Extraction And Crystallization Of Clavulanic Acid

Clavulanic acid(Clavulanic acid)is currently the most widely used ?-lactamase inhibitors for clinical application.It can significantly reduce their minimum inhibitory concentration and greatly enhance its antibacterial activity when it is used with amoxicillin sodium and ticarcillin sodium in a certain proportion.This would be an effective way to solve bacterial resistance.In industry,clavulanic acid is mainly produced by fermentation of Streptomyces clavuligerus.The production process of membrane filtration,extraction,concentration,decolorization,crystallization of amine salt and crystallization of potassium salt is carried out.The existing process is complex,high cost,and serious environmental pollution.Clavulanic acid is extremely sensitive to temperature and pH,resulting in its high degradation during the separation process.In this paper,the crystalline form of potassium clavulanate with high purity was prepared by studying the source of product impurity,screening and optimizing salting-out extraction system and adopting a new one-step crystallization operation.Firstly,this paper would find the source of impurity by studying the degradation of clavulanic acid under the existing process conditions and to analyze the impurity content in each operating unit.The experimental results showed that the impurity E is derived from the degradation of CA,and mainly produced in the thin film evaporation unit.The impurity E is synthesized by two molecules of clavulanic acid.If the impurity E was more,the solution was more yellow.The impurity G is the fermentation by-product.Due to unstable fermentation,the amount of impurity G in the micro-filtrate is from thousands to tens of thousands ?g/m L.The impurity at 1 minute peak in HPLC chromatogram is the degradation product under acid conditions.Secondly,the selection and optimization of salting-out extraction systems were proposed for the fermentation broth and nano-filtrate.The results suggested the optimum extraction system was 36% methanol + 30% NaH2PO4?2H2O for fementation broth,and 25% PEG400 / 21% ammonium sulfate for nanofiltration,respectively.Finally,the reaction crystallization instead of the existing two-step crystallization was chosen.And the effects of operating conditions such as stirring rate,flow rate,seeding method and decolorization pretreatment on crystallization were investigated.The optimum crystallization conditions were as follows: solvent A 90 m L,reaction liquid ratio 1:1.2;stirring rate 280 rpm and 180 rpm;flow rate 4 mL/min;crystallization temperature 13-15? for reaction;gradient cooling down to 5?.Activated carbon decolorization: 0.3-0.5% activated carbon,decolorization at 5? for 30 min,stirring rate of 180 rpm.After the magnification experiment,the yield of crystal products was 72 ± 1% and the purity above 99.32%.Crystal products were not agglomerated.In summary,the salting-out extraction of clavulanic acid and new crystallization process not only have a high yield and stability,but also reduce environmental pollution,which is green and has good operability and application prospects.