Tips
An accurate test requires some wise steps.
An accurate test requires some wise steps.
Such as:
WASHING:
1. Wash your test tubes with soft washing materials like LIQUID VIM.
2. During washing make sure that, there is no sign of residual washing materials like the bubbles/foam of LIQUID VIM, in the equipments. After being confirmed the absence of bubbles/foam, wash it with Distilled Water (DW).
1. Wash your test tubes with soft washing materials like LIQUID VIM.
2. During washing make sure that, there is no sign of residual washing materials like the bubbles/foam of LIQUID VIM, in the equipments. After being confirmed the absence of bubbles/foam, wash it with Distilled Water (DW).
DRYING:
3. Completely dry each test tube. Because, as we are dealing with
microgram (μg) of concentration, any residual water even a single drop would change the desired concentration of sample/STD solution.
microgram (μg) of concentration, any residual water even a single drop would change the desired concentration of sample/STD solution.
4. For drying, use hot air oven. In the oven place the equipments to be dried ‘‘invertly”. This will place the opening/mouth of the equipment towards the ground & accordingly the residual debris (if any) would be deposited in the mouth/opening, instead of being in the bottom of that equipment.
5. Never put your hands/figures inside the dried equipments.
MEASURING:
6. Use waxy paper for weighing of the samples, standards, reagents etc.
For an accurate weighing of the solid reagents with normal paper, take 1.2/1.3 mg to weigh 1 mg of solids. Because 0.4/0.3/0.5 mg may adhere to the paper on which you are taking your weights.
For an accurate weighing of the solid reagents with normal paper, take 1.2/1.3 mg to weigh 1 mg of solids. Because 0.4/0.3/0.5 mg may adhere to the paper on which you are taking your weights.
MAKING SOLUTION:
7. Use large test tubes (16×150) for 5 ml of total final volume, & small test tubes (12×100) for 3 ml total volume of final solution. Similarly use beakers of various sizes as per requirement of the volume of the solution to be prepared in it.
8. Always mark all the test tubes with their corresponding concentrations as well as the beakers with their corresponding solutions to be prepared in it.
9. If your sample is re-dispersible, then dry the samples (bone dry) in small amount, and re-disperse them after accurate weighing.
10. After taking out any samples, standards, reagents etc from the refrigerator, keep at least 20 minutes in the room temperature before using. Therefore take out them at least 20 minutes before your need.
TAKING ABSORBANCE:
11. Make sure that the absorbance cell is free from all kinds of contamination including residual debris.
12. Take the absorbance from the solutions with the lowest concentration to the solutions with the highest concentration. (i.e. Gradual increment of the test solution concentrations)
13. After taking each absorbance, before proceeding to the next one with different concentrations, if possible ALWAYS completely discard the residual solutions;
i.e. solutions remaining in the ABSORBANCE CELL.
i.e. solutions remaining in the ABSORBANCE CELL.
14. If you have enough test solutions (e.g. more than 3 ml, which may be
5 ml/6ml/7ml) then, range the ABSORBANCE CELL with small volumes of the test solutions having different concentrations in each turn before taking the absorbance of that solution. This will prevent the cross contamination.
5 ml/6ml/7ml) then, range the ABSORBANCE CELL with small volumes of the test solutions having different concentrations in each turn before taking the absorbance of that solution. This will prevent the cross contamination.
15. If Precipitation (PPT) appears, then CENTRIFUGE the solution and use the supernatant layer for taking the absorbance. You can use micropipettes to withdraw the supernatant layer more conveniently.
16. Generally 2.5 ml (more than 2 ml) of solution in the absorbance cell is enough to take the absorbance.
17. Use new reagents and freshly prepared solvents & solution for each tests.
18. Always use the ‘‘Serial Dilution theory’’ whenever applicable, to make the sample & standard solutions.
pH ADJUSTMENT:
19. If measurements are taken successively in different samples, it is recommended to rinse the electrode thoroughly with de-ionized water or tap water and then with some of the next sample in order to prevent cross-contamination.
20. The pH reading is affected by temperature. In order to measure the pH accurately, the temperature effect must be compensated for. ( For detailed description seeing pH adjustment manual is mandatory)
CENTRIFUGATION:
Centrifuge Safety Guide
Centrifuge Safety Guide
Centrifugation may present two serious hazards:
i. Mechanical failure and
ii. Dispersion of aerosols.
i. Mechanical failure and
ii. Dispersion of aerosols.
Therefore this segment would describe safety and maintenance procedures to minimize centrifuge hazards.
Safe Procedures for Centrifugation:
Before centrifugation
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- Check tubes, bottles, and rotors for cracks and deformities before each use.
- Make sure that the rotor, tubes, and spindle are dry and clean.
- Never overfill centrifuge tubes (don't exceed ¾ full).
- Always cap tubes before centrifugation.
- Always balance buckets, tubes, and rotors properly.
- Check that the rotor is seated on the drive correctly, close the lid on the centrifuge, and secure it.
- When using swinging bucket rotors, make sure that all buckets are hooked correctly and move freely.
During centrifugation
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- Close lids at all times during operation. Never open a centrifuge until the rotor has stopped.
- Do not exceed safe rotor speed.
- The operator should not leave the centrifuge until full operating speed is attained and the machine appears to be running safely without vibration.
- Stop the centrifuge immediately if an unusual condition (noise or vibration) begins and check load balances.
After centrifugation
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- Allow the centrifuge to come to a complete stop before opening.
Emergency Procedures:
Emergency Situations
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The following events are considered an emergency:
• If there is a spill in the centrifuge
• If centrifuge malfunctions
• If there is rotor failure
• If there is tube breakage
Emergency Procedures
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• Turn centrifuge off immediately, close the centrifuge lid.
• Notify others, evacuate the lab,
Overall, things would be clear to you, during your practical session.
Molecular Weights Essentials
| |
Name of the Atom(Symbol)
|
Mean Relative Atomic Mass
|
Hydrogen (H Nitrogen (N) Oxygen (O) Sodium (Na) Phosphorus (P) Sulphur (S) Chlorine(Cl) Potassium (K) Ferrous(Fe) | 1.0079~1 14.0067~14 15.9994~16 22.9897~23 30.9737~31 32.065~32 35.45 39.09983~39.1 55.85 |
In A Nutshell
Name of the reagents
| Molecular Formula | Molecular weight (g/mol) |
Ammonium molybdate
| [NH4]6Mo7O24.4H2O. | 1235.9 |
Trisodium phosphate; TSP | Na3PO4 | 163.94 |
DI-POTASSIUM PHOSPHATE, Potassium Hydrogen Phosphate, Potassium dibasic phosphate, Potassium phosphate dibasic. |
|
|
Potassium acid phosphate | KH2PO4 | 136.09 |
Caustic potash; Potash lye | KOH | 56.11/56.1056 |
2-deoxy-L-erythro-pentose;
|
|
|
Edetate disodium salt dihydrate | C10H14N2Na2O8·2H2O | 372.24 |
Ferric chloride;
|
|
|
Oxydol; perhydrol | H2O2 | 34.01/ 34.01468 |
Vitamin C;
|
|
|
2-Amino-2-(hydroxymethyl)-1,3-propanediol TRIS BASE |
|
|
Potassium Chloride | KCl | 74.55 |
Iron (III) chloride | FeCl3 | 162.204 |
Hydrogen chloride | HCl | 36.46 |
Sodium Hydroxide, Pellets | NaOH | 40 |
5,5′-dithiobis-(2-nitrobenzoic acid) | C14H8N2O8S2 | 396.35 |
Sodium Chloride | NaCl | 58.44 |
Magnesium Chloride, Hexahydrate | MgCl2.6H2O | 203.30 |
Acetylthiocholine iodide |
C7H16INOS (Linear Formula)
CH3COSCH2CH2N(CH3)3I | 289.18/289.17751 |
S-Butyrylthiocholine iodide | 317.23/ 317.23067 |
Physical properties of Hydrochloric acid
kg HCl/kg
|
kg HCl/m3
|
Baumé
|
kg/L
|
mol/dm3
|
mPa·s
|
kJ/(kg·K)
|
kPa
|
°C
|
°C
| |
10%
|
104.80
|
6.6
|
1.048
|
2.87
|
−0.5
|
1.16
|
3.47
|
1.95
|
103
|
−18
|
20%
|
219.60
|
13
|
1.098
|
6.02
|
−0.8
|
1.37
|
2.99
|
1.40
|
108
|
−59
|
30%
|
344.70
|
19
|
1.149
|
9.45
|
−1.0
|
1.70
|
2.60
|
2.13
|
90
|
−52
|
32%
|
370.88
|
20
|
1.159
|
10.17
|
−1.0
|
1.80
|
2.55
|
3.73
|
84
|
−43
|
34%
|
397.46
|
21
|
1.169
|
10.90
|
−1.0
|
1.90
|
2.50
|
7.24
|
71
|
−36
|
36%
|
424.44
|
22
|
1.179
|
11.64
|
−1.1
|
1.99
|
2.46
|
14.5
|
61
|
−30
|
38%
|
451.82
|
23
|
1.189
|
12.39
|
−1.1
|
2.10
|
2.43
|
28.3
|
48
|
−26
|
The reference temperature and pressure for the above table are 20 °C and 1 atmosphere (101.325 kPa). Vapour pressure values are taken from the International Critical Tables, and refer to the total vapour pressure of the solution.
N.B.The Baumé scale is a pair of hydrometer scales developed by French pharmacist Antoine Baumé in 1768 to measure density of various liquids.
The Test Reagents
Name of the Reagents (Formulae)
|
Name of the Reagents (Formulae)
|
Folin-Ciocalteu Reagent: FCR
|
Phosphate Buffer (K2HPO4+KH2PO4) pH 6.6
|
Sodium Carbonate (Na2CO3)
|
Potassium Ferricyanide :K3Fe(CN)6
|
Aluminium Chloride (AlCl3)
|
Trichloro Acetic Acid (TCA)
|
Sodium Nitrate (NaNO2)
|
Ferric Chloride (FeCl3)
|
Soium Hydroxide (NaOH)
|
2-Deoxy -D- ribose, (C5H10O4)
|
DPPH
|
KH2PO4-KOH Buffer :pH 7.4
|
Sulfuric Acid (H2SO4)
|
EDTA
|
Sodium Phosphate (Na3PO4)
|
Gallic Acid & Catechin (Standard)
|
Ammonium Molybdate
|
Hydrogen Peroxide (H2O2)
|
Thio-Barbituric Acid (TBA)
|
Ascorbic Acid,(C6H8O6)
|
Vanillin
|
The Test apparatuses
02. UV machine
03. pH meter
04. Vortex Machine
05. Water Bath
06. Centrifuge Machine
07. Electrical Balance
{3 Digits after the point (0.000g); 4 Digits after the point (0.0000g)}
08. Hot Air Oven
09. Measuring cylinder (25 ml, 100 ml, 500 ml)
10. Beaker (10 ml, 50 ml,100 ml, 250 ml, 500 ml,1000 ml)
11. Test tubes (12×100, 16×150, 16×125)
12. Falcon tubes (15 ml, 50 ml)
13. Eppendrop Tubes
14. Glass rod
15. Spatula
16. Pipettes (1 ml,2 ml,10 ml)
17. Micropipettes (10-100 μl,100-1000 μl)
18. Tips
19. Reagent Bottles
20. Glass Vials
21. Test tube Stands etc.
For Pdf File:https://www.facebook.com/download/644807085660434/tips%20for%20thesis%20students.pdf
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