preparation of distilled water

7/28/2019 Preparation of Distilled Water

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PREPARATION OF DISTILLED

WATER


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Water distillation is the oldest system of water filtration and

purification known to be used by man.

Yet, with all the new technology, distillation remains the most

effective in removing organic, chemical, and metal water

contaminants.

Water is some times referred to as natures universal solvent and

being such we must remember that soluble salts many times

cannot be removed by simple filtration or chemical means.

Distillation is the process by which chemical substances are

separated by the differences in their volatilities in a boiling

mixture.

The liquid reaches its boiling point and than begins to evaporate

and is directed through a cooling condenser in which it

condenses back in to the liquid having left virtually all impurities

behind.

Distillation provides you with the purest water known to mankind.


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Water Distillation


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Distillation will remove from water almost anything, even heavy metals, poisons, bacteria

and viruses.

However, it does not remove substances that have boiling points at a lower temperature

than water.

Some of these substances are oils, petroleum, alcohol and similar substances, which in

most cases don't mix with water.

Also, remember that substances removed from water remain in the boiler, so you'll need

to clean it up every once in awhile.


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The Distillation Process

Distillers use heat to boil water into steam which is condensed backinto water and collected in a purer form.

When water boils, it leaves impurities behind in the boiling chamber.

The rising steam passes into a cooling section and condenses backinto a liquid.

The condensed liquid (water) then flows into a storage container .

Distillers remove almost all of the impurities from water supplies.

In fact, distillation is the only means of removing some contaminants.

Water used in laboratory applications that require a purity level above99.97% use steam distillation.


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RECEPTION AND RECORDING OF SAMPLES


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RECEPTION

Specimens are normally transported to the laboratory in a rack or in individual

plastic bags accompanied by a request form. On arrival in the laboratory the

following steps must be taken.


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1. Specimen registration

This can be undertaken by a technician, laboratory assistant orclerk.

Remove the sample from the rack or from the bag.

Check that the tube is firmly stoppered and check for any leakage of the specimen.

Read the patient's full name from the request form and check that the sample is labelled

with the same name.

If the sample is unlabelled or has a different name to that on the request form, treat as a

rejected specimen.

If the labelling is satisfactory, record the details in the day-register and assign a unique

laboratory number; this number must be recorded in the register, on the specimen tube

and on the request form.

From the request form ascertain what tests are required. Record requests for any tests

other than a blood count in a special register.

Recheck that the sample is correctly labelled with the patient's name, that the laboratory

number has been correctly assigned, and that the specimen tube and request form bear

the same number. If possible this step should be carried out by a second person.

For a blood count place the specimen in a dedicated rack.

Requests for other tests should be noted and appropriate action taken.


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2. ADDITIONAL TESTS

If the request is only for a special test (e.g. ESR, Sickle screen, Hb electrophoresis, IMscreen, Coagulation screen, Direct antiglobulin test), check that the correct sample has

been provided.

Place the specimen in a dedicated rack and take with the request form to the appropriate

section of the laboratory.

If the request combines additional test(s) with the blood count, make a copy of the

request form and tick the original form to show that this has been done. Place thespecimen in the blood-count rack with both request forms.

The technician or technologist will decide whether to separate part of the specimen for

the additional test or to carry out the blood count, followed by the additional test on the

same sample.

If the request is for malaria parasites, copy the request form, tick the original form toshow that this has been done; take the specimen and copy of request form to the

appropriate section of the laboratory and make sure that someone knows that it is there.


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3. ON-CALL SAMPLES

These are samples received after the normal working day and during the week-end.

The technician/technologist on duty must enter details in a special register and allocate a

consecutive laboratory number from that register.

On the next working day a record of the on-call tests will be entered in the day-register, and

renumbered as for routine specimens.

4. URGENT TESTS

The processing of urgent tests has priority over other samples. These may be from an out-patient clinic, accident and emergency cases, obstetrics, surgery, or neonatal unit.

On arrival they must be immediately entered in the register. Special note must be made of the

telephone number or other method of contact with the sender.

The specimen tube and request form must be clearly marked (e.g. a red label or red ink) and

immediately taken to the blood-count bench, making sure that a technician or technologistknows that it is there.

The test must be carried out without delay. Normally it should be possible for provisional

results (for some tests) to be telephoned to the clinic within 30 minutes of receiving the

specimen.


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REJECTION OF SAMPLE

There are several reasons why a specimen may be unacceptable. Only a senior technologist or

medically qualified member of the laboratory staff may reject any specimen.

Unlabelled or incorrectly labelled samples:

These must not be analysed and the doctor requesting the test must be informed without

delay.

If the doctor is confident that the sample can be correctly identified, it may be analysed after

the tube has been correctly labelled by the doctor or his authorized representative, who must

sign a form accepting responsibility for any error.

If there is any doubt about the correct identity of the sample, it must be discarded.

Leaking samples

Where a small volume of blood has leaked from the specimen tube, the sample should be

treated as potentially hazardous and gloves should be worn to handle the tube.

If the request form is contaminated a new form must be completed and the original form

discarded.

If a larger volume of blood has leaked from the tube, the sample should be discarded as the

results may be misleading.

The doctor requesting the test should be informed immediately and a fresh specimenrequested.


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Outdated samples:

If the specimen is over-aged by the time it is received in the laboratory the doctor requesting

the test(s) should be informed immediately by a technologist or medically qualified member

of staff.

If it is not possible to obtain a fresh specimen the laboratory staff member must discuss with

the sender which tests, if any, might still be carried out on the old sample without

compromising the reliability of the analysis.

Unsuitable samples

Some tests may be performed on either plain blood or anticoagulated blood, whereas onlyanticoagulated blood can be used for other tests (e.g. blood count, ESR);

furthermore, when blood is anticoagulated, the reliability of analysis may be affected by the

type and amount of anticoagulant and its concentration.

If there is an obviously wrong tube (clotted sample with a blood count request) the person in

charge of specimen registration must immediately inform the doctor who requested the

test(s).

If there is insufficient blood in the tube resulting in significantly excessive anticoagulant, a

senior member of the laboratory staff must decide whether or not to carry out the requested

test(s).

He/she must immediately inform the doctor who requested the test(s) and discuss the

potential analytic error. If the test(s) are carried out, the report must include a note of thislimitation.


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RECORDS

Test requests

Request forms are stored for three months

Reports of results

Copies of reports are stored for three months

Result work-books

Stored for at least five years.

If computerised, results are stored in the analyser database or on a PC for up to three

months and then transferred to storage disks and stored for at least five years

Blood grouping and blood transfusion records

Stored for at least ten years


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SPECIMENS

EDTA blood samples: Stored for seven days at 40C but suitable only for haemoglobin after

24 hours.

Citrated blood samples: Stored for three weeks at 40C.

Blood films: Stored for five years.

Plasma for coagulation tests: As coagulation tests must be carried out within a few hours,

specimens are not stored at the end of the working day. If samples are required for specific

purposes (e.g. repeating abnormal tests), the plasma can be kept for a few days frozen at

200C; if a deep-freezer at -400C is available, plasma can be stored for 2-3 months.

Serum or plasma for blood group serology: Kept for up to 1-2 weeks at 40C until completion

of antibody tests or transfusions. Samples may be stored frozen at 200C for three months or

longer if they are to be retained for subsequent cross-matching.


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SPECIMEN COLLECTION

As a rule, blood specimens will be collected by the clinical staff or phlebotomists under their

direction. In some cases the collection of venous blood may be undertaken in the laboratory

by or under the direction of a doctor. The laboratory director has the duty to ensure that allstaff who collect specimens have been instructed on the correct procedure as follows:

Identify the patient

Fill out test request form(s) and ensure that the correct identification is marked on the

specimen tube(s).

Prepare the patient and cleanse the venepuncture site with 70% alcohol or other antisepticsolution, followed by drying with a clean piece of cotton wool or gauze.

Avoid prolonged compression of the vein by tourniquet prior to collecting the blood; this

should not be for more than one minute.

The correct anticoagulants for various tests.

Ensure adequate mixing of blood with the anticoagulant but avoid frothing by excessive

shaking of the specimen.

Ensure that the tubes are securely stoppered and placed in plastic bags or a rack for delivery

to the laboratory.

Ensure that adequate arrangements are made for rapid despatch of the specimens to the

laboratory.


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Capillary blood

Capillary blood may be collected by the laboratory staff either in the laboratory or in the wards.

The same principles apply with regard to identifying the patient and filling out the request

form. Performance of a skin puncture then requires the following procedures:

Select a suitable site for the puncture: blood samples may be taken from a capillary puncture

of the heel [lateral or medial plantar surface] in young infants and a finger [palmar surface of

the distal phalanx] in others.

Warm the site by gentle massage of the area or applying a warm wet cloth for a few minutes.

Clean the puncture site with 70% alcohol or other antiseptic solution and dry with a cleancotton-wool swab or piece of gauze.

Make a quick stab-puncture with a sterile lancet and remove the first drop of blood with a

gauze pad.

Ensure free flow of blood; this will be facilitated by holding the puncture site downwards and

applying gentle pressure to the surrounding tissue, but do not squeeze as this will cause

contamination of the sample with tissue fluid.

Collect the blood into a capillary tube or pipette, etc. as required for the test.

After collecting the sample(s) apply gentle pressure with a gauze pad and, if necessary, cover

the puncture site with an adhesive skin plaster.


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RECORDS

Test requests

Request forms are stored for three months

Reports of results

Copies of reports are stored for three months

Result work-books

Stored for at least five years.

If computerised, results are stored in the analyser database or on a PC for up to three

months and then transferred to storage disks and stored for at least five years

Blood grouping and blood transfusion records

Stored for at least ten years


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SPECIMENS

EDTA blood samples: Stored for seven days at 40C but suitable only for haemoglobin after

24 hours.

Citrated blood samples: Stored for three weeks at 40C.

Blood films: Stored for five years.

Plasma for coagulation tests: As coagulation tests must be carried out within a few hours,

specimens are not stored at the end of the working day. If samples are required for specific

purposes (e.g. repeating abnormal tests), the plasma can be kept for a few days frozen at

200C; if a deep-freezer at -400C is available, plasma can be stored for 2-3 months.

Serum or plasma for blood group serology: Kept for up to 1-2 weeks at 40C until completion

of antibody tests or transfusions. Samples may be stored frozen at 200C for three months or

longer if they are to be retained for subsequent cross-matching.

preparation of distilled water

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