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Anonymous asked in Science & MathematicsBiology · 1 decade ago

What is a Semi-quantitative test?

Doing it for bio but don't really understand what it means...

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  • 1 decade ago
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    A semi-quantitative test is one that doesn't give you the absolute amount of analytes in a sample. It only gives the amount of analytes relative to the others. For example it will tell that there is 3 times as much aluminium than iron in a sample but it won't tell how much of either is in the sample.

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  • Anonymous
    1 decade ago

    Consider the results that you can get from say a chemical or biological test.

    The results could be descriptive and we say the result is qualitative. For example, eye colour. You can see that the result describes a 'quality.'

    If the test leads to a result that is expressed as a numerical answer with the appropriate units we say it is a quantitative test. For example, the concentration of glucose is 5.6 mg per litre. You can see the results describes a 'quantity.'

    Many test, especially in the biological field are half way between these two. For example, you use a starch/iodine test to detect amylase. You can get a range of positive results in which the colour of the test solution ranges from a very pale blue to a dark ink blue. So the test is not entirely qualitative and you haven't got a numerical answer so its not qualitative. You might describe a result as 'weak positive' or 'very strong.' Here we are approximating the amount of amylase in very rough terms. Such tests are described as semi-quantitative.

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  • 4 years ago

    This Site Might Help You.

    RE:

    What is a Semi-quantitative test?

    Doing it for bio but don't really understand what it means...

    Source(s): semi quantitative test: https://shortly.im/sEBlo
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  • Carlos
    Lv 4
    3 years ago

    2

    Source(s): Remedies for Kidney http://teres.info/KidneyHealth/?I39w
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  • elmer
    Lv 4
    3 years ago

    1

    Source(s): I Treated My Diabetes http://ReverseDiabetesToday.enle.info/?ZXL0
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  • drape
    Lv 4
    3 years ago

    Semiquantitative

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  • 4 years ago

    a

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  • 1 decade ago

    Semi-Quantitative Tests

    Specific Gravity (Mass Density)

    Urinometer method

    Principle

    Specific gravity is a function of the number, density and weight of the solute particles present and is used as a measure of the concentrating power of the kidney. The specific gravity of urine is its density compared with the density of distilled water that is conveniently fixed as 1.000 at 200C.

    It ismeasured using a weighted cylinder called "urinometer", which floats in the urine and which is calibrated against distilled water at 20° C. Check the working of the urinometer by floating it in distilled water to see if the reading is 1.000. As the specific gravity varies with temperature, apply temperature correction before reporting.

    Procedure

    Pour about 40 - 50ml of urine into a 100ml glass measuring cylinder.

    lower the urinometer gently into the urine, rotate and release (avoid frothing).

    Wait for the urinometer to settle (make sure that the urinometer does not come into contact with the sides or bottom of the cylinder).

    Read the specific gravity given on the scale at the surface of the urine (use the lower point of the meniscus for reading).

    Observe the temperature of the urine.

    Result

    Check the temperature at which the urinometer is calibrated. It is usually at 200C. For every 30C that the urine temperature is above the calibration temperature, add 0.001 to the measured specific gravity and for every 30C that the urine temperature is below the calibration temperature, subtract 0.001 from the measured specific gravity.

    Example

    Urinometer is calibrated at 200C

    Urine temperature 230C

    The measured specific gravity 1.023

    The temperature of urine is 30C higher than the calibration temperature.

    \ Specific gravity to be added to the measured specific gravity =

    3/3 x 0.001 = 0.003/3 = 0.001.

    \ The actual specific gravity = 1.023+0.001=1.024.

    Interpretation and quality control

    The normal urine-specific gravity is 1.010 – 1.030

    The presence of an increased amount of protein affects the specific gravity by 0.001 for every 0.4g/dl protein level in urine. As a quality control measure, the functioning of the urinometer must also be checked by floating in other liquids whose densities are greater than distilled water. There is also an adjustment for glucose Subtract 0.001 for every 270 mg/dl glucose in the urine.

    Proteins – Heat and acetic acid method

    Principle

    Proteins in urine are coagulated by heat and the degree of coagulation isdirectly proportional to the amount of proteins present. Coagulation can be further enhanced when drops of acetic acid are added.

    Procedure

    Pour 2-3 ml of urine into a 13 x 100mm glass tube and hold it using a tube holder. Check the urine pH; if it is >pH 7 or <3, adjust to between 4-5 using 3% acetic acid. Heat the upper half of the column of urine in a flame until it boils. Look for the appearance of cloudiness in the heated portion and contrast it with the lower portion of the tube. Appearance of cloudiness in the upper portion indicates the presence of proteins. Add 2-3 drops of 3% acetic acid to the precipitate and observe. If the precipitate disappears, it indicates the presence of phosphates and carbonate (later produces effervescence when the precipitate disappears). Persistence of the precipitate shows the presence of albumin. On adding 2-3 drops of conc. HN03 ifthe precipitate disappears, the presence of mucin or nucleoprotein is suggested.

    Result

    This test may be used as semi-quantitative, as follows;

    Colour change

    Result

    No cloudiness

    Negative

    Faint cloudiness

    (may be observed only if the tube

    is held against a black background).

    Trace

    Definite nongranular cloud without flocculation

    1+

    Heavy and granular cloud without flocculation

    2+

    Dense cloud with marked flocculation

    3+

    Thick curdy flocculation & coagulation

    4+

    Interpretation and quality control

    This test is sensitive enough to detect protein down to a concentration of 2-3 mg%.

    For quality control, dilute 22g% of human albumin solution to get a concentration of 5 mg/dl. Use this as a test and check the reliability and sensitivity of this method.

    Note: If an alkaline urine is boiled, the protein may be converted into the so- called "alkaline metaprotein", which is not coagulated by heat. Therefore it is always better to acidify the urine before doing this test.

    If too much acetic acid is added, the protein may be converted to the so-called "acid metaprotein", which is also not coagulated by heat. Therefore the urine should be only mildly acidic.

    Protein – Sulphosalicylic acid method

    Principle

    Urine proteins are precipitated by sulphosalicylic acid, which gives a white precipitate, and the degree of the precipitate is proportional to the protein level.

    Reagent

    3g % sulphosalicylic acid (SSA)

    Weigh 7.5 g of sulphosalicylic acid and dissolve it in about 200ml of distilled water and then make up to 250 ml with distilled water. Store at 25 - 350C. Stable for 6 months.

    Procedure

    To 2ml of urine taken in a 13 x 100mm glass tube, add 2 ml of 3g% SSA. Mix gently. Leave for 5 minutes at room temperature. Compare the degree of the precipitate with 4ml of SSA taken in a similar test tube.

    Result

    Same as given on page 99 "(c) Result"

    Interpretation and quality control

    The sulphosalicylic acid method will not detect protein in a normal urine, but will be sensitive enough to detect protein present down to 20mg%. As a quality control measure, a 22g/dl albumin solution can be diluted appropriately with 0.9 g/dl sodium chloride to get standards containing 20, 50, 200, 500 and 2500 mg/dl proteins. These standards are stable for one month when stored at 2-80C. When they are subjected to the same procedure as urine, the results can be interpreted as follows:

    Concentration of proteins

    Reported as

    20 mg/dl

    Trace

    50 mg/dl

    1+

    200 mg/dl

    2+

    500 mg/dl

    3+

    2500 mg/dl

    4+

    Sugar: Benedict's test

    Principle

    Urinary sugars when boiled in Benedict's reagent reduce copper sulphate to a reddish cuprous oxide precipitate in hot alkaline medium, the intensity of which is proportional to the amount of sugar present in the urine. The results are reported as I+,2+, etc. depending upon the colour and intensity of the cuprous oxide precipitate.

    Reagent

    Dissolve 17.3g of crystalline copper sulphate in about 800ml of distilled water, then add 100 g of sodium carbonate, mix to dissolve and finally add 175g of sodium citrate. Mix well to dissolve and then make up to one litre with distilled water. Store in an amber coloured bottle at 25-350C. Stable for one year.

    Procedure

    To 5 ml of Benedict's reagent taken in an 18 x 150mm glass tube, add 8 drops (0.5 ml) of urine, mix well and boil for 2.3 minutes, preferably in a boiling waterbath. Cool the tube and observe for any colour change.

    Result

    The results are reported as follows:

    Observation

    Inference

    No change in the original colour of Benedict’s solution

    Negative

    Solution appears pale green

    and slightly cloudy

    Trace

    Definite cloudy green

    1+

    Yellow to orange precipitate

    2+ (1 g/dl)

    Orange to red precipitate

    3+ (2 g/dl)

    Brick red precipitate & clear supernatant

    4+ (>2 g/dl)

    Interpretation and quality control

    Normal urine does not contain any reducing sugar. If protein is present in large amounts, it may interfere with the precipitation of the cuprous oxide.

    To overcome this problem, precipitate the proteins using 3% SSA filter using a Whatman filter paper and use the filtrate to test the amount of sugar present.

    As a quality control measure, standards containing known amounts of glucose are prepared in saturated benzoic acid and one of the standards is used every day to check the reliability of the patient’s results. The standard results may be transformed in the following semi-quantitative way.

    100mg/dl

    Trace

    250mg/dl

    1+

    500mg/dl

    2+

    750mg/dl

    3+

    2 g/dl

    4+

    False positive reactions are known to occur due to the presence of non- carbohydrate substances like ascorbic acid, homogentisic acid, creatinine and uric acid. Reducing sugars like lactose, galactose, fructose and pentoses will also give a positive reaction.

    The dipstick technique is specific for glucose and eliminates the false positive reaction due to the substances mentioned above.

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