analytical

QUALITY LAB WORK 

  • Good results 

  • Valid and accurate

  • Things rthat affect it - accuracy, precision, proper technique, cleanliness, reductio of erroneous data 

How to produce 

  • Proper lab technique

  • Proper weighing 

  • Ensuring equipment is calibrated 

  • Using procedures are regulated by the appropriate organizing body 

Organizing bodies

  • Provides guidelines and regulations 

  • Accuracy and precision are independent of another 

What to document 

  • Chemical names

  • Lot numbers 

  • Expiry date

  • Equipment numbers/identifier

  • Instrument settings 

  • Specific instrument information including column information 

  • Attribution to any work completed by your partner 

Uncertainty 

  • Relative and absolute 

  • Absolute uncertainty is the margin of uncertainty 

  • Relative uncertainty is the uncertainty associated with the sample size

  • Eg +/-0.01ml

Error

  • systematic , random, blunder 

  • Systematic- consistent error that can be determined and corrected 

  • Random - cannot be identified or corrected ; however improved technique can reduce the impact 

  • Blunder - accidental and significant technician errors

Balance location 

  • Store them in places that are free from draft, biration, uneven surface, free from dust water and chemical residues, temp fluctuations 

Weighing technique 

  • Direct measurements - place object directly on the balance 

  • Weigh by difference - take a measurement before and after to obtain an accurate final measurement 

Weighing vessels

  • Weigh boat, weighing vial 

  • Weigh paper 

Moving weighing vessels 

  • Never touch with your hand always use forceps, oils from hands can alter recording and results

  • Kim wipes are vessels to move 

Things to remember 

  • Always use the same balances to ensure accuracy 

  • No leaning on the benchtop 

  • Ensure all sides are closed when using the analytic balance




Marking on scietnifc glassware

  • ‘A’ refers to the quality of glassware

    • A is higher quality it is more accurate than ‘B’, tighter tolerance 

  • Number 7100 iso marking ; international stnards organization, some glassware refers to ISo number 

  • 25 +-3 = accurately messenger 25ml / +-3 is the margin of error

    • You would write on the paper 25 

  • TD = to deliver 

  • TC= to contain 

  • 20 degrees celsius is where its calibrated at 

  • B tolerance give by NIST 

  • We can calibrate a B to an a

MENISCUS 

  • Concave or convex 

  • Must be read at the bottom 

  • Must be read at a 90 degree angle to avoid parallax

PARALLAX

  • The deceptive change in the position of the object which happened bc of a change in position of the observer 

SCIENTIFIC GLASSWEAR

Beaker 

  • Used to create non accurate solutions holding solution heating and transferring 

  • Accuracy is low with respect to the graduation aproxx 5%

  • Not an idea piece of glassware to use to make an accurate solution 

Erlenmeyer flask/concial flash 

  • Used for recrystallizations ans well as tritrations due to the concial shape of their neck 

  • Accuracy associated with the flash is approx the same as a beaker 5%

  • Not ideal for transferring an accurate volume or creating an accurate solution 

Side arm flask 

  • Used for vacuum filtrations, more rapid filtration 

  • Allows tubing to be hooked to the side and attached to the vacuum source 

  • 5% accuracy 

Graduated cylinder 

  • Tiger accuracy of approx 1% for the graduation

  • Useful for transferring colmes when accuracy is not important 

Volumetric flask 

  • Calibrated to give you exactly what it says 

  • Do not heat 

  • Never rest upside down 

  • Used to make standard solutions 

General rules with glassware 

  • Inspect for cracked 

  • Show any to your instructor 

  • Dispose in glass waste not the grabage 

Powder transfer 

  • Wash you scoopula 2 times with tap water and once with DI water 

  • Dry scoopula with kimwhip *VERY IMPORTANT

  • Take only what you need EXCESS GOES TO WASTE 

  • Close lid of reagent

  • Clean scoopula 

QUANTITATIVE TRANSFER 

Making solution from a powder




  • Spelling pipet is interhchangable, aka pipette 

  • Uses:

    • Accurately transfer volume 

    • Accuracy will vary depending upon the type of pipet

    • General use is the same however there are key difercnes 

Volumetric/transfer Pipet

  • Delivers a set volume 

  • Considered to be a free drain pipet 

  • Calibrated to retain the extra solution that remains at the tip of the pipet 

  • Considered a TD - to deliver pipet 

Mohr/measuring pipet 

  • Delivers a variety if volumes 

  • Read to 2 decimal places 

  • 2 ways to use it to do the radiation 

  • Not considered free drain 

  • Numbers start before the tip, you have to stop the meniscus right at the 10ml mark, if you let it drain all the way there will be an over delivery 

Serological pipet /blowout pipet 

  • Delivers a variety of volumes 

  • Look very similar to a mohr pipet however are used dffernteky 

  • Serolohgical pipette java double rings at the top indicating tht i s a blowout pipet 


Mohr pipet

  • You can fill to 0 then go down three

  • Or fill it 7 and go down three 


****LEARNING FINE MOTOR SKILLS HANDLING PIPETTE AND TIREATION****



Blow out pipet

  • Double rungs indicate it requires a blowout 

  • Serologica lpipet not always blowout 

  • Only from 7-10 uou blow out 

Bulb usage

  • Dont hold pipet clse to the bottom, hold it close to the top ; more likely to breal when held at the bottom 

  • Never pipet out of a volumetreic flask, not safe, might not fit

Conditonong glassware

  • So nothing sticks when tranferign 

  • Replacing whatever is in it to the solution you want

  • Diluting the concentration 

Buret 

  • Used for titrations 

  • Allows for control of tiratn (solution contained iwthi the buret)

  • Allows for ocntrolled of deliver of liquid 

  • Round to 2 decimals places - also the Mohr pipet *******

  • Higher precision than pipets

  • Used in titrations predominantly 

Titration 

  • Takes conceratrion of a known colutionto to figure out unknown concentration of another solution 

  • Titrant - known solution

  • Analyte- unknown solution 

  • Make sure theres no bubble bc taking up space that should be liquor, take it out bubbles by opening and closic stopcock fast 

  • Dont fill overhead 

  • Dont leave funnel in buret 

  • Wrap hand around the back to control stopcock




  • Page 41 for SDS for analytical teqhcines 


TITRATION SETUP 

  • Buret 

  • Buret clip

  • Water squirt bottle 

  • Long stem funnel

  • Elermael flash 

  • Standard solution 

  • Solution to be standardized 

  • Indicator 


Tirtatio : chemical reaction when one regane is added in a controlled manner so tha the eact amount of reagent which reacts with an exact amount of a known manner

  • Processes of determine the aunty of a substance A by adding measured increments of substance B the titrant, with which it reacts until the exact chemical equivalence is chived 

2 possible siattio n

  • Situation 1: burett- contains a standard solution which you already know the exact concentration of 

  • Flask- contains a solution of an exact volume; without an exact concentration 

  • Situation 2: burette- contains a solution of unknown concentration 

  • Flask- contains a solution which has known weight 

End point 

  • An indicator which will change colors will visually tell you when you titration has come to a completion 

  • You will be watching for this change in colpur 

  • Equivalent point is when chemical are molar equivalent  

  • End point is visual = color change 

Titration steps

  • 1- fill burette with standar solution usuing funnel 

  • 2- read exact volume to the 0.01ml of the starting point 

  • 3- accurately transfer the solution that you are looking to determining the concentration of the flask using a voumteric pipette/or transfer an accurate weight if you are using a powdered chemical 

Indicator 

  • Do not forget to add a fe drops of idictaor to the flask solution of unknown concentration 

  • Should do titration 4 times, the first one is a trial run, dont care if its accurate, the whole purpose is so that you can see approximately where youll see the colour change and this helps speed up the real titration 

Nearing the end point 

  • Once you are about 10ml out you wil begin to add the tyrant in 1ml increments unti you begin to see a light colour change 

  • You will carefully rinse rhe tio of the buret off with water to ensure that all of the titrants is being removed 

DENSITY

  • Mass divided by the volume 

CALIBRATION CURVE

  • Shows the response of an analytical method to known quantities of analyte 

  • Used to assist in quantitative analysis 

  • Qunatiarive analysis is defined as the measurement of how much of a chemical substance is present 

  • What is required 

  • Standard solutions - known concentrations

  • External standard solutions 

How to do quantitative analysis 

  • create= creator a set of standard solutions 

  • Idenfifty = identify the appropriate instrument require to obtain a response 

  • run= run the standards and your unknown sample to obtain a response 

Standard solutions 

  • Done by creating a known STOCK solution using an acuralrty weighted material and diluting it to exactly the correct volume 

  • After this initial stock solution is created you can create a sub-solution called DILUTIONS of varying known concentrations 

Instrument choice 

  • Depemdinig upon the sample that you are testing there are many options the marketing for instruments 

Running solutions 

  • Once you have determined what nstruemtns youare going to use to obtain your response you will then run your standrsa and your unknown to obtain indivufla repsinses for each 

  • Very important to always run your unknown with your standards 

What to plot 

  • Concentration is plotted as your independent variable on the x-axis 

  • Response is plotted as you dependent variable on the y-axis 

Hand drawn curves

  • Use graph paper, label, approaote scale, draw scale, position your points and connect the dots

Data interpretation 

  • Do not plot your unknown value on the graph

  • To obtain an approximation you can draw a line from the response value obtained when you ran unknown solution to the concentration 

Equation of a straight line









WHMIS

  • Workplace hazardous materials information systems 

  • Goals 

  • Reduce injury, disease, death 


Main compoenets 

  • Hazard identification 

  • Product classification 

  • Labelling

  • GHS: global harmonized system 

  • Woker education and training 

  • Material safety data sheet 

GHS

  • Produced by the united nations 

  • Standardizes how products are classified and handled

  • Requires standardized testing for classification of hazardous pridcts, stadnaesdsized symbols, labels and information supplied on SDS

  • Ensures consistency from country to country 

Hazard classes

  • Physical (oxidizing, corrosive, flammable), health (skin corrosion, carcinogencity), and environmental (hazardous to aquatic or ozone layer)


WHMIS does not cover

  • Explosives (defined in the explosibves act)

  • Pestciddes - defined in the pest control products act 

  • Consumer products - defined in the canada consumer product safet act 

Pictorgrams 

  • Graphic representation to show the user what hazards is present pictorgram is a red diamon with a symbol inside 

  • These pictograms are assigned to specific hazards 


Workplace labels 

  • Requirements 

  • Produced in the workplace 

  • Transfers to another container 

  • Supplier label lost or unreadable

  • Exceptions 

  • Substance is poured into a container and is going to be used immediately 

SDS

  • Descroebs the properties and potential hazards of the material 

  • Helsp understand and be knowledgeable on the chemicals being handled 

  • Prepared by the manifactrure or chemical supplier 

Requirements 

  • Be in both english and french 

  • Follow 16 part format in standardized order 

  • Include chemical classification 

  • Include label elements 

  • Include pictorgrams 

  • SOLUTIONS


    • Mixture of 2 or more substances 

    • Solute- the substance in lesser amount 

    • Solvent - the substance in greater amount

    • Concentration - how much solut is contained within the known amount of solution or solvent 

    DILUTION 

    • Prepared from a more concentrated solution 

    • 1 can of orange juice to 3 parts water 

    • 4 parts total 

    • Fraction is ¼

    • Denominator represent the total amount not just the amount required to dilute 

    Representation as a dilution factor

    • You can find DF

    • Totalt volume of solution/volume of sample

    • DF= 4 cans of total/1 can of juice

    • DF= 4

    Volumetric dilutions

    • How would we do a 1 in 4 dilution volumetrically

    • Obtain a 4ml volumetric flask, add 1 ml of juice and top with water so the meniscus is on the line 

    • We do not add 3 additional mL’s as the volumes are not additive, you must not assume that they are as the juice will take up “space”

    SERIAL DILUTIONS 

    • Stepwise series of dilution of a solution 

    • They are found in biological applications including, but not limited to biochemistry and microbiology

    • Do not always require the use of volumetric flask 

    • They allow you to make a stock solution less concentrated 

    How to complete a serial dilution 

    • You will take a set volume from your stock and add it to the next tube 

    • To the 1ml of stock added from the first tube you will then add 9 ml of water to tube B

    • From tube B you will take 1mL and add it to tube C  along with 9 additional mL of water 

    • You continue this until you have the concentration you are looking for 

    • Always using the previous solution as the initial or stock solution 

    Parallel dilutions

    • Reminder: never pipet directly from the volumtetric flask always pour into a beaker first 

    EQUATION

    • This equation allows for you to determine the concentration of a less concentrated solution made from a more concentrated solution 

    • The principle is basd upon a ration; therefore, the units MUST be the same

    • C1 = concentration of initial solution/more concentrated solution

    • V1= volume of the aliquot that you will be adding to the less concentrated solition (how much of the initial solution you will need)

    • C2=  concentration of the new solution 

    • V2= volume of the solution that the new solution will be made into 



    pH

    • Finger to corntrol pipette

    • Non dominant hand to control buret

    • Tare balance 

    • Calibrate pH meter 

    What i ph 

    • Measure of hydrogen ion concentration in solution 

    • P stands for power, power of hydrogen 

    • Solution with high H have low pH meaning they are acid 

    • With low H have high pH meaning its basic 

    pH ewuagion 

    • pH = -log[H+] concentration 

    pH scale

    • Rangers from 0-14 

    • If lower than 7 its gonna be acidic 

    What does it mean to be acid

    • An acid will donate hydrogen ions

    • When an acid is dislved in wate the balance between the hydrogen ions and hydroxide ions is shifted 

    • More hydrogen iosn than hydroxide ion s

    • This makes the solution acidic 

    What does it mean to be base

    • Inverse of acid 

    • Take the hydrogen ions in to increase hydroxide ions 

    pH and its scale 

    • Is a logarithmic scale 

    • A strongly acidi solution may have one hundred million rmes mre hydrogen ions than strongly basic solution 

    • Due to the sie of these numbr we use a lograthrimthimh scale to make the number more manageable 

    • CONC or concentration written were taking it straight from the bottle 

    • Glacial acetic acid just means concentaed, striaght from the bottle 

    Why do we care in pH 

    • Pays important tole on industry 

    • Some places operate at a certain pH 

    • Ensure we get the apporaytr moisture value 

    • In food we need to know 

    • In biological processes 

    • It can alter the ecosystem 

    pH indicator 

    • Phenolthphaelin 

    • Red cabage changes colour - universal indicator bc it allows you to go thru the whole scale, turmeric and poinsettias 

    • pH test paper - introduces a source of error 

    • Exact ph - pH meter, the most precise - select for hydrogen compared to that in the reference electrode 

    • Bulb has a permeable surface to allow hydrogen ions to diffuse - boundary area, gell permeable boundary area, only selected for hydrogen ions 

    • Wait for stabilixation to allow hydrogen ions time to diffuse 

    • Need to calibrate it using buffers

    • Have to calibrate it everytime you use it, sometimes before every reading, depends on what your reading

    • Might have to calibrate fot evey thing you test to ensure you get the mos accurate reading 

    • SOP - tsnadaer operating procedure 

    pH meter

    • Wil be the most precis method to determin the pH of a solution 

    • Measuring teh electrical potential difference between teh reference electrode and a pH electrode 

    • Electrical potential is converted to pH reading

    • Require a regular calibration with reference standards

    • Must be kept clean and bulb protected due to delciated nature of it 

    Junction potential 

    • Is the voltage difference present at the interface between 2 dissimilar electrolyte solutions 

    • Develop bc oppositvely charged ions often have differcent mobilties 



    INTRODUCTION TO SPECTROSCOPY

    • Electromagnetic radiation 

    • Visible light, x-ray, mircowaves and radio 

    • Falls within the electromagnetic spectrum 

    Visible region 

    • Extednds from 380 nm to 780 nm

    • Located between the ultraviolet and infrared regions 

    SPECTROSCOPY

    • Dispersion of an object's light into its components colours 

    • Interaction of electromagnetic radiation with matter gives riase to electronic excitations 

    • Light properties are characterized with wavelengths and frequcnies 

    How do we see colour

    • Surface of an object will reflect teh soem colours while absorbing all others 

    Sample cuvette 

    • Different instruments will requires difference sample cuvettes 

    • Plastic quartz or tube-like cells 

    • Avoid touching with your fingers 

    • Handle with kim wipes to avoid leaving marks on the surface 

    Data analysis 

    • The output generated by the Spec, is an absorbance value 

    • It exploits the principle that the absorbance is direedctly proportional to the concentration of the solution 

    • Standard and samples must be run using the same wavelengths 

    • Wavelengths is specific for that chemical 

    Colorimetric analysis 

    • Spectrophotmetric analysis utilzes a law which allows us to be able to determine the concentration of a solution from the absorbance measurements 

    • There are few ways which you can do this: proportionality, graphing, beers law

    Graphing 

    • Requires the presence of several stadrdn solutions which provides us with the concentration and absorbance 

    • This uses the principles of beers law - that the cocnetation and absorbance are proportional 

    • Absorbance = e L c

    • You will then plot the concentration against absorbance 

    • Using the ewution of the line you can determine the concentration 


    ROOT CAUSE ANALYSIS (RCA)

    • Systematic process for identidfying the root cause of problems or events 

    • Helps creative approach to be able to respond to issues such as what, how, why 

    PRINCIPLES

    • Corrective measures of root causes rather than just treating symptoms 

    • There could be more than one root cause

    • Uses systematic process where evidence is used to come to the conclusions 

    • Why the situation happened not who caused it 

    Application 

    • Major accidents, everday incidetns, human errors, minor=near misses

    GENERALIZED METHOD

    • define= define the problem

    • Gather = gather evidcne and data required 

    • Identify = identify all sources/areas of concern

    • determine= determine root causes

    • Identify = identify/sugget recommendations to avoid another incident from happening 

    • implement= implement the recommendation 

    5S METHOD 

    • Developed in japan 

    • Used to streamline processes and eliminate time waste 

    • Has basis in manufacturing processes, but the theory can be applied across many ideologies 

    • Focuses on putting everything where it belongs and keeping the workplace clean 

    • Sort, set in order, shine, standardize, sustain 

    BENEFITS 

    • Reduction in cost 

    • Higher quality increased in prodcutiviey of employers

    • Increased employee satisfaction and engagement 

    • Increase in safety 

    SORT 

    • Purpose? Frequency of use?

    • Application of use? Job usage?

    • Do we need it ?

    SET IN ORDER

    • Who uses with iten and when are they used?

    • Which item is regularly used?

    • Is there a way to organize them ?

    • Is there a place to put them which would help with “flow”?

    SHINE

    • Cleaning up the workplace 

    • Regular maintenance and calibrations 

    STANDARDIZE

    • Standardiizing helps systemize everything 

    • Turns one-time efforts into habits 

    • For ex: assign regular tasks, creates schedules, posts instructions to ensure routine activities take place 

    SUSTAIN 

    • Once everything is streamlines it must remain that way 

    SAFETY 

    • Some consider it to be the 6th S