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Potassium-E Enzymatic Test METHOD / PRINCIPLE Potassium is an activator for the enzyme Pyruvate Kinase (PK). Therefore the kinetic measurement of PK can be used to determine potassium in serum. The interference of other activating ions is eliminated by complexing and decomposition reactions. REFERENCE RANGE 3.5 - 5.1 mmol/l (13.7 - 19.9 mg/dl) Note: It is recommended for each laboratory to establish and maintain its own reference values. The given data are only an indication. The procedure is based on the following reaction scheme: Substrate* + ADP ANALYTICAL PROCEDURE PK / K+> Pyruvate + ATP Pyruvate + NADH + H+ This is the standard procedure, specific Applications for Analyzers are available upon request. LDH> Lactate+ NAD+ * Substrate = derivative of phosphoenolpyruvate The decrease of the absorbance of NADH is measured at 380 nm; this is proportional to the concentration of potassium in the sample. REAGENTS Wavelength Temperature Cuvette 380 nm (380 - 405nm) 37°C 1 cm light path Read against reagent blank (RBL) RBL Standard Sample Reagent R1 200 µL 200 µL 200 µL Standard 5 µL Sample 5 µL Mix well, and incubate for about 5 min, then add Reagent R2 50 µL 50 µL 50 µL Mix well, and after 1 min read absorbance A1, and exactly 3 min later read A2 Constituents (concentrations in the test) R1: Good's-Buffer (pH 8.5) Complexing cryptand 0.5 mmol/l LDH < 50 U/ml NADH < 10 mmol/l Stabilizers R2: Good's-Buffer (pH 6.5) Pyruvate Kinase < 50 U/ml Stabilizers A = (A1 – A2) Sample or Standard - (A1 – A2) RBL Storage and Stability R1 and R2 are ready for use. The sealed reagents are stable up to the expiry date printed on the labels, when stored at 2° to 8°C. Stability after opening : At least 3 months at 2° to 8 °C, if contamination is avoided On board stability depends very much on the internal contamination which mostly is different for any analyzer Do not freeze ! CALCULATION with standard (Std) Potassium[mmol / l] A sample Conc. Std. [mmol / l] A S tan dard CALIBRATION & QUALITY CONTROL For the calibration of automated analyzers Greiner special calibrator / standard is recommended, for quality control use Greiner Unitrol-I and -II . Warnings and Precautions Reagents contain 0.05% Sodium Azide. Do not swallow and avoid contact with eyes, skin and mucous membranes. WASTE When discarding the reagents, dispose them according to local or federal regulations. SAMPLE MATERIAL Serum (free of hemolysis) Page 1/2 Greiner Diagnostic GmbH - Unter Gereuth 10 – D-79353 Bahlingen – Germany www.greiner-diagnostic.com PERFORMANCE DATA BIBLIOGRAPHY 1. - Analytical range The linear range is up to 8.0 mmol/l. If the obtained value exceeds this, repeat the test using serum diluted 1+3 with ultra pure water. Multiply result by 4. - Lower range The lower linearity limit is 0.9 mmol/l. 2. Wu, A.H.B., ed. Tietz, Clin. Guide to Lab.Tests, 4th edition, p.880, W.B.Saunders Co. M.N. Berry, R.D. Mazzachi, M.Pejakovic, M.J.Peake, Clin Chem.35/5, p.817-820 (1989) SYMBOLS USED - Precision Within run n = 50 Sample 1 Sample 2 Average [mmol/l] 4.62 6.96 SD [mmol/l] 0.052 0.083 CV [%] 1.12 1.20 Run to Run n = 50 Sample 1 Sample 2 Average [mmol/l] 4.62 6.96 SD [mmol/l] 0.082 0.123 CV [%] 1.77 1,77 - Correlation A comparative study has been performed between the Greiner test and the ISE method on 50 human serum samples. The parameters of linear regression are as follows: For in vitro diagnostic medical use Batch Code Use by Temperature limitation Correlation coefficient r = 0.98 Linear regression y = 1.07 x - 0.30 mmol/l INTERFERENCES - Ascorbic Acid: no interference up to 10 mmol/l - Bilirubin: no interference up to 20 mg/dL - Triglycerides: no interference up to 1000 mg/dL - Hemoglobin: no interference up to 500 mg/dL - Sodium: no interference up to 150 mmol/l - Ammonium: no interference up to 0.5 mmol/l - Calcium: no interference up to 7.5 mmol/l - Zinc: no interference up to 0.5 mmol/l - Copper: no interference up to 0.5 mmol/l Page 2/2 Greiner Diagnostic GmbH - Unter Gereuth 10 – D-79353 Bahlingen – Germany www.greiner-diagnostic.com