scholarly journals TLC Determination of Mebendazol and Pentoxifylline as Residues on Pharmaceutical Equipment Surfaces

2001 ◽  
Vol 84 (4) ◽  
pp. 1258-1264 ◽  
Author(s):  
Irena Vovk ◽  
Breda Simonovska
Keyword(s):  
Stainless Steel ◽  
Steel Surface ◽  
Stainless Steel Surface ◽  
Linear Calibration ◽  
Coefficients Of Variation ◽  
The Mean ◽  
Steel Surfaces ◽  
Narrow Concentration Range ◽  
Calculated Amount

Abstract This paper presents the applicability of thin-layer chromatographic methods with a subsequent densitometric or video densitometric quantitation for determination of residues in controlling pharmaceutical equipment cleanliness. Analytical methods were developed for monitoring residues of pentoxifylline at 10 mg/m2 and mebendazol at 1 mg/m2 on stainless steel surfaces. Simulated samples were prepared by addition of a calculated amount of pharmaceutical (as a solution) on a 35 × 35 cm stainless steel surface. After evaporation of solvent, the residues were wiped with wetted cotton. The cotton was extracted with dichloromethan–methanol (1 + 1). Filtered extract was concentrated by vacuum evaporation and an aliquot applied to the plate, where standards were also applied. In the narrow concentration range near the acceptable residue limits, linear calibration curve could be obtained for both substances. The mean recovery (n = 4) obtained by densitometric quantitation was 93.4% for pentoxifylline and 85.6% for mebendazol, with coefficients of variation of 3.5 and 8.3%, respectively. Results of video densitometric quantitation did not differ significantly. However, data acquisition and evaluation is faster compared with densitometry and allows better archiving possibilities as required by the regulatory authorities. Both quantitation modes can be applied to routine control of pharmaceutical equipment cleanliness.

scholarly journals Development and Validation of a Thin-Layer Chromatographic Method for Determination of Chloramphenicol Residues on Pharmaceutical Equipment Surfaces

2005 ◽  
Vol 88 (5) ◽  
pp. 1555-1561 ◽  
Author(s):  
Irena Vovk ◽  
Breda Simonovska
Keyword(s):  
Stainless Steel ◽  
Detection Limit ◽  
Thin Layer ◽  
High Performance ◽  
Steel Surface ◽  
Stainless Steel Surface ◽  
Surface Areas ◽  
Absolute Detection Limit ◽  
Development And Validation

Abstract A thin-layer chromatographic (TLC) method with densitometric quantitation using the absorption reflectance mode at 280 nm was developed and validated for the determination of chloramphenicol residues in controlling pharmaceutical equipment cleanliness. Simulated samples at residue levels 0.5, 1, and 1.2 mg/m2 were prepared by spreading the calculated amount of chloramphenicol solution on a 10 dm2 stainless steel surface. After evaporation of the solvent, the residue was removed by 2 methanol-wetted cotton swabs, which were then extracted with methanol. The extract was applied on a high-performance TLC (HPTLC) silica gel F254 plate together with standards ranging from 10 to 60 ng. Plates were developed in a horizontal developing chamber from both sides (36 applications per plate) by using n-hexane–ethyl acetate (35 + 65, v/v) as developing solvent. The mean recovery (n = 6) at 1 mg/m2 was 95.8%, and the coefficient of variation was 5.8%. The absolute detection limit was 3 ng, and the quantitation limit 10 ng. The method detection limit was 0.3 mg/m2 by swabbing 2.5 dm2 and 0.075 mg/m2 by swabbing 10 dm2. Chloramphenicol was stable on the plate 2 h before and 24 h after development. Additionally, it was stable during 7 days storage on the cotton swabs in the solvent at room temperature and in diluted standard solution stored in darkness at 4°C. The method can be applied to routine control of pharmaceutical equipment cleanliness by sampling from the stainless steel surface areas of 2.5 to 10 dm2, and an acceptable residue limit of 1 mg/m2.

Scanning Electron Microscopic Examination of Yersinia enterocolitica Attached to Stainless Steel at Selected Temperatures and pH values1

1988 ◽  
Vol 51 (6) ◽  
pp. 445-448 ◽  
Author(s):  
PAULA J. HERALD ◽  
EDMUND A. ZOTTOLA
Keyword(s):  
Stainless Steel ◽  
Yersinia Enterocolitica ◽  
Steel Surface ◽  
Electron Microscopic Examination ◽  
Growth Conditions ◽  
Stainless Steel Surface ◽  
Electron Microscopic ◽  
Scanning Electron Microscopic ◽  
Steel Surfaces ◽  
Scanning Electron

Attachment of Yersinia enterocolitica to stainless steel surfaces at 35, 21, and 10°C was investigated using scanning electron microscopy (SEM). Cells adhered at all three temperatures, but, in general, the greatest number of adhered cells were observed at pH 8 and 21°C. Multi-flagellated cells were noted under these growth conditions. When grown at pH 9.5 and 21°C, fibrils were observed between cells and extending to the stainless steel surface. Fewer cells with flagella were seen at this pH. Adherence may be related to the flagella and any exopolymer surrounding the cells.

Anti-Corrosion Performance of Conductive Copolymers of Polyaniline/Polythiophene on a Stainless Steel Surface in Acidic Media

2020 ◽  
Vol 19 (03) ◽  
pp. 1950023
Author(s):  
Shouqing Xue ◽  
Yuanzhong Ma ◽  
Yunxia Miao ◽  
Weinan Li
Keyword(s):  
Stainless Steel ◽  
Corrosion Behavior ◽  
Steel Surface ◽  
Electrochemical Impedance ◽  
Oxalic Acid Solution ◽  
Stainless Steel Surface ◽  
Corrosion Performance ◽  
Acidic Media ◽  
Steel Composite ◽  
Steel Surfaces

The composite conductive copolymers of polyaniline/polythiophene (Pani/PTH) were successfully prepared by an electrochemical method on a stainless steel surface containing both aniline and thiophene in a 0.3[Formula: see text]mol/L oxalic acid solution. The anti-corrosion performance of the Pani/PTH on stainless steel surfaces was investigated in acidic media by polarization curve analysis and electrochemical impedance spectroscopy (EIS). Additionally, the surface morphology of Pani/PTH composite conductive copolymers was observed by scanning electron microscopy (SEM). The results showed that the Pani/PTH copolymers strongly adhered to the surface of the stainless steel. Compared with that of bare stainless steel, composite conductive copolymers of Pani/PTH on the stainless steel surface provided good anti-corrosion behavior; additionally, the corrosion potential could be improved by approximately 400[Formula: see text]mV, while the current density decreased by two orders of magnitude in the corrosion media. The above results were in accordance with the SEM characterization results. The SEM spectrum showed that the Pani/PTH film had a uniform, dense and shiny structure, so it had better anti-corrosion behavior.

scholarly journals Study on the effect of Weber Number to heat transfer of multiple droplets on hot stainless steel surface

2018 ◽  
Vol 154 ◽  
pp. 01114 ◽  
Author(s):  
Aria Riswanda ◽  
Indro Pranoto ◽  
Deendarlianto ◽  
Indarto ◽  
Teguh Wibowo
Keyword(s):  
Stainless Steel ◽  
Surface Temperature ◽  
Weber Number ◽  
Steel Surface ◽  
Cooling System ◽  
Spray Cooling ◽  
Stainless Steel Surface ◽  
Temperature Decrease ◽  
Evaporation Time ◽  
Decrease Rate

Multiple droplets are drops of water that continuously dropped onto a surface. Spray cooling is an application of the use of droplet on a cooling system. Spray cooling is usually used in a cooling system of electronic devices, and material quenching. In this study, correlations between Weber number and surface temperature decrease rate during multiple droplets impingement are investigated and analyzed. Visualization process is used to help determine the evaporation time of droplets impingement by using high speed camera. Induction stove is used to maintain a stainless steel surface temperature at 120°C, 140°C, and 160°C. The Weber number was varied at 15, and 52.5 to simulate low and medium Weber number. The result of this study shows that increase in Weber number does not increase the temperature decrease rate noticeably. Whereas the Weber number decrease the time required for surface temperature to reach its lowest surface temperature. It was also found that for low and medium Weber number, Weber number affect the evaporation time of multiple droplets after impingement.

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