QUANTITATIVE ANALYSIS & BASIC TOOLS MISS NOORULNAJWA DIYANA YAACOB School of Bioprocess Engineering University Malaysia Perlis 02600, Kangar Perlis 6 January 2011

the particular problem  your expertise  the apparatus or equipment available.  The analyst should be involved in every step.

 Before we begin defining the problem for an analysis procedure, we must have some information: 1)Who is the client (EPA, engineers) 2)The purpose of analysis 3)What type of sample to be analyzed

 Once the problem is defined, next question: 1) How sample is to be obtained 2) How much is needed 3) What separation may be required to eliminate interference

 Accuracy/precision needed  Economic factor  Speed  Complexity of the sample and the number of component in the sample

 The material to be analyzed- solids, liquids and gases  Homogeneous or heterogeneous in composition  Usually, in analysis, a simple “grab sample” will taken at random.  If the sample is large, the gross sampling is needed  The gross sample must be reduced in sized to obtain laboratory sample

Soil 1kg Soil 1kg Soil 1kg Soil 1kg Soil 1kg Soil 1kg Soil 1kg Soil 1kg Soil 1kg Soil 1kg Soil 1kg Soil 1kg Soil sample for laboratory test 50gram GROSS SAMPLING

 Some precautions should be taken during handling and storing samples to prevent or minimize contamination, loss, decomposition or matrix change  We must prevent contamination or alteration of the sample by 1)Light 2)Atmosphere 3)Container

 Step1: Measure the amount being analyzed…Replicate samples are taken for analysis (WHY??)

 1)to obtain statistical data on the precision of the analysis  2)to provide more reliable results

 Step2: Sample pretreatment Example: The organic materials sample are analyzed for inorganic constituents The organic constituent may be destroyed by dry ashing HOW??

 The organic materials is slowly combusted in a furnace at degrees  Organic material escape out, leaving behind an inorganic residue which is soluble in dilute acid  Aim of unwanted constituent that make up the whole sample

 Step3: Optimizing sample condition  Aim of step 3 is to prepare sample for the next stage of analysis (the separation or measurement step)  The solution condition is optimized..HOW???

 For example, the pH may have to adjusted or reagent is added to mask interference from other constituent  The analyte may have to be reacted with a reagent to convert it to a form suitable for measurement or separation

 Why conduct chemical separation? 1)To eliminate interference 2)To provide suitable selectivity in the measurement 3)To preconcentrate the analyte for more sensitive or accurate measurement

 Methods of carrying out the measurements: 1)Gravimetric analysis 2)Volumetric analysis 3)Instrumental analysis

 Calibration and measurement  y = mx + b  y – measured signal  x – concentration  Calculations  Calculate x from value of y for analyte  Statistics

Modern balances are electronic. They still compare one mass against another since they are calibrated with a known mass. Common balances are sensitive to 0.1 mg. Fig Electronic analytical balance.

Fig. 2.2 Volumetric flask. Volumetric flasks are calibrated to contain an accurate volume. See the inside back cover of the text for tolerances of Class A volumetric glassware.

Erlemenyer flask.

Fig Transfer or volumetric pipettes. Volumetric pipettes accurately deliver a fixed volume.

Fig Measuring pipets. Measuring pipets are straight-bore pipets marked at different volumes. They are less accurate than volumetric pipets. Measuring pipets are straight-bore pipets marked at different volumes. They are less accurate than volumetric pipets.

Fig Hamilton microliter syringe. Syringe precisely deliver microliter volumes. They are commonly used to introduce samples into a gas chromatograph. Syringe precisely deliver microliter volumes. They are commonly used to introduce samples into a gas chromatograph.

Fig. 2.6 Single-channel and multichannel digital displacement pipets and microwell plates. These syringe pipets can reproducibly deliver a selected volume. They come in fixed and variable volumes. The plastic tips are disposable. These syringe pipets can reproducibly deliver a selected volume. They come in fixed and variable volumes. The plastic tips are disposable.

Fig Measuring cylinder.

Fig Wash botltles: (a) polyethylene, squeeze type; (b) glass, blow type. Use these for quantitative transfer of precipitates and solutions, and for washing precipitates. Use these for quantitative transfer of precipitates and solutions, and for washing precipitates.

 Next topic: Basic statistics

 Thank you  QUIZ...

 1.What is quantitative analysis  2. State the phases of carrying out tests using instrumentation for quantitative analysis in the right order