• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2
3. 3
3
4. 4
4
5. 5
5

# Determination of pka of the given drug sample. The importance of pKa is that one can easily conclude how much drug is ionized and unionized. Unionized drug is better absorbed

Extracts from this document...

Introduction

Determination of pka of the given drug sample INTRODUCTION: Dissociation constant of a drug/compound is commonly refered to as pKa. It is a characteristic of drug. It is the estimation of ionized and unionized drug concentration at a particular pH. It is the pH at which 50% of drug is ionized and 50% is unionized. The dissociation constants of both acidic and basic drugs are expressed by pKa values. The importance of pKa is that one can easily conclude how much drug is ionized and unionized. Unionized drug is better absorbed. pKa can be calculated by following equation. pKa = pH +log(di -d/ d- dm) Where, di = absorbance of the ionized species. d = absorbance of solution tested. dm = absorbance of the unionized species. U.V. spectroscopy is widely used in pKa determination as we know lambda max is different for ionized and unionized drug or we can say that there is great difference between absorbance of ionized and unionized drug at a particular lambda. ...read more.

Middle

pH 6 : 5 ml of 0.2 M potassium hydrogen phthalate + 0.56 ml of 0.2 M Sodium hydroxide (6) pH 7 : 5 ml of 0.2 M potassium hydrogen phthalate + 2.9 ml of 0.2 M Sodium hydroxide (7) pH 8 : 5ml of 0.2 M boric acid + 5 ml of 0.2 M potassium chloride + 0.39 ml of 0.2 M Sodium hydroxide (8) pH 9 : 5ml of 0.2 M boric acid + 5 ml of 0.2 M potassium chloride + 2.08 ml of 0.2 M Sodium hydroxide (9) pH 10 : 5ml of 0.2 M boric acid + 5 ml of 0.2 M potassium chloride + 4.37 ml of 0.2 M Sodium hydroxide Preparation of primary stock: 10 mg of drug was accurately weighed and dissolved in 10 ml of 7:3 = methanol: water mixture as solvent to get concentration of 1 mg/ml. ...read more.

Conclusion

pH 296 nm 300 nm 303 nm Abs ?Abs/?pH Abs ?Abs/?pH Abs ?Abs/?pH 2 0.5229 - 0.5651 - 0.568 - 3 0.0215 0.5014 0.0571 0.508 0.1 0.468 4 0.01 0.0115 0.0158 0.0413 0.0437 0.0563 5 0.0436 0.0336 0.0448 0.029 0.1244 0.0807 6 0.2592 0.2156 0.5629 0.5181 0.5095 0.3851 7 0.436 0.1768 0.4736 0.0893 0.4318 0.0777 8 0.455 0.019 0.4683 0.0053 0.4541 0.0223 9 0.4824 0.0274 0.4909 0.0226 0.4707 0.0166 10 0.4788 0.0036 0.4708 0.0201 0.4399 0.0308 Plot of absorbance vs pH and its derivative graph (?Abs/?pH vs pH) were ploted at selected wavelengths as shown below. 296 nm: 300 nm: 303 nm : The peak in the derivative graph corresponds to the pKa of the drug since it is the point at which there is maximum change in absobance with a small change in pH. The average of three pka was calculated as: pka = (6 +6+6)/3 pka = 6 CONCLUSION : The pKa of the given drug was found to be 6. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our University Degree Chemistry section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related University Degree Chemistry essays

1. ## Method's of Drug Characterisation

5 star(s)

Take a few crystals of the unknown compound and dissolve it in 1ml of chloroform then spot the solution onto the chromatoplate using the 2 needles prepared. 4. Place the chromtoplate in the sealed tank. 5. Remove the plate once the solvent has travelled near to the top and

2. ## Determining the concentration of copper(II) ions

Making solutions of different concentrations by serial dilutions gives rise to more accuracy than making each solution separately. This is because the subsequent dilutions are direct divisions and there is less room for error, taking into account the pipettes were used correctly and accurately.

1. ## Werner Complexes - Preparation and Determination of Structural Formula

While stirring, finely powdered cobalt(II) chloride hexahydrate (7.465g) was slowly added. The solution turned orange/brown when approximately 1.8g was added. After complete addition the solution was a bright orange and pink color with a small brown layer on top. Hydrogen peroxide (7.2mL, 30%) was added to this mixture which created vigorous effervescence of oxygen gas and a very dark red color.

2. ## Synthesis of chloropentaaminecobalt(lll) chloride

This may be caused due to impurities. The product may not isolated and purified perfectly and residues may be remained in the product that was not washed properly. An IR for [Co(NH3)5Cl]Cl2 was run in ATR accessory. The results showed that there were peaks at 3284.43, 1612.66, 1300, and 849.60

1. ## Experiment 4 - Preparation and Reactions of Boric Acid, H3BO3

Boric acid is produced mainly from borate ores containing sodium or calcium by the reaction with sulphuric acid in the presence of a hot aqueous boric acid liquor to recycle. Boric acid, also known as boracic acid or orthoboric acid, is a weak acid usually used as an antiseptic, insecticide

2. ## Synthesis and Characterization by UV-Vis Spectroscopy, EPR, and HNMR of H2TPP and CuTPP Porphyrins

chamber with several milliliters of the developing solvent or mixture of solvents-the so-called mobile phase(s)-and allowed to develop until the solvent reaches an arbitrary position close to the top of the plate (Landgrebe, 2005). As the mobile phase moves through the stationary phase, and depending on the relative polarity of

1. ## Forensic Chemistry - Ion Selective Electrode. The objective of experiment is to determine ...

Direct measurements are particularly useful for ions which have specifically designed electrodes. However, the accuracy can be increased by using different methods of measurement, e.g. standard addition, known subtraction or titration. It is possible to use the ion selective electrode as an end point indicator, just as litmus or universal indicator can be used as indicators for acid/base titrations.

2. ## The aims of this experiment are to measure the heat of decomposition of hydrogen ...

Heat capacity(C) is the amount of heat required to raise the temperature of an object or substance a given amount. The exact amount of heat absorbed is equal to the heat capacity times the temperature rise: q = CÃÎT. 2.

• Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to