This document provides an overview of analytical chemistry concepts including sampling, rounding off numbers, and statistical analysis. It discusses sampling heterogeneous and homogeneous samples, the different types of samples taken (gross, laboratory, analysis), and appropriate sampling tools for different materials like powders, bags, and biological fluids. It also covers rules for rounding numbers and key statistical concepts. Experimental errors are categorized as random, systematic, constant determinate, gross, and sampling errors. The presenter is M. Saleem Shahzad from the Chemistry Department providing a 5th semester presentation on these analytical chemistry topics.

1. ASSALAM-O-ALAIKUM
WELCOME
TO
ANALYTICAL
CHEMISTRY

2. NAME : M.SALEEM SHAHZAD
DEPARTMENT: CHEMISTRY
SEMESTER: 5th
PRESENTATION TOPICS: SAMPLING, ROUNDING OFF, STATISTICAL
ANALYSIS
LET’S START

3.  SAMPLING
 Sampling Is The Process Of Obtaining A Representative Sample (We Cannot Analyze The
Whole Thing!) • A Sample Is The Representative Of The Whole Bulk.

4.  SAMPLE MAY BE HOMOGENEOUS OR HETEROGENEOUS
Homogenous Sample:
A Grab Sample Is Often OK. For Instance, In Clinical Lab, Gross Sample (Blood, Urine) Can
Be Analyzed Directly As It Is Homogenous.

5.  HETEROGENEOUS SAMPLE
 Several Individual Samples Are Taken. E.G., Analyzing Average Protein Content Of Shipment Of Grains, One Has
To Collect Little Grain From Each Bag During Loading/Unloading Using A Sampling Spear (Sack Sampler) And
Combine To Obtain A Gross Sample.

6.  GROSS SAMPLE
Consists Of Several Portion Of The Material To Be Tested Laboratory Sample Consists Of A
Small Portion Of Gross Sample Made Homogenous Analysis Sample Is That Which Is
Actually Analyzed Gross Sample Laboratory Sample Analysis Sample (Few G To Kg) Bulk
Of Material (Few G) (A Drop Few Mg,)

7.  GRAB SAMPLE

8.  SAMPLING FROM BAGS
Simple Bag Sampling Spears (Sack Samplers) Are Most Commonly Used For Taking
Samples From Bags Because They Are Relatively Cheap And Sample Quickly. To Obtain A
Good Cross Section Of Sample, The Spear Should Be 40 To 45 Cm In Length. Tapered Type
Of Sampling Spears Penetrates Bags Easily.

9.  SAMPLING OF POWDER:
Small Particulate Materials Such As Powder Are Best Collected With A Sample
Thief. Sample Thief Allow Material To Be Collected Simultaneously From Several
Locations.

10.  BIOLOGICAL FLUIDS:
Timing For Biological Samples Is Important. E.G., Blood Composition Changes Before And
After Meal. Sampling After 12h Fasting Is Often Recommended. 24h Urine Collection Is
Better Than A Single Specimen. In Case Of Blood, A Grab Sample Is OK. Syringes Are Used
To Collect Blood Samples. Glass Or Plastic With Stainless Steel Needle Are Available.

11.  ROUNDING OFF:
RULES FOR ROUNDING
FANTASIES ABOUT FIVES
ADDITION AND SUBTRACTION
MULTIPLICATION AND DIVISION

12.  STATISTICALANALYSIS:
Another Very Important Stage In Any Analytical Method Of Analysis Is Evaluation Of
Results, Where Statistical Tests (I.E., Quantities That Describe A Distribution Of, Say,
Experimentally Measured Data) Are Always Carried Out To Determine Confidence In
Our Acquired Data

13.  KEY CONCEPTS:
 Accuracy
 Determinate errors
 Error analysis
 Indeterminate errors
 Mean (m)
 Median
 Precision
 Range
 Random Error
 Sample
 Sampling
 Sampling error
 Significant figures
 Standard deviation (s)
 Variance (s2)

14. TYPES OF EXPERIMENTAL ERRORS:
 Random (or indeterminate) errors
 Systematic (or determinate) errors
 Constant determinate error
 Gross errors

15.  Sampling Errors
Uncertainty In Measurements

16. ANY QUESTION?
REGARDING TO THESE TOPICS:

17. THANK YOU
BEST OF LUCK