How calibration is carried out using an internal standard?

Answer 1

You can find the calculation from this paper,

D.E. Willis (1972). Internal Standard Method Calculations, Chromatographia 5, Springerlink.

Answer

According to the Southeast Missouri State University website (refer to the link, below):

"The internal standard method is an additional method to account

for some analytical errors in the measurement.

An internal standard is added to all known and unknown solutions.

The analyte of interest is measured along with the internal standard

and the ratio of signals is plotted as in the calibration curve method."

When you calibrate something using an internal standard, you spike a known quantity of "standard" into your samples and use that to create a reference in your tests.

You know how much "standard" is in your sample, so you can match up a result with that known concentration.

Answer 2

----Welcome--- Lecture on Calibration of Volumetric Glassware By B.S.Rajwar
References to IS: Specifications Sr. No IS: CodeSpecification For 1 IS:915-2006 One-Mark Volumetric Flask 2 IS:1117-1975 One-Mark Pipettes 3 IS:1997-1982 Burettes 4 IS:4162 (Part-I)-1985 Graduated Pipettes 5 IS:4162 (Part-II)-1985 Graduated Pipettes(For which no waiting time is specified) 6 IS:4162 (Part-III)-1985 Graduated Pipettes(For which waiting time is specified) 7 IS:4162 (Part-IV)-1985 Graduated Pipettes(Blow-Out Pipettes) 8 IS: 875-1975 Graduated measuring cylinders
One Mark Volumetric Flask-Specification (Guidelines References)IS: 915-2006 Terminology: Unit of volume: The unit of volume shall be milliliter (ml), which is equivalent to cm3 . Nominal Capacity: The volume of water at 27OC in ml, contained by the flask at 27 OC, when filled to the graduation line. Graduation line: Graduation line shall be clear, permanent, uniform line of thickness 0.4 mm, completely encircling the neck of the flask s and lying in a plane parallel to the base of the flask. Apparatus Required for Calibration of Volumetric Glassware's. 1: Calibrated Electronic Weighing Balance with accuracy 0.0001 gm or better accuracy. 2: Thermometer with accuracy of 0.1OC 3: Recipient (e.g. Erlenmeyer Flask) filled with some water. 4: Calibrated volumetric flask of known volume to check density of water. Procedure For determination of Density of distilled water: Ø Set the temperature of the room at 27± 2OC. Ø First of all determine the density of the distilled water to be used for the calibration of the flask. Ø Take empty weight of the calibrated volumetric flask in calibrated weighing balance, record the weight as M1 gm. Ø Fill the calibrated volumetric flask with distilled water to be used for volume measurement & calibration. Ø Take weight of the flask with distilled water, record the weight as M2 gm. Ø Repeat the process of taking empty weight (M1) and filled weight (M2) of the volumetric flask at least three times. Ø Calculate the density of the water as table format given below. Sr. No. M1 (Weight of Empty volumetric flask) gm M2 (Weight of the volumetric flask with water) gm Known calibrated volume of flask (ml) Density of water = (M2-M1)/Volume 1 2 3 Average density of water = Procedure for calibration of volumetric flask: (Weight by density method) Ø Clean the pipette to remove any adhering dirt or grease with chromic acid. Ø Take the empty weight of the volumetric flask to be calibrated as W1 gm. Ø Fill the flask with distilled water to the mark at the set temperature. Ø Set the meniscus so that the plane of the top edge of the graduation line is horizontally tangential to the lowest point of the meniscus, the lime of sight being in the same plane. Ø Take weight of the flask with distilled water as W2 gm. Ø Repeat the process of weighing W1 and W2 at least three times. Ø Calculate the volume of the flask as table format given below. Sr. No. W1 (Weight of Empty volumetric flask) gm W2 (Weight of the volumetric flask with water) gm Known density of water (gm/cc) Volume of flask (cc) = (W2-W1)/Density 1 2 3 Average volume of the flask = Dimension and Maximum Permissible Errors in Capacities As per IS: 915:2006

S.No. Essential Dimensions Tolerance Maximum Permitted Errors Recommended Dimensions Nominal Capacity (ml) Internal Neck Diameter d1)-mm Distance of graduation line h2 (mm) Class A (ml) Class B (ml) Overall height (h1 ± 5 mm) Bulb Diameter d2 (mm ) approx. Base Diameter d3 (mm) Min. Walls thickness (mm), Min. 1 1 7 ± 1 5 ± 0.015 ± 0.030 65 13 13 0.7 2 2 7 ± 1 5 ± 0.015 ± 0.030 70 17 15 0.7 3 5 7 ± 1 5 ± 0.025 ± 0.050 70 22 15 0.7 4 10 7 ± 1 5 ± 0.025 ± 0.050 90 27 18 0.7 5 20 9 ± 1 5 ± 0.040 ± 0.080 110 39 18 0.7 6 25 9 ± 1 5 ± 0.040 ± 0.080 110 40 25 0.7 7 50 11 ± 1 10 ± 0.060 ± 0.120 140 50 35 0.7 8 100 13 ± 1 10 ± 0.100 ± 0.200 170 60 40 0.7 9 200 15.5 ± 1.5 10 ± 0.150 ± 0.300 210 75 50 0.8 10 250 15.5 ± 1.5 10 ± 0.150 ± 0.300 220 80 55 0.8 11 500 19 ± 2 15 ± 0.250 ± 0.500 260 100 70 0.8 12 1000 23 ± 2 15 ± 0.400 ± 0.800 300 125 85 1.0 13 2000 27.5 ± 2.5 15 ± 0.600 ± 1.200 370 160 110 1.2 14 5000 38 ± 3 15 ± 1.200 ± 2.400 475 215 165 1.2 Tolerance of Volumetric Flasks (Reference - ASTM E694- Standard) SizeTolerance(class A) Tolerance(class B) 10ml ±0.02 ±0.04 25ml ±0.03 ±0.06 50ml ±0.05 ±0.1 100ml ±0.08 ±0.16 200ml ±0.1 ±0.2 250ml ±0.12 ±0.24 500ml ±0.2 ±0.24 h 1

h2

d 3

d1

d 3

d 2

s

Meniscus

One Mark Volumetric Flask Precautions: 1: Flask should be cleaned properly so as to avoid sticking of droplets. 2: Flask should be marked properly to identify the calibrated flask. 3: Exact volume of the flask should be reflected in calibration certificate with its identification number. Calibration of One Mark Pipette(Guidelines References)IS: 1117-1975 Terminology: Nominal capacity: The volume of water at 27oC in cubic centimeter (cm3) or in milliliter (ml) delivered by the pipette at 27o . Delivery Time: The time taken by the free descent of the water meniscus from the graduation mark to the point at which it appears to come to rest in the jet. Material: The pipettes shall be made of colorless glass not having any pronounced tint. They shall be as free as possible from visible defects and shall be reasonable free from internal strain. Procedure For determination of Density of distilled water: Ø Set the temperature of the room at 27± 2OC. Ø First of all determine the density of the distilled water to be used for the calibration of the flask. Ø Take empty weight of the calibrated volumetric flask in calibrated weighing balance, record the weight as M1 gm. Ø Fill the calibrated volumetric flask with distilled water to be used for volume measurement & calibration. Ø Take weight of the flask with distilled water, record the weight as M2 gm. Ø Repeat the process of taking empty weight (M1) and filled weight (M2) of the volumetric flask at least three times. Ø Calculate the density of the water as table format given below. Sr. No. M1 (Weight of Empty volumetric flask) gm M2 (Weight of the volumetric flask with water) gm Known calibrated volume of flask (ml) Density of water = (M2-M1)/Volume 1 2 3 Average density of water = Procedure for calibration of One Mark- Pipette: (Weight by density method) Ø Clean the pipette to remove any adhering dirt or grease with chromic acid. Ø Take the empty weight of the dried conical flask as W1 gm. Ø Fill the pipette with distilled water to the mark at the set temperature. Ø Set the meniscus so that the plane of the top edge of the graduation line is horizontally tangential to the lowest point of the meniscus, the lime of sight being in the same plane. Ø Allow the distilled water to come out in the conical flask which has been weighted as W1. Ø Take weight of the conical flask with distilled water as W2 gm. Ø Repeat the process of weighing W1 and W2 at least three times. Ø Calculate the volume of the pipette as table format given below. Sr. No. W1-gm (Weight of Empty flask) W2-gm (Weight of the flask and pipette out water) Known density of water (gm/cc) Volume of Pipette (cc) = (W2-W1)/Density 1 2 3 Average volume of the Pipette =
Tolerance on capacities (As per IS: 1117-1975) Sr. No. Nominal Capacity (cm3) or ml Maximum permitted tolerance Class AClass B 1 0.5 ± 0.005 ± 0.01 2 1 ± 0.007 ± 0.015 3 2 ± 0.010 ± 0.02 4 5 ± 0.015 ± 0.03 5 10 ± 0.02 ± 0.04 6 20 ± 0.03 ± 0.06 7 25 ± 0.03 ± 0.06 8 50 ± 0.05 ± 0.10 9 100 ± 0.08 ± 0.16 10 200 ± 0.10 ± 0.20 Tolerance for Bulb Pipettes (with reference to ISO-648) SizeTolerance 1 ml ±0.008 2 ml ±0.01 5 ml ±0.015 10 ml ±0.02 Specifications for Grade A Graduated Pipettes (with reference to IS: 4162-1985, Reaff: 2002(part I/ Part II) - 1985, Reaff: 2002) Capacities, Sub - division and Limits of Error:Nominal Cpacity (ml) SmallestScale Division (ml) Limits of Errors(± ml) Class A Class B 0.5 0.01 0.005 - 1 0.01 0.06 0.01 2 0.02 0.01 0.02 5 0.05 0.03 0.05 10 0.1 0.05 0.1 25 0.1 0.1 - 25 0.2 0.1 0.2 Method For Determination of Delivery Time of the solution from pipette: Ø Clean the pipette to remove any adhering dirt or grease with chromic acid. Ø Fill the pipette with distilled water to the mark at the set temperature. Ø Remove any drop adhering to the jet of the pipette by bringing the surface of a glass vessel into contact with the tip of the jet. Ø Start stopwatch and simultaneously deliver the water thus measured into another clean and tared glass vessel into contact slightly inclined so that the tip of the jet is in contact with the inside of the vessel, but without movement of one against the other throughout the delivery and waiting periods. Ø Allow the pipette to empty until the meniscus comes to the rest in the jet. Ø Stop the watch and note the time. This time will be observed as delivery time. Delivery Time (Seconds) For Pipettes As per IS: 1117-1975 Sr. No. Nominal Capacity (cm3) or ml Class-A Class-B Permissible difference between observed and inscribed delivery time (Max.) Min. (Sec.) Max. (Sec.) Min. (Sec.) Max. (Sec.) 1 0.5 10 20 7 20 2 2 1 10 20 7 20 2 3 2 10 25 7 25 2 4 5 15 30 10 30 3 5 10 15 40 10 40 3 6 20 25 50 20 50 4 7 25 25 50 20 50 4 8 50 30 60 20 60 5 9 100 40 60 30 60 5 10 200 50 70 40 70 5 Specifications for Grade A Graduated Pipettes (with reference to IS: 4162-1985, Reaff: 2002(part I/ Part II) - 1985, Reaff: 2002) Capacities, Sub - division and Limits of Error: Delivery Times type -1 pipettes: Nominal Capacity (ml)Delivery Time (Seconds) Class A Class BMin Max Min Max 1 7 10 2 10 2 8 12 2 12 5 10 14 5 14 10 13 17 5 17 25 15 21 9 21 Delivery Times of Type 2 Pipettes: Nominal Capacity (ml)Delivery Time (Seconds) Class A Class BMin Max Min Max 1 5 7 2 10 2 6 9 2 12 5 8 11 5 14 10 10 13 5 17 25 25 16 9 21 Delivery Times of Type 3 Pipettes: Nominal Capacity (ml) Delivery Time (seconds) Class B Min Max 1 2 10 2 2 12 5 5 14 10 5 17 25 9 21 Specifications for Grade A Burettes(Reference IS: 1997 - 1982 Reaff: 1998) NominalCapacity (ml) Smallest Scale Division(ml) Delivery Time (seconds) Type-I Class AClass B Min Max Min Max 1 0.01 35 45 20 50 2 0.01 50 70 25 70 5 0.02 75 95 30 95 10 0.02 75 95 30 95 10 0.05 75 95 40 95 25 0.05 70 100 35 100 25 0.1 45 75 25 75 50 0.1 60 100 30 100 FRom : Birendra Singh Rajwar (Quality Manager)