ceftriaxone sodium is a long acting , broad - spectrum cephalosporin antibiotic for parenteral use . it exerts in vitro activity against a wide range of gram - negative and gram - positive microorganisms . it is highly stable to most beta - lactamases , both penicillinases and cephalosporinases , of gram - positive and gram - negative bacteria . a thorough literature survey has revealed that hplc method for ceftriaxone sodium with combination of other drugs and individually in dosage forms [ 215 ] , microbial bioassay methods [ 16 , 17 ] , and spectrophotometric methods in dosage forms [ 1822 ] have been reported for analysis of ceftriaxone sodium . costlier and volatile solvents were used as mobile phase solvent system and the time of analysis was more in some reported methods . some spectrophotometric methods are recently described in the literature for analysis of drugs in raw material and finished products such as ceftazidime [ 2325 ] , cefuroxime , and cefazolin . these spectrophotometric methods involve the use of no toxic organic solvents , which do not contribute to the generation of this kind of waste by the chemicals or industries . in this context therefore , the trend is that the industries look for ways to reduce the impacts of their activities on the environment . so , the principle objective of this study was , therefore , to develop a simple , selective , precise , less time consuming , and economical method with a wide linear range and good sensitivity for assay of ceftriaxone sodium in the powder for injection dosage forms . the parent drug stability guidelines issued by the international conference of harmonization ( ich )   require that analytical test procedure should indicate stability . therefore , the present study was extended to establish the inherent stability of ceftriaxone sodium under different stress conditions such as , alkaline , acidic , oxidative , and photolytic conditions . thus , this method can be utilized to compare the results for the content analysis of stability samples , since the purpose of stability studies is to monitor possible changes to a product or a material over a time at different storage conditions . spectrophotometric analysis was carried out on a systronics 2201 , uv - visible double - beam spectrophotometer with matched 1  cm path - length quartz cells . absorption spectra were recorded on a medium scan speed , setting slit width to be 1  nm . ceftriaxone sodium was obtained as a gift sample from orchid chemicals and pharmaceutical ltd . , the other chemicals like sodium hydroxide , hydrochloric acid , and hydrogen peroxide used were of merck - ar grade and double distilled water was used throughout the experiment . a stock solution was prepared by dissolving 100  mg of ceftriaxone sodium pure drug in 100  ml of distilled water to get standard stock solution ( 1  mg / ml ) . to a set of 10  ml volumetric flasks , aliquot volumes containing the drug were quantitatively transferred from standard stock solution and made up to the mark with distilled water to obtain final concentrations of 550  g / ml of ceftriaxone sodium . the absorbance was measured at 241  nm and calibration graph was constructed by plotting the absorbance versus the concentration of the drug . the validity of the method was tested regarding linearity , specificity , accuracy , and precision according to ich q2b recommendations . accuracy and precision of the method were evaluated with the help of percent recovery , standard deviation ( sd ) , and percent relative standard deviation ( rsd ) by using standard addition method . three levels of standard drug ( 10% , 20% , and 30% ) were spiked individually with the 100  mg equivalent of powder for injection dosage form ceftriaxone sodium and analysed in six replicates during the same day ( intraday precision ) and six consecutive days ( interday precision ) . a linear correlation was found between absorbance at   max and various concentrations of ceftriaxone sodium . the linearity graph obeyed beer 's law in the range from 5 to 50  g / ml and it was described by regression equation ( y = mx + c ) and correlation coefficient ( r ) which were displayed on the graph . molar absorptivity , sandell 's sensitivity , standard error on slope , confidence limit of slope ( 95% ) , standard error on intercept , confidence limit of intercept ( 95% ) , lod , and loq were calculated . for the determination of lod and loq , the method is based on residual standard deviation of regression line and slope . to determine lod and loq , the specific calibration curve was studied using the sample containing analyte in the range of detection limit and quantitation limit . robustness was studied by evaluating the influence of small but deliberate variations in the experimental condition like storing the similar concentration ( 20  g / ml ) of drug solution at two different temperatures ( 20c and 30c ) for 1  h and performing the stability of the sample solution at various time intervals ( after 1  h and after 6  h ) on the analytical performance . a 2  ml aliquot of standard stock solution of ceftriaxone sodium ( 1  mg / ml ) was taken in four replicates in a volumetric flask ( 100  ml ) and mixed with 10  ml of 0.1  n hcl ( acid hydrolysis ) or 0.1  n naoh ( alkaline hydrolysis ) or 5% h2o2 ( oxidative degradation ) and set aside for 1  h at room temperature . a solution of drug ( 20  g / ml ) was prepared as per the procedure under construction of the calibration graph and was exposed to uv radiation of wavelength 254  nm and of 1.4 flux intensity for 24  h in a uv chamber . for thermal degradation solid drug was kept in an oven at 100c for 24  h. after cooling to room temperature , 20  g / ml concentrated drug solution was prepared as per above said method . finally , absorbance of all the solutions resulted from acid and alkaline hydrolysis , and oxidative degradation , photolytic degradation , and thermal degradation were measured at 241  nm against respective solvent as blank in each case . for the estimation ceftriaxone sodium from injection ( by procuring three brands from market ) , a portion of powder equivalent to 100  g of the drug from each brand was accurately weighed and transferred into 100  ml volumetric flask . the drug was dissolved by adding 70  ml of distilled water and sonicated for 15  min . aliquot containing suitable concentration ( 20  g / ml ) of ceftriaxone sodium was analyzed as described under construction of the calibration graph . the nominal content of the drug in injection for each brand was determined using the corresponding regression equation and results of % rsd of drug content were statistically compared with reported method . aqueous solution of ceftriaxone sodium showed absorbance maximum (   max ) at 241  nm ( figure 2 ) , and at this wavelength distilled water did not show any significant absorbance . least square regression equation of ceftriaxone sodium in aqueous medium has shown that the r value very close to 1 indicated high degree of correlation between two variables , such as absorbance and concentration ( figure 3 ) . beer 's law was obeyed over the range of 550  g / ml ; high values of molar absorptivity and low values of sandell 's sensitivity and lod revealed that proposed methods are highly sensitive . lod and loq values for the drug were found and all the parameters of calibraration curve were displayed in table 1 . to check accuracy and precision , assays were carried out for six times within a day ( intraday precision ) and in six consecutive days ( interday precision ) by adding three different levels of analyte to the formulation . % rsd values were 0.5 ( intraday ) and 1.18 ( interday ) indicating high precision of developed method . accuracy of the method was ascertained as mean % recovery between measured actual concentration and taken concentration for ceftriaxone sodium . the values of % recovery , very close to 100% , demonstrate high accuracy of the proposed method ( table 2 ) . robustness studies assumed that the small variations in any of the variables did not significantly affect the results ( table 3 ) . ceftriaxone sodium sterile formulations were analysed by proposed method and by reported method , which involved the analysis of analyte with 0.1  m sodium hydroxide and absorbance measured at 258.8  nm . results were compared by student 's t - test and variance - ratio f - test . calculated t - values and f - values did not exceed tabulated values of 2.776 ( t ) and 6.39 ( f ) at 95% confidence level and for four degrees of freedom ( table 4 ) which indicates close similarity between proposed and reported method . ceftriaxone sodium was subjected to various stress conditions like acid , alkaline , hydrogen peroxide induced degradation , and thermal and photolytic condition . analysis was performed by measuring absorbance of ceftriaxone sodium after subjecting it to stressed conditions at   max of pure drug . percentage degradation was calculated by the formula : % degradation = ( expected concentrationactual concentration)/expected concentration  100 , and percentage recovery also was calculated for each case ( table 5 ) . results revealed no change in absorbance of drug solution at alkaline hydrolysis , so its percentage recovery is very close to 100% which indicates the drug stability . but there was significant change in absorbance after acid and hydrogen peroxide treatment , confirming that ceftriaxone sodium is susceptible to acid hydrolysis ( % degradation of 11.0% ) and oxidation ( % degradation of 7.95% ) . analyte undergoes significant degradation under acid hydrolysis and oxidation , whereas it is stable under alkaline treatment . proposed method was validated for linearity , accuracy , precision , and robustness and method was applied to various formulations and results were statistically compared with reference method which showed that there were no significant changes in the result . so , method can be utilized for determination of purity of drug available from various sources without any tedious procedure and also used in analysis of stability study samples .
a simple , selective , and stability indicating spectroscopic method has been selected and validated for the assay of ceftriaxone sodium in the powder for injection dosage forms . 
 proposed method is based on the measurement of absorbance of ceftriaxone sodium in aqueous medium at 241  nm . 
 the method obeys beer 's law in the range of 550  g / ml with correlation coefficient of 0.9983 . 
 apparent molar absorptivity and sandell 's sensitivity were found to be 2.046  103 l  mol1  cm1 and 0.02732  g / cm2/0.001 absorbance units . 
 this study indicated that ceftriaxone sodium was degraded in acid medium and also underwent oxidative degradation . 
 percent relative standard deviation associated with all the validation parameters was less than 2 , showing compliance with acceptance criteria of q2 ( r1 ) , international conference on harmonization ( 2005 ) guidelines . 
 then the proposed method was successfully applied to the determination of ceftriaxone sodium in sterile preparation and results were comparable with reported methods .