I can't remember the tube color (probably speckled or red for serum after clotting and centrifugation) but when I worked in a medical laboratory (until 2001) the key thing was to protect the specimen from light by wrapping the tube in aluminum foil!
red/black tube is used (gel barrier tube) a clear tube is used when getting results from the spectrophotometer
it is a blue tube
blue
gold top
Blue
A PKU is a serum test, so it goes in a red top.
This test is used to measure bilirubin in urine. The product of the reaction between bilirubin and a diazonium salt, in acidic medium is an azo dye, colored pink to violet, depending on the concentation.
Carbon is settled on the test tube.
If bacterium cannot use glucose the fermentation tube will stay the same color. Gas may also occur inside the fermentation tube.
You could use a Red/Gray SST tube, or you could use a Green sodium heparin tube.
Green tube which contains the anticoagulant Heparin is ideal for electrolyte testing.
Red
The color tube you use when drawing blood for a lab test depends on the type of test you are running. For a Na blood test you would use a red tiger strip tube.
gray
Blue
The color tube u would use for the Creatinine test is GREEN...
SST
red
red/gray mollted
lt blue
Test tube rack is use to hold test tube when they are not in use.