DEPARTMENT OF PHARMACY UNIVERSITY OF MALTA · DEPARTMENT OF PHARMACY . UNIVERSITY OF MALTA . MEDICINAL CHEMISTRY PRACTICALS PHR 20. 28. PRACTICALS HANDBOOK . 2 ... Flour is a worldwide

1

Claire Shoemake; GZ 2016

DEPARTMENT OF PHARMACY

UNIVERSITY OF MALTA

MEDICINAL CHEMISTRY

PRACTICALS PHR 2028PRACTICALS HANDBOOK

2

PRACTICAL SESSIONS

BSc.(Hons) Pharm Sci

PHR 2028 Summary of

Sessions

1. Calibration of volumetric glassware

This scope of this session is to demonstrate the importance of eliminating readings

from non-calibrated glassware as a source of error in analytical laboratories. This

particular session involves the calibration of a glass burette using distilled water

or deionised water as a suitable calibration liquid.

Your write up should include information on the methodology used, results

obtained and a discussion on the importance of using calibrated glassware in a

chemical laboratory.

2. Moisture content in Flour

Flour is a worldwide staple foodstuff. Studies indicate that its stability and quality

are compromised in the presence of high humidity. The scope of this practical

session is an estimation of the moisture content of a provided sample of flour

using two different methodologies- specifically the hot air oven and the moisture

analyzer.

Your write up should contain details of the specific methodologies used and

respective references. A comparison of the results obtained from both

methodologies should be carried out using appropriate statistical tools.

3. Water for injection

Water for injections is water used for the preparation of medicines for parenteral

administration, when water is used as a vehicle for dissolving or diluting

substances of preparations for parenteral administration. A sample of water is

provided for the determination of the following parameters:

Acidity and Alkalinity

Oxidisable substances

Sulphates

Conductivity

Residue on evaporation

pH

3

Your write up should include the methodologies used and a discussion of the

result obtained. Comment on other tests which should be carried out to determine

the suitability of use of water for injections.

4. Determination of the sugar content in honey

You have been provided with a honey sample for the determination of its reducing

sugar content.

Your write up must include information on the principle of the test, the

methodology used and calculation of results.

5. Dry Run

Nitrite and Nitrate Analysis in Foods

Nitrites and Nitrates occur naturally in foods but may also be present as a result of

their use as preservatives. A copy of the results obtained in a local survey

conducted to measure the residual level of nitrite and nitrate in a variety of meat

samples is attached.

Describe the methodologies for testing of nitrites and nitrates. Discuss their main

use and importance in preservation. Compare these results to the permitted levels

according to local regulations on the use of preservatives in foodstuffs and

discuss.

4

TABLE OF CONTENTS

PRACTICAL 1

1.0 CALIBRATION OF VOLUMETRIC GLASSWARE p. 5

Marking Scheme p. 5

1.1 Introduction p. 6

1.1.1 To Contain vs To Deliver p. 6

1.1.2 The Analytical Balance p. 6

1.1.3 Volumetric Glassware p. 6

1.1.3.1 Direct Calibration p. 7

1.1.3.2 Indirect Calibration p. 7

1.1.3.3 Relative Calibration p. 7

1.1.4 In Conclusion p. 7

1.2 Methodology p. 7

1.2.1 Calibration of Burette p. 7

1.3 Results p. 9

1.4 Definitions & Formulæ p. 11

1.5. Further Data Manipulation p. 11

1.5.1 Calculation of Standard Deviation p. 11

1.5.2 Calculation of Absolute Error p. 11

1.5.3 Calculation of Relative Error p. 11

1.5.4 Significance of Results p. 11

PRACTICAL 2

2.0 CALCULATION OF THE PERCENTAGE MOISTURE

IN FLOUR USING THE HOT AIR OVEN METHOD

p. 12

Marking Scheme p. 12



2.3 Data Manipulation p. 14

PRACTICAL 3

3.0 WATER FOR INJECTIONS p. 15




3.2.1 Acidity or Alkalinity p. 17

3.2.2 Oxidisable Substances p. 17

3.2.3 Sulphates p. 17

3.2.4 Residue on Evaporation p. 18

3.2.5 pH p. 18


PRACTICAL 4

4.0 DETERMINATION OF THE SUGAR CONTENT IN

HONEY

p. 19



4.2 Preparing a Sugar Standard Solution – 1% p. 20

4.3 Standardisation p. 21

4.4 Results p. 21

4.5 Calculations p. 21

5

4.6 Determination p. 21

4.7 Results p. 21

4.8 Calculations p. 21


PRACTICAL 5

5.0 DRY RUN: NITRITE AND NITRATE ANALYSIS IN

FOOD

p. 22


5.2 Supplied Data p. 22


READING LIST p. 26

6

Practical 1 - Marking Scheme

Calibration of the Volumetric Glassware

Name of Student

Carrying out the Experiment 6 marks

Criteria Marks

obtained Maximum

marks

handles equipment correctly and with skill 2

observes/ measures systematically and accurately 2

records the results accurately 2

6

Calculations 6 marks

Criteria Marks

Obtained Maximum

marks

calculates the standard deviation accurately 2

calculates the standard error accurately 2

calculates the relative error accurately 2

6

Evaluation 8 marks

Criteria Mark

obtained Maximum

marks

comments on the significance of the results obtained. 2

shows scientific knowledge and understanding of the results obtained 2

comments on the quality of the experiment and the results obtained 2

suggests improvements to the experiment 2

8

Total Mark / 20 marks

Name of Demonstrator: _____________________________

Signature of Demonstrator: __________________________

7

Experiment 1

1.0 Calibration of Volumetric Glassware

1.1 Introduction:

Calibration is the process by which a stated measure such as the volume of a container is

checked for accuracy. In general, measurements of mass can be determined more precisely

and accurately than measurements of volume. Therefore, the mass of the liquid contained or

dispensed by the glassware will be measured and the corresponding volume calculated using

the density of the liquid. However, a relatively small change in temperature causes a change

in the liquid’s volume and thus its density.

1.1.1 To Contain vs To Deliver

Volumetric glassware is calibrated either to contain (TC) or to deliver (TD) the stated

volume. Beakers and graduated cylinders are generally calibrated to contain while most

pipettes and burettes are calibrated to deliver.

1.1.2 The Analytical Balance

The basic measuring device in the laboratory is the analytical balance. The accuracy of the

counterweights inside the balance is much better than one part per thousand and the balances

are serviced and calibrated at regular intervals to ensure their accuracy.

In the most accurate work two corrections are required. One is to correct for difference

between an object weighed in air and the same object weighed in vacuum. According

Archimedes’ principle an object is buoyed up by a force equal to the weight of air it

displaces. Second, is the fact that glass expands with increasing temperature, so the volume

of a container also increases. By convention, volumetric glassware is always calibrated at

20°C. Since the temperature at which the calibration is done may be somewhat different

there is a small correction for the cubic coefficient of expansion of glass. Fortunately the

correction is very small within a few degrees of 20°C and can be neglected in ordinary work.

1.1.3 Volumetric Glassware

Volumetric glassware is calibrated at a specific temperature, usually 20°C, but quite often it

is used to deliver or contain volumes at a different temperature. The temperature variations

make it necessary to adjust samples and/or standards to the calibration temperature before

measurement, or to apply temperature corrections to the volumes measured. Glassware that

is designed to deliver specific volumes also may have specific drain time associated with its

calibrated volume and must be scrupulously cleaned to drain properly. Therefore it can be

seen that variances in volumetric measurements can be a major, if not the chief, source of

error in an analytical laboratory.

There are three general methods commonly employed to calibrate glassware:

1. Direct, absolute calibration

2. Indirect, absolute calibration

3. Relative calibration

8

1.1.3.1 Direct Calibration

A volume of water delivered by a burette or contained in a volumetric flask is obtained

directly from the weight of the water and its density. For example, if at 25°C, a 20.00 ml

pipette delivered 19.970 g of water then the volume delivered at 25°C would be 19.970 g x

1.0040 ml/g = 20.05 ml. At 20°C the volume would be 19.970g x 1.0037 ml/g = 20.04mL.

(See table in Section 3.0 on page 3 for temperature specific values for water density)

1.1.3.2 Indirect Calibration

Volumetric glassware can be calibrated by comparison of the mass of water it contains or

delivers at a particular temperature with that of another vessel which had been calibrated

directly. The volumes are directly related to the masses of water. This method is convenient

if many pieces of glassware are to be calibrated.

1.1.3.3 Relative Calibration

It is often necessary to know only the volumetric relationship between two items of

glassware without knowing the absolute volume of either. The situation arises, for example,

in taking an aliquot portion of a solution. Suppose that it is desired to titrate one-fifth of an

unknown sample, the unknown sample might be dissolved and diluted to volume in a 250 ml

volumetric flak. A 50 ml pipette would then be used to withdraw an aliquot for titration.

For the calculation in this analysis, it would be necessary to know the exact volume of the

flask or the pipette, but it would not be necessary to know the exact volume of the flask or

the pipette, but it would be required that the pipette deliver exactly one-fifth of the contents

of the flask. The method used for the relative calibration in this case would be to discharge

the pipette five times into the flask and marking the level of the meniscus on the flask.

1.1.4 In Conclusion

The use of calibrated glassware is of great importance in a chemical laboratory in order to

ensure that any volumes measured are known with a certain degree of accuracy.

1.2 Methodology

1.2.1 Calibration of Burette

Record the temperature in the laboratory

Wash the supplied burette thoroughly with deionised water such that no drops of

distilled water are left on the internal surface of the burette.

If droplets of water are still observed to adhere to the inner surface of the burette after

delivering deionised water, the burette must be considered as still dirty and the

cleaning process repeated.

Allow the burette to drain for some time.

Clean and dry a small flask using paper towels and a stream of warm air. Handle the

flask using the paper towels since fingerprints and sebaceous oils may cause the

calibration process to be imprecise.

Fit the flask with a stopper.

Weigh the flask on an analytical balance to the nearest 0.1 mg.

Using a transfer pipette, rinse the burette with distilled water at room temperature.

9

Drain the burette completely into a beaker.

Place the burette into the burette clamp.

Ensure that the clamp is mounted tightly and is level.

Using a funnel, re-fill the burette with deionised distilled temperature equilibrated

water.

Ensure that the burette is not over-filled. (The burette must be filled to slightly past

the 0.00ml mark.)

Carefully wipe off any solution spilled on the outside of the burette.

Open the stopcock and drain the burette to the 0.00ml mark.

Ensure that no air bubbles are present in the burette or in the stopcock tip. If any are

present, the burette must be re-drained slightly to force out the air bubbles and re-

filled.

Touch the beaker to the tip of the burette to remove any adhering drops of water.

Allow the burette to stand for 5 minutes.

If the level of the burette has changed, more water must be added slowly, to reach the

0.00ml mark.

Place the flask under the burette.

Open the stopcock and slowly transfer 10ml into the flask

Touch the tip of the burette to the wall of the flask.

Allow the flask to stand for 30 seconds such that the film of liquid on the walls of the

burette to drain.

Stopper the flask in order to prevent evaporation.

Record the apparent volume of liquid extracted from the burette to the nearest

0.01ml.

Weigh the flask to the nearest 0.1mg.

Repeat the procedure in 10ml increments, all the way to 50ml.

Refill the burette was re-filled and repeat the entire procedure for a further 2 times.

Record your results onto the tables provided in Section 1.3 below. Refer to the

definitions included at the end of Section 1.4 prior to recording your results.

Estimate the Standard Deviation, Absolute and Relative Error of these results.

Comment on the significance of these results

10

1.3 Results

Interval 0-10ml

Final Reading (ml)

Initial Reading (ml)

Apparent Volume (ml)

Mass

Actual Volume (ml)

Correction

Average Correction for interval 0-10ml:

Consequently, the burette delivers ------------ml less than indicated by the burette reading.

Interval 10-20ml

Final Reading (ml)



Mass

Actual Volume (ml)

Correction



Interval 20-30ml

Final Reading (ml)



Mass

Actual Volume (ml)

Correction



11

Interval 30-40ml

Final Reading (ml)



Mass

Actual Volume (ml)

Correction



Interval 40-50ml

Final Reading (ml)



Mass

Actual Volume (ml)

Correction



Total average correction over the 0-50ml range = ml

12

1.4 Definitions & Formulae:

The apparent volume is calculated by finding the difference between the final and initial

volumes read from the burette.

The mass volume is calculated by weighing the flask after adding each 10ml increment by

means of an electronic balance

The actual volume is calculated by simple proportion using the density of water 23°C as

shown:

Example: 1g of water weighs 0.9975415g

Thus Yg of water weighs ? g

Actual volume of water delivered = (0.9975415 x Y)/1 = Zml

The correction factor is calculated by finding the difference between the actual volume and

the apparent volume in each case.

1.5 Further Data Manipulation

1.5.1 Calculation of Standard Deviation:

σ = Σ [ x – x]2

n - 1

1.5.2 Calculation of Absolute Error

Absolute Error = measured value – actual value

1.5.3 Calculation of Relative Error

Absolute error / actual value * 100

1.5.4 Significance of Observed Results

Comment on the significance of the results obtained.

13


Calculation of the Percentage Moisture in Flour Using the Hot Air Oven

Name of Student


Criteria Marks

obtained Maximum

marks




7


Criteria Marks

Obtained Maximum

marks

calculates the percentage humidity in the provided sample accurately 3

3

Evaluation 10 marks

Criteria Mark

obtained Maximum

marks

comments on results obtained. 2




10

Total Score / 20 marks



14

Experiment 2

Calculation of the Percentage Moisture in Flour Using the Hot Air Oven

2.1 Introduction

Flour is derived from wheat after this has been subjected to a process known as milling.

Accurate determination of the moisture content of flour is considered to be a very important

process that is instrumental in the determination of its shelf life. The lower the level of

moisture in flour, the better its storage stability will be. The deterioration of baking quality is

also less at lower moisture content. This may be attributed to the retarded respiration and

activity of microorganisms.

Moisture is an important factor in controlling grain infestation. Insects that live on stored

grains and their products, depend upon the moisture supply. Generally, a moisture content of

9% or lower is considered restrictive to infestation. Moisture is also of great importance for

the safe storage of cereals and their products regarding microorganisms, particularly certain

species of fungi. At lower moisture fungi will not grow but at about 14% or slightly above,

fungal growth takes place.

Higher lipolytic and proteolytic activities are related to higher moisture content, which

further lead to loss in nutrients (protein and fat) and production of more free fatty acids

resulting in inferior characteristics.

Adequate food packaging is consequently very important because of the protection that this

affords the enclosed product from contamination by macro and micro-organisms, prevention

from loss or gain of moisture, shielding the product from oxygen and facilitation of

handling.

With respect to moisture, the establishment of methods which reliably quantify the resident

humidity are important in establishing the quality and shelf life of flour samples destined for

human consumption.

2.2 Methodology

The Hot Air Oven Method

Switch the oven on and set it to 131OC

Label the supplied petri-dishes and their corresponding covers

Place the uncovered petri dishes and their corresponding lids into the previously

heated oven facing upwards

After 10 mins have elapsed, remove the petri dishes and their lids from the oven, and

place them into a dessicator until they reach room temperature

Weigh the covered petri dishes and record their weight

Weigh 10g ± 0.05g of flour for each supplied petri dish

Place this amount into each petri dish

Cover each petri dish

Weigh and record the weight of each covered petri dish

Remove the cover once again

Place the uncovered petri dishes together with their cover into the oven for 20

minutes

15

After 30 minutes have elapsed, cover the petri-dishes with their corresponding lid

while these are still in the oven

Remove them from the oven and place them in the dessicator until they reach room

temperature

Weigh and record the weight of the covered petri dishes.

Calculate the moisture content of each sample.

2.3 Data Manipulation

Present your result in tabulated format

Calculate the percentage humidity in the provided sample

Comment on your results critically

16


Water for Injections

Name of Student


Criteria Marks

obtained Maximum

marks



6

Results 4 marks

Criteria Marks

Obtained Maximum

marks


4

Evaluation 10 marks

Criteria Mark

obtained Maximum

marks

comments on the results obtained. 2




10




17

Experiment 3

Water for Injections

3.1 Introduction:

Water for Injection (WFI) is water purified by distillation or reverse osmosis. It is used for

the preparation of parenteral medicines. Water is used as a vehicle (water for injections in

bulk) and for dissolving or diluting substances or preparations for parenteral administration

(sterilised water for injections).

Water for injections in bulk is a clear, colourless, odourless, and tasteless liquid. It is

obtained from water that complies with the regulations on water intended for human

consumption laid down by competent authorities or from purified water by distillation in an

apparatus of which the parts in contact with the water are of neutral glass, quartz or suitable

metal and which is fitted with an effective device to prevent the entrainment of droplets. The

correct maintenance of the apparatus is essential.

During production and subsequent storage, appropriate measures are taken to ensure that the

total viable aerobic count is adequately controlled and monitored. Appropriate alert and

action limits are set so as to detect adverse trends. Under normal conditions, an appropriate

limit is a total viable aerobic count of 10 microorganisms per 100ml. For aseptic processing,

stricter alert limits may need to be applied. Water for injections in bulk is stored and

distributed in conditions designed to prevent growth of microorganisms and to avoid any

other contamination.

Sterilised water for injections is water for injections in bulk that has been distributed into

suitable containers, closed and sterilised by heat in conditions which ensure that the product

still complies with the test for bacterial endotoxins. Sterilised water for injections is free

from any added substances. It is clear and colourless.

18

3.2 Methodology

The following parameters will be determined for the supplied sample of water for injections:

Acidity or Alkalinity

• Oxidisable substances

• Sulphates

• Residue on evaporation

• pH

3.2.1 Acidity or Alkalinity

Measure 20ml of tap water in a measuring cylinder and transfer this to a beaker.

Add 0.05ml of phenol red solution. Note any colour change

Add 0.1ml of 0.01M NaOH. Note any colour change

Add 0.15ml of 0.01M HCl. Note any colour change.

Repeat the above tests on a 20ml sample of distilled water

Comment on your results

3.2.2 Oxidisable Substances

Transfer 100ml of tap water into a beaker.

Add 10ml of dilute H2SO4 and boil the mixture.

Add 0.2ml of 0.02M KMnO4 and allow the mixture to re-boil for 5 minutes

Note any colour change


3.2.3 Sulphates

Transfer 10ml of tap water to a beaker.

Add 1ml of dilute (0.01M) HCl and 0.1ml of 0.001M BaCl2 solution.

Leave the solution to stand for at least an hour.

Note any changes to the appearance of the solution


19

3.2.4 Residue on evaporation

Weigh an empty beaker

Add 100ml tap water

Weigh the beaker containing 100ml water

Evaporate the tap water to dryness.

Weigh the beaker after the tap water has been evaporated to dryness

Quantify the concentration of the residue on evaporation

Repeat the entire procedure using 100ml water for injection


3.2.5 pH

Allow an electrode to stand for a few minutes in a beaker containing unionized water.

Record the reading on the pH meter

Fully immerse the electrode into a beaker containing 100ml of tap water.

Record the reading on the pH meter



Discuss the results obtained. Mention other tests that you consider vital in the quality control

of water for injections.

20


Determination of Sugar Content in Honey

Name of Student


Criteria Marks

obtained Maximum

marks




6


Criteria Marks

Obtained Maximum

marks

Standard solution: calculates the total sugar required to reduce the Cu2+

ions 3

calculates the percentage reducing sugars in honey 3

6

Evaluation 8 marks

Criteria Mark

obtained Maximum

marks

comments on the results obtained. 2




8




21

Experiment 4

Determination of the Sugar Content in Honey

4.1 Introduction

Honey is a sweet fluid produced by honey bees (genus Apis), and derived from the nectar of

flowers. A label stating pure honey implies that no other additives have been added to the

honey including water or other sweeteners.

Honey derives its sweetness from the monosaccharides fructose and glucose and has

approximately the same relative sweetness as granulated sugar (97% of the sweetness of

sucrose, a disaccharide). Honey has attractive chemical properties for baking, and a

distinctive flavor which leads some people to prefer it over sugar and other sweeteners.

Most micro-organisms do not grow in honey because of its low water activity of 0.6.

However, honey frequently contains dormant endospores of the bacterium Clostridium

botulinum, which can be dangerous to infants as the endospores can transform into toxin-

producing bacteria in the infant's immature intestinal tract, leading to illness and even death.

The study of pollens and spores in raw honey (melissopalynology) can determine floral

sources of honey. A main effect of bees collecting nectar to make honey is pollination,

which is crucial for flowering plants.

4.2 Preparing a Sugar Standard Solution – 1%

1. Weigh 4.75g pure sucrose.

2. Add 7.5ml HCl and dilute with water to approximately 50ml.

3. Store several days at room temperature (about 7 days at 12-15oC or 3days at 20-

25oC).

4. Dilute to 500ml. (acidified 1% invert sugar solution is stable for several months)

5. Neutralise approximately 75ml of the sugar solution with 1M and 0.5M NaOH

accordingly.

6. Dilute to desired concentration immediately before use.

4.3 Standardisation

1. Accurately pipette 12.5ml of Fehling’s solution A and Fehling’s solution B into a

conical flask.

2. Add antibumping granules.

3. Fill the burette with the neutralised sugar solution till the 0.00ml mark.

4. Add 8ml of the sugar solution into the conical flask.

5. Heat the cold mixture to its boiling point on wire gauze over a Bunsen burner and

maintain moderate boiling for 1 minute.

6. Without removing from flame add 1ml of 0.2% aqueous methylene blue solution.

7. Complete titration within total boiling time of approximately 3 minutes by small

additions (2-3 drops) of sugar solution to decolouration of indicator.

8. Maintain continuous evolution of steam to prevent reoxidation of Cu+ or

indicator

9. After complete reduction of Cu2+

methylene blue is reduced to colourless compound

and the solution resumes an orange colour which it had before addition of indicator.

10. Repeat step 1 – 9 to obtain three titre values

http://en.wikipedia.org/wiki/Honey_bee

http://en.wikipedia.org/wiki/Nectar_%28plant%29

http://en.wikipedia.org/wiki/Flower

http://en.wikipedia.org/wiki/Sweetener

http://en.wikipedia.org/wiki/Monosaccharides

http://en.wikipedia.org/wiki/Fructose

http://en.wikipedia.org/wiki/Glucose

http://en.wikipedia.org/wiki/Sweetness

http://en.wikipedia.org/wiki/Sucrose

http://en.wikipedia.org/wiki/Sucrose

http://en.wikipedia.org/wiki/Disaccharide

http://en.wikipedia.org/wiki/Water_activity

http://en.wikipedia.org/wiki/Endospore

http://en.wikipedia.org/wiki/Clostridium_botulinum

http://en.wikipedia.org/wiki/Clostridium_botulinum

http://en.wikipedia.org/wiki/Pollen

http://en.wikipedia.org/wiki/Spore

http://en.wikipedia.org/wiki/Melissopalynology

http://en.wikipedia.org/wiki/Pollination

http://en.wikipedia.org/wiki/Flowering_plant

22

4.4 Results

Final Reading (ml)


Titre value (ml)

Average titre value for standard sugar solution: __________________________

4.5 Calculations

1. Taking the first titre value as a rough value, use the other two titre values to obtain an

average.

2. Multiply the average titre by mg/ml standard solution to obtain the total sugar

required to reduce the Cu2+

.

4.6 Determination

1. Accurately pipette 12.5ml of Fehling’s solution A and Fehling’s solution B into a

conical flask.

2. Add antibumping granules.

3. Fill the burette with the honey solution till the 0.00ml mark.

4. Add 5ml of the honey solution into the conical flask.

5. Heat the cold mixture to its boiling point on wire gauze over a Bunsen burner and

maintain moderate boiling for 15 seconds.

6. Without removing from flame add 1ml of 0.2% aqueous methylene blue solution.

7. Complete titration by small additions (2-3 drops) of honey solution to decolouration

of indicator.

8. Maintain continuous evolution of steam to prevent reoxidation of Cu+ or indicator.

9. After complete reduction of Cu2+

methylene blue is reduced to colourless compound

and the solution resumes an orange colour which it had before addition of indicator.

4.7 Results

Final Reading (ml)


Titre value (ml)

Average titre value for honey solution: __________________________

4.8 Calculations

1. Taking the first titre value as a rough value, use the other two titre values to obtain an

average.

2. Calculating the % reducing sugar in honey:

Titre value for standard sugar solution

Titre value for honey solution


Comment on the results obtained

X 100 =

23

Experiment 5

Dry Run: Nitrite and Nitrate Analysis in Food

5.1 Introduction

Nitrites and nitrates occur naturally in meats, but are also used as preservatives for hams,

bacon and pickled meats. The brine baths used for this purpose may contain nitrite and

nitrate levels well over a 1,000ppm and needs to be monitored on a regular basis in order to

ensure that the meats do not exceed the statutory level of 200ppm. Apart from their

preservative properties nitrites and nitrates have the effect of enhancing the natural redness

of the meat products.

5.2 Supplied Data

The following is a table of results obtained in a local survey conducted to measure the

residual level of nitrite and nitrate in a variety of meat samples.

Foodstuff Sample

No.

Residual Nitrite

Level

(ppm)

Residual Nitrate

Level

(ppm)

Country

25 B3 Ham 2 5.8 24.6 Malta

25 B3 Ham 3 5.6 28.9 Malta

25 B3 Ham 4 5.3 32.4 Malta

25 B3 Ham 5 6.4 33.9 Malta

25 B3 Ham 6 8.2 41.4 Malta

26 B4 Mortadella (Sausage

Type)A 1 5.7 169.4 Malta











27 B4 Mortadella B 1 5.2 129.3 Malta






31 B7 Sausages (Maltese) 1 0.2 16.0 Malta






24

32 C1 Bacon (Back) A 1 58.7 49.9 Malta






33 C1 Bacon (Collar) B 1 4.0 501.7 Malta






34 C1 Bacon (Streaky)C 1 0.0 81.0 Malta






35 C2 Beef Burgers A 1 0.3 31.1 Malta






36 C2 Beef Burgers B 1 0.3 21.1 Malta






37 C3 Sausages

(BBQ/Grill) A

1 0.1 37.5 Malta

37 C3 Sausages

(BBQ/Grill) A 2 0.2 35.7 Malta

37 C3 Sausages


37 C3 Sausages


37 C3 Sausages


37 C3 Sausages


38 C3 Sausages(Beef)B 1 0.0 82.6 Malta






39 C3 Sausages(Beef)C 1 0.0 69.1 Malta






40 C3 Sausages (Chick. &

Turk. Franks.)D 1 5.1 161.2 Malta

25









40 C3 Sausages

(Frankfurters) E 6 5.8 148.3 Malta

41 C3 Sausages


41 C3 Sausages


41 C3 Sausages


41 C3 Sausages


41 C3 Sausages


41 C3 Sausages


42 C3 Sausages

(Frankfurters) F

1 40.1 170.9 Malta

42 C3 Sausages

(Frankfurters) F 2 37.8 160.2 Malta

42 C3 Sausages


42 C3 Sausages


42 C3 Sausages


42 C3 Sausages


43 C3 Sausages

(Frankfurters) G 1 8.6 215.5 Malta

43 C3 Sausages


43 C3 Sausages

(Frankfurters) G

3 7.3 201.5 Malta

43 C3 Sausages


43 C3 Sausages


43 C3 Sausages


44 C3 Sausages

(Frankfurters) H 1 8.3 57.9 Malta

44 C3 Sausages


44 C3 Sausages


44 C3 Sausages


44 C3 Sausages


26

44 C3 Sausages


45 C3 Sausages (Pork) I 1 0.0 57.4 Malta






46 C3 Sausages (Pork)J 1 0.0 68.5 Malta






47 C3 Sausages (Other) K 1 7.3 58.0 Malta






48 C3 Sausages (Other) L 1 6.5 35.3 Malta






49 C3 Sausages (Other) M 1 10.0 56.9 Malta






50 C3 Sausages (Other) N 1 0.6 26.5 Malta


Describe the methodologies for testing of nitrites and nitrates. Discuss their main use and

importance in preservation. Compare these results to the permitted levels according to local

regulations on the use of preservatives in foodstuffs and discuss.

27

READING LIST

European Pharmacopoeia: 6th Edition. Council of Europe; 31 Jul 2007

Kanare, H. M. Writing the Laboratory Notebook, Washington DC: American

Chemical Society, 1985.

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DEPARTMENT OF PHARMACY UNIVERSITY OF MALTA · DEPARTMENT OF PHARMACY . UNIVERSITY OF MALTA . MEDICINAL CHEMISTRY PRACTICALS PHR 20. 28. PRACTICALS HANDBOOK . 2 ... Flour is a worldwide