to hair dryer hot air stalls before the play to make formic acid (120 ℃ oven baking set, the effect is not ideal.) Thin-layer plate along the long soak in the developing solvent, formic acid is not easy play to do, can be spotted along the part of the TLC plate covered with a thin layer of ammonia smoked click along the yellow part of the plate can be.
Trials for the preparation of the test solution of different extraction methods (ultrasonic and reflux and solvent extraction), different extraction solvents (methanol, 75% methanol, 50% methanol, 25% methanol, water and mobile phase), different solvent volume (10 , 25,50,75,100 ml) and different extraction time (15,30,45,60 min) were investigated. The results of ultrasonic extraction with 50 ml of water 30 min was the highest peaks of impurities less.
Diode array detector at 190 ~ 380 nm were scanned within the reference substance, the sample solution UV absorption peak of citric acid, citric acid peak is the end result of absorption, maximum absorption peak at 190 nm, at about 210 nm at a turning point , 250nm Department has almost no absorption, in order to avoid interference with other impurities, measured wavelength selection in the 210 nm.
Choice test in the mobile phase was investigated 0.01 mol · L-1 potassium dihydrogen phosphate solution (pH adjusted to 2.7 with phosphoric acid) [6]; 0.5% ammonium dihydrogen phosphate solution (adjusted with phosphoric acid pH 2.8) [7]; methanol -0.1% phosphoric acid (5:95); acetonitrile -0.1% 0.1% triethylamine phosphate solution (1:99), etc. in different proportions, flow rate and column temperature. Was found that the mobile phase of acetonitrile -0.1% 0.1% triethylamine phosphate solution (1:99), flow rate 0.6 ml · min-1, the column temperature was 25 ℃, suitable retention time, the best separation, so the use of this flow phase.
Experiments using thin layer chromatography of citric acid on the gold film for qualitative identification of the throat, and content was determined by HPLC, accurate and precise, with good repeatability and recovery of citric acid can be used for the quality of the preparation control.
ã€Reference】
[1] National Pharmacopoeia Committee. Chinese Pharmacopoeia, â… Ministry [S]. Beijing: Chemical Industry Press, 2005: Appendix 31.
[2] Chen Yong, Chen Han-deep, Dong Yi. Guang hawthorn and leaf quality analysis [J]. MATERIA MEDICA, 1999,10 (07): 511.
[3] Wang Xuejie, Ho Ching. Cang Wu quality standard mixture [J]. MATERIA MEDICA, 2002,13 (09): 515.
[4] drug information network. Xintai quality standard. [DB / OL] http://www.chemdrug.com/ZstandsInfo.asp.ID=478
[5] drug information network. Hu Mei tablet quality standards. [DB / OL] http://www.chemdrug.com/ZstandsInfo.asp.ID=628 ,2006-06-18.
[6] Guo Ying, Xiao Zhaoping, Wang Hong. Ebony organic acids by high performance liquid chromatography [J]. Analytical Chemistry, 2004, 32 (12): 1624.
[7] Chen Warring States Period, En Boti, bloods. RP-HPLC Determination of 8 Kinds of Organic Acids ebony [J]. Chinese Materia Medica, 2006,31 (21): 1783. Reposted elsewhere in the paper for free download http: / / www.studa.net
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