CALIBRATION OF PIPETTELABORATORY EXPERIMENT NO. 1

ANALYTICAL CHEMISTRYGROUP 1

CONTENT OF THE PRESENTATION

I. INTRODUCTION II. METHODOLOGY (ILLUSTRATED) III. DATA AND RESUTS

TABULAR SET OF VALUES AND VARIABLES DERRIVED FROM THE TRIALS HAD

*STANDARD DEVIATION *MEAN *RELATIVE STANDARD DEVIATION

IV. DISCUSSION V. CONCLUSION VI. REFERENCES

I. INTRODUCTION

In this course-Analytical Chemistry, precision and accuracy are the fundamentals to gain realistic findings, hence we must first secure the measurement glass wares usually used in the laboratory by checking its calibration.

Calibration is the operation that determines the functional relationship between measured values wherein there is the standard value and the unit under test.

In this experiment, pipette is the measuring device being calibrated.

II. OBJECTIVES

To forecast good precision and accuracy of the pipette.

To demonstrate proper usage of pipette.

To identify instrumental errors during the calibration.

To calculate and detect error by formulating solutions.

WHAT IS A PIPETTE?

A pipette is used for measuring small volume directly from the reagent bottle.

III. METHODOLOGY

Then, do the 3rd and 4th procedure continuously until you arrived at 10th trial.

IV. DATA AND RESULTSWEIGHT OF THE LIQUID IN PIPETTE IN (ML)

MEASUREMENT

WEIGHTg/OC

TRIALS

MASS OF BEAKER WITH H2o IN (g)

gram of H2O

V= M/D (ml) X

WEIGHT OF EMPTY BEAKER

66.9 1 76.9 10.00 10.06ml

WEIGHT OF BEAKER + 10ml H2O

76.9 2 88.65 11.75 11.82ml

WEIGHT OF THE SAMPLE (H2O)

10 3 98.65 10.00 10.06ml

TEMPERATURE 30oC 4 108.40 9.75 9.80mlDENSITY 0.995

g/ml5 115.40 7.00 7.04ml

6 129.15 13.75 13.83ml

7 139.80 10.65 10.71ml

8 150.15 10.35 10.41ml

9 160.00 9.85 9.91ml

10 170.00 10.00 10.06ml

MEAN (X)

X x n (number of x)

103.7 10

10.47

∑

STANDARD DEVIATION

X X-x [x-x] (x-x)2

10.06ml -0.31 0.31 0.096111.82ml 1.45 1.45 2.102510.06ml -0.031 0.031 0.0009619.80ml -0.57 0.57 0.32497.04ml -3.33 3.33 11.088913.83ml 3.46 3.46 11.971610.71ml 0.34 0.34 0.115610.41ml 0.04 0.04 0.00169.91ml -0.46 0.46 0.211610.06ml -0.31 0.31 0.0961

∑ (x-x)2= 26.009

SOLUTION:

S = √∑(X-x)2/n-1

=√ 26.009/9 =√ 2.88 = 1.69

RELATIVE DEVIATION

%RDS = s/x * 100= 1.69/10.37=0.162=0.162*100=16.20%

RANGE OF PRECISION AND ACCURACY

TRIAL 1-3 TRIAL 4-6 TRIAL 7-9 TRIAL 100

2

4

6

8

10

12

14

16

Series 1Column1Series 3

V. DISCUSSION

In this study we used to identify the significance of calibration certainly in our course-Analytical Chemistry which was the basic foundation in our discipline.

Based on our further study, we do commit errors commonly and this error was subdivided; the two frequently commit are:

*INSTRUMENTAL ERROR*PERSONAL ERROR

Thus, this two usual error must be lessen to achieve precision and accuracy.

MEAN/AVERAGE/ XX=10.4

7X

10.06ml

11.82ml

10.06ml

9.80ml

7.04ml

13.83ml

10.71ml

10.41ml

9.91ml

10.06ml

WE THEREFORE GET ABOVE THE EXACT CALIBRATION SINCE NEARLY AT FIRST TRIAL WE DO GET HIGHER CALIBRATION AND THE FLOW OF THE TRIALS IS NOT CONSTANT .

STANDARD DEVIATIONS= 1.69

THIS MEANS THAT THIS VALUE IS THE VALUE THAT DENOTES TO HOW CLOSE THE SET OF NUMBERS ARE.

THIS VALUE WAS INFLUENCED MOST OF THE MASS GOT BEFORE CONVERTING IT TO VOLUME BECAUSE ACCORDING TO OUR OBSERVATION, THE TRIPLE BEAM BALANCE HAS ALSO A DEFECT WHILE IN USE, AND THIS WAS PRESENTED IN THE DIVERGING SET OF NUMBERS

RELATIVE DEVIATION%RSD=16.20%

RSD WAS DERIVED FROM DEVIDING THE STANDARD DEVIATION TO THE MEAN THEN MULTIPLY THE QUOTIENT TO 100 AS THE % SIGNIFIES.

THIS VALUE WAS KNOWN TO BE THE PERCENTAGE ERROR THAT YOU WILL COMMIT WHENEVER YOU USED THE PIPETTE THAT WAS CALIBRATE.

THIS PERCENT OF ERROR IS A “NO, NO, NO” IF YOU DESIRE PRECISION AND ACCURACY.

OTHER SIGNIFICANT AND USUALLY USED MEASURING GLASSWARES

BURETTE-like pipette is also significant in measuring discharge or collected liquid as it has a stopper for controlling it.

VOLUMETRIC AND ERLENMEYER FLASK-are both use for measuring large quantity of liquid thus they will also offer large error if its calibration is not correct.

THERMOMETER-its calibration ranges from 0OC to 100OC and it is very complex to solve some analysis if it has a failure particularly as it will present incorrect measurement. Such getting the density, temperature play a role in providing the solution, that’s why we need to assure those cases.

V. CONCLUSION

Precision and

accuracy

Error

VI. REFERENCES http://www.chemometry.com/Index/Calibratio

n.html Microsoft ® Encarta ® 2009. © 1993-2008

Microsoft Corporation http://www.idc-online.com/technical_referenc

es/pdfs/instrumentation/CALIBRATION%20OF%20INSTRUMENTS.pdf

http://www.idconline.com/.../instrumentation/calibration

Skoog, Douglas A.,et.al. Introduction to Analytical Chemistry, 8th edition,©2012

THANK YOU FOR ATTENTIVE LISTENING

PRESENTED BY;

AGUILAR, PRINCESS ALEN I.

BUMAGAT, GIANE CARLA C.

LUIS, ANA PATRICIA V.