N Acetylcysteine Quality Control

N Acetylcysteine Quality lockN-acetylcysteine (C5H9NO3S Mr 163.2) is the N-acetyl derivative of the naturally occurring amino tart, l-cysteine. The do drugs occurs as a white, perspicuous powderise with a slight acetic odor. N-acetylcysteine is freely soluble in water and in alcohol. N-acetylcysteine is commercially available as aqueous re re resolves of the atomic subjugate 11 salt of the drug. It is apply as a mucolytic or as an antidote for paracetamol. The British Pharmacopoeia contains a number of tests for this heterogeneous designed to train the quality.N-acetylcysteine acts to degrade mucous secretion viscosity by splitting disulfide bonds linking proteins manifest in the mucus (mucoproteins). Inhaled N-acetylcysteine is indicated for mucolytic (mucus-dissolving) therapy as an adjuvant in respiratory conditions with excessive and/or deep mucus production. Such conditions include emphysema, bronchitis, tuberculosis, bronchiectasis, amyloidosis, pneumonia. It is withal utilise post-operatively, as a diagnostic aid, and in tracheostomy c be. It may be considered ineffective in cystic fibrosis (Rossi, 2006). However, a recent paper in the Proceedings of the issue Academy of Sciences reports that high-dose oral N-acetylcysteine modulates inflammation in cystic fibrosis and has the potential to proceeds the intertwined redox and inflammatory imbalances in CF (Tirouvanziam et al., 2006). Oral N-acetylcysteine may also be give as a mucolytic in less flagitious cases.N-acetylcysteine also acts to augment glutathione reserves (depleted by toxic paracetamol metabolites) in the frame and, together with glutathione to directly bind to toxic metabolites. These actions serve to protect hepatocytes in the liver from toxicity due to paracetamol overdose. Intravenous N-acetylcysteine is indicated for the treatment of paracetamol (acetaminophen) overdose. Oral N-acetylcysteine for this peculiarity is uncommon as it is forgetfully tolerated owing to the high doses askd (due to poor oral bioavailability), unpleasant taste or odour and adverse drug replys (particularly nausea and vomiting). However, some people birth shown an adverse allergy to endovenous N-acetylcysteine which includes extreme breathing difficulty, light-headedness, rashes, severe coughing and some clips also vomiting. ingeminate overdoses depart cause the allergic answer to get worse and worse.N-acetylcysteine is prostrate to some(prenominal) hydrolysis and oxidation and some of the impurities from these reactions are shown beneath.Scheme 22. data-based2.1. MaterialsThe materials utilise in this experiment were N-acetylcysteine powder, di atomic number 11 edentate stem, 1M atomic number 11 hydrated oxide and conflate phosphate buffer pH 7.0, water, edit come in hydrochloric corrosive, potassium unity ancestor, 0.05M iodine, 0.1M sodium hydroxide, starch, hydroxybenzene red and phenolphthalein as exponents.The apparatus used were optical re volution analyser, conical flaskfuls, 10mL and 50mL pipettes, burette, electronic weigh balance and beakers.2.2. Methodsa) circumstantial optical rotation +21 to +271.25g N-acetylcysteine powder was weighed and allowed dissolve in a form of 1ml of 10g/L beginning of disodium edentate, 7.5ml of 1M sodium hydroxide and sufficient come in of blend phosphate buffer pH 7.0 to 25ml total flock. Optical rotations of the freshly wide-awake stem and the old outcomes of N-acetylcysteine provided were measured and recorded.b) study 98.0%-101.0% C5H9NO3S (as dried material)0.14g N-acetylcysteine powder was weighed by dissimilitude and poured into a conical flask. 60 ml of water and 10ml dilute hydrochloride erosive were measured and added into the conical flask. The conical flask was shaking to plug the N-acetylcysteine powder was fully dissolved. The ascendent was left to cool. An other 10ml of potassium iodide solution was added into the cooled solution in the conical flask. The solution was then titrated with 0.05M iodine by using starch as indicator. secondment titration was carried out to ensure finished and arrogate result.c) Assay by titration with 0.1M sodium hydroxide0.3g N-acetylcysteine powder was weighed by difference and poured into a clean conical flask. around 50 ml of distilled water was measured and added into the conical flask. The conical flask was shaking to ensure the N-acetylcysteine powder was fully dissolved. The solution was titrated with 0.1M sodium hydroxide using phenol red as indicator. Second titration was carried out to ensure accurate and small result.0.3g N-acetylcysteine powder was weighed by difference and poured into a clean conical flask. Approximately 50 ml of distilled water was measured and added into the conical flask. The conical flask was shaking to ensure the N-acetylcysteine powder was fully dissolved. The solution was titrated with 0.1M sodium hydroxide using phenolphthalein as indicator. Second titration w as carried out to ensure accurate and precise result.d) coat Not to a greater extent than 10ppm surface1.00g of N-acetylcysteine powder was weighed and dissolved in 0.001M hydrochloric acid. The solution was diluted to 50ml with 0.001M hydrochloric acid and solution 1 was obtained.Three solutions were fain for analysis. The inaugural solution consists of 10ml solution 1 diluted to 20ml with 0.001M hydrochloric acid, second solution consists of 10ml solution 1 and 1ml of 5ppm zinc standard diluted to 20ml with 0.001M hydrochloric acid and the tertiary solution consists of 10ml solution 1 and 2ml of 5ppm zinc standard diluted to 20ml with 0.001M hydrochloric acid.The absorbance of to separately one solution was measured at 213.8nm using an atomic absorption spectrophotometer. The absorbance for each solution was tabulated. The zinc content in each have was metrical using the method of standard addition.e) Loss on drying Not much than 1.0%w/wA standard of N-acetylcysteine wa s dried at 70 C in vacuo for 3 hours and the data was recorded and the parting blemish on drying of this ideal was cipher.f) Related substancesThe chromatograms obtained from the HPLC analysis of two fresh solution and old solution of N-acetylcysteine was examined.3. Resultsa) particular optical rotation smoke of measure sauce gravy boat(g)26.6089 battalion of weighing boat + audition (g)27.8609 aggregative of weighing boat + residue (g)26.6079 skunk of try on transferred (g)1.253 instrument panel 1 The slew of N-acetylcysteine used to make a solution for measurement of specific optical rotation. unhurriednesss consort to British Pharmacopoeia (BP 1999 page 40-41), it states that the specific optical rotation is +21.0 to +27.0. To obtain the tip off of rotation, the comparability under is used,Where, = specific optical rotation = observed fish of rotationC = tightfistedness of active substance in g/100mL of the solutionl = length of tugboat in 2dcmsFor freshly hu stling solutionAngle obtained () 2.45 assimilation of N-acetylcysteine (c) 5.012 %w/vPath length = 2 dmSpecific optical rotation= 100 x 2.452 x 5.012g/ml= +24.5For old solutionAngle obtained () -3.29 absorption of N-acetylcysteine (c) 5.012 %w/vPath length = 2 dmSpecific optical rotation= 100 x 3.292 x 5.012g/ml= -32.9b) ASSAY 98.0%-101.0% C5H9NO3S (as dried material) stress 1 judge 2Mass of boat + sampling (g)3.87973.8777Mass of boat + residue (g)3.73933.7398Mass of Acetylcysteine transferred (g)0.14040.1379Table 2 The mickle of N-acetylcysteine powder in sample 1 and sample 2 for titrations with iodine. freshman teachingSecond readingInitial brashness (mL)17.4026.70Final flock (mL)26.4035.50Volume of 0.05M iodine used (mL)9.008.80Table 3 The volume of iodine used for both titration using sample 1 and sample 2 of N-acetylcysteine solution and starch as indicator. tallysActual assiduity of iodine used 0.0476MMolecular weight of N-acetylcysteine (C5H9NO3S) 163.2The balanced com parability for the reaction among N-acetylcysteine and iodine2 C5H9NO3S + I2 C5H8NO3SSC5H8NO3 + 2HI2KI I2 + 2K+harmonize to British Pharmacopoeia, 1mL of 0.05M iodine is resembling to 16.32mg of C5H9NO3S. This means, 2 gram bulwarkcule of C5H9NO3S equal to one mole of iodine.Therefore when 1mL of 0.05M iodine = 16.32mg of C5H9NO3S,1mL of 0.0476M iodine = 0.0476M x 16.32mg/ 0.05M= 15.54mg of C5H9NO3SFirst titration1mL of 0.0476M iodine = 15.54mg of C5H9NO3SSo, 9.00mL of 0.0476M iodine = 9.00mL x 15.54mg/ 1mL= 139.86mg= 0.13986g of C5H9NO3SSecond titration1mL of 0.0476M iodine = 15.54mg of C5H9NO3SSo, 8.80mL of 0.0476M iodine = 8.80mL x 15.54mg/ 1mL= 135.52mg= 0.13552g of C5H9NO3SCalculation of Percentage of goodness render 1 of N-acetylcysteineSample 2 of N-acetylcysteineMass transferredActual mass carefulMass transferredActual mass aspired0.14040.13990.13790.1355According to British Pharmacopoeia (BP), the per centum of honour should be deep down 98.0 101.0% of dried sub stance.Equation of the Percentage of goodnessSample 1Sample 2c) Assay by titration with 0.1M of sodium hydroxidei) Titration by using phenol red indicatorSample 1Sample 2Mass of boat + sample (g)3.89163.9199Mass of boat + residue (g)3.59133.6198Mass of N-acetylcysteine transferred (g)0.30030.3001Table 4 The mass of N-acetylcysteine powder in sample 1 and sample 2 for titrations with 0.1M of sodium hydroxide.First readingSecond readingInitial volume (mL)1.001.00Final volume (mL)18.1518.10Volume of 0.05M iodine used (mL)17.1517.10Table 5 The volume of 0.1M sodium hydroxide used for both titration using sample 1 and sample 2 of N-acetylcysteine solution and phenol red as indicator.CalculationsActual closeness of sodium hydroxide (NaOH) used 0.1062MMolecular weight of N-acetylcysteine (C5H9NO3S) 163.2The balanced equation for the reaction between N-acetylcysteine and sodium hydroxide (NaOH)C5H9NO3S + NaOH C5H8NO3SNa + H2OFrom the equation, one mole of N-acetylcysteine reacts with one mole of NaOH. So the reaction is a 11 ratio. To find out the number of mole of NaOH, the equation below is usedFirst titrationMoles of NaOH = (0.1062M x 17.15mL)/ deoxyguanosine monophosphate= 1.821 x10-3 molesAs the reaction is 11 ratio so the number of moles of N-acetylcysteine is equal to the number of moles of NaOH used which is 1.821 x10-3 mole.Mass of N-acetylcysteine = 1.821 x10-3 moles x 163.2= 0.2972gSecond titrationMoles of NaOH = (0.1062M x 17.10mL)/1000= 1.816 x10-3 molesAs the reaction is 11 ratio so the number of moles of N-acetylcysteine is equal to the number of moles of NaOH used which is 1.821 x10-3 mole.Mass of Acetylcysteine = 1.816 x10-3 mole x 163.2= 0.2964gCalculation of Percentage of honestySample 1 of N-acetylcysteineSample 2 of N-acetylcysteineMass transferredActual mass calculatedMass transferredActual mass calculated0.30030.29720.30010.2964According to British Pharmacopoeia (BP), the per centum of naturalness should be at heart 98.0 101.0% of dried substance.Equation of the Percentage of PuritySample 1Sample 2ii) Titration by using phenylic acidphthalein as the indicatorSample 1Sample 2Mass of boat + sample (g)3.89163.9195Mass of boat + residue (g)3.59153.6195Mass of N-acetylcysteine transferred (g)0.30010.3000Table 6 The mass of N-acetylcysteine powder in sample 1 and sample 2 for titrations with 0.1M of sodium hydroxide.First readingSecond readingInitial volume (mL)18.2017.10Final volume (mL)36.8036.95Volume of 0.05M iodine used (mL)18.6019.85Table 7 The volume of 0.1M sodium hydroxide used for both titration using sample 1 and sample 2 of N-acetylcysteine solution and phenolphthalein as indicator.CalculationsActual ingress of sodium hydroxide (NaOH) used 0.1062MMolecular weight of N-acetylcysteine (C5H9NO3S) 163.2The balanced equation for the reaction between N-acetylcysteine and sodium hydroxide (NaOH)C5H9NO3S + NaOH C5H8NO3SNa + H2OFrom the equation, one mole of a N-acetylcysteine reacts with one mole of NaOH. So the r eaction is a 11 ratio. To find out the number of mole of NaOH, the equation below is usedFirst titrationMoles of NaOH = (0.1062M x 18.60mL)/1000= 1.975 x10-3 moleAs the reaction is 11 ratio so the number of moles of N-acetylcysteine is equal to the number of moles of NaOH used which is 1.821 x10-3 mole.Mass of N-acetylcysteine = 1.975 x10-3 mole x 163.2= 0.3224gSecond titrationMoles of NaOH = (0.1062M x 19.85mL)/1000= 2.108 x10-3 moleAs the reaction is 11 ratio so the number of moles of N-acetylcysteine is equal to the number of moles of NaOH used which is 1.821 x10-3 mole.Mass of N-acetylcysteine = 1.816 x10-3 mole x 163.2= 0.3440gCalculation of Percentage of PuritySample 1 of N-acetylcysteineSample 2 of N-acetylcysteineMass transferredActual mass calculatedMass transferredActual mass calculated0.30010.32240.30000.3440Calculation of Percentage of PurityAccording to British Pharmacopoeia (BP), the portion of purity should be within 98.0 101.0% of dried substance.Equation of the Pe rcentage of PuritySample 1Sample 2d) Zinc Not to a greater extent than 10ppm Zinc (Zn)To determine the concentration of Zinc alloy manifest in a standardised sample, atomic absorption spectrophotometer was applied. This was done so as to comply with the British Pharmacopoeia (BP) standards, where the notice concentration of Zinc should not be to a greater extent than than 10ppm.Mass of Acetylcysteine sample used 1.00gThis sample was diluted then and then analysed or measured by an atomic absorption spectrophotometer at a set wavelength of 213.8nm. According to the laboratory transcript, the absorbances were stipulation, so the calculation was carried out to determine the concentrations for each solution. rootageConcentration (mg/L)Absorbance (at 213.8nm)(a)0.000.056(b)0.250.115(c)0.500.173Table 8 The absorbance of solution a, b and c using atomic absorbance spectrophotometer.From the table 8 above, a standard additions calibration graph of concentration of zinc in mg/L agains t absorbance at 213.8nm is plotted. A rather small absorbance indicates that there is a trace or small measuring stick of Zinc (Zn) present in solving A, which practically contained only the N-acetylcysteine sample. Hence, we can plot a line of products of best fit and extrapolate to find the concentration of Zn present within our sample. Note that the amount of Zn present is proportional to the absorbance marked at 213.8nm wavelength.Graph 1 The graph of absorbance against concentration of Zinc.Extrapolated measure out= -0.24 issue A = 0.24ppm base 1 = 0.24 - 2 = 0.48 ppm solvent 10.48g in 100 000 mL = 2.4 - 10-4g in 50 mLIf 1g of N-acetylcysteine contains 2.4 - 10-4g of zinc ions, 104g of acetylcysteine will contain 2.4g of zinc ions.So concentration of zinc ions in N-acetylcysteine = 2.4ppm exploitation the calibration graph, we obtained an equation for the line of best fit as shown belowUsing the line of best fit we can calculate the concentration of Zinc (Zn) present wit hin Solution 1. This is determined by the difference between the origin (x = 0) and where the line of best fit intercepts the x-axis. To be more accurate, the equation of the line of best fit can be used by assuming the absorbance of N-acetylcysteine at 213.8nm (y-axis) is 0 (y = 0). We can then calculate and find the exact concentration of Zn added (x-axis in mg/L) which gives an absorbance reading of 0.0562 at the wavelength of 213.8 nm. This calculation is shown below where absorbance y = 0.Concentration of Zinc in solution (a) where no Zinc is added-(Concentration comes in positive value)Therefore, the diluted Solution 1 contains an exact concentration of 0.2402mgL-1 or 0.2402ppm. We can straight use this concentration and work backwards from the dilution to obtain the mass of Zn within the 20mL Solution 1, as shown in the calculation below,Mass of Zinc in Solution 1-From the mass of Zinc present in Solution 1 as calculated, we can say that this equals to the 10mL of N-acetylcy steine sample in Solution (a). This is because Solution 1 was diluted to 20mL using 0.001M hydrochloric acid and contained no other sources of Zinc. Hence, 4.8034g of Zinc in 20mL of Solution 1 is equal to 4.8034g of Zinc in 10mL of Solution (a). Now using this mass of 4.8034g in 10mL of Solution (a) we can find out the total mass of Zinc within 50mL. However, the total mass of Zinc within 50mL of Solution (a) is equivalent to 1.00g of N-acetylcysteine sample which is the original sample mix. Using these data, the mass of Zinc can be calculated as shown in the calculation below,Mass of Zinc in 1.00g of N-acetylcysteine Hence, 2.4017gmL-1 of Zinc is present in 1.00g. We can now calculate an exact concentration of Zinc in parts per gazillion (ppm) as shown in the calculation below,Concentration of Zinc within sample in ppm-e) Loss on drying Not more than 1.0% w/w-Initial mass of N-acetylcysteine sample (g)1.0965Mass after drying under undertake conditions (g)1.0893f) Related substan ces1) Acetylcysteine fresh sample 8.57mg/mLFrom British Pharmacopoeia, the retention time for the N-acetylcysteine substances as below. amountRetention time (min)L- cystine virtually 2.2L- cysteine intimately 2.42-methyl-2 thiazoline-4 carboxylic acidAbout 3.3N,N-diacetyl-L- cystineAbout 12N,N-diacetyl-L- cysteineAbout 14acetylcysteineAbout 6.41) Acetylcysteine fresh sample 8.57mg/mL unionRetention time (min) apex retention time obtainedConcentrationL- cystineAbout 2.21.930.5948L- cysteineAbout 2.42-methyl-2 thiazoline-4 carboxylic acidAbout 3.33.250.0794N,N-diacetyl-L- cystineAbout 12N,N-diacetyl-L- cysteineAbout 1413.6230.3944AcetylcysteineAbout 6.46.97294.7507Calculation of impurities upper side empyrean/ Total sector x 100SubstanceAreaConcentrationImpurityL- cystine2386060.59480.5948L- cysteine2-methyl-2 thiazoline-4 carboxylic acid318610.07940.0794N,N-diacetyl-L- cystineN,N-diacetyl-L- cysteine1582110.39440.3944Acetylcysteine3800744094.750794.7507Total area= 401130722) Ace tylcysteine old sample 2.5mg/mLSubstanceRetention time (min)Peak retention time obtainedConcentrationL- cystineAbout 2.22.110.7214L- cysteineAbout 2.42-methyl-2 thiazoline-4 carboxylic acidAbout 3.33.2560.8946N,N-diacetyl-L- cystineAbout 12N,N-diacetyl-L- cysteineAbout 1413.41515.3284AcetylcysteineAbout 6.46.3433.7241Calculation of impuritiesPeak area/ Total area x 100SubstanceAreaConcentrationImpurityL- cystine629350.72140.7214L- cysteine2-methyl-2 thiazoline-4 carboxylic acid780460.89460.8946N,N-diacetyl-L- cystineN,N-diacetyl-L- cysteine133726315.328415.3284Acetylcysteine294211833.724133.7241Total area= 87240873) Cysteine/ cystine 0.5mg/mLSubstanceRetention time (min)Peak retention time obtainedConcentrationL- cystineAbout 2.22.0185.2956L- cysteineAbout 2.42.323 2.652.3189 2.3842-methyl-2 thiazoline-4 carboxylic acidAbout 3.33.008 3.20724.9029 65.0987N,N-diacetyl-L- cystineAbout 12N,N-diacetyl-L- cysteineAbout 14AcetylcysteineAbout 6.4Calculation of impuritiesPeak area/ Total are a x 100SubstanceAreaConcentrationImpurityL- cystine870015.29565.2956L- cysteine38097 391672.3189 2.3842.3189 2.3842-methyl-2 thiazoline-4 carboxylic acid409128 106950324.9029 65.098724.9029 65.0987N,N-diacetyl-L- cystineN,N-diacetyl-L- cysteineAcetylcysteineTotal area= 16428954. Discussiona) Specific optical rotationThe specific rotation of a chemical compound is defined as the observed angle of optical rotation in stereochemistry, when plane-polarized light is passed through a sample with a pathway length of 1 decimetre (dm) and a sample concentration of 1 gram (g) per 1 millilitre (mL). The specific rotation of a arrant(a) material is an intrinsic property of that material at a given wavelength and temperature. The reading should be accompanied by the temperature at which the measurement was performed and the solvent in which the material was dissolved, and this often assumed to be room temperature. The exact unit for specific rotation values is deg dm1cm3 g1 or can use degre es (). Levorotatory rotation (l) means a negative reading obtained and the rotation universe to be left. While right-handed rotation (d) means a positive reading and the rotation is being to be right. The specific optical rotation for the freshly prepared solution of N-acetylcysteine is +24.5 which it is dextrorotatory rotation and the old solution of N-acetylcysteine is -32.9 which means levorotatory rotation. beat of optical rotation is a way to assess optical purity of a sample containing a mixture of enantiomers. An enantiomer is one of cardinal stereoisomers that are mirror images of each other that are non-superposable or not identical much as ones left and right hands are the same but opposite. The specific optical rotation of N-acetylcysteine solution is within the endure +21 to approximately +27. The freshly prepared of N-acetylcysteine solution is found to be in the range however the old N-acetylcysteine solution is not in the range. This reveals stability alteration oc curred in the old N-acetylcysteine solution. The impurities have found in the old N-acetylcysteine solution because the presence of small amount of impurities can affect the rotation of the sample.The actual optical rotation value for freshly prepared N-acetylcysteine solution is measured by single polariscope because if the sample is in truth concentrated or it has very large specific rotation or the sample larger than 180, single polarimeter cannot be used. The variation of specific rotation with wavelength is the basis of optical circle dispersion (ORD) which used to elucidate the absolute configuration of certain samples. higher(prenominal) performance liquid chromatography (HPLC) is used to determined the enantiomeric ratio with a chiral column because the aggregation in the N-acetylcysteine solution cause optical rotation of a sample maybe not linear dependent due to enantiomeric excess.b) ASSAY 98.0%-101.0% C5H9NO3S (as dried material)From the result obtained above, the ma ss obtained from the titration of N-acetylcysteine solution with iodine with starch as indicator for world-class titration is 0.13986g and second titration is 0.13552g. The percentage of purity obtained from the experiment for first sample is 99.64%. The percentage of purity from second sample is 98.26%. According to British Pharmacopoeia (BP), the percentage of should be within 98.0 101.0% of dried substance. The percentage of purity for both samples is within the range stated in the BP. BP prefer the iodine titration to a titration using sodium hydroxide because iodine is a very recyclable oxidising titrant which react with reducing agent ,N-acetylcysteine solution using starch as indicator. Iodine forms an intensely dark blue complex with starch. Starch is an oxidation reduction indicator that shows a reversible rubric change between the oxidised and reduced forms. It is not affected by the presence of iodide (I-). both(prenominal) starch and iodide must be present for the starch to change falsify during the titration. Iodine is consumed by thiosulfate in the titration step. The amount of thiosulfate used is proportional to the amount of iodine liberated from the salt. Sodium hydroxide is a strong base. It is more useful in acid- base titration using weak acid or base indicator.c) Assay by titration with 0.1M of sodium hydroxideFrom the result obtained in this experiment, the mass obtained from the titration of N-acetylcysteine solution with0.1M sodium hydroxide with phenol red as indicator for first titration is 0.2972g and second titration is 0.2964g. The percentage of purity obtained from the experiment for first sample is 98.97%. The percentage of purity from second sample is 98.77%. According to British Pharmacopoeia (BP), the percentage of should be within 98.0 101.0% of dried substance. The percentage of purity for both samples is within the range stated in the BP.The mass obtained from the titration of N-acetylcysteine solution with 0.1M sod ium hydroxide with phenolphthalein as indicator for first titration is 0.3224g and second titration is 0.3440g. The percentage of purity obtained from the experiment for first sample is 107.43%. The percentage of purity from second sample is 114.67%. According to British Pharmacopoeia (BP), the percentage of should be within 98.0 101.0% of dried substance. The percentage of purity for both samples is out of the range stated in the BP.Phenol red and phenolphthalein are acid-base indicators. The un-dissociated form of the indicator is a different people of saturation than the iogenic form of the indicator. An Indicator does not change colour from pure acid to pure alkaline at specific hydrogen ion concentration, but rather, colour change occurs over a range of hydrogen ion concentrations. This range is termed the colour change interval. It is expressed as a pH range. The pH range for phenol red is 6.8- 8.4 and phenolphthalein is 8.0- 10.0. The selection of indicator will depend on the actual expected pH at the equivalence point which selects an indicator with a pKa right in the middle of the pH change at the equivalence point. N-acetylcysteine solution has pKa 4.0 and 9.5, and a weak acid indicator has to be used to determine the end point of the titration. Phenol red say a good result compared to the phenolphthalein as indicator when titrate N-acetylcysteine solution with 0.1M sodium hydroxide.d) Zinc Not more than 10ppm Zinc (Zn)By perform the atomic absorbance technique, we have determined that the N-acetylcysteine sample contained a Zinc concentration of 2.4017ppm. This sample complied with the requirement from the British Pharmacopoeia (BP) monograph standards by not having a Zinc concentration of greater than 10ppm.Atomic absorbance technique can only detect specifically one heavy(p) metal at a time. So, it is very time consuming to detect a wide spectrum of heavy metal impurities within our sample. Plus, the N-acetylcysteine monograph only indicates the need to monitor the level of Zinc present within the sample by atomic absorbance spectrometry. Therefore, to detect other heavy metals we would prefer to use the more generic Limit Test C for Heavy Metals as specified in the British Pharmacopoeia (2008), Volume IV, and appendix VII.e) Loss on drying Not more than 1.0% w/w-According to British Pharmacopoeia (BP), it states that there should be no more than 1.0% in mass. This sample is complied with the BP monograph standards with a loss of only 0.66% in mass.f) Related substances-HPLC is used in pharmaceutical analysis to quantitative determinations of drugs in formulations. These analyses do not require long time to optimising mobile phase and selecting columns and detectors. Some formulations contain more than one active ingredient and may present more of an uninflected challenge since the different ingredients may have quite different chemical properties and elute at very different times from HPLC column.5. ConclusionsQual ity realise is an essential operation of the pharmaceutical industry. Drugs must be marketed as skillful and therapeutically active formulations whose performance is consistent and predictable. A bundle of modern analytical methods are being developed for the drugs evaluation in pharmaceutical industry. Requirements governing the quality control of pharmaceuticals in accordance with the British Pharmacopoeia (BP) or European Pharmacopoeia.Titration is a procedure used in chemistry in order to determine the molarity of an acid or a base. A chemical reaction is set up between a cognise volume of