Zandra's anatomy

The beyond ultimate personality survey

              [beyond basics]

name: Zandra Flores

age: 19

height: 5"6

weight: 7 stone

eye color: Brown

nationality: British/Filipino

natural hair color: Dark Brown

hair style: Short hair

do you dye your hair: Used to

do you wear contacts/glasses: Glasses

schooling: University desired

occupation: Biomedical Science Student

job: Part-time catering assistant

tattoos: None

piercings: Earrings

tattoos you want: None, henna pede pa.

piercings you want: Ala na akong gusto sa piercing piercing kung saan man yan :))

religion you were raised under: Roman Catholic

religion you are now if any: Roman Catholic pa rin

zodiac sign: Libra

boyfriend/girlfriend? Kaizer Kevin P. Martin

siblings? Erica, Rochelle, Mark         

[beyond intrests]

what do you do for fun? Be with my bf and friends

any hobbies? singing, drawing, baking, dancing, playing sports, reading, knitting, painting, chatting, browsing

do you collect anything? Uu! Mga remembrance ng kung anong makakapagpaalala sakin ng isang event.

what do you do when you hang with friends? Magkwentuhan, magcine, kumain, maglaro ng tongits.

do you watch tv? No, very often actually.

do you listen to music? Yes.

fav bands? Flipcydaz

fav songs? Love songs, mga ballad, rap, RnB, rock music.

do you watch movies? Yes, ofcourse. When I hang out with friends lang kaso.

fav movies? marami naman eh

prefer to rent or go to theater? Both

fav actors? John Lloyd Cruz

fav actresses? Bea Alonzo

do you watch cartoons? Yes

fav cartoons? Disney land animations

do you like anime? Yes

what are your favs? Naruto!

do you like sports? Yes what are your

fav sports? Tennis, Chess, Badminton, Basketball, Volleyball, Swimming, Football

do you read? Yes, a lot

fav books? Science-fiction

do you play video games? No

any favorites? None how often

do you go on the internet? Everyday, everyminute, hahahaha

any fav websites? Friendster, multiply, ammm... yun lang?                

[beyond love]

do you have a boyfriend/girlfriend/lover/husband/wife? Boyfriend

whats their name? Kaizer Kevin Martin

how did you meet? Sa housewarming kena ate Gayle nung Nov. 24, 2004

how long have you been together? 4 years , 9 days, 4 hours, 43 minutes, and 21 seconds.

how long do you want it to last? --------

what do you see in your future? TO become a professional worker, still looking good, earning enough money with a fine house, fine car, fine and loving husband, and with children. Nakow!

how far have you gone with them? -------

are you in love with them? Mmhhh.... hulaan mo na lang....

best memories with them? Every moment I spent with him

what do you love most about them? Every bit about him

do you trust them? Yes, with all my heart

do you think you will some day marry them? ---------           

[beyond friends]

do you have a best friend? Marami, super dami.

whats their name: Jem, Ate Yen, Emma, Charlotte, Fiona, Gareth, Ate Joy, Charmie,  Jerryl, and Catherine

who are you close friends: Cecille, Krizelle, Jovi, Charben, Elan, Kalvin, Krizia, Kuya Jonas, Kuya Jephoy, Danica, Ate Gayle many more...

do you have any online friends: Kadami eh...

who are they: Madami nga eh

who are your closest online friends: mmhh.... si James Lenihan (kaklase ko nung elem.)

what friends can you talk to about anything: Jem, Ate Joy, and Jerryl

what friends do you fight with a lot: Si Jem ^_^

what friends are most like you: I dunno

do you have many friends or just a few? Many friends

do you want more friends? La naman mawawala sakin eh

what do you like to do with your friends? Hang-out and have fun

where do you like to go with your friends? Anywhere basta ba libre nila ako eh... Hahahhaa...          

[beyond spiritual]

do you have a religion? Yes

what is it? Roman Catholic

believe in god/gods and or goddess/goddesses? God

do you believe in heaven/hell? Both

reincarnation? Yes spirits/ghosts? Both

karma? Yes

the law of 3? Mmhh... ano kaya toh?

the 10 commandments? I believe it was made to restrict us from doing bad from good. It is basically for our disciplinary actions.

angels? Yes how long have you believed in what you believe currently? Nung simulang nagkaisip ako...

do you believe in fairies? No. Love to collect figurines ng fairies though. Display sa bahay.

the existence of a devil? Yes

an afterlife? Yes

what do you think of other religions? Being different couldn't be controlled and based on my knowledge from the comparison of one religion to another. It is true that other religion can be more strict than the other. Somehow, it is able to discipline more the actions of an individual. The restriction of doing bad is higher in percentage.

do you think your religion/belief is the RIGHT one? There is nothing wrong with believing what we believe in right now. As long as I am not doing anything wrong in the senses of hurting someone else. Then, I believe that my religion is the right one for me.

[beyond family]

do you get along with your parents? Yes, at times no.

are they still married? Yes.

do you listen to what they say? Yes, pero there's a time when I become so defensive when getting told off. You know, the pride comes before being able to understand them.

are you close with them? Yes

are they good parents? Yes, as much as they could give, they would do anything in the world to make us a better person. They hurt us in such a way to realize our wrong doing. They've given us everything they are able to provide.

any siblings? Yes

how old are they? 21, 14, and 13 do you get along with them? There's some times na hindi... -----------

[beyond favorites]

fav colors: Pink

fav foods: Mtm.

fav drinks: Chocolate drink, and apple juice

fav scents: My naney's scent.

fav time of day: Ala naman

fav day of the week: Ala naman din

fav season: Holiday season.. Kasi nakakasama ko sya...

fav month: December, January and October (birthday kasi naman na dalawa, sabay kami)

fav holiday: Christmas

fav restaurant: Pizza Hut (yung unang restaurant na pinuntahan namin as gf/bf, and Nandos)

fav stores: Marami

fav brands: D&G, Oasis, Levis

fav magazines: La naman... Anything basta mabasa

fav piece of clothings: Marami

fav piece of jewelry: My naney's gift for me which is a set of jewellery (2 rings, 2 bracelets and a necklace), my mom's regalo na necklace, ate joy's regalo na necklace, and Tita Cora's regalo na necklace sakin.          

[beyond "are you..."]

creative? Yes

logical? Yes

rational? Yes, minsan hindi!

melodramatic? Hay nakoo... Sinabi mo paaa

crazy? uu

nice? Uu, kung mabait sila sakin mabait ako sa kanila pero magmaldita sila sakin. Mas maldita ako sa kanila!

bitchy? Hay nako same dito. Ayaw na ayaw kong nakakarinig ng kung ano man tungkol sakin kasi ito lang siguro masasabi ko "kung may sasabihin nila eh sabihin nila sa harap ko dahil mas gustong kong magpakatotoo sila kaysa makipagplastican pa sila, kung ano man ang mali edi e-settle agad." Ayaw na ayaw ko lang sa di honest na tao

happy? Oo syempre.

sad? No.

mean? Sabi nila mabait ako sa mabait pero mas masama pa ako sa masama sakin

loving? mmhhh.... I think...

romantic? Yes, very much. Pero, itong romantic ko na to eh.. Ginagawa ko lang sa mga special na tao. At sa iisa lang. Kaya special na special talga.

friendly? Super!

unique? Mmhhh... Di ako makakapagsabi nito

dark? No. Light brown ang skin tone ko eh.

interesting? sabi nila sakin uu. Marami daw akong katangian na talga daw unique sa iisang babae. Kaya they wanted to get to know me.

cynical? hahaha... I think so

hateful? Kung hate nila ako mas hate ko sila. Yun lang.

promiscuous? dalawa meaning nito eh... hahahaha... Kung tungkol sa relationships eh noh. Kung sa ugali eh... Yes, di ako mapili.

stoned? No.

drunk? No.

fake? I tried to be pero di nagwowork eh.. hahaha... Kahit sa anong palabas ko sa kanila halata pa rin ang totoo kong nararamdaman.

real? Yes! without a doubt. You only get what you will receive nga.

truthful? uu...          

[beyond other quetions]

do you love yourself? Yes, ofcourse naman. Before you can love others you have to love yourself first.

do you love your life? Yes, I am contented with what I got right now.

do you have any pets? No

do you want more pets? I want a dog someday...

fav animal? Dog do you care what people think of you? Yes, ofcourse. Uncontrollably.

do you follow trends? Yes

what do you value most in life? My love ones

what do you enjoy most in life? Being with my loved ones

do you value your individuality? Yes ofcourse, I love being different and I love to stand out from a crowd. I love being in the centre of attraction. I love being unique and basically just being me.

do you like shopping? Love not like... Pero ofcourse with limits... I need to handle my money well

do you love money? Yes, the world is revolving around money. we need money to be able to survive in this world. We need to control the money and not let the money have a control over us.

do you wear prefume/cologne/body spray? yes, perfume

do you shower/bath? Both,

how often? shower daily/every other day, take a bath frequently.

do you paint your nails? No, occasionally

what colors? What matches my outfit

what kind of clothes do you wear? Different style that matches the event that I  goes to... if you had to label yourself

what would you say you are? prep/punk/goth,etc Natural!

do you drink coffee? No

do you drink soda? Yes, very often pag alang choice na uminom ng tubig.

tea? Yes, at times.

do you use lotion? Yes.

fav flowers? Rose

do you like the sims? Yes, nearly got addicted to playing it.

favorite gem stone? My birth stone. Opal.

do you like candles? Yes, specially sa birthday ko.. It changes the ambience dramatically eh.

do you eat breakfast? Yes

what are your views on abortion? Against

gun control? Hay nako... Disappointed dahil di naman nacocontrol ng government ang ownership ng gun sa mga tao eh. Mas lalong dumadaming crime dahil dito.

peace? At the moment, marami pa rin kaguluhan ngyayari!

george w. bush? Wala!

the war? Against! Wlang dahilan! It just decrease the population no. ng tao sa mundo.

where do you want to go/countries you want to see? All around the world (Nice places)

what do you want to do before you die? All the things I wanted to do.

are there any celebrities you'd like to kill? Hahahaha....

who and who would you kill them? Hahahhahaaha.....

how easily do you trust people? Quite easy pero, I analyze muna very carefully. I am more concerned with the history of that one person. I take into account the views of other people about that one person unless I know them totally my self.

do you like people? Yes...

are you popular? I can be popular when I want to I guess

how many dvds do you own? I own one dvd, gift ng honey ko... Ayun eh...

cds? A lot.

do you like horror movies? No!

any favorites? Wala!

have you ever had braces? Yes how often

do you brush your teeth? twice a day. do you floss? No.

are you afraid of needles? Yes

when are you getting your next/first/any tattoos? None

when are you getting your next/first/any piercing? None

do you think tattoos are sexy? No tattoos

do you think piercings are sexy? sa earss ko? Uu naman syempers! hahahaha

are you addicted to surveys? lol No, not at all.. Ngayon lang ako gumawa ng dire-diretsong survey dahil sa pahinga na kailangan ko and to kill time. ^_^

SPECTROPHOTOMETRY (due date: 09/11/07)

SPECTROPHOTOMETRY

Introduction:

A spectrophotometer is commonly used in analytical laboratories to measure the concentration of a certain solution. 0.

<!--[if !vml]--><!--[endif]-->

It works by shining a light of a certain wavelength generated by a tungsten lamp through an absorption cell (cuvette). The light being passed through a monochromator provides the desired section of the ERE (Electromagnetic Radiant Energy) spectrum that is to be used for measurements. The absorption happens by the normal existence of the atoms and molecules in a solution in a ground energy level. So, whenever ERE is absorbed exactly equal to the energy gap ∆E, an electron is promoted from the lowest possible energy (ground) state to a higher energy (excited) state. This energy is provided by the ultraviolet (UV), visible light (vis) and infra-red (IR) regions of the spectrum. The absorption by the medium reduces the intensity of light that emerged from the lamp. Therefore, the transmitted light is detected depending on the energy level of a compound and a certain value of absorbance is obtained. The narrow slits are used to improve the chromatic purity and reduce the bandwidth of the light to obtain accurate data.

Overall, there are three factors that should be taken into consideration for light absorption.

<!--[if !supportLists]-->·         <!--[endif]-->Wavelength, λ – the distance between repeating segments of a wave

<!--[if !supportLists]-->·         <!--[endif]-->Amplitude, A - the maximum height of the wave

<!--[if !supportLists]-->·         <!--[endif]-->Frequency, v -  the number of oscillations per second

The spectrophotometer determines the concentration of an unknown solution using a calibration graph. Standard solution with known concentration is used that are similar with whatever is actually being measured is important. The calibration technique is applied to test and adjust the spectrophotometer to determine the relationship of the unknown solution with the standard solution.

Aim:

The main aim for this experiment is to become familiar with the concept of a light spectrophotometer. 

Objectives:

The purpose of this experiment is to determine the concentration of cytochrome c (cyt c) solution by comparing its light absorption with the light absorption of a standard 0.1 mg/ml solution. The requirements are to:

<!--[if !supportLists]-->·         <!--[endif]-->Plot a spectrum of light absorption against wavelength for cyt c

<!--[if !supportLists]-->·         <!--[endif]-->Prepare a series of cyt c standard solutions of known concentration and plot a calibration graph of light absorbance against concentration

<!--[if !supportLists]-->·         <!--[endif]-->Measure the concentration of a solution of cyt c of unknown concentration

Materials:

<!--[if !supportLists]-->·         <!--[endif]-->Spectrophotometer

<!--[if !supportLists]-->·         <!--[endif]-->7 Cuvettes

<!--[if !supportLists]-->·         <!--[endif]-->De-ionized water

<!--[if !supportLists]-->·         <!--[endif]-->0.1 mg/ml cyt c solution (ml)

<!--[if !supportLists]-->·         <!--[endif]-->Unknown (X) cyt c solution

<!--[if !supportLists]-->·         <!--[endif]-->5 ml pipette

Methods:

<!--[if !supportLists]-->1.       <!--[endif]-->Determination of wavelength of peak absorbance

Firstly, the spectrophotometer was set to 380 nm.

<!--[if !supportLists]-->·         <!--[endif]-->Repeated process - Then, the meter was set to read exactly 100% absorbance as the cuvette containing 3 ml dH­­₂O (reference cuvette) was in the chamber. All the cuvettes was kept clean and handled only on their rough sides due to the reason that the light was passed through the smooth sides.  The reference cuvette was replaced with a cuvette filled half way with 0.1 mg/ml cyt c solution. The absorbance value of the 0.1 mg/ml cyt c solution on the meter was then recorded.

The wavelength of the spectrophotometer was re-set to 385 nm. The procedure above was repeated until the wavelength at max is determined.

<!--[if !supportLists]-->2.       <!--[endif]-->Calibration graph of the unknowns

Four dilution stock of 0.1 mg/ml cyt c solution was made and labelled in universals using a 5 ml pipette. Four cuvettes were filled with the four different stock solutions that were made. The absorbance of each solution of each of the solutions made and the undiluted stock solution was measured at the wavelength of maximum absorbance which was 410 nm. Finally, the cuvette was filled with water and the absorbance was determined.  It was to see whether the cuvettes differ in amount of light transmitted.  A line graph was obtained.

<!--[if !supportLists]-->3.       <!--[endif]-->Determination of unknown cyt c concentration

A cuvette was filled with the cyt c solution X and the absorbance was measured at the same wavelength that was used above (410 nm).  The concentration of the unknown was estimated by extrapolating the absorbance value obtained by the solution X on the calibration graph.

Results:

Table 1 related to graph 1: The wavelength determination of peak absorbance of 0.1 cyt c mg/ml solution

Wavelength (nm)	Absorbance (ABS)
380	0.231
385	0.268
390	0.322
395	0.417
400	0.527
405	0.627
410	0.635
415	0.525
420	0.368

The wavelength value of 410 nm was used to measure the concentration of an unknown cyt c sample because it is the peak wavelength value that the molecules in the solution absorb best.

Table 2 related to graph 2: The calibration graph of unknowns

Cell Number	1	2	3	4	5
0.1 mg/ml cyt c solution (ml)	1	2	3	4	5
De-ionised water	4	3	2	1	0
Absorbance (ABS)	0.119	0.247	0.394	0.493	0.635
Final concentration of cyt c (mg/ml)	0.02	0.04	0.06	0.08	0.10

The absorbance value of the unknown cyt c solution (X) was 0.157. Therefore, by extrapolating this value on the calibration graph, the value of the concentration of solution X is approximately 0.023 mg/ml.

Discussion:

The wavelength I chose to measure the concentration of an unknown cyt c sample is 410 nm as this is the value that the molecules in the solution absorb best.

On graph 1, it shows that the maximum absorbance is 409 nm and not 410 nm. Then looking at graph 2, I believe that my sample obeys the Beer-Lambert for the reason that the absorption values of the solutions are directly proportional to the concentration of the solutions. The r-squared is 0.997 which indicates that the results obtained are effective. Therefore, this shows that my results are reliable enough to be taken into consideration of determining the concentration of cytochrome c.

The concentration was calculated as shown below that was needed for the graph:

5 x 0.1 = 0.5         0.5 / 5 = 0.10

4 x 0.1 = 0.4         0.4 / 5 = 0.08

3 x 0.1 = 0.3         0.3 / 5 = 0.06

2 x 0.1 = 0.2         0.2 / 5 = 0.04

1 x 0.1 = 0.1         0.1 / 5 = 0.02

I calculated below the approximate percentage error of the determination to find out whether my instrument reading is accurate to +/- 0.02 absorbance units.

0.18/0.16 x 100 % = 111%

0.14/0.16 x 100 % = 89 %

111 – 89 = ± 11 %

This shows that the percentage error in determining the measurement of the concentration of each sample is about 11%.  A common possible cause for this is due to human error. This could be because of the poor performance while carrying out the experiment such as, holding the cuvette on the smooth side where the light penetrated through instead of the rough side. The reason for this is that the moist (sweat production) from our fingers or the dead skin skills can attach to the cuvette might have had a slight effect on the absorption of ERE which lead to anomalous results. Another possible source of the error could be that the instrument itself has a slight change in its detection system sensitivity.

Lastly, to minimize or avoid such errors mentioned above: more repetition can be made so, that the mean can be used for the calculation which, results to a more reliable results; more concentration can be used to show a wider viewpoint of the data; and the use of a double-beam spectrophotometer to improve the accuracy of the given value for the absorbance of ERE by the sample.

References:

Lab Math – A handbook of measurements, calculations, and other quantitative skills for use at the bench by Dany Spencer Adamas.

Practical skills of biomolecular sciences (third edition) by Rob Reed, David Holmes, Jonathan Weyers, and Allan Jones.

Micropipette and pH write-up (due date: 09/11/07)

GENERAL LABORATORY METHODS I

Introduction:

The air and positive displacement pipettes are the two basic types of micropipettes used for measuring and dispensing liquids in a biomedical science laboratory. It is to perform qualitative and quantitative analyses on biological matters as it is adjustable and can be pre-set in a fixed volume. The air displacement micropipettes are the common use for routine work with dilute aqueous solutions. It operates on the principle of positive piston displacement which gives high accuracy and precision in volumetric measurements. An example is the Gilson pipette which was used during the experiment. On the other hand, the positive displacement micropipettes are used for non-standard applications. It is for the reason that it includes the dispensing of dense, glutinous or volatile fluid. It is also used for molecular genetics such as the PCR, whereby, an air displacement pipette is not advisable as there is a possibility of aerosols being created which could result to errors.

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Most organization of a biological and chemical matter is affected by the pH. First of all, pH means “the negative of the log of the H which stands for the concentration of protons”.

pH = -log₁₀[H⁺]

It is the measure of hydrogen ions (H⁺) in a solution whether it can be classified as an alkaline or an acidic substance. The pH is considered as an alkali if the pH is greater than 7 while, if it is less than 7 it is considered as an acid. At certain temperature, water is at pH 7/neutral.

There are some factors that affect the [H⁺] of an aqueous solution:

• Ionisation (dissociation) of water:

Dissociation of water, K_w, is enhanced as temperature increase. So, the pH of H₂O increases slightly therefore, it is considered as a weak acid.

H₂O      H⁺ + OH^-

In reversible reaction, equal amounts of hydrogen and hydroxyl ions are being liberated.

So, K_w = [H⁺][OH^-]

• Dissociation of acids:

H-A      H⁺ + A^-

As the acid dissociates, this increases the hydrogen ions if added to a solvent. This would lead to the reduction of hydroxyl ions due to the formation of water. On the other hand, the addition of base reduces the [H⁺] due to the formation of conjugate acid.

X-OH      X⁺ + OH^-

This principle leads to a formation of buffers. A buffer solution is a solution which resists changes in pH when small amount of alkali or acid is added to it.

One way of determining the pH of an unknown solution is by using a pH electrode coupled with the Jenway 3310 pH meter. It works by the immersion of the pH electrode to the solution which is sensitive to H⁺.

Aims: The main aim for this experiment is to recognize the principle skills of exact volumetric measurement and measurement of reagents by pH and mass.

Objectives:

The purposes of this experiment are the following:

• Calculate and test the precision and accuracy of a micropipette.

• Calculate the mass of reagents using a balance

• Determine the pH of different solution using a pH meter

Material:

• 1000 microlitres Gilson micropipette

• De-ionised water

• Analytical Balances

• HCl

• Phosphate buffer

• Lemon juice and milk

• Universal tubes

Methods: (Refer to the Developing Professional Skills 1 2007-2008 module handbook

Results:

Part 1 Table 1: The inspection of the performance of the micropipette

We were given a density table of pure water at temperatures 16 °C – 25 °C. The calculated temperature of the water during the experiment was 22ºc. Therefore, the density value that I am going to use is 0.99672 g/ml to calculate the volume (ml).

1000 μl data

Tube No.	Tube weight (g)	Tube weight with de-ionised  water (g)	Weight of de-ionised water / Mass (g)	Mass / Density = Volume (ml)
1	4.723	5.671	0.948	0.9511
2	4.721	5.713	0.992	0.9953
3	4.726	5.723	0.997	1.0003
4	4.713	5.752	1.039	1.0424
5	4.719	5.745	1.026	1.0294

100 μl data

Tube No.	Tube weight (g)	Tube weight with de-ionised  water (g)	Weight of de-ionised water / Mass (g)	Mass / Density = Volume (ml)
1	4.696	4.850	0.154	0.1545
2	4.720	4.877	0.157	0.1575
3	4.690	4.844	0.154	0.1545
4	4.718	4.877	0.159	0.1595
5	4.720	4.882	0.162	0.1625

Part 2 Table 2: Estimation of accuracy and precision of the micropipette

<!--[if !supportLists]-->(1)   <!--[endif]-->1000 μl data

Calculation of the mean value: 0.9511 + 0.9953 + 1.0003 + 1.0424 + 1.0294 = 5.0185

5.0185 / 5 = 1.0037

Calculation of the accuracy:

To calculate the accuracy I needed to convert the mean value in ml to μl.

So, 1.0037 ml is 1003.7 in μl

1003.7 – 1000 = 3.7

Calculation of the accuracy percentage:

((1003.7 – 1000) / 1000) x100 = 0.37 %

Calculation of the Standard Deviation:

(1.0037 – 0.9511)­² + (1.0037 – 0.9953)² + (1.0037 – 1.0003)² + (1.0037 – 1.0424)² + (1.0037 – 1.0294)² = 0.00500706

0.00500706 / (5-1) = 0.001251765

√0.001251765 = 0.035380291

Calculation of the coefficient of variation:

0.035380291 / 1.0037 = 0.035249866

0.035249866 x 100 = 3.524986649

Tube No.	Mean Volume (ml)	Standard Deviation	Coefficient of variation	Accuracy	Accuracy percentage
1 to 5	1.0037	0.035380291	3.52 %	3.7	0.37 %

(2) 100 μl data

Calculation of the mean value: 0.1545 + 0.1575 + 0.1545 + 0.1595 + 0.1625 = 0.7885

0.7885 / 5 = 0.1577

Calculation of the accuracy:

To calculate the accuracy I needed to convert the mean value in ml to μl.

So, 0.1577 ml is 157.7 in μl

157.7 – 100 = 57.7

Calculation of the accuracy percentage:

((157.7 - 100) / 100) x100 = 57.7 %

Calculation of the Standard Deviation:

(0.1577 – 0.1545)­² + (0.1577 – 0.1575)² + (0.1577 – 0.1545)² + (0.1577 – 0.1595)² + (0.1577 – 0.1625)² = 0.0000468

0.0000468 / (5-1) = 0.0000117

√0.0000117 = 0.003420526275

Calculation of the coefficient of variation:

0.003420526275 / 0.1577 = 0.021690084

0.021690084 x 100 = 2.169008418

Tube No.	Mean Volume (ml)	Standard Deviation	Coefficient of variation	Accuracy	Accuracy percentage
1 to 5	0.1577	0.003420526275	2.17 %	57.7	57.7 %

This shows that setting the micropipette at 100 μl gives more accurate results as the accuracy percentage is a lot higher than setting it at 1000 μl.

Part 3 Table 3: Determination of pH of different solutions

The temperature of the solutions during this experiment was 13°c. The temperature should be taken into consideration as it affects the dissociation factor of any certain molecules in a solution.

Phosphate buffer

HCl drop	pH
+0	7.17
+1	7.16
+2	7.13
+3	7.09
+4	6.95
+5	6.82

Distilled water

HCl drop	pH
+0	7.49
+1	4.72
+2	3.66
+3	2.72
+4	2.26
+5	1.92

Tap water

HCl drop	pH
+0	6.49
+1	6.00
+2	4.97
+3	3.97
+4	2.97
+5	2.16

Discussion:

Table 1 shows the weight of 10 different tubes with and without the water, the mass and the calculated volume. The importance of weighing the tubes individually and the area where the tubes are weighed on the balance is high. Each tubes weighs differently. The concept of accuracy and precision should be taken into consideration while weighing the tubes with and without the water as this will make a difference in obtaining an accurate value for mass of water.

In part 2, it shows my calculation of the mean value, accuracy (μl), accuracy percentage, standard deviation, and the coefficient of variation. Looking at the tables on part 2, it indicates that the standard deviation for 1000 μl data is higher than the one in 100 μl data. Standard deviation equals to standard error. So, if the standard error is smaller in 100 μl data it means the value for the mean is much more reliable as an estimate of the true value. The coefficient of variation (CoV) for 100 μl data is smaller than the one in 1000 μl data. This means that the smaller the CoV, the more precise is the micropipette at 100 μl. The accuracy percentage of the second data is a lot closer to 100% than the first data which, indicates a big difference in accuracy whenever using a micropipette at different volumes. The percentage difference is 57.7 - 0.37 = 57.33 %.

Overall, setting the micropipette at 100 μl gives a more precise, more accurate and more reliable results than setting it at 1000 μl.

During the experiment, I believe that possible errors which are unavoidable might have occurred that affected my results. It is mostly the human error such as spillages while transferring the fluid from a universal to a small tube using a micropipette might have occurred. Water is a volatile liquid that is easy to evaporate and is inevitable.

If I was to repeat this experiment again, I would plan to carry out repetitions of the sample to achieve more reliable results as it will improve the mean value. To keep the error to the minimum, careful handling of the equipments should be done. A quick replacement of the cap will prevent the water from evaporating into the air.

Part 3 of my results shows tables for the determination of pH of phosphate buffer, distilled water and tap water in addition of HCl. Looking at the table and graph for the phosphate buffer, it shows that there is a slight decrease of pH compared to the distilled water and tap water.

The reason for the decrease of pH is the increase of [H⁺] is explained below:

• Equation for addition of HCl to Phosphate buffer:

Example:

HPO₄^2-­ + HCl        H₂PO₄^-­+ Cl^-

H₂PO₄^-­ + HCl        H₃PO₄­ + Cl^-

It occurs in two stages until it becomes H₃PO₄­ that changes the pH of the solution. This leads to a slow decrease of the pH.

• Equation for addition of HCl to distilled water and tap water:

H₂O + HCl       H₃O⁺ + Cl^-

Recurrent addition of acid increases [H⁺]; hydronium ions are formed; acidity increases.

This proves that phosphate buffer is a good buffer to use in Biomedical Science laboratory as its pH decreases fairly slowly in addition of acid. The phosphate buffer is in fact effective in maintaining the pH of the cellular fluid. So, this buffer is widely used to maintain the pH of solutions used for biological matters.

References:

Lab Math – A handbook of measurements, calculations, and other quantitative skills for use at the bench by Dany Spencer Adamas.

Practical skills of biomolecular sciences (third edition) by Rob Reed, David Holmes, Jonathan Weyers, and Allan Jones.