What is phadebas reagent test?
Phadebas is a presumptive test used in forensic science examinations for the detection of areas of possible saliva staining. The test is designed to react with amylase, a digestive enzyme present in saliva.
How is a phadebas test carried out?
Phadebas® Forensic Press Test – An overview
- Step 1: Place item to be tested on a flat and clean surface.
- Step 2: Dampen Phadebas® paper with water.
- Step 3: Trace an outline of the testing area on the Phadebas® paper.
- Step 4: Cover the Phadebas® paper with a clean glass board.
How are phadebas test results analyzed?
The test used to identify amylase uses Phadebas®, consisting of starch microspheres with a blue dye cross-linked to the starch. In the presence of amylase the starch is digested, releasing the water soluble dye into solution. The resulting blue colour is read semi-quantitatively using a spectrophotometer.
What is the chemical composition of phadebas tablet?
A Phadebas® tablet consists of homogeneously interlinked starch polymers, taking the form of globular microspheres of defined size. These Bio-Degradable Starch Microspheres (DSM)are insoluble in water. To the DSMs, a blue dye is covalently bound. When the dye is bound to the microsphere, it remains water insoluble.
What is the color change expected for a positive Phadebas test?
Results Interpretation A yellow color change was a positive result while no color change indicated a negative result. All experimental results were interpreted within the frame of valid positive and negative controls.
What enzyme is detected in saliva detection?
Amylase activity
Amylase activity was detected after immersing the gel in 0.4 M tris-HCI buffer pH 7.4 to equilibrate the pH gradient. The enzyme activity was detected after diffusion into an overlayer of agarose gel containing an insoluble dye-starch polymer (Phadebas).
What is the color change expected for a positive phadebas test?
What happens when iodine is added to saliva?
Iodine is a chemical that turns purple when mixed with starches, and orange when mixed with sugars. When you mixed saliva with the cracker, amylase in your saliva broke down some of the cracker’s starches into sugars, making the iodine less purple and slightly yellow.”
How does the RSID saliva test work?
RSID™ – Saliva uses two anti-human salivary amylase, monoclonal antibodies, in a lateral flow format, that detects the presence of salivary amylase, rather than the activity of the enzyme (see Specificity below). RSID™ – Saliva uses two mouse monoclonal antibodies specific for human salivary -amylase.
Which amylase is present in saliva?
enzyme α-amylase
The most abundant protein in human saliva is the digestive enzyme α-amylase [8].
How much amylase is in saliva?
Salivary Amylase Measures The average amount (±SD) of amylase was 2.64 mg/ml (±1.8), with a range of 0 to 7.5 mg/ml, while the average concentration per minute was 5.7 mg/min (±7.1) (range 0–42.8 mg/min). The average activity per unit saliva was 93 U/ml (±62), ranging from 1 to 371 U/ml.
Why is iodine used in starch test?
The basic principle involved in the iodine test is that Amylose interacts with starch to form a blue-black colored complex with the iodine. The helical structure of Amylose forms a charge transfer (CT) complex with iodine, wherein iodine is present inside the spiral or helical structure of the Amylose.