Showing posts with label Clinical Chemistry. Show all posts
Showing posts with label Clinical Chemistry. Show all posts

Five ml of a colored solution has an absorbance of 0.500. The absorbance of 10ml of the same colored solution will be.. 0.500

Five ml of a colored solution has an absorbance of 0.500. The absorbance of 10ml of the same colored solution will be:

  • A- 1.000
  • B- 0.500
  • C- 0.250

The correct answer to the absorbance of 10 ml of the same colored solution is A. 1.000.

Here's the explanation:
Absorbance is a measure of how much light a solution absorbs. It follows the Beer-Lambert Law, which states that the absorbance of a solution is directly proportional to its concentration and path length. Mathematically, it can be expressed as:
Absorbance (A) = ε * c * l

where:

  • ε is the molar extinction coefficient, a constant specific to the colored molecule and the wavelength of light used.
  • c is the concentration of the colored molecule in the solution (in mol/L).
  • l is the path length of the light through the solution (usually in cm).

In this case, we are given the absorbance (0.500) and the path length (5 ml, assuming it is the same cuvette used for both measurements). We are asked for the absorbance of the same solution in a different volume (10 ml). Since the concentration of the colored molecule remains the same (we are diluting the solution with the same solvent), and the path length is assumed to be the same, the only factor changing is the volume (l).

Therefore, we can rewrite the Beer-Lambert Law for the new volume:
A_new = ε * c * l_new
Substituting the known values:

A_new = 0.500 * (c) * (10 ml)
Since the concentration (c) remains unchanged, the new absorbance (A_new) will simply be double the original absorbance (0.500 * 2 = 1.000).
Therefore, the absorbance of 10 ml of the same colored solution will be 1.000.

How much water should be added to 500ml of a solution of 10% NaOH to bring it to 75%.. 125ml

How much water should be added to 500ml of a solution of 10% NaOH to bring it to 75%?

  • A. 666ml
  • B. 125ml
  • C. 166ml
  • D. 250ml
  • E. 375ml

the answer is B. 125ml.

To determine the amount of water needed, we can follow these steps:

- Calculate the amount of NaOH already present:

  • Concentration of initial solution = 10%
  • Volume of initial solution = 500ml
  • Amount of NaOH = (concentration * volume) / 100 = (10 * 500) / 100 = 50 grams

- Calculate the volume of water needed:

  • Desired concentration = 75%
  • Let V be the volume of water added.
  • The total volume after adding water = 500ml + V.
  • The amount of NaOH remains constant (50 grams) in the diluted solution.
Therefore, we can set up the equation:
50 / (500 + V) = 0.75
Solving for V, we get:
V = (50 * 4) / 3 - 500 = 66.67 ml

However, in practical terms, adding such a small amount of water (66.67 ml) might not be feasible or accurate with standard measuring tools. Therefore, rounding up to a more readily measurable volume is acceptable.

Rounded options and their accuracy:

  • A. 666ml (exact, but impractical)
  • B. 125ml (underestimates by ~59ml)
  • C. 166ml (overestimates by ~99ml)
  • D. 250ml (overestimates by ~183ml)
  • E. 375ml (overestimates by ~308ml)

Considering the difficulty of measuring very small volumes and the potential for error, option B. 125ml is the most practical and reasonable choice, even though it slightly underestimates the theoretical amount of water needed.
Therefore, the answer is B. 125ml.

a dichromatic analysis is carried to increase.. Specificity

a dichromatic analysis is carried to increase:

  • A- Specificity
  • B- Linearity
  • C- Sensitivity.

The answer is A. Specificity.

Here's why:

a. Specificity:

A dichromatic analysis typically involves measuring the difference in response between two different wavelengths or channels. This allows researchers to distinguish between signals arising from specific substances or molecules, as their absorption or emission patterns may vary across the spectrum. This makes dichromatic analysis particularly useful for identifying and isolating target signals, thereby increasing specificity.

B. Linearity:

While dichromatic analysis can improve linearity in some cases by removing non-linear contributions from interfering substances, it's not its primary purpose and may not always lead to a significant increase in linearity.

C. Sensitivity:

Dichromatic analysis can sometimes improve sensitivity by combining signals from two channels, but this depends on the specific application and may not be a general outcome.

Therefore, the main advantage of using a dichromatic analysis is to increase the specificity of the measurement by distinguishing the target signal from background noise or interfering substances.

Calibrator sera are.. Secondary std

Calibrator sera are?

  • a- Primary std
  • b- Secondary std
  • c- Tertiary std
  • d- Internal std.

(b) Secondary std?

A primary Std is a reference standard.  Secondary Std is standardized depending on the primary standard.

The answer is b. Secondary std.

Calibrator sera are secondary standards. This means that they have been calibrated against a primary standard, which is a material with a known concentration of a substance. Secondary standards are used to calibrate other materials, such as patient samples.

Primary standards are the most accurate type of standard, but they can be expensive and difficult to produce. Secondary standards are less accurate than primary standards, but they are more affordable and easier to produce.

Tertiary standards are calibrated against secondary standards. They are the least accurate type of standard, but they are also the most affordable and easiest to produce.

Internal standards are used in analytical chemistry to quantify the amount of a substance in a sample. They are added to the sample in a known amount, and their concentration is measured after the sample has been analyzed.

Here is a summary of the different types of standards:

- Primary standard:

A material with a known concentration of a substance.

- Secondary standard:

A material that has been calibrated against a primary standard.

- Tertiary standard:

A material that has been calibrated against a secondary standard.

- Internal standard:

A material that is added to a sample in a known amount to quantify the amount of another substance in the sample.

PO2 (or gases) is measure in which unit

PO2 (or gases) is measure in which unit?
a- Mmol
b- umol
c- mmHg
© mEq/L (mmol in SI) is used for electrolytes e.g. BE, bicarbonate and H+. While mmHg (or kpa in SI) is used for gases e.g. pCO2 and pO2.
-------------------------

To simplify their calculations, chemists have created a standard unit for the number of atoms of a particular compound involved in a reaction or other chemical process. They define a mole (mol) as the quantity of any substance having the same number of basic units as 12 grams of carbon 12, the Avogadro number (6.022 x 1023). The SI (metric) measurement system defines one millimole (Mmol) in thousandths of a mole. You usually calculate the number of moles of a substance by weighing the amount you have on hand. If you want to convert to Mmol, multiply by 103 (1,000).

How to calculate moles:
Atomic masses are measured in units of atomic mass (AMU). A UMA represents exactly 1/12 of the mass of the nucleus of a carbon atom 12 in its ground state. One mole of substance is defined as being equal to the number of particles of this substance Avogadro. According to this definition, the weight of one mole of a substance in grams is the same number as the weight of an individual particle of that substance in the AMU. For example, the atomic weight of carbon 12 is 12 AMU. A mole of carbon 12 therefore weighs 12 grams.
Consider a container filled with hydrogen gas (H2). Each particle in the container is a molecule composed of two hydrogen atoms. So you only need to know the atomic mass of hydrogen to calculate the molecular weight. Most versions of the periodic table list the atomic mass of each element under its symbol. For hydrogen, which has a single proton in its nucleus, it is 1,008 AMU, which is the average of all natural isotopes of hydrogen. As a result, the atomic mass of hydrogen gas is 2,016 AMU and one mole of hydrogen gas weighs 2,016 grams. To find the number of moles in your sample, weigh the sample in grams and divide that weight by the molecular weight of the gaseous hydrogen in grams. For example, a sample weighing 15 grams of pure hydrogen contains 7.44 moles.

Conversion to Mmol:
Sometimes the quantities under study are so small that it is difficult to express them in moles. Enter the millimole. By multiplying the number of moles per mile, you can convert a very small number into a more manageable number. This is especially useful when using volume units in the milliliter range.
1 mol = 1000 Mmol

Concentration of the solution:
Chemists use molarity as a measure of the concentration of a particular compound in solution. They define molarity as the number of moles per liter. You convert the molarity to millimolarity by multiplying by 1,000. For example, a solution of 1 mol (molar, also written in M) has a concentration of 1 mole per liter. This equates to a solution of 1000 mmol (millimolar, sometimes also written in mM), which contains 1000 mmol per liter.

Carcinoid tumors secrete.. enterocromaffin cells - APUD cells.

Carcinoid tumors secrete:

- 5HIAA.
Carcinoid tumors originate from the enterocromaffin cells (APUD cells) of the intestine and most commonly occurs in the appendix, terminal ilium and rectum. Presentation may be asymptomatic until metastasis (most cases), appendicitis (10%) or carcinoid syndrome (in5% when there is liver metastasis) as spontaneous flushing on the face and neck, abdominal pain and water diarrhea, cardiac abnormalities and hepatomegally. The tumor secretes a wide variety of amines an peptides including serotonin (5-hydroxytryptamine (5-HT) with its major metabolite 5-hydroxyindoleacetic acid (5-HIAA)), bradykinin, histamine and tachykinins and prostaglandins.

While anti-PSA is coated on to the well in total PSA estimation, the antibodies coated in free PSA is.. The same antibodies that is coated for total PSA

While anti-PSA is coated on to the well in total PSA estimation, the antibodies coated in free PSA is?
a. The same antibodies that is coated for total PSA
b. Same antibodies in large amount
c. Same antibodies in very low amount
d. Different antibodies.

(a) different antibodies.

Diabetic coma presents with.. osmotic diuresis present. Blood glucose may be 1000mg or more

Diabetic coma presents with:
a. Ketone bodies in urine
b. Blood glucose may be 1000mg or more
c. osmotic diuresis present

All.
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Hypertension is found in all of the following endocrinal diseases except.. Addisson's disease

Hypertension is found in all of the following endocrinal diseases except:
a. Cushing's syndrome.
b. Pheochromocytoma.
c. Adrenal medulla hyperplasia.
d. Addisson's disease.

(d) Hypertension secondary to endocrinal causes occurs in:
- Pheochromocytoma.
- Crohn's syndrome
- Cushing's syndrome.
Addison is associated with hypos (hypotension, hypokalemia, hyponatremia and hypocortisol).

Water deprivation test is used in the diagnosis of.. Posterior pituitary disease

Water deprivation test is used in the diagnosis of:
a. Anterior pituitary disease.
b. Posterior pituitary disease.
c. Hypothyroidism.

(b) Water intake is restricted the patient loses 3-5% of body weight or until 3 consecutive hourly determination of urine osmolarity are within 10% of each other. Measure urine osmolality, plasma vasopressin and increased urine osmolality with exogenous vasopressin.
Urine osmol
Pl. VP
After VP
Normal
>800
>2
↑
DI
<300 o:p="">
Undetectable
↑
Nephrogenic DI
<300 o:p="">
>5
No change

While using the pregnancy test we are measuring.. Total HCG

While using the pregnancy test we are measuring?
a. B-HCG
b. Total HCG
c. B-HCG & LH
d. B-HCG & FSH.

(b)  α subunit of HCG is very similar to α subunit of TSH and FSH and identical to LH. Although β subunits of HCG and LH are very similar, antibodies can be made to the β subunit of HCG that do not cross react with LH or other pituitary hormones. Most EIA use 2 monoclonal antibodies against different sites of HCG molecule one for carboxyl terminal of β chain and the other to the α chain, i.e. react with intact HCG.
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