Question { 4615 }

Explain the Heterogenous ?

Answer

In chemistry, heterogeneous mixture is a mixture of two or
more different substances in the form of solution or
colloids. For example, salad is an heterogeneous mixture

A heterogeneous mixture is a mixture that can be separated.

Here are some examples of heterogeneous mixtures
Sandy water
cake mix and cookie dough
sugar and salt mixed in a bowl
carbonated beverage or beer (the CO2 gas is mixed with the
liquid)
orange juice with pulp in it
water with ice cubes in it
chicken noodle soup

Question { Amneal Pharmaceuticals, 13529 }

what is specificity?

Answer

Specificity is the ability to assess unequivocally
the analyte in the presence of components which may expect
to be present. Typically these might include impurities,
degradents, matrix, etc.

Question { Dr Reddys, 116166 }

How to calculate LOD & LOQ in HPLC Validation Method

Answer

Limit of Detection (LOD):
• Based on visual limitation
– Visual evaluation may be used for non-instrumental
methods but may also be used with instrumental methods.
– The detection limit is determined by the analysis
of samples with known concentrations of analyte and by
establishing the minimum level at which the analyte can be
reliably detected.
• Based on signal-to-noise
– This approach can only be applied to analytical
procedures which exhibit baseline noise.
– Determination of the signal-to-noise ratios is
performed by comparing measured signals from samples with
known low concentrations of analyte with those of blank
samples an establishing the minimum concentration at which
the analyte can be reliably detected. A signal-to-noise
ratio between 3 or 2:1 is generally considered acceptable
for estimating the detection limit.
• Based on the standard deviation of the response
and the slope
– The detection limit = 3.3 s / S
– Where s is the standard deviation of the response
and S is slope of the calibration curve.
– The estimate of S may be carried out in a variety
of ways, for example:
• Based on the standard deviation of the blank
• Based on the calibration curve


Limit of Quantification (LOQ):
• Based on visual limitation
– Visual evaluation may be used for non-instrumental
methods but may also be used with instrumental methods.
– The quantification limit is determined by the
analysis of samples with known concentrations of analyte
and by establishing the minimum level at which the analyte
can be quantified with acceptable accuracy and precision.
• Based on signal-to-noise
– This approach can only be applied to analytical
procedures which exhibit baseline noise.
– Determination of the signal-to-noise ratios is
performed by comparing measured signals from samples with
known low concentrations of analyte with those of blank
samples an establishing the minimum concentration at which
the analyte can be reliably quantified. A typical signal-to-
noise ratios is 10:1.
• Based on the standard deviation of the response
and the slope
– The quantification limit = 10s / S
– Where s is the standard deviation of the response
and S is slope of the calibration curve.
– The estimate of S may be carried out in a variety
of ways, for example:
• Based on the standard deviation of the blank
• Based on the calibration curve

Question { Aurobindo, 21558 }

what is a drug?

Answer

Any substance or mixture of substances intended to
be used to furnish pharmacological activity or other direct
effect in the diagnosis, cure, mitigation, treatment, or
prevention of disease or to affect the structure and
function of the body.

Question { 10524 }

x- rays travel with the velocity of

Answer

X-rays are a type of electromagnetic radiation, and
therefore travel at the speed of light. About 300000 km/sec.

Question { Dr Reddys, 18791 }

How you can calculate pKa ?

Answer

The equation for pKa is this:

Presuppose you have a compound HX is

HX --> H+ + X-
pKa = -log Ka

To find the Ka:
Ka = [H+] x [X-]/[HX]

Ka (is dissociation constant) is always products over
reactants.

Question { Dr Reddys, 17440 }

What is the formula for Tapdensity /

Answer

Weight of the substance
Tapped density = --------------------------
Volume of the substance (after tapping)

The density of solids normally expressed in g per cm3
and liquids is normally expressed in g per ml. However
because powder volumes are measured in cylinders graduated
in ml, tapped density is expressed in g/ml.

Question { 15525 }

what is the film thickness in ftir

Answer

0.038 (0.04)mm

Question { 23980 }

what is the difference between c-8 and c-18 column

Answer

In chromatography silanol groups (Si-OH) at the
surface of silica gel are reacted with substituted Chloro
Silanes.

CH3 CH3
| | | |
--Si–OH + Cl - Si--R → --Si-O - Si - R
| | | |
CH3 CH3

By changing characteristics of group i.e. from changing R
from C1 to C18 we can alter the nature of stationary phase
from polar to non polar. Since C18 columns is non polar.
This helps separating various combinations of polar – non
polar constituents from the analyte.
C-8 columns contain 8 carbons and C-18 contains 18
carbons are attached to silicon group to form stationary
phases for chromatography. The C-18 columns are highly
Non polar compared to C-8 columns and most of the compounds
are well separated in C-18 carbon packed columns.

Question { Aurobindo, 9119 }

what is thickness of the polystyrene film

Answer

0.04 (0.038)mm

Question { 21517 }

what is mean by assay?

Answer

A quantitative or qualitative test of a substance
(especially an ore or a drug) to determine its components;

An analysis of the composition or strength of a
substance, esp. a determination of the amount of metal in
an ore, alloy, etc.

Question { 5457 }

The gas that used in bulb is............?
a) Oxygen b)nitrogen c)hydrogen d)co2

Answer

Answer is b) Nitrogen.

The gas usually argon and/or nitrogen is used in bulbs.

Question { Reliance, 24324 }

why ph is between 0 to 14

Answer

*** The equation for finding the pH of a solution is –log
([H+]). That is, the negative log of the molarity of the
hydrogen ions released by the compound in solution. Almost
no chemicals can release hydrogen ions with a molarity
greater than 1 or less than 10^-14. However, there are some
rare cases where the pH of a solution is not between 0 and
14. For example, 10 molarity hydrochloric acid (there are
ten moles of hydrochloric acid for every liter of water.),
has a pH of -1 (-log (10) =-1). But these are so rare in
occurrence

Question { Zydus Cadila, 26174 }

what is the definition of limit of stray light in UV calibration

Answer

Stray light is defined as the detected light of any
wavelength that is outside the bandwidth of the selected
wavelength, Stray light causes a decrease in absorbance and
reduces the linearity range of the instrument. High
absorbance measurements are more severely impacted by stray
light....

Question { 23467 }

why we are performing residue on ignition?

Answer

Residue on ignition means at a define temp.
(about 600 deg C). how much matter driven off form your
sample means after ending the test you will get the residue
on ignetion all part of organic matter will removed and
only inorganic matter will present because we are finding
how much inorganic impurity present in sample.