Based on this experiment, we can discuss that we had conducted four tests. These all four tests are for proteins. Firstly, in biuret test we used albumin, peptone and casein. We poured 2ml of each proteins solution into each test tubes. After that, we added 2 ml of 0.1 solution sodium hydroxide and ! drops of 1" copper#$$% sulfate solution. &o, as a result, we 'ot (iolet color for albumin and peptone but for casein it turns to pale (iolet color. )owe(er, the expected result for peptone should be (iolet color. Besides, in precipitation of proteins by hea(y metals, we also used albumin, casein and peptone. We poured 2ml of each proteins solution into each test tubes. Then, we added * drops of hea(y metal solutiom such as cuprum sulphate, mercuric nitrate and plumbum acetate into each proteins solution. After that, we added another ! drops of 0.1 cuprum sulphate. &o as a result, for albumin that contain cuprum sulphate it turns to cloudy blue, for mercuric nitrate it turns to brown with precipitate, and for plumbum acetate it turns to cloudy blue. For casein that contain cuprum sulphate it doesn+t chan'e, for mercuric nitrate it turns with precipitate and for plumbum acetate it turns to cloudy blue with blac precipitate. For peptone that contain cuprum sulphate it does not chan'e with mercuric mercuric plumbum acetate it turns to li'ht blue. oreo(er, in precipitation of proteins by acid, a cid, we also used albumin, casein and peptone. We poured 2ml of each proteins solution into each test tubes. Then, we added ! drops of acidic solution such as trichloroacetic acid, tannic acid and picric acid into each proteins solution. After that we added 2ml of 0.1 sodium hydroxide. &o, as a result after we added -a), for albumin that contain trichloroacetic acid it has clear precipitate and no chan'e, for tannic acid it turned to dar brown and for picric acid it turned li'ht yellow,for yellow,for sulphosalicyclic acid,it turned colorless with white precipitate. For casein cas ein that contain trichloroacetic acid it has white precipitate and no chan'e, for tannic acid it ha(e no precipitate and for picric acid it has precipitate trace while for sulphosalicyclic acid,it is cloudy and no precipitate. For peptone that contain trichloroacetic acid it has colorless, for tannic acid it has brown with precipitate solution and for picric acid it has yellow solution. . /ast but not least for isoelectronic isoelectronic point of casein, we used casein only. only. $n this experiment experiment we had added 1 ml of casein into 10 test tubes and mix with )/ and -a) into each tubes with the 'i(en (olume of both solution in the table. &o as a result, for test tubes 1,it is li'htly cloudy and no precipitate,test tube 2 ha(e pecipatet but colorless.test tube ha(e white precipitate and sli'htly cloudy solution the tube * and ! ha(e cloudy solution with white
precipitate.the other tubes remain colorless and no precipitate. $n this experiment also, there are se(eral errors such as the eyes not perpendicular to the scale readin' .Besides, rea'ent that we used are not pure. oreo(er, the test tubes that we used not completely dried.
&o,we ha(e some su''estion on way or precautions to o(ercome these errors. First, the eyes must be perpendicular to the scale readin' or the meniscus of the apparatus, so that we can 'et the readin' accurately. Besides, we ha(e to mae sure that rea'ent tat we want to use is in pure condition. /ast but not least, we ha(e to mae sure the test tubes that we want to use are in completely dry conditions.
