Standard for food grade salt - Nigerian Industrial Standard 168 of 2004

Microsoft Word - NIS 168 2004.DOC NIGERIAN INDUSTRIAL STANDARD NIS 168: 2004 Standard for Food Grade Salt ICS 67.200.20 Price Group B © SON 2004 Approved By: SON Governing Council STANDARDS ORGANISATION OF NIGERIA Operational Headquarters Corporate Headquarters Plot 13/14 Victoria Arobieke Street, Plot 1687, Lome Street, Off Admiralty Way, Wuse Zone 7, Lekki Peninsula Scheme 1, Abuja, Nigeria. Lekki, Lagos, Nigeria. NO COPYING WITHOUT SON PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW uos Jc10J ~ ~ J'¥ ffl(Y~r11l (I) 2 TECHNICAL COMMITTEE ON FOOD GRADE SALT S/No. Name Organisation Represented 01 Dr. (Mrs.) K. Olayinka (Chairperson) Chemistry Department, University of Lagos. 02 Engr. O. A. Mabogunje Consumer Protection Agency, Lagos 03 Mr. S. A. Durojaiye Consumer Protection Agency, Lagos 04 Dr. O. A. Fakankun Nestle Nigeria Plc. 05 Dr. Y. A. Soile Cadbury Nigeria Plc. 06 Mrs. F. M. Akinkunmi Consolidated Food & Beverages Ltd. 07 Mr. I. A. Bakare Dangote Industries (Salt Plant) 08 Mr Usman Rabiu Royal Salt Industry Ltd. 09 Mr.A. A. Adebayo Institute of Public Analyst of Nigeria 10 Mrs. D. O. Afuanyo National Agency for Food, Drug Administration and Control 11 Mrs. I. E. Olajide National Agency for Food, Drug Administration and Control 12 Mr. S. A. Unobagha Standards Organisation of Nigeria 13 Mr. P. A Nwajagu Standards Organisation of Nigeria 14 Mrs. M. E. Eshiett Standards Organisation of Nigeria 15 Mrs. G. O. Owoyele (Tech. Secretary) Standards Organisation of Nigeria Type text here 3 Foreword The first edition of the Standard for Food Grade Salt was published in 1983. The Standard was revised in 1992 to incorporate iodine fortification inline with World Health Organisation (WHO) summit of 1990 goal of eliminating Iodine Deficiency Disorder (IDD) as a public health problem by year 2000. The Standard for Food Grade Salt, NIS 168: 2004 incorporates current developments in the manufacture, packaging and sale of Food Grade Salt. Towards certifying Nigeria as Universal Salt Iodization (USI) compliant, the International Council for Control of Iodine Defiency Disorder (ICCIDD) recommended method for the determination of iodine in iodated salt has now been incorporated into the revised Standard. In elaborating this Standard, references were made to International and National Standards for Food Grade Salt, ICCIDD test methods, AOAC Official methods of analysis and data collected from local manufacturers 4 1. Scope The standard prescribes the quality requirements and test methods for food grade salt. The standard applies to salt chemically known as sodium chloride crystals for food, both for direct consumption and for food manufacturing. It also applies to such food grade salt used as a carrier of food additives and/or nutrients for human consumption. 2. Normative References (i) Codex Alimentarius Commission Standard for food grade salt. (ii) AOAC Official Methods of Analysis 2000. (iii) Iodine Determination – Demeyer, Lowenstein & Thily (1979) – International Council for Control of Iodine Deficiency Disorders ICCIDD – Universal Salt Iodization Publication, 1995. (iv) Indian Standard – IS 253: 1985 (v) NIS 168: 1992 – Standard for Food Grade Salt. 3. Terminology For the purpose of this standard, food grade salt is predominantly sodium chloride crystals, a natural food product which can be obtained in any of the following: 3.1 By direct extraction of rock salt from mines and quarries. 3.2 By deliberate production of salt from evaporation of natural brine. 3.3 By collection of sea salt from salt marshes and salt lakes. 3.4 By dissolving rock salt and evaporation after filtration. 3.5 Food Grade Salt is classified thus, depending on itspurpose for use: 3.5.1 Table Salt This is of fine particle size and for direct use in served food. 3.5.2 Butter Salt This is of very fine particle size use in butter, margarine and bakery Industry. 3.5.3 Cooking or Kitchen Salt This is of coarse particle size. NOTE 1 Salt obtained by any of the above methods shall be further purified to meet the specification provided by this standard. NOTE 2 Salt obtained by any other method, notably as a by - or co- product of chemical and fertiliser industries is not covered by this standard. 5 4. Essential Composition and Quality Factors The composition of food grade salt shall be determined on dry matter basis. 4.1 Food grade salt shall be of white crystalline sodium chloride coated suitably with free-flowing and anti-caking agents (see section 5 and 5.1) 4.2 In addition, food grade salt shall comply with the following requirements. 4.3 Iodine Fortification Food grade salt shall be fortified with iodine using potassium iodate. The level of fortification shall be as follows: As Iodine mg/kg - At the factory/Port of entry 50 - At retail sale 30 *For method of analysis see section 7.4 Table 1: Essential Compostion CHARACTERISTICS REQUIREMENTS METHOD OF TEST REF. TO SECTIONS Sodium Chloride expressed as NaCl (%) (min) 98.6 7.2 & 7.9 Moisture content (%) (max) 1.0 7.5 Calcium content expressed as Ca (g/kg) (max) 3.0 7.7.2 Magnesium content expressed as Mg. (g/kg)(max) 3.0 7.7.3 Water insoluble matter percentage by weight (max) 0.01 7.6 Sulphate content (g/kg) (max) 5.0 7.3 Residual (comprising of only natural secondary products such as calcium, potassium and sodium sulphates, carbonates bromides and chlorides) Traces 6 4.4 Organic and other Biological Contaminants Food grade salt shall not contain any yeast, moulds, bacteria and/or any organic materials. 4.5 Chemical Contaminants The salt shall not contain contaminants in amounts, which may be harmful to health. The maximum limits allowable for trace elements as contaminants in food grade salt shall be as follows: Table II: Chemical Contaminats ELEMENTS LIMITS mg/kg (max) Arsenic (As) 0.5 Copper (Cu) 2.0 Iron (Fe) 30.0 Lead (Pb) 0.1 Mercury (Hg) 0.1 Cadmium (Cd) 0.1 4.6 Particle Size Not less than 99% of the salt shall pass through the following sieve sizes: Types of salt Particle Size 99% (min) Through Sieve Sizes (micron sieve) Table/Butter salt 300 Kitchen/Cooking salt 850-1200 5. Additives All additives used shall be of food grade quality. The following is the list of permitted additives. 7 Table III: Permitted Free Flowing Agent ADDITIVES QUANTITIES (mg/kg) (max) Singly or in Combination Silicic Acid Calcium carbonate Tricalcium orthophosphate Calcium Silicate Magnesium silicate Calcium stearate Magnesium stearate } } } } 10 } } } Table IV: Permitted Anti Caking Agent ADDITIVES QUANTITIES (mg/kg) (max) Singly or in Combination Sodium Ferro-Cyanide Potassium Ferro-Cyanide Calcium Ferro-Cyanide 10 6. Packaging, Labelling and Storage 6.1 Packaging 6.1.1 Bulk Salt The salt shall be packed in food grade polypropylene bag or suitable material with food grade polyethene inner lining that must not allow the salt to deteriorate or be contaminated. 6.1.2 Small Units Packaging (1kg, 500g, and 250g) The salt shall be packed in food grade high density polyethene packs/pouches that must not allow the salt to deteriorate or be contaminated. 6.2 Labelling In addition to pre-packaged food labelling regulation by NAFDAC, the package shall be securely closed and marked with the following 6.2.1 Manufacturer's name and full locational address of company. 6.2.2 Weight of salt in the package. 8 6.2.3 Recognised trade mark, if any. 6.2.4 The designation shall include on the label, a declaration of either, "Food Grade Salt", "Table salt" or “Kitchen/Cooking Salt”. 6.2.5 Where salt is used as carrier of one or more nutrients, and sold as such for public health reasons, the name of the fortificant shall be declared, for example “Iodized Salt”, when salt is fortified with iodine or its compound. 6.2.6 Batch number, date of manufacture and Best Before Date (Two years from date of manufacture). 6.2.7 Nigerian Industrial Standard (NIS) Certification Mark if the manufacturer is a licensee. 6.3 Storage and Transport 6.3.1 To minimise avoidable losses of iodine during transit, transport or sale, Food Grade Salt shall not be exposed to the following conditions: (i) Strong light or sunlight (ii) Strong heat or high humidity/moisture (iii) Inclement weather, various forms of contamination - Dust and Chemicals. (iv) Bad storage conditions - lack of aeration. 7. Methods of Analysis 7.1 Preparation of Salt Sample Solution Weigh about 50g of salt sample and grind in porcelain mortar. Weigh out 20g of the ground sample and dry in an oven at 140 o C for at least four hours. Cool to constant temperature. Weigh accurately 10g of dried salt sample. Dissolve in 100mL distilled water or deionised water. Heat to boiling and cool. Filter by suction filteration through an accurately weighed sintered glass crucible, which has been dried at 110 o C for a minimum of 2 hours and cooled to room temperature. Wash the residue till it is free from soluble salts. Collect the filterate and washing and make up to the mark in 500mL standard flask. 9 7.2 Chloride Determination 7.2.1 Reagents preparation Ferric Ammonium Sulphate 5% Iron (III) Indicator Dissolve 5g of Ferric Ammonium Sulphates into 100mL of distilled water. Store in a clean reagent bottle and label. 0.1M Ammonium Thiocyanate Weigh 7.613g Analar Ammonium Thiocyanate transfer into 1 litre volumetric flask and dissolve with distilled water. Make up solution to mark in the 1 litre flask. 6M Nitric Acid (HNO3) Measure carefully 375mL concentrated Nitric acid and slowly with stirring add to 625mL distilled water. Store in a reagent bottle and label. Nitrobenzene (Analar Grade) 0.1M Silver Nitrate (AgNO3) Dry some Analar (re-crystallized) silver nitrate at 120 o C for two hours and allow to cool in a dessicator. Weigh out accurately 17.0g and dissolve in distilled water. Make up solution to 1 litre. 0.1M Sodium Chloride solution Weigh about 10g sodium chloride (Analar) in a watch glass. Heat in an air oven at 100 – 110 o C for about an hour. Cool in a dessicator. Weigh out 1.5g of the dried sodium chloride into 250mL volumetric flask. Add water to dissolve and finally make up to the mark with distilled. Potassium Chromate (5%) (Indicator) Standardisation of silver nitrate solution Pipette 10mL of standard sodium chloride solution into a flask. Add a few drops of potassium chromate indicator and about 50mL distilled water. Titrate solution against silver nitrate solution. Stir continuously, until appearance of reddish brown colouration. 10 Calculation V1 x M1 = V2 x M2 Where V1 = volume of AgN03 M1 = Molarity of AgN03 V2 = Volume of NaCl M2 = Molarity of Sodium Chloride Molarity of AgN03 M1 = V2 x M2 V1 7.2.2 Procedure 1 Measure 25mL of the sample solution into 250mL conical flask. Add 50mL 6M Nitric Acid, and then add 30ml standard 0.1M Silver nitrate. Shake, or boil the suspension for few minutes to coagulate the precipitate. Filter either through a quantitative filter paper, porous porcelain or sintered glass crucible. Wash thoroughly, with very dilute nitric acid (1:100). Add 1mL ferric ammonium sulphate (indicator) solution to the combined filtrate and washings in the conical flask, and titrate the residual silver nitrate with standard 0.1M ammonium thiocyanate solution to a definite colour change. Titrate to obtain a minimum of three titres with a maximum range of 0.10mL. Calculate the mean titre (V2) 7.2.3 Procedure 11 Measure 25mL of the sample solution into a 250mL conical flask. Add 5mL Nitric acid then add 30mL 0.lM silver nitrate. Add 5mL Nitrobenzene shake vigorously and filter. Add 1mL ferric ammonium sulphate (indicator) to the filtrate and washings in the conical flask, and titrate against ammonium thiocyanate solution calculation. Calculation % Chloride = (30.0 x 0.1) – M2 V2 x 14.188 M1 = Molarity of AgN03 V1 = Volume of AgN03 M2 = Molarity of thiocyanate V2 = Volume of thiocyanate 7.2.4 Procedure III Measure 5mL of the sample solution into 100mL conical flask. Dilute to 50mL with distilled water. Add 1mL of potassium chromate indicator (the solution turns yellow) Titrate the solution against 0.1M silver nitrate until the colour changes from yellow to reddish brown. Note the volume of 11 silver nitrate (AgN03) required to react with the chloride present in the salt sample solution to form silver chloride Calculation 1mL 0.1M AgN03 correspond to 0.03546g Cl (chloride). 7.3 Sulphate Determination 7.3.1 Method 1 7.3.1.1 Reagent Preparation Methyl orange indicator Dissolve 0.1g methyl orange in 100mL distilled water Hydrochloric Acid (HCI) 1:4 Measure 10mL concentrated hydrochloric acid. Dilute it with 40mL distilled water (add acid slowly to water) Barium chloride solution (10% solution) Weigh 10g barium chloride and dissolve in distilled water and make up to 100mL with distilled water. 7.3.1.2 Procedure Measure 50mL of the sample solution into 250mL beaker. Dilute to about 150mL with distilled water. Add a drop of methyl orange and a few drop of the dilute hydrochloric acid till colour change to pink (i.e make solution acidic) then boil. Add to the boiling solution 5 to 10mL barium chloride solution dropwise with constant stirring. Continue boiling for 5 minutes to get granular precipitate. Leave to stand for a few hours. Filter through previously weighed sintered glass crucible (suction filtration). Wash the precipitate with hot water till it is free from chloride. Dry the crucible with the precipitate in an oven. Cool in a dessicator weigh to constant weight. Calculation % Sulphates = M2 x 10 x 96 x100 233.4 x M1 Where M2 = Mass of SO4 in 50mL of solution. M1 = Mass of sample taken. (96g of SO4 is present in 233.4g BaSO4) 12 7.3.2 Method II 7.3.2.1 Reagent Preparation Preparation of 0.1M Zinc Standard Solution Accurately weigh 6.58g of washed Analar granulated zinc accurately into a litre volumetric flask. Add 20mL of Analar Conc hydrochloric acid. Ensure that the zinc dissolves completely. Add 400mL distilled water and a small strip of universal indicator paper. Use 10% sodium hydroxide (Analar) solution to adjust the pH to 3. Make up to mark. Pour into a reagent bottle, appropriately labelled. Preparation of 0.1M EDTA Solution Weigh 37.3g of EDTA and transfer into a litre volumetric flask with distilled water. Make up to mark with distilled water and mix thoroughly. Measure 25.0mL of this solution into a 250mL conical flask. Add distilled water, 10mL ammonia buffer (pH 10) and few drops of eriochrome BLACK T indicator. Titrate with standard zinc solution to a wine end point. Obtain three titre values in the range of 0.10mL. Calculate mean titre (V). Calculate the concentration of the EDTA solution. M = 0.1 x V 25 M should be slightly greater than 0.1M. Estimate the amount of water to add to the remaining EDTA solution to make its concentration exactly 0.1M. Add this quantity of water and mix well. Repeat titration to obtain the adjusted concentration of the EDTA solution. If the concentration is still greater than 0.1M, add more water (estimated) and titrate. Repeat this operation until the EDTA solution is exactly 0.1M. Preparation of 0.1M Barium Solution Dissolve 24.43g Barium Chloride in water in a litre volumetric flask and make up to mark. Measure 25.0mL of this solution into a conical flask then add 50mL distilled water, 10mL ammonia buffer and few drop of eriochrome black T indicator. Titrate to 0.1M following a procedure similar to that described for EDTA above Preparation of Barium - EDTA Solution Using a pipette, carefully measure 50.0mL, 0.1M EDTA solution into a litre standard flask. Similarly measure 50.0mL, 0.1M Barium solution into the same flask. Make up to mark with distilled water and shake 13 vigorously to mix. (Check that 1 or 2 drops of EDTA solution changes the colour of 25.0mL of this solution to blue at pH to using eriochrome black T indicator and that 1 or 2 drops of Barium Solution similarly changes the colour to wine). Sample Titration Use a pipette to measure 50.0mL of sample solution into a 250mL conical flask. Add 2 drops of 1:3 hydrochloric acid solution in water. Add 10mL of Ba - EDTA solution drop by drop shaking the conical flask vigorously. Boil for 10 minutes and cool for 5 minutes. This process precipitates BaS04 and liberates EDTA from Ba - EDTA. The EDTA liberated combines with any Ca and Mg in the sample. Three cases are possible. (i) Liberated EDTA is in excess of total Ca and Mg in sample (ii) Liberated EDTA is equivalent to Ca and Mg in sample and (iii) Liberated EDTA is less than Ca + Mg in sample To the cool solution add 20mL methyl alcohol. Mix and set aside for 5 minutes. Add Mg - EDTA solution (10mL), 10mL ammonia buffer, 1mL hydroxyylamine hydrochloride and eriochrome black T indicator. Case (i): Indicator colour is blue. Titrate with standard 0.01M zinc solution to wine end-points obtain mean titre Vx Case (ii) Indicator is blue-wine; Vx – O Case (iii) Indicator is wine. Titrate with standard 0.01M EDTA to blue end point, and obtain mean titre VCs. Calculate sulphate in sample as follows: Case (i) Vso4 = VC (Ca + Mg) + Vx Case (ii) Vso4 = VC (Ca + Mg) Case (iii) Vso4 = VC (Ca + Mg) - Vx % SO4 = Vso4 X 0.192 7.4 Iodine Determination 7.4.1 Iodometric Titration of Iodate. This test method shall be used to determine the iodine content of edible salt sample fortified with potassium Iodate (KIO3) only 14 7.4.1.1 Reagents preparation 10% Potassium Iodide (KI) Weigh 100g Potassium iodide, dissolve in distilled water and make it to 1L. Keep in a cool and dark place. This volume is sufficient for 200 samples. The solution is stable for six months if properly stored. 1.0M Sulphuric Acid (H2SO4) (2.0N Sulphuric Acid) Add slowly 6mL concentrated Sulphuric Acid to 90mL distilled water (stir solution while adding acid). Make to 100mL with distilled water. The solution is stable indefinitely. 0.005M Sodium thiosulphate (Na2S2O3) Weigh 1.24g sodium thiosulphate (Na2S2O3. 5H20). Dissolve in 1000mL distilled water. Keep in a cool and dark place. This volume is sufficient for 100 – 200 samples depending on iodine content of sample. The solution is stable for at least 1 month if properly stored. Starch Indicator Solution Make 100mL of a saturated NaCl solution, by adding NaCl to approximately 80mL distilled water in a beaker, with stirring and/or heating, until no further solid will dissolve. This solution is stable for at least one year. Weigh 1g soluble starch into a 100mL beaker; add 10mL distilled water, heat to dissolve. Add saturated NaCl solution to the hot starch solution to make up to 100mL Store in a cool, dark place. This volume is sufficient for 50 samples. The solution is stable for up to one month, and should be heated (not boiled) each day it is used to re- suspend any solids. 7.4.2.1 Analytical Steps Dissolve 10g of salt sample with 30mL distilled water in a 250mL volumetric flask with a stopper. Make up the salt solution to 50mL with distilled water. Add 1mL 1.0M H2SO4. Add 5mL 10% KI. Colour change to yellow is an indication of presence of iodine. Caution – Do not pipette reagent by mouth Stopper the flask and put in a dark place (cupboard or drawer) for 10 minutes Rinse and fill burette with 0.005M Sodium thiosulphate (Na2S2O3). Adjust –the fill level to zero and note the initial reading. Bring out the flask (with the salt solution) from the dark place. Add 0.005M sodium thiosulphate to the flask, until solution turns pale yellow. Add 15 approximately 2mL of starch indicator solution (observe colour change to dark purple) and proceed with titration until solution turns pink, and finally colourless. Record the final burette reading at the end point of titration to know the volume of thiosulphate used. Convert the volume of thiosulphate used in millilitre (mL) to parts per million (ppm) using the conversion table (Appendix 1) NOTE 3 Analyses time is approximately 20 minutes per sample. NOTE 4 Precaution to be taken for salt Iodine Analysis (i) The analysis should be done at cool room temperature (<30 0 c) since iodine is volatile and sensitivity of the starch indicator diminishes when exposed to high temperatures. (ii) Inaccurate result may occur if starch solution is used while still warm. (iii) Starch solution indicator should be added near 2 nd point of titration when very little iodine is left and solution has a faint yellow colour. If starch solution is added early, strong iodine-starch complex is formed, which reacts slowly, and gives falsely elevated result. (iv) The reaction mixture should be kept in a dark place prior to titration. When solution is exposed to light, the iodine ions are oxidized to iodine. 7.5 Moisture Content Determination 7.5.1 Method I Place about 10g test sample in dry, weighed 200mL Erlenmeyer flask. Weigh flask and test portion. Spread test portion evenly over bottom of flask by shaking gently and insert small funnel in neck. Heat flask and test portion for periods of 0ne hour each at about 250 o C until 2 consecutive weighings agree within 5mg. occasionally shake flask. (Cool in a desiccator before weighing test portion will dry evenly). Report loss of weight as water. Calculation % Moisture content = M1-M2 M1 Where X 100 16 M1 = initial weigh of sample taken before drying M2 = final weigh of sample after drying to constant weigh. 7.5.2 Method II Dry a clean wide dish at 110°C for 2 hours. Cool to room temperature and weigh (W1) accurately to 0.1mg. Grind about 50g of the salt sample quickly in a porcelain mortar and weigh (W2) about 10g of it accurately (to 0.1mg) into the dish. Dry the salt in the dish at 110°C for 2 hours. Cool in the desicator to room temperature and weigh (W3) accurately to 0.1mg. Calculate the moisture content. % Moisture = (W2 – W3) x 100 (W2 - W1) 7.6 Matter Insoluble in Water – Determination 7.6.1 Preparation of Test Samples If salt sample is coarse, grind in porcelain mortar. 7.6.2 Procedure Place 10g test sample in 250mL beaker, add 200mL distilled water at room temperature, and allow to stand for 30 minutes, stirring frequently. Filter through weighed Gooch crucible with glass fiber filter mat dried at 110 o C. Transfer residue to Gooch crucible with aid of policeman using total of ≤ 50mL distilled water. Wash residue with about 10mL portions of water until, filterate shows only faint opalescence upon addition of few drops AgN03 solution. Dry crucible and contents to constant weight at 110 o C. Report increase in weight of Gooch crucible as “matter insoluble in water” and report results in percent on water free basis. If matter insoluble in water is > 0.1%, determine their nature. Calculation % Insoluble = W2 – W1 W Where W1 = weight of empty dried sintered glass crucible W2 = weight of sintered glass crucible with the insoluble W = weight of the salt sample taken for test. X 100 17 7.7 Determination of Calcium Solution and Magnesium 7.7.1 Preparation of Sample and Reagents Preparation of Sample Solution Weigh out accurately 10.0g of the sample salt into a 300mL beaker and add about 100mL of distilled or de ionised water to dissolve it. If the sample solution is cloudy or has visible insoluble matter, filter the solution through a filter paper and wash the residue several times with about 5.0mL of distilled or de-ionised water until the wash water tests chloride - free. Transfer the filtrate and the wash water to a 500mL standard flask, dilute to mark with distilled or deionised water. Prepare two different sample solutions from the salt sample. For the determination of such component, take out the sample solution separately from each solution and analyse to obtain two measured values. Standard Solution of 0.01M Zinc Place 10g of A.R. zinc metal in a 250mL beaker and add 20mL distilled water and then add hydrochloric acid in drops until gentle effervescence is observed. Stop adding HCl. Allow the effervescence to go on for 2 or 3 minutes. Decant off the liquid and rinse the zinc metal with distilled water several times. Dry the metal between filter paper. Leave to dry under laboratory ambient condition. Store in a clean bottle labelled washed zinc. Weigh 0.6538g of the washed zinc accurately into a 100mL beaker. Add about 10.0mL conc. hydrochloric acid to dissolve the zinc. Evaporate the solution to about 5.0mL. Quantitatively transfer this solution to a 1L standard flask and dilute to mark with either distilled or de ionised water. This solution is 0.01M with respect to zinc. Use this as standard zinc solution. Erio Chrome Black T Indicator (ECBT) Dissolve 0.5g of ECBT and 4.5g hydroxylamine hydrochloride in 100mL of ethanol, and store in a clean brown bottle. Ammonia Buffer Solution (pH 10) Dissolve 70.0g of ammonium chloride in 570mL of ammonium hydroxide solution and about 200mL of distilled or deionised water and dilute to 1L in a standard flask. 18 Standard Solution of EDTA (M/100) Dissolve 3.723g of sodium salt of EDTA in 1L of distilled water and store in polythene bottle. Standardise this solution as follows: Pipette 10.0mL of the standard zinc solution into a 250mL of pH 10 buffer solution and three to four drops of eriochrome Black T solution with standard EDTA solution. The end point is marked when clear blue solution is obtained. Titrate to obtain a minimum of three titres with a maximum range of 0.10mL. Calculate the mean titre (V) EDTA. Calculate the molarity of EDTA as follows: M (EDTA) = 0.1 x 10.0 (V) EDTA Calcon Indicator Grind together 0.50g calcon and about 50.0g anhydrous sodium sulphate. Transfer the homogenous mixture into a tightly closed brown bottle and store in a dessicator. 5% Hydroxylamine – Hydrochloride Dissolve 5.0g of hydroxylamine - hydrochloride in distilled water and dilute to 100mL store solution in a brown reagent bottle. 4% Sodium Hydroxide Solution Dissolve 4.0gm of sodium hydroxide in distilled water and dilute to 100mL. 7.7.2 Procedure for EHE Determination of Calcium Measure 50.0mL of the sample solution into a 250mL conical flask using a pipette. Add 10.0mL of 4% sodium hydroxide. Mix thoroughly. Add 110mL 5% hydroxylamine - hydrochloride and 0.10g of indicator, shake well. Titrate with standard EDTA solution until a colour change from red to clear blue is observed. Titrate to obtain a minimum of three titres. Calculate the mean titre = VCa: and the Calcium content of the sample as follows: % Ca = 4.008 x (VCa x M EDTA) 7.7.3 Procedure for the Determination of Magnesium Pipette 50.0mL of the sample solution into a 250mL conical flask; then add 5.0mL of the buffer solution, to adjust solution to pH10. 19 Thereafter add 1.0mL of 5% hydroxylamine - hydrochloride 1.0mL triethanolamine (1:10), 2.0mL Mg-EDTA solution and three to four drops of erio chrome Black T indicator. Shake well. Titrate the solution with the standard EDTA solution until a clear blue colour is obtained. Titrate to obtain a minimum of three times. Calculate the mean titre VMg. The magnesium content is calculated as follows: % Mg = 2.432 x M EDTA x VMg. 7.8 Determination of Potassium 7.8.1 Potassium Standards Dry analar KCl at 110 o C for 2 hours. Cool to room temperature. Accurately weigh 19.07g of the dried salt and transfer quantitatively with distilled water into a standard flask. Shake gently to dissolve. Make up to mark with distilled water. Store in a reagent bottle labelled 1000ppm potassium. Using this solution, prepare 100ppm potassium solution (10.0mL) diluted to 100mL in standard flask). From the 100ppm solution measure 5,10,15,20 each with a pipette into separate 100mL standard flask. Dilute to mark severally and mix to obtain 5ppm, 10ppm, 15ppm and 20ppm working standards. 7.8.2 Potassium By Flame Photometry Set up the flame photometer as per manufacturer's operating instruction. Use the 0 - 20ppm standards to produce a potassium calibration graph (emission versus concentration). Measure the slope (s) of the calibration graph. Read the emission of the sample solution (10g/L) on the instrument and calculate percent K in sample as shown below: % Potassium = E 100S 7.8.3 Calculation of % NaCl in Sample (i) Calculate correction factor (F) F= (2.92 x %Ca) + (4.81 x %Mg) - (1.22 x S04) (ii) If F is positive then % NaCl = 91.6485 x %Cl) - (1.49 x %X) - F (iii) If F is negative or zero then %NaCl = (1.6485 x %Cl) - (.149 x %K) (%NaCl obtained in (ii) and (iii) is on wet weight basis) (iv) Calculate % NaCl on dry basis as follows: - 20 %NaCl = %NaCl (wet basis) 100 - % moisture Appendix 1 CONVERSION TABLE: IODINE CONTENT IN PARTS PER MILLION (Titration Methods for Salt Iodine Analysis) Burette Reading Parts Per Million (ppm) Burette Reading Parts Per Million (ppm) Burette Reading Parts Per Million (ppm) Burette Reading Parts Per Million (ppm) 0.0 0.0 2.5 26.5 5.0 52.9 7.5 79.4 0.1 1.1 2.6 27.5 5.1 54.0 7.6 80.4 0.2 2.1 2.7 28.6 5.2 55.5 7.7 81.5 0.3 3.2 2.8 29.6 5.3 56.1 7.8 82.5 0.4 4.2 2.9 30.7 5.4 57.1 7.9 83.6 0.5 5.3 3.0 31.7 5.5 58.2 8.0 84.6 0.6 6.3 3.1 32.8 5.6 59.2 8.1 85.7 0.7 7.4 3.2 33.9 5.7 60.3 8.2 86.8 0.8 8.5 3.3 34.9 5.8 61.4 8.3 87.8 0.9 9.5 3.4 36.0 5.9 62.4 8.4 88.9 1.0 10.6 3.5 37.0 6.0 63.5 8.5 89.9 1.1 11.6 3.6 38.1 6.1 64.5 8.6 91.0 1.2 12.7 3.7 39.1 6.2 65.6 8.7 92.0 1.3 13.8 3.8 40.2 6.3 66.7 8.8 93.1 1.4 14.8 3.9 41.3 6.4 67.7 8.9 94.2 1.5 15.9 4.0 42.3 6.5 68.8 9.0 95.2 1.6 16.9 4.1 43.4 6.6 69.8 9.1 96.3 1.7 18.0 4.2 44.4 6.7 70.9 9.2 97.3 1.8 19.0 4.3 45.5 6.8 71.9 9.3 98.4 1.9 20.1 4.4 46.6 6.9 73.0 9.4 99.5 2.0 21.2 4.5 47.6 7.0 74.1 9.5 100.5 2.1 22.2 4.6 48.7 7.1 75.1 9.6 101.6 2.2 23.3 4.7 49.7 7.2 76.2 9.7 102.6 2.3 24.3 4.8 50.8 7.3 77.2 9.8 103.7 2.4 25.4 4.9 51.9 7.4 78.3 9.9 104.7