1. INTRODUCTION:

Analytical chemistry deals with quantitative analysis of work of substances and multipart materials in various matrices via measuring a physical or chemical goods of a distinctive ingredient of the components of interest. Analytical methods are classified according to the possessions of the analyte measured^[1] The pharmaceutical analysis is single of the most important fields in analytical chemistry. Modern analytical chemistry is dominated by instrumental analysis. There are so many different types of instruments used today that, it seems like a confusing array of acronyms rather than a unified field of study^[2] The analytical methods should be accurate as required and not as accurate as possible.^[3]Analytical methods are classified into instrumental and chemical method. Instrumental method involves measurement of a light absorption or emission, fluorescence, conductivity and electrode potential. Chemical method involves measurement of mass of the analyte by gravimetric or volumetric method. Analytical technique play an important role in maintaining and assuring the quality of substance and are critical components of quality assurance and quality control. Several instrumental methods are used in pharmaceutical analysis, amongst these some important methods are separation techniques, spectrometric techniques and other analytical techniques.^[4] Pharmaceutical analysis is the integral part of the pharmaceutical sciences. In pharmaceutical analysis section, the research analyst is responsible for three important functions viz:

a) Development of analytical method for raw materials, active ingredients and chemical intermediates of the product.

b) Development of analytical methods for selective analysis of drug, excipients, degradation products and impurities along with identification of degradation product, degradation pathway and extent of degradation when stored at ambient and accelerated conditions.

c) Development of analytical method for micro and semi micro quantities of drugs and its metabolites in biological system.

Linezolid may be a synthetic antibacterial agent of the oxazolidinone class of antibiotics. It has in vitro activity against aerobic Gram positive bacteria, certain Gram negative bacteria and anaerobic microorganisms. It selectively inhibit bacterial protein creation through binding toward sites on the bacterial ribosome along with prevents the development of a functional 70S-beginning complex. Specifically, linezolid bind to a site on top of the bacterial 23S ribosomal RNA of the 50S subunit and prevent the formation of a functional 70S initiation compound, which is an necessary element of the bacterial conversion development.

Figure no. 1: Structure of Linezolid ^[5]

The results of time-kill studies have shown linezolid to be bacteriostatic against enterococci and staphylococci. For streptococci, linezolid was found to be bactericidal for the bulk of strains. Linezolid is additionally a reversible, n"art-7">Therefore, linezolid has the potential for interaction with adrenergic and serotonergic agents.

1.1 HISTORY OF ANALYTICAL CHEMISTRY:^[6]

Analytical chemistry have be important since the foremost days of chemistry, provide methods for formative which fundamentals and chemicals are present contained by the object in question. During this phase important analytical support to chemistry contain the progress of logical fundamental analysis by Justus von Liebig with systematize organic analysis found on the definite reaction of practical group.

The primary instrumental analysis was light up emissive spectrometry developed via Robert Bunsen also Gustav Kirchhoff who exposed rubidium (Rb) and caesium (Cs) in 1860.

Most of the main developments in analytical chemistry happen after 1900. During this era instrumental analysis becomes progressively dominant within the field. In exacting many of the fundamental spectroscopic and spectrometric techniques were discovered in the during 20th century and advanced in the overdue 20th century. The separation sciences follow an identical time line of development and also become increasingly transformed into high performance instruments. In the 1970s many of these techniques began to be used together to achieve a complete characterization of samples.

preliminary in approximately the 1970s into today systematic chemistry has increasingly become additional inclusive of biological questions (bioanalytical chemistry), where it had earlier been basically focused on inorganic or else small organic molecules. Lasers are increasingly utilized in chemistry as probes and even to start out and influence a good sort of reactions. The late 20th century in addition saw an development of the application of analytical chemistry since somewhat educational chemical examination to forensic, environmental, business and medical questions, similar to in histology. Modern analytical chemistry is dominated by instrumental analysis. Many analytical chemists specialise in one sort of instrument. Academics tend to either specialise in new applications and discoveries or on new methods of study. The discovery of a chemical present in blood that increases the danger of cancer would be a discovery that an analytical chemist could be involved in. An effort to develop a replacement method might involve the utilization of a tunable laser to extend the specificity and sensitivity of a spectrometric method. Many methods, once developed, are kept purposely static in order that data are often compared over long periods of your time. This is principally true in trade quality assurance (QA), forensic as well as environmental application. Analytical chemistry acting an increasingly more vital role within the pharmaceutical manufacturing wherever separately from QA, it's make use of in discovery of latest drug candidates beside with in clinical purpose where compliant the interactions with the drug by the patient are severe.

1.2 METHOD DEVELOPMENT:

Method validation is that the tactic want to confirm that the analytical procedure employed for a selected test is suitable for its intended use. Results from method validation are often used to judge the quality, reliability and consistency of analytical results; it's an integral a neighborhood of any good analytical practice. it's the tactic of defining an analytical requirement, and confirms that the tactic under consideration has performance capabilities consistent with what the appliance requires. Use of kit that's within specification, working correctly and adequately calibrated is prime to the tactic validation process. Similarly the worker transport out the studies must be expert within the assessment under study and have sufficient knowledge of the procedure analysis to replica conclusions as of the analysis because the validation attempt proceeds. very frequently method validation evolve from method development followed by the 2 activities are frequently closely tied, by the validation study employ the techniques also steps inside the analysis as define by the scheme development.

Analytical methods got to be validated or revalidated

· Before their introduction into routine use;

· Whenever things change that the means has been validated (e.g., an instrument with dissimilar characteristics of samples among a special matrix); and when the tactic is modified with the change is exterior the first capacity of the process.^[7]

1.3. CLASSIFICATION OF ANALYTICAL METHODS:

1.3.1. Qualitative analysis:

It deals with the identification of substances. It is concern with what elements or comound present in sample.

1.3.2. Quantitative analysis:

It provides numerical information concerning the quantity of analyte in measured amount of sample.

Modern physical methods of analysis are extremely sensitive, providing precise and detailed information from small samples of materials. These are, for the most part, rapidly applied and in general, are readily amenable to automation. For these reasons, these are now in widespread use in product development, in the control of manufacture and formulation, as a check on the stability during storage and monitoring the use of drugs and medicines^.[8]

The study of analytical chemistry provides ideal training for nearly all scientists. A course in quantitative analysis equips one with ability to plan and exercise the experimental work; it develops the ability to record and to interpret such experimental work, and it trains to understand and to communicate what has been done. The course in quantitative analysis is a very important link in the chain of studies that develops the scientific ability in the chemist with its multiple emphases on theory, laboratory work and high accuracy in the analysis of unknown sample, quantitative analysis is one of the most valuable courses in scientific training.

The pharmaceutical dosage sorts of combinational drugs are considerably useful in multiple therapies instead of the utilization of single drug formulation due to

· Multiple action

· Fewer side effects

· Quicker relief, etc.

To device an accurate estimation procedure for each ingredient of such multicomponent dosage form containing several therapeutically active drugs is not an easy task, as they are present in widely divergent proportions^.[9]

Quantitative Analysis:

There are various methods used in Quantitative Analysis which are broadly classified as-

1.3.2.1. Chemical/Classical methods:

1.3.2.2. Instrumental method:

Chemical/classical methods:^[^10]

These methods depend upon quantitative performance of a suitable chemical reaction and either measuring the amount of reagent needed to complete the reaction or ascertaining the amount of reaction product obtained, e.g. Titrimetric (acid-base titration, oxidation-reduction titration, non-aqueous titration, complex formation), gravimetric and volumetric methods, etc.

Instrumental methods:

These methods are based upon the measurement of physical properties of a substance such as electrical or optical and to correlate them for determination of concentration of analyte. These properties are being exploited for developments of analytical methods such as spectrophotometry, HPLC, GLC, Polarography, etc. Now a day’s instrumental methods of analysis are widely accepted over the classical methods. These methods are extremely sensitive, providing precise and detailed information from small sample materials. Depending upon the nature and type of material, either single or in combination, an appropriate method of analysis is adopted. Instrumental methods are usually much faster than chemical methods and are applicable at concentration far too small to be amenable to determination by chemical methods and find wide application in industry.

Advantages of instrumental methods:

· Small sample can be used

· High sensitivity is obtained

· Measurements obtained are reliable

· The determination is very fast

· Even complex sample can be handled easily.

Fig. 1: Steps involved in quantitative analysis ^[11]

Quality is built in from the time of inception of the thought to make a product to the time, it is finally made and set out. Analytical monitoring of pharmaceutical product is important to make sure its safety and efficacy throughout all phases of its time period, including storage distribution and use. Methods of analysis are routinely developed, improved, validated collaboratively studied and applied well developed methods may never require modification or redevelopment during its lifetime creating large saving. The need for redeveloping quick method later because of shortcomings in resolution or reliability results in additional expenses, loss of productivity and frequently missed project goals^{.[12],[13],[14]}

1.4. CHROMATOGRAPHY:^[15]-[16]

The word Chromatography (Greek: Khromatos: dye and Graphos: write means, “Color writing”.

The term chromatography and its principles were first discovered in 1903 by Mikhail Tswett.

1.4.1 Principle of chromatographic separation:^[17]

The feature that distinguishes chromatography from most other physical and chemical methods of separation is that two mutually immiscible phases are bought into contact; one phase is stationary and other mobile. A sample introduced into a mobile phase is carried along through a column (manifold) containing a distributed stationary phase. Species in the sample undergo repeated interactions (partitions) between the mobile phase and the stationary phase. When both phases are properly chosen, the sample components are gradually separated into bands in the mobile phase. At the end of process, separated components emerge in order of increasing interaction with the stationary phase. The least retarded component emerge first; the most strongly retained component elutes last. Partition between the phase exploits difference in the physical and chemical properties of the components in the sample. Adjacent components(peaks) are separated when the later-emerging peak is retarded sufficiently to prevent overlap with the peak that emerge ahead of it.

1.4.2. HIGH PERFORMANCE LIQUID CHROMATOGRAPHY (HPLC):^[18]

Liquid chromatography though more troublesome than gas chromatography, has the main advantage of operating at low temperature and can be used with advantage for separation of substance as proteins, nucleosides which are thermolabile.

In conventional liquid chromatography, a dilute solution of sample is passed through a column packed with solid particles. Thus, liquid is skilled vertical columns under gravitational flow. This is passed with slow speed and especially if the packing granules were small enough to give efficient separation, then the delivery under gravity decreases even upto a few drops per minute. The obvious way to increase the flow rate and get efficient separation is to force the liquid by a positive displacement pump or by gas pressure. This versatility can be achieved by making certain modification in column and by using smaller diameter and smaller surface area of column particles and by using other suitable packing structure. This is HPLC i.e. High Pressure Liquid Chromatography.

Thus, HPLC is a high resolution and high speed liquid chromatography. It has several times more resolving power than open column liquid chromatography. It is used for speedy resolution of complex mixtures.

Advantages of HPLC:

1. It provides a specific, sensitive and precise method for analysis of different complicated samples.

2. There is ease of sample preparation and sample introduction.

3. There is speed of analysis.

4.2.1 Instrumentation of HPLC ^[19]

Fig. No. 2: Schematic diagram of HPLC system

1.4.2.2 Modes of HPLC:^[20]

1. Normal phase chromatography:

Mechanism: Retention with interaction of the immobile phase’s polar surface among polar parts of the test molecules.

Stationary phase: SiO2, Al2O3, -NH2, -CN,-NO2

Mobile phase: Heptane, hexane, cyclohexane, CHCL3

Application : Separation of non-ionic, non-polar to medium polar substance.

2. Reverse phase chromatography:

Mechanism: Retention by interaction of the stationary phase’s non-polar hydrocarbon chain with non- polar parts of the sample molecules.

Stationary phase: n-octadecyl (PR-18), n-octyl(RP-8), ethyl (RP-2), phenyl.

Mobile phase: Methanol or acetonitrile /water or buffer ( sometimes with addetives of THFor dioxane).

Application: Separation of non-ionic and ion-forming non polar to medium polar substance (carboxylic acid-hydrocarbon). If forming substances (as carboxylic acid ) are to be separated, a pH control by buffers is necessary.

3. Ion-exchange chromatography:

Mechanism : Retention by reversible ionic bond to charged group on the immobile phase.

Application : Separation of substance which can form ions:

· Inorganic ions

· Organic acid, Organic bases

· Proteins

· Nucleic acid

4. Size Exclusion Chromatography:

This is a separation mode based on the analytes molecular size. In this mode large molecule is excluded from the pores and migrates quickly, whereas a small molecule can penetrate the pores and migrate more slowly down the column

1. Information about sample:^[21]

1) Number of components present in the sample

2) Pka values of different components

3) UV spectra of each analyte

4) Concentration range of each component

5) Solubility behaviour

6) Nature of sample (solid, liquid, semisolid)

7) Formula

Table No.1: Separation goal and its remarks in chromatography

Aim	Remarks
Resolution (Rs)	For precise and accurate quantitative method, Rs should be> 1.5
Separation time	For routine procedure<5-10 min.
Quantitation pressure	RSD <2.0%
Pressure	<150 bars
Peak height	Narrow peaks for large S/N ratio
Solvent consumption	Minimum per sum is desirable

2. SYSTEM SUITABILITY PARAMETERS^[22]

A system suitability test is an integral a part of gas and liquid chromatographic method. They are wont to verify that the resolution and reproducibility of the chromatographic system are adequate for the analysis to be done. The test is predicated on concept that the equipment, electronic, analytical operation and sample to be analyzed constitute an integral system which will be evaluated intrinsically.

It is the confirmation of the system to make sure system performance prior to or during the study. Parameter like plate tally tailing factor, reproducibility and purpose are determined with compared against the plan set for the tactic. The area under curve (AUC) of 5 replicate injections shouldn't be quite 2% of relative variance (RSD).

A. Retention time (Rt)

Retention time is the time of elution of peak maximum after injection of compound.

B. Theoretical plates (N)

It is also called as column efficiency. A column are often considered as being made from sizable amount of theoretical plates where distribution of sample between liquid-liquid or solid-solid phase occurs. The number of theoretical plates in column is given by the connection

N=16(t_R/w) ^2

Where tR is the retention time and w is the width at the base of the peak.

HETP = L/N

HETP = height equivalent to a theoretical plate

L = length of column

Theoretical plates should be more than 2000.

C. Resolution (R)

It is a purpose of column efficiency and is precise to ensure that directly eluting compounds are determined from each other to launch the general resolving power of the system. For the separation of two components in mixture the resolution is determined by equation.

R=2(t_2-t_1)/ (W_1+W_2)

where t2 & t1 is the retention time of second and first compounds respectively, where as w2 and w1 are the corresponding widths at the bases of peak obtained by extrapolating straight sides of the peaks to baselines.

D. Tailing factor (T)

It is the measure of peak symmetry, is unity for perfectly symmetrical peaks and its value increases as tailing become more pronounced.

T= W_0.05/2F

Where, W0.05 is the width of peak at 5% height and F is the distance from the peak maximum to the leading edge of the peak height from the baseline. Tailing factor should be less than 2.

E. Capacity factor (k’)

It is calculated by the formula

k^'=t/(t_a-1)

Where t is the retention time of the drug ta is the retention time of non-retarded component, air with thermal conductivity detection.

F. Selectivity (α)

Also known as separation factor, it is a measure of peak spacing and expressed as

α=(K_2^,)/(K_1^,)

1.7. VALIDATION OF METHOD^[23]-[25]

Method validation is that the process wont to confirm that the analytical procedure employed for a selected test is suitable for its intended use. Results from method validation are often wont to judge the standard, reliability and consistency of analytical results; it's an integral a part of any good analytical practice.

The USP has published specific guidelines for method validation for compound evaluation. USP defines eight steps for validation:

Fig. No. 3: eight steps of analytical method of validation

a) Precision:

The precision of analytical method is that the degree of agreement among individual test results when the tactic is applied repeatedly to multiple sampling of homogenous sample. The precision of an analytical method is usually expressed as the standard deviation or relative standard deviation (coefficient of variation) of a series of measurement.

b) Accuracy:

The accuracy of an analytical process is that the proximity of test results, obtain by that process to truth . The accuracy of an analytical process should be establish across its series. In the case of the assay of a drug in the formulated product, accuracy may be determined by application of the analytical method to synthetic mixtures of drug product components to which known amount of analyte are added within the range of the tactic. Average recovery should be 99 to 101 you look after drug at each level.

c) Limit of Detection:

The lowest conc. of the analyte in the sample that the method can detect but not necessarily quantify under the stated experimental conditions simply indicates that the sample is below or above certain level. Limit test prescribed as percentage or as parts per million. The limit of detection will not only depend on the procedure of analysis but also on type of instrument.

d) Limit of Quantitation:

The limit of quantitation (LOQ) is that the lowest amount of analyte during a sample which will be determined with acceptable precision and accuracy under the stated experimental conditions. It is expressed as the conc. of analyte (e.g., percentage, parts per billion) within the sample. The S/N ratio should not less than 10 and RSD ≤ 3%.

e) Specificity:

The specificity is the ability to assess unequivocally the analyte of interest in the presence of component that may be expected to be present, such as impurities, degradation products, and matrix components. In case of assay, demonstration of specificity requires that the procedure is unaffected by presence of impurities or excipients. In practice, this may be done via spiking the drug substance or product with suitable levels of impurity or excipients, and representing that the assay result is unchanged by the existence of these unrelated materials. If impurity of degradation sunstance standards are engaged specificity might even be established by match up to the test results of samples include impurities of degradation substace toward second fit characterize method These comparisons should include samples stored under relevant stress conditions (e.g., light, heat, humidity, acid or base hydrolysis and oxidation).

f) Linearity and range:

The linearity of an systematic method is its capacity to elicit test results to be directly, or by a well-distinct mathematical conversion proportional to the concentration of analyte into sample inside the given series. It should be established across the range of the analytical procedure. Linearity is generally reported as the correlation coefficients, the slope of regression line i.e., r2 ≥ 0.999. The range of analytical technique is that the gap between the upper and lower rank of analyte that are established to be determined with appropriate level of precision, accuracy, and linearity via method written. The range is normally expressed in the same unit as test results (e.g., percent, part per billion).

g) Ruggedness:

The ruggedness of analytical process is that the quantity of reproducibility of test results obtain by the analysis of the similar samples under a choice of conditions similar to dissimilar laboratories, dissimilar instruments, dissimilar lots of reagents, dissimilar temperatures, dissimilar days, dissimilar analysts, etc. It is normally expressed as the lack of influence on test results of proportional and environmental variables of the analytical method. For ruggedness study, the conc. of analyte is measured using different parameters such as.

· Different operator in same laboratory

· Different equipment in same laboratory

· Different source of segment and solution

· Different laboratory

h) Robustness:

The robustness of systematic method be that the measure of its ability, to remain unaltered by little but deliberate variation in method parameters as well as provides a symbol of its consistency during normal procedure. Experiments are performed by changing conditions such as temperature (± 5 0C), buffer pH (± 0.5), and ionic strength of buffers, level of additives to mobile phase. The method must exist robust enough toward withstand slight change and allow usual analysis of sample.

Table No. 2: Characteristics to be validated in HPLC

Characteristics	Acceptance Criteria
Accuracy/trueness	Recovery 98-102% (individual) with 80, 100, 120% spiked
Precision	RSD < 2%
Repeatability	RSD < 2%
Intermediate Precision	RSD < 2%
Specificity / Selectivity	No interference
Detection limit	S/N > 2 or 3
Quantitation limit	S/N > 10
Linearity	Correlation coefficient r > 0.999
Range	80 –120 %
Sample solution stability	>12 h

METHODS:

1. A rapid high presentation liquid chromatographic technique was developed also validate for the purpose and stability estimation of linezolid into pharmaceutical dose form. Separation of linezolid was effectively achieved on a C-18 column utilize water: methanol (50:50 v=v) at a flow speed of 1mL=min with eluate was monitor at 254 nm, by a maintenance time of 5.117 minute.

The process was validated as well as the reaction was found to be real linear in the drug absorption range\ of 0.001 mg=mL to 3.4 mg=mL. The mean values RSD of the slope and the correlation coefficient were found to be 51169_0.290 and 0.9999, respectively. The RSD values for intra- and inter-day precision were found to be 0.782.

2. The proposed RP-HPLC method utilizes Phenomenex Luna C18 (250×4.6×5 μm) at 300C and mobile phase consisting of buffer: methanol (65: 35 v/v) at a flow rate 1.5 ml/min.

Chromatographic conditions:

The mobile phase consisted of Buffer: Methanol (65:35 v/v) and filtered through 0.22 mm filter and degassed before use. The flow rate was 1.5ml/min and Phenomenex Luna, C18 (250 x 4.6mm i.d., 5.0mm particle size) column at 30oC was used. The runtime was 55 min. The elution was monitored with a PDA detector in the UV range and the injection volume was 20ml.

Preparation of buffer:

Dissolve 1.36gm Potassium dihydrogen phosphate in 1000 ml Milli-Q water. Adjust PH 4.6 dilut Orthophosphoric acid. Filter through 0.22 μm membrane filter paper.

Preparation of mobile phase: Buffer:

Methanol (65:35 v/v) were used and filtered through 0.22 mm filter, sonicated for 10min and used as mobile phase. Mobile phase only is used as diluents.

Preparation of Linezolid Standard stock solution:

100mg of standard Linezolid was weighed and transferred to 100ml volumetric flask containing a few ml of diluent. It was sonicated for few minutes, and volume was made upto the mark to give a stock solution having strength 1 mg/ml (1000 mg/ml). From this an aliquote of 1ml was taken and diluted to 10ml to obtain the working standard solution of concentration 100mg/ml.

Diluted Standard Preparation:

Dilute 2.0 ml of the working standard solution to 50.0 ml with diluents and mix.

Preparation of Sample solution of Linezolid:

Accurately 20 tablets were weighed to determine average weight of tablets. Then tablets were finely crushed and tablet powder equivalent to 100 mg of Linezolid was transferred into 100 ml volumetric flask. Then 50 ml diluents was added to flask and sonicated for 40 minute with intermittent shaking. Make up volume upto 100 ml. than solution was filtered and the final concentration of test sample solution was made upto 100 mg/ml of Linezolid.

Method Validation:

The method was validated for accuracy, precision, specificity, detection limit, quantitation limit and robustness.

3. A easy HPLC method for the fast and precise purpose of linezolid within several biomatrices (e.g., plasma, tissue, bone, dialysis liquid and used microbiological bisque) was developed and validated. Proteins were precipitate by acetonitrile as well as separation was execute on a reversed-phase C8 column with a movable phase consisting of water/acetonitrile (80:20, v/v). UV detection was performed at 251 nm.

This method features a lower limit of quantification of 0.3 microg/mL and a linear calibration range of 0.5-40 microg/mL. The process showed superb reproducibility, by an inter- and intra-day assay accuracy of linezolid.

CONCLUSION:

This RP-HPLC method for assay of Linezolid in pharmaceutical dosage form (Tablet) was successfully developed and validated for its intended purpose. The method was revealed to be specific, linear, precise, true reproducible as well as robust. Because the method separates linezolid and the degradation products formed under the variety of stress conditions, it can be regarded as stability indicating.

REFERENCES:

1. Anjaneyules Y., Chandrasekhar K.A text book of Analytical Chemistry, 1^sted. Publisher ministry of defence, defence research and development organization, recruitment and organization centre, Lukhnow Road, Timarpur Delhi, 2006: Page No.1.

2. Rashmin. An introduction to analytical method development for pharmaceutical formulations. Pharma info.net, 2008: 6(4): Page No.1.

3. Sethi. PD. In; HPTLC Quantitative analysis of pharmaceutical formulations, 1^st ed. CBS publishers and distributors, New Delhi, 2001; preface IIV, Page No.3.

4. Douglas AS., Holler FJ., Crouch SR. Principle of Instrumental Analysis, 6^th ed, Thomson Publication, 2007: Page No.1.

5. Sharma BK., Instrumental Methods of Chemical Analysis, 23^rded, Goel Publishing House, Meerut, 2002: Page No.7-8.

6. https://en.wikipedia.org/wiki/Analytical_chemistry

7. Kalra K. Method Development and Validation of Analytical Procedures, Quality Control of Herbal Medicines and Related Areas, Prof. Yukihiro Shoyama (Ed.), ISBN: 978-953-307-682-9, InTech:2011: Page No.1-5

8. Beckette AH., Stenlake GH. Practical Pharmaceutical Chemistry. CBS Publishers and Distributors, New Delhi: 4^th ed. Vol. II. 2004. Page No.1.

9. Jeffery GH. Besset J. Mendham J. Denney RC. Vogel’s Text Book of Quantitative Chemical Analysis. 5^th ed. Longman Scientific and Technicals. 1999.Page No.3.

10. Sharma BK. Instrumental Methods of Chemical Analysis. 23^rd ed. Meerut: Goel Publishing House; 2004. Page No.7-8.

11. Skoog DA, West DM, Holler FJ. Analytical chemistry – An Introduction, 6^thed. Saunder college Publishing. Page No.3.

12. Quality Assurance of Pharmaceuticals. A compendium of guidelines and related materials. Universal Publishing Corporation, Mumbai; Vol. I: 1999. Page No. 119-123.

13. Sethi PD. High Performance Liquid Chromatography. Quantitative analysis of Pharmaceutical Formulation. 1^sted. CBS Publication and Distributors; 2001. Page No.7.

14. Willard HH, Merritt LL, Dean JA, Settle FA. Instrumental Methods of Analysis. A^7th ed. CBS Publisher and Distributors, New Delhi.Page No.5.

15. Kasture AV, Wadodkar SG, Mahadik KR, More HM. A Textbook of Pharmaceutical Analysis. 10^th ed. Vol. II. Pune: Nirali Prakashan; 2004.Page No.4.

16. Beckett AH, Stenlake JB. Practical Pharmaceutical Chemistry. 4^th ed. Vol. II, New Delhi: CBS Publisher and Distributors; 2002.Page No.86.

17. Willard HH, Merit LL, Dean JA, Settle FA. Instrumental Methods of Analysis.7^th ed. New Delhi: CBS Publishers and Distributors; 1996.Page No.513.

18. Kasture AV, Wadodkar SG, Mahadik KR, More HM. A Textbook of Pharmaceutical Analysis. 10^th ed. Vol. II. Pune: Nirali Prakashan; 2004.Page No.48

19. Kasture AV, Wadodkar SG, Mahadik KR, More HM. A Textbook of Pharmaceutical Analysis. 10^th ed. Vol. II. Pune: Nirali Prakashan; 2004.Page No.49.

20. Sethi PD. High Performance Liquid Chromatography Quantitative Analysis of Pharmaceutical New Delhi: CBC Publication and Distributors; 2001.Page No.8-10

21. Sethi PD. High Performance Liquid Chromatography. Quantitative Analysis of Pharmaceutical Formulations. I^st ed. New Delhi CBS Publication and Distributors, 2001. Page No.116-120.

22. Skoog D, Holler F, Nieman T. Principles of Instrumental Analysis. 5^th ed. New Delhi: Thomson Books; 2006.Page No.11-16.

23. Cindy Green, RAC. A Step by Step Approach to Establishing a Method Validation. Journal of Validation Technology August 2007; 13(4): Page No.317-323.

24. Vasant D. Khasia, Hetal V. Khasia, Dhara Desai, Dharmishtha N. Bhakhar, Ashok R. Parmar, “Development and Validation of Stability Indicating RP-HPLC Method for Linezolid Immediate Release Tablet Dosage Form”, Journal of Pharmacy research, 2012, 5(8),4115-4118.

25. K. Jaya Prashanti, B. Syama Sunder, “A Validated RP-HPLC Method for the Determination of Linezolid in Pharmaceutical Dosage Form”, International Journal of Pharma and Bio- Science, 2012,3(3) Page No.44–51.

Received on 08.01.2020 Modified on 31.01.2020

Research J. Science and Tech. 2020; 12(1):13-22.

DOI: 10.5958/2349-2988.2020.00002.9