Field factory assignment is a compulsory course unit offered by department of forestry and environmental science, University of ________, to the B.Sc. I carried out my internship  program (Field factory assignment) at Sri Lanka Standards Institution in a duration of 40 working days.

The internship program provided the undergraduate students to experience, “real work”, before entering into the industry after graduation and the opportunity for development of skills both technical and social.

The internship was a bridge that connected our academic knowledge to the industry which is more practical and experience-based.

This report includes various analysis tests such as water analysis, cosmetics analysis, Salt analysis etc. All the experiments were carried out following test methods in national (SLS) and International (ISO) standards and specifications.

Also, I hereby include a brief introduction of the Sri Lanka Standards Institution.

Sri Lanka standards institution (SLSI) background and location

Sri Lanka standards institution (SLSI) is the national standards body of Sri Lanka established under the bureau of Ceylon standards Act no.38 of 1964.

The institute now functions under the Ministry of Technology, Research and Atomic Energy (and is governed by a council appointed by the minister in terms of the above act.)


To promote standardization and quality control in industry and commerce while; uplifting the quality of life of the nation with standards in all sectors of the economy considering the national & international requirements & demand and enhancing relationships with all stakeholders in standardization.


To undertake, promote and facilitate standardization, measurement quality assurance and other related activities in all sectors of the economy.

Formulate standards on national and International basis relating to structures, commodities, products, materials, practices, and operations; Revise, alter and amend the same for the current use; Promote the adoption of such standards; Promotion of standards within the community and Remove the trade barrier with harmonization of standards.


Address: 231 Elvitigala Mawatha, Colombo 00800

Activities performed

At Scientific Standardization Division

  • In the first day of our internship we attended a working group meeting held at scientific standardization division as observers.
  • I have familiarized with international standards and standards formulation process at scientific standardization division through various lectures given to us by many assistant directors.

At Laboratory services division

  • I have participated in many testing activities under supervision of senior analysts in chemical laboratory, food and microbiology laboratory.

Testing activities

  • Assisted in media preparation process at microbiology laboratory
  • Testing carried out for various products as per SLS & ISO standards.
  • Products that are being tested in this laboratory are shown in the table in appendix z. Out of these products, I have participated in testing carried out for below products, to determine relevant parameters for each of them.
ProductStandardParametersTest method
Bottled drinking water

Potable water

Ice for use in food processing and catering industries

SLS 894

SLS 614

SLS 971

  1. Odor
  2. Taste
  3. Color* ,Hazen units
  4. Turbidity, NTU
  5. pH at 25C ±2C
  6. Total dissolved solids, mg/l
  7. Chloride, (as Cl¯), mg/l
  8. Free residual chlorine, mg/l
  9. Free ammonia and albuminoid ammonia (as NH3), mg/l
  10. Sulfate, (as SO4), mg/l
  11. Fluoride (as F¯)*, mg/l
  12. Total alkalinity, (as CaCO3), mg/l
  13. Total hardness, (as CaCO3), mg/l
  14. Chemical oxygen demand (COD)*, mg/l
  15. Nitrate, (as NO3¯), mg/l
  16. Nitrite (as NO2¯)*, mg/l
  17. Total phosphate (as PO4)
  18. Calcium
  19. Magnesium


APHA 2120 B

APHA 2130 B

APHA 4500_H+B

APHA 2540_C

APHA 4500Cl¯_B

APHA 4500 Cl¯_G

SLS 614:2013

APHA 4500 SO4E

APHA 4500 F¯C

APHA 2320 B

APHA 2340_C

APHA 5220 B

APHA 4500_ NO3¯ B

APHA 4500_ NO2¯ B

APHA 4500_PC

APHA 3500Ca B

APHA 3500Mg B

(Refer pg 7-10 &

Appendix: A)

Porcelain table wareSLS 1222
  1. Release of lead/Cadmium
  2. Edge warpage and slope
SLS 1222: part 2: 2001

SLS 1222: part 2: 2001

(Refer pg 15-16)

FertilizersSLS 645
  1. Calcium content
  2. Magnesium content
  3. Phosphorous content
  1. pH at 25C ±2C

Refer pg 16 & Appendix C

Hair Color

Skin cream & lotion


SLS 1439

SLS 611

SLS 275

  1. pH at 25C ±2C
  2. PPD (Paraphenyl diammine)
Refer pg 12
  1. Peroxide value
  2. pH at 25C ±2C
  3. Cd, Pb
Refer pg 13
  1. Fineness
  2. Total Fluoride
  3. Abrasion
  4. Moisture content
  5. Extrusive content
  6. pH
  7. Thermal stability
Refer pg 13-14
Soap & Detergents
Bathing Bar

Toilet soap

SLS 1220

SLS 34

  1. Free caustic alkali
  2. pH (of a 1% solution)
Refer pg 15
  1. Total fatty matter
Refer pg 15
Other Products
Salt (Powdered form)

Salt (granular form)

SLS 80

SLS 79

  1. Moisture content
  2. Particle size
  3. Matter insoluble in water
  4. Iodine content
  5. Determination of NaCl
    1. CO3
    2. Total chloride
    3. Potassium
    4. Ca & Mg
    5. SO4
Refer pg 10-12 & Appendix B
Other products
Sugar confectionaries


Canned fish

Fruit juices


Milk powder

Ice cream

Meat balls

SLS 191

SLS 271

SLS 591

SLS 1328

SLS 420

SLS 731

SLS 223

SLS 1218

  1. Cd, Pb
Refer pg 15-16
  1. Cd, Pb
  2. Moisture content
  1. Cd, Pb
  2. Detection and enumeration of coliforms
  3. Salinity
  4. Acidity
  1. Refractive index
  1. Cooking time
  2. Total solids in gruel
  1. Coliforms MPN/g

APHA: Standard methods for the examination of water & waste water, published by American public health association, USA 22nd edition

Testing procedures followed;

Water analysis

Determination of physical parameters

The odor

The bottle was opened and the odor was tested immediately by sniffing.

Requirement: Unobjectionable

      1. Taste

The sample was tasted by taking in a suitable volume of it into the mouth.

Requirement: Unobjectionable

      1. Turbidity

Water sample was gently agitated and waited until air bubbles disappear and poured into cell. Then the turbidity was read directly from instrument display.

Instrument –Turbiditimeter

Requirement: SLS 894: 2003 permissible limit is 5 (Max)

      1. pH at 25ᵒC ± 2ᵒC

Before use the electrodes were removed from storage solution. Then it was rinsed blot dried with a soft tissue and placed in initial buffer solution (pH – 7) and then pH – 4 buffer solution was selected as second buffer. After calibrating the pH meter, it was set to the pH mode and the temperature was adjusted to 25 C. Then the electrode was placed in the water sample to be tested.

Requirement: pH should be in between 6.5 – 8.5 to have passed the test

    1. Determination of chemical parameters
      1. Total dissolved solids (mg/l)

About 250ml of filtered sample was evaporated and dried at 180 C ± 2 C. Then total dissolved solids, mg/l were calculated using a formula weight of empty beaker and weight of beaker + residue were recorded in a worksheet.

Requirement: 1000 (Max) mg/l.

      1. Chloride (as Cl¯)

The pH of 100ml water sample was adjusted to pH 7, with 1N H2SO4/ 1N NaOH, and titrated against 0.0141N AgNO3 using 1.0ml potassium chromate indicator until a slightly perceptible pinkish yellow color is obtained. A blank titration was carried out with 100ml of distilled water. The readings were recorded in a worksheet.

Requirement: 250 (Max) mg/l

      1. Free residual chlorine (mg/l)

Firstly KMnO4 working standard solution series were prepared. 50ml water sample and 50 ml check sample were taken into 50ml volumetric flask. Separate beakers were taken for each standard solutions, water and check samples. 5ml of phosphate buffer was put into a beaker. 1 DPD tablet was added to it and dissolved completely. The first standard solution was added to it. Then, the absorbance were measured at 515nm immediately against distilled water by UV/VIS Spectrophotometer. The same process was repeated using the other standard solutions and sample solutions.

Requirement: 0.2 (Max) mg/l.

      1. Free ammonia (mg/l) and albuminoid ammonia
  • Free ammonia:

About 500ml water sample was taken into distillation flask and 0.2g MgCO3 and few glass beads were added. It was distilled over four 50ml portions into Nessler tubes commencing the distillation slowly.2ml of Nessler reagent was added to the portions, mixed and allowed to stand for 5 minutes. The tube was placed in the right hand compartment of the Nessleriser. The ammonia disc was fit in to the Nessleriser. The disc was rotated until the nearest color match is obtained. The disc reading was noted.

Requirement: 0.06 (Max) mg/l

  • Albuminoid ammonia:

To the residue of free ammonia 300ml of distilled water and 25ml of alkaline KMnO4 were added. The distillate was collected into 50ml Nessler tubes until last portion of 50ml contains no ammonia. The check sample was prepared as in free ammonia.

Requirement: 0.15 (Max) mg/l

      1. Sulfate

Firstly, sulfate working standard solution series were prepared. First standard solution was taken in to a beaker and 20ml of buffer solution was added to it. 2.00g of BaCl2 were added to the beaker and began stirring immediately for 60±2s using magnetic stirrer. Turbidity was measured at 420nm using 4 cm cell by UV/VIS Spectrophotometer. The process was repeated using other standard solutions, check and water samples.

Requirement: 250 (Max) mg/l

      1. Fluoride

After calibrating the instrument, Fluoride concentration of water samples was directly measured using a fluoride sensitive electrode by pH meter.

Requirement: 1.5 (Max) mg/l

      1. Total alkalinity

About 100ml of sample was titrated with 0.1N HCl using mixed indicator (bromocresol green-methyl red). Readings were recorded in a worksheet.

Requirement: 200 (Max) mg/l

      1. Total hardness

Exactly 2.0ml of pH 10 buffer was added to 100ml of sample and titrated with 0.01M EDTA with EBT indicator.

Requirement: 250 (Max) mg/l

      1. Chemical Oxygen Demand

Exactly 50ml of homogenized sample was added to a refluxing flask. Then 1g of HgSO4 and few glass beads were added. Then 5ml of H2SO4 was added slowly to dissolve HgSO4. Then 25.00ml of 0.04167M K2Cr2O7 solution was added and mixed. Reflux flask was attached to the condenser and cooling water was turned on. Remaining H2SO4 reagent was added through open end of condenser and refluxed for 2 hours. Condenser was cooled and washed down with distilled water. It was cooled to room temperature and titrated excess K2Cr2O7 with 0.25M FAS using ferroin indicator.

Requirement: 10 (Max) mg/l

      1. Nitrate

Firstly nitrate working standard solution series was prepared and 1ml of 1N HCl was added to each solution. 50ml of check sample and 50ml of water sample was taken in to 50ml volumetric flask and 1 N HCL was added. Then the absorbance was measured at 220nm and 275nm against distilled water after drawing a calibration curve using standard solution series by UV / VIS Spectrophotometer

Requirement: 50 (Max) mg/l

      1. Nitrite

Exactly 50 ml sample was taken and the pH was adjusted to 7 with 1N HCl or NH4OH. 2ml of color reagent was added to the sample and kept for 30 minutes. The colors between sample and check samples were compared using Nessleriser.

Requirement: 3 (Max) mg/l

      1. Total phosphate

Firstly working standard solution series was prepared. 10ml of vanado molybdate reagent was added and made up to 50ml. The blank solution was prepared by adding 10ml of vanado molybdate and dilute to 50ml in a volumetric flask. 25ml of sample was taken into 50ml volumetric flask and 10ml of vanado molybdate reagent was added and made up to the mark. After 10 minutes the absorbance of standards, sample, and check sample were measured at 400nm against reagent blank.

Requirement: 2.0 (Max) mg/l

      1. Calcium

Exactly 2ml of 1N NaOH solution was added to 100ml of sample and titrated with 0.01M EDTA with Patton & Reeder’s (HSN) indicator.

Requirement: 100 (Max) mg/l

      1. Magnesium

mg Mg/L = [Total hardness(as mg CaCO3/L) – Calcium hardness (as mg CaCO3/L )] * 0.243

Requirement: 30 (Max) mg/l

  1. Salt analysis
    1. Moisture content

Exactly 10g of sample was weighed to the previously weighed crucible. It was dried at 150 C for 4 hours. Dried sample was weighed and readings were recorded.

Requirement: 0.5 % by mass (max)

    1. Particle size

Exactly 100g of sample was weighed to the collector. Sieve (1000µm for powdered salt and 4.75mm for crystal salt) until all the sievable particles were passed through. Then it was weighed and readings were recorded.


Refined salt –minimum 99 % by mass of the product shall pass through a sieve of aperture size 1000µm

Vacuum evaporated salt –the product shall pass completely through a sieve of aperture size 1000µm

    1. Matter insoluble in water (MIS)

Exactly 20g of sample was weighed and dissolved in 200ml of distilled water and heated to boil. The solution was cooled and filtered through a weighed sintered glass crucible. The crucible was dried at 105 C for 1 hour and weighed. The readings were recorded.

Requirement: 0.5 % by mass (Max) on dry basis

    1. Iodine

Exactly 10g of sample was weighed and dissolved in 100ml distilled water in a 250ml stoppered conical flask. 2ml of 1 MH2SO4 and 5ml of 10% KI was added. It was stirred well and kept in dark for 5 minutes. The solution was titrated with standard 0.005M Na2S2O3 to a light straw color and 2ml of 1% starch solution was added and titration was continued to a colorless end point. A blank titration was carried out with 10g analytical grade NaCl.


Manufacturer’s level: 20-35 as I on dry basis mg/kg

Distribution channel including retail level: 15-35 as I on dry basis mg/kg

    1. Determination of NaCl

Exactly 20g of sample was weighed and dissolved in 1000ml volumetric flask and made up to the mark with distilled water. (Solution B)

Requirement: 98 % by mass (min) on dry basis

      1. Carbonate

Exactly 100ml of the solution B was titrated against standard 0.1N HCl using methyl orange as an indicator. Used volume was recorded.

      1. Total Chloride

Exactly 2 ml of solution B was taken to the 250ml conical flask and made up to 100ml with distilled water. It was titrated against standard 0.1N AgNO3 using 1ml potassium chromate as an indicator. Volume was recorded. A blank titration was carried out with 100ml distilled water.

      1. Ca / Mg

Ca: About 100ml of solution B was titrated against standard 0.01N EDTA with 5ml of 10% NaOH using Patton & Reeders indicator (HSSNNA). The volume was recorded.

Requirement: 0.1 % by mass (max) on dry basis

Ca / Mg: Exactly 100ml of solution B was titrated against standard 0.01N EDTA with 10ml pH 10 buffer solution using Eriochrome Black T indicator. The volume was recorded.

      1. Sulphate

Exactly 100ml of solution B was heated to boil with 2 drops of 1N HCl. 20ml of BaCl2 was added to the boiling solution and boiled for extra 5 minutes. It was allowed to cool and titrated against standard 0.01N EDTA with 10ml of pH 10 buffer using EBT indicator. The volume was recorded.

Requirement: 0.7% by mass (max)

      1. Potassium

Exactly 50ml of solution B was taken and the concentration was determined using Atomic Absorption Spectrometer.

  1. Cosmetics analysis
    1. Hair color analysis
      1. pH at 27 C ± 2 C

2.5g of hair dye was weighed and 50ml of distilled water was added. After stirring, the solution’s pH was determined after stabilization using the pH meter at 27 C ± 2 C.

Requirement: pH should be in between 6-10 to have passed the test

      1. Determination of dye content (PPD)

About 5g of sample was weighed in to a thimble and it was extracted with dichloromethane in a soxhlet extractor for 5 hours. The extract was transferred in to a beaker and diethyl ether was evaporated, to about 25ml. Then 1ml of acetic anhydride was slowly added with stirring. After letting it stand for 1 hour, it was filtered on a weighted sintered glass crucible. It was washed with dichloromethane and the crucible was dried at 120 C until a constant weight is obtained calculations were made.


Type 1- 3% by mass

Type 2-1.5% by mass

    1. Skin cream analysis
      1. pH at 27 C ± 2 C

About 5g of skim cream sample was stirred with 45ml of distilled water. pH of the sample was determined with a pH meter at 27 C.

Requirement: pH should be in between 5.5-8.0 to have passed the test.

      1. Peroxide value

Skin cream sample was put in to a separating funnel and a sufficient amount of petroleum ether was added. Then the apparatus was left to separate out the oil present in cream to the pet ether layer. Then the pet ether layer was evaporated in a water bath. Then 10ml of chloroform was added along with 15ml of glacial acetic acid. After swirling 1ml of saturated KI solution was added. Then a titration was carried against 0.002N sodium thiosulphate, as starch as an indicator.

Requirement: 10 milliequivalents /kg, max

    1. Toothpaste analysis
      1. Determination of Fineness

About 10g of the toothpaste was weighted. It was washed by means of a slow stream of running tap-water in a 150µm sieve conforming to SLS 124. Then the residue (if there was) was drained and dried in an oven at 105 ± 2 C. It was cooled in a desiccator and the weight was measured then calculations were carried out.


Particles retained on 150µm sieve -1.0 %by mass (max)

Particles retained on 75µm sieve -2.5% by mass (max)

      1. Determination of total fluoride

About 5g of toothpaste was weighted and 10ml of cold distilled water was added and worked to smooth cream with a glass rod. It was transferred into 100ml volumetric flask and diluted it to volume. Then it was centrifuged at 4000rpm. The supernatant was decanted into a clean dry flask. TISAB buffer was added to the flask and stirred. And fluoride content was determined by fluoride sensitive electrode from a pH meter.


For type 1: 850-1150 mg/kg

For type 2, max 50 mg/kg

      1. Determination of Abrasion

Glass slide was cleaned, rinsed in water and dried. Then about 1g of toothpaste was placed on the slide and the “glass slide disc test apparatus” was operated for 100 double strokes using a load of 200g on the disc. Then check for visible scratches produced by the toothpaste trade. If so its’ considered as fails the test.

Requirement: To satisfy the test

      1. Determination of moisture content

About 2g of toothpaste was weighed in to a tared dish. It was dried at 105 ± 2 C in an oven to a constant mass. Then it was cooled in a desiccator and weighed. Readings were recorded.

Requirement: % by mass 12-55

      1. Determination of extrusive content

First the gross mass of the tube was weighed (m1). Then, after opening the tube and extruding the bulk of contents by applying light pressure, the tube weight was weighted (m2). Then the tube was cut opened and remaining toothpaste is removed by washing. After drying the empty tube was weighted (m3). Then calculations were made.

      1. Determination of pH value

About 10g of toothpaste was weighted in a 150ml beaker and 45ml of distilled water was added and mixed well. The pH was determined with a pH meter using glass calomel electrodes.

Requirement: pH should be in between 5.8-10.5 to have passed the test

      1. Determination of thermal stability

Toothpaste tubes/sachet were heated at 45 C for 72h. Then examined the toothpaste for separation, fermentation & deterioration. Another 2 tubes were cooled to 0 C for 1h and examined as above.

  1. Soap analysis
    1. Bathing bar analysis
      1. Free caustic alkali [/as NaOH, percent by mass]

About 5g of scraped bathing bar was added to neutralized ethanol portion in a flask adding phenolphthalein as the indicator. It was refluxed in a reflux condenser and checked whether a pink color was present and increasing. If the color increases, a titration was carried out against ethanolic HCl, to determined free caustic alkali as NaOH %.

      1. pH at 40 C ± 0.5 C

About 1.0g of bathing bar sample was weighed first into an Erlenmeyer flask and about 100ml of boiling distilled water was added to it then rapidly cooled under tap water to 43 C ± 0.5 C. Enough solution was poured into a beaker while stirring. Then the pH of the solution was taken using a pH meter at 40 C ± 0.5 C.

    1. Toilet soap analysis
      1. Total fatty matter

About 5g of soap was weighed to a beaker and 150ml of hot distilled water was added. The solution was poured into a separating funnel and few drops of methyl orange indicator was added. The solution was cooled to room temperature before adding 100ml of diethyl ether. The mixture was shaken vigorously for a minute and allowed to separate into two phases. Diethyl ether layer was extracted and distilled by boiling gently. The residue was dissolved in 20ml of the ethanol. The ethanolic solution of fatty acids were titrated with ethanolic NaOH solution using phenolphthalein as indicator. The used volume was recorded.

  1. Analysis of trace metals using atomic absorption spectrometer
    1. Porcelainware analysis
      1. Determination of release of Pb & Cd

4 % acetic acid were poured into labeled porcelainware (cups, mugs, flatware, and hollowware) for 24 hours at a temperature of 22 C ± 2 C in a dark room. Then the acetic acid in porcelain were collected to glass bottles. Those samples were loaded in to AAS one by one, after calibrating the instrument first. The readings were obtained.


Type of TablewarePermissible limit CriterionUnit of measureLead (Pb) limitCadmium limit
FlatwareMean ≤ limitmg/dm20.80.07
Small Hollow-wareAll specimens ≤ limitmg/l20.5
Large Hollow-wareAll specimens ≤ limitmg/l10.25
Storage Hollow-wareAll specimens ≤ limitmg/l0.50.25
Cups and MugsAll specimens ≤ limitmg/l0.50.25
    1. Fertilizer analysis
      1. Determination of Ca and Mg content

Fertilizer samples were digested using HCL and HNO3, (10ml aliquots from both) on a hotplate with 50ml of distilled water. Then it was filtered and the samples to be loaded into AAS was prepared. The samples were loaded into AAS after calibrating the instrument first.

      1. Phosphorous content

Samples were read by UV / VIS spectrophotometer

Refer Appendix C.

    1. Sugar analysis
      1. Determination of Cd & Pb

Sugar samples were prepared for the determination of Cd and Pb. Firstly, AAS was calibrated using standard sample series, and a check sample was loaded. After that sugar samples were loaded into AAS one by one. Then the readings were taken.

Requirement: Pb mg/kg, max 2

    1. Canned fish analysis
      1. Determination of Cd, Pb and As

Canned fish samples were prepared by first charred in a hotplate and then ashed in a furnace. Test sample solutions were loaded into AAS after calibrating the equipment and the readings were obtained.

Requirement: As 1.0 mg/kg, Pb 1.0 mg/kg, Cd 1.0 mg/kg (Hg 1.0 mg/kg)

    1. Biscuits analysis
      1. Determination of Cd and Pb

Previously prepared test samples were loaded in to AAS after calibrating the instrument first. Then the readings were obtained.

Learning Outcomes

  • I acquired new knowledge and practical experiences for example in handling different lab equipment and carrying out different tests such as water analysis, salt analysis, cosmetics analysis, etc.
  • I learned practical skills in operation and safety of lab apparatus and machines involved in activities of an operational environment.
  • I was able to handle different laboratory equipment and instruments such as:
  • UV / VIS Spectrophotometer
  • Atomic Absorption Spectrophotometer
  • pH meter
  • Analytical balance
  • I developed time management skills and interpersonal skills on how to relate with coworkers.
  • I was able to apply the principles I learned in class into real life situations carried out in the laboratory.




  • Specification for bottled (Packaged) drinking water SLS 894: 2003
  • Methods of tests for potable water SLS 614: 2013
  • Specification for ice for use in food processing & catering industries SLS 971 : 1992
  • Specification for food grade salt (powdered form) SLS 80
  • Specification for food grade salt (Granular form) SLS 79
  • Specification for Porcelain tableware SLS 1222 : 2001
  • Specification for Toothpaste SLS 275 : 2014
  • Methods of tests for Skin creams and lotions for babies SLS 611 : 1983
  • Specification for White sugar SLS 191:1989
  • Specification for Canned fish SLS 591 : 2014
  • Methods of tests for fertilizers SLS 645
  1. Appendices


Figure: 01