1.0 PURPOSE:
1.1 To lay down a procedure for Operation of Nephlometer.
2.0 SCOPE
2.1 This procedure is applicable for Operation of Nephlometer located in the QC Chemical Lab.
3.0 RESPONSIBILITY
3.1 Microbiologist /Chemist
4.0 ACCOUNTABILITY
4.1 Head-Quality Control
5.0 PROCEDURE
5.1 Preparation of Blank / ‘0’ - Water
5.1.1 Pass purified water through a membrane filter having a precession pore size of less than 10 micron – Whatman filter No 42.
5.1.2 Rinse collecting flask at least twice with that filtered water and discard.
5.1.3 Use this filtered purified water for setting “0” of the instrument.
5.2 Preparation of Stock Solution of Formazine
5.2.1 Preparation of standard solutions FORMAZINE (HYDRAZINE SULFATE &HEXAMINE)
5.2.1.1 Solution I
5.2.1.1.1 Weigh accurately 5.0 g of Hydrazine Sulphate in to a 500 ml volumetric flask and add purified water to make up to the mark. Leave the mixture to stand for 4 hours.
5.2.1.2 Solution II
5.2.1.2.1 Weigh accurately 5.0 g of Hexamethlene tetramine (Hexamine) in to a 500 ml volumetric flask and add purified water to make up to the mark.
5.2.1.2.2 A mixture of equal volumes of solution I and II form Formazine Turbidity concentrate (Stock Solution).
5.2.1.2.3 Allow it to stand in a closed container at 25 to 30° c for 48 hrs. to produce insoluble white turbidity corresponding to 4,000 NTU.
5.2.1.2.4 Store this solution at room temperature as a up to 2 months.
5.3 Preparation of 100 NTU Solution
5.3.1.1 Dilute 25 ml of the Stock solution to 1 liter with blank water to obtain 250 ppm or 100 NTU solution.
5.3.1.2 Once prepared this 100 NTU solution may used 3 days or can be prepared freshly as on when required.
5.4 Operation
5.4.1 Connect the power cord to 230volts A/C power supply and switch on.
5.4.2 Put on the mains Switch, displays “00.0” on the monitor.
5.4.3 Open the sample compartment door.
5.4.4 Fill the Nephlometric cell with purified water as a “Blank” and insert in the compartment in such a way that the marking of the cell coincides the marking of the compartment.
5.4.5 Close the sample compartment door, ”Blank” reading displays on the monitor.
5.4.6 Set the “Blank” reading to zero by using “Set 0” knob.
5.4.7 Remove the cell from the compartment.
5.4.8 Set the “range NTU” button at 100 NTU and take the 100 NTU solution into the cell and insert in the compartment in such a way that the marking of the cell coincides the marking of the compartment.
5.4.9 Close the sample compartment door, “100 NTU” reading displays on the monitor.
5.4.10 Set the “100 NTU” reading to 100 by using the “Set 100” knob.
5.5 Sample measurement
5.5.1 Remove the cell from the compartment and rinse with Blank water.
5.5.2 Measure the sample as per point no 5.4.3 –5.4.5, in place of “Blank” use the sample.
5.5.3 Screen displays the turbidity value.
5.5.4 Record the readings directly.
5.5.5 Enter the usage time in Instrument usage logbook as per XXXXX
5.5.6 Switch off the mains switch followed by power supply of the instrument after completion of analysis.
END OF DOCUMENT
Operating of nephlometer, quality control, completion of analysis
