QC TECHNIQUES

A] WEIGHING

1. Check the spirit level before commencement of weighing.

2. Do not tare weights as high as 130 g.

3. Do not record the weight of butter paper before commencement of weighing.

4. Corrosive chemicals like NaOH, to be weighed in a glass apparatus and not on a butter paper .

5. Record balance no. on the calculation sheet.

6. Use a correct size butter paper.

7. Tare the balance to zero at the completion of weighing.

8. Clean the pan and leave the area around the pan in a clean condition.

9. Check the status of desiccant in the balance compartment and change desiccant if necessary .

10. The time of cooling of the dish must be identical for preheating as well as for subsequent drying. The optimum time for cooling is 30 minutes.

11. Ensure that there is no impact to the table on which the balance is placed.

12. Weighing operation must be carried out taking into account the capacity of the balance.

13. Ensure that the top/side doors are firmly closed during weighing operation.

14. Check the calibration status of the balance.

B] PIPETTING

1. Hold the pipette to eye level. Adjust the lower meniscus for colourless solution and upper meniscus for coloured solution.

2. Do not use graduated pipettes of 5 ml, 10 ml. for assay dilutions.

3. Do not force the last drop either by blowing or heating the bulb using palm. Pipette must be allowed to drain by touching the tip to the glassware and holding it for about 15 seconds.

4. Wipe the pipette with a tissue paper prior to adjusting the volume.

5. Keep pipettes on a clean paper on the work bench to avoid contamination of the tips.

6. Clean pipettes regularly with chromic acid.

7. Rinse a pipette before starting the analysis, by draining the complete volume.

8. Avoid usage of cracked pipettes or pipettes broken at the tip.

9. Pipette carefully so as to avoid accidentally pipetting the solution in the bulb.

10. Do not put pipettes into original packs of chemicals.

C] USE OF BURETTES

1. Burettes must be used from zero and not from any other volume.

2. Memo titrator burettes must be rinsed two -three times to avoid formation of air bubbles and to ensure cleaning of burettes.

3. Adjust the burette at eye level.

4. Select burette properly.

5. Check the meniscus before actual titration to ensure starting the titration at 0.0 ml.

6. Ensure that there are no air bubbles in the burette during filling.

D] USE OF VOLUMETRIC FLASKS

1. Volumes to be made by holding the flask to the eye level.

2. Volumetric flasks to be wiped at the neck from inside to avoid the butter paper getting wet.

3. Release pressure, during mixing, after making upto volume with solvents.

4. Do not mix volumetric flasks prior to specking. Mixing must be done at the work bench.

5. The final volume must be made using a clean and dry pipette.

6. Do not merely tumble the flask in order to mix the solution in the volumetric flask. The flask must be shaken vigorously to make effective dilution.

E] SOL VENT EXTRACTION

1. Use safety goggles.

2. Release the pressure intermittently, during extractions, to avoid build up of pressure inside a separator.

3. After releasing the pressure, blow the last drop trapped in the stop-cock, back into the bulk being extracted.

4. At the end of each extraction, swirl the separator to get clean boundaries of the layers.

5. Transfer the layer upto the boundary into another separator / flask.

6. Wet the Sodium sulphate bed in the funnel, with the solvent, prior to filtration.

7. Do not use excessive quantity of Sodium sulphate.

8. At the end of each extraction, remove the stopper and place it properly on the work bench, taking care to avoid contamination.

9. Use very small quantity of silicone grease, during its application to the stop-cock.

F] SAMPLING

1. Observe the bulk being sampled, very carefully for critical defects.

2. Use nose mask, gloves, clean spatula during sampling.

3. Prior to using the sampling booth for sampling, observe the manometer reading, which must be between 8 to 12.

4. Sample as early as possible, to avoid over exposure of the material being sampled.

5. Tie the inner bag promptly, at the completion of sampling.

6. Affix under test labels promptly at the completion of sampling to retain the correct identity of samples.

7. Water sampling for chemical analysis must be done with adequate flushing of water and rinsing of the bottle.

G] GENERAL

1. Correct manner of reporting pH as pH and not as PH or ph, or Ph.

2. Whenever more aliquot is available, discard the filtrate twice during filtration to ensure complete saturation of filter paper .

3. Solvent filtration to be carried out covering the funnel.

4. Check the validation status while using any instrument.

5. Check the status regarding change of desiccants.

6. Correct method of preparing 50% w/v solution is dilution in a volumetric flask.

7. All glassware to bear status label during use.

8. Arresting the progress of solvent front during TLC operation.

9. Solvents to be covered during usage.

10. Concurrent recording and calculation.

11. Proper planning of work.

12. Weighing at a time to save on time taken for complete analysis.

13. Use of WS after following instructions on the bottle is a must.

14. Use of a dryer during TLC spotting must be avoided to ensure that degradation of the spotted material does not take place.

15 Do not crowd the work-bench with unnecessary apparatus. Keep the used apparatus, promptly in the washing trolley.

16. Do not keep pair of tongs in a tip down position on the work-bench.

17. Do not correct figures by scratching and overwriting. Correct the figures with cancellation and initial the cancellation.

18. Do not use thermometer as a glass rod.

19. Check the oven temperature and vacuum, before commencement of the test.

20. Take prompt action on pending reports, by discussing the problem with the section head. Do not keep pending reports, awaiting action, in drawers.