Creatinine (Cr) Picric Acid Assay Kit Instruction Manual

Creatinine (Cr) Picric Acid Assay Kit Instructions
Spectrophotometry 50 tubes/48 samples

 
Note: Before the formal determination, select 2-3 samples with large expected differences for pre-determination
.

Significance of the measurement:
Creatinine is formed in muscle from phosphocreatine by spontaneous and irreversible conversion, unless there are large changes in muscle mass, the amount of creatinine formed is usually fairly constant
.
The circulating amount of free creatinine is completely dependent on its excretion rate, so the amount of creatinine in urine, serum or plasma can be measured and used for renal function tests
.
Increased creatinine levels are commonly seen in: decreased excretion in chronic renal failure and acromegaly
.


Measurement principle:
creatinine reacts with excess picric acid under alkaline conditions to generate orange-red picric acid creatinine
.
There is a maximum absorption peak at a wavelength of 490 nm, and the complex is measured within a certain period of time to calculate the content of creatinine in the sample and avoid interference
.

Creatinine + alkaline picric acid ---- creatinine picric acid complex Self-
provided instruments and supplies:
visible spectrophotometer, ordinary centrifuge, ultracentrifuge, adjustable pipette, 1mL glass cuvette and distilled water
.


Reagent composition and preparation:
Reagent 1: liquid × 1 bottle, stored at 4°C, filtered before use
.
Reagent 2: liquid × 1 bottle, stored at 4°C
.

Reagent 3: 10x standard solution × 1 bottle, stored at 4°C, before use, diluted 10 times during distillation, the final concentration is 0.
1 mg/ml
.

*Working solution: Reagent 2: Reagent 1 = 1:10, configure before use

Sample collection:
1.
Serum, plasma, creatinine in serum or plasma can be stored at 2-8°C for 24 hours
.

2.
Urine: Dilute fresh urine by 1/50 with distilled water before the test, and multiply the result by 50
.


Measurement operation:
1.
Preheat the spectrophotometer for 30 min, adjust the wavelength to 490 nm, and adjust to zero with distilled water
.

2.
Add sample reagents according to the table below, mix well, put in a water bath at 37°C for 30 seconds, select a wavelength of 490 nm, read the initial absorbance (A1) at the zero point of the blank tube, and read the final absorbance (A1) after 90 seconds.
A2)
Remarks: The amount of reagent and sample can be changed in constant ratio according to the different instruments used
.
Note: The blank tube only needs to be done once
.

Reagent name (μL)	sample tube	blank tube	standard tube
sample	100
Reagent Three 1x			100
distilled water		100
working fluid	1000	1000	1000

Calculation formula:
sample tube absorbance A2 sample tube absorbance Al
creatinine (umol/L) = X standard solution concentration