BUN

BUN Interference Comparison Urea is one of the few serum analytes which can be measured using ultraviolet detection without serious chromatic interference. The reason can be seen from the molar concentration at the upper limit of normal. Urea is one of the most plentiful molecules in serum. Additionally, two molecules of NADH are oxidized per molecule of urea. Thus, the signal [chromophore absorbance] to noise [serum background absorbance] is very favorable, relative to other serum analytes.

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Principles of the Reaction

The Synermed® blood urea (BUN) method is based on the enzymatic conversion of urea to two molecules of ammonia. The ammonia participates in an enzymatic reaction with glutamate dehydrogenase in which NADH is oxidized to NAD. The rate of decrease in absorbance of NADH at 340 nm is proportional to urea concentration.

The reagents are supplied as stable ready-to-use liquids for simplicity of use. The extended "on board" life of the reagents results in economies due to the elimination of wastage and reconstitution time.

urea + H20 -> 2 NH3 + CO2
2 α-ketoglutarate + 2 NH4+ + 2 NADH -> 2 L-glutamate + 2 NAD+ + 2 H20

Special Performance Characteristics

The Synermed urea nitrogen methodology was correlated to a widely accepted enzymatic method. The linear regression on 55 samples, run in duplicate, ranging from approximately 6 to 90 mg/dL (2.1 to 32 mmol/L) with Synermed results on the Y-axis gave an equation of Y = 0.98X + 0.7 with a correlation coefficient of 0.999.
The sensitivity of the procedure is such that an absorbance change of 0.001 will detect as little as 1.3 mg/dL (0.48 mmol/L) urea nitrogen.
The average within run precision of the method as applied to an automated analyzer was determined by assaying 30 samples of quality control material at two levels of urea nitrogen concentration:

Mean SD CV

15.7 mg/dL (5.6 mmol/L) 0.36 (0.13) 2.5%

54.5 mg/dL (19.5 mmol/L) 0.56 (0.20) 1.1%
The run to run reproducibility of the method as applied to an automated analyzer was determined from the values obtained by 5 replicate analyses of quality control material assayed over a 23 batch period.

Mean SD CV

15.7 mg/dL (5.6 mmol/L) 0.48 (0.17) 3.0%

55.5 mg/dL (19.8 mmol/L) 1.30 (0.46) 2.3%

Product Packaging and Storage

Cat. No.	Product Name	Packaging	Package Volume (mL)	Storage
UV190-X	BUN	1x200 mL + 1x100 mL	300	0-4° C
UV190	BUN	3x200 mL + 3x100 mL	900	0-4° C
UV191-L	BUN Coenzyme	6x500 mL	3,000	0-4° C
UV192-L	BUN Enzyme	6x500 mL	3,000	0-4° C
UV190-911	BUN	6x50mL + 3x50mL	450	0-4° C
UV190-WK	BUN	4x25mL + 4x12.5mL	150	0-4° C
UV195-X	BUN	1x200 mL + 1x100 mL	300	0-4° C
UV195	BUN	3x200 mL + 3x100 mL	900	0-4° C
UV193-L	BUN Enzyme	6x500 mL	3,000	0-4° C

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Principles of the Reaction

Analytical Range

Expected Values

Special Performance Characteristics

SDS

Product Packaging and Storage

Mean	SD	CV
15.7 mg/dL (5.6 mmol/L)	0.36 (0.13)	2.5%
54.5 mg/dL (19.5 mmol/L)	0.56 (0.20)	1.1%

Mean	SD	CV
15.7 mg/dL (5.6 mmol/L)	0.48 (0.17)	3.0%
55.5 mg/dL (19.8 mmol/L)	1.30 (0.46)	2.3%

BUN

Principles of the Reaction

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