Technical Summary: Industrial Lactate Analysis (Bulletin ref. TB098720D)
 

A rapid high performance analysis based on the direct reaction with the specific enzyme L-Lactate Oxidase (LOD).
 

Name:
Codes:

Lactate (II)
GMRD-090/093/092 - Kits for 100/250/4x250 analyser cycles respectively
 

Instruments:
 

LM5/GL6/GM8 Series analysers
 

Principle:

In the presence of molecular oxygen, lactate is oxidised by the enzyme lactate oxidase to pyruvate and hydrogen peroxide:
 

Under the conditions of the assay, oxygen consumption is directly proportional to the L-lactate concentration:
 

Samples:

Aqueous or semi-aqueous samples such as dairy products, e.g. milk, can be used directly.  Turbidity or opacity is not a problem as the detection method is electrochemical rather than optical. Specimens should be in the pH range 4-8 and free from overt bacterial contamination.
 

Sample volume:
Analysis time:
Detection Limit:
Precision:

Typically 5 µl (variable 3.5 - 25 µl)
20 seconds
0.06 mmol/L (0.5 mg/dl)
Typical within-run C.V. 2 % @ 2.5 mmol/L
 

Linearity:

10 mmol/L (7 µl sample); 0.9 g/L
20 mmol/L (3.5 µl sample); 1.8 g/L
Higher concentrations can be measured after a simple aqueous dilution.
 

Accuracy:

Method comparison: Analox vs classical UV spectrophotometric
y (Analox) = 0.99x - 0.05mmol/L, r = 0.996
 

Reagent Stability:

Shelf-life 1 year unopened when stored at 0 - 5°C, 60 days after reconstitution, when stored at 0 - 5°C between use. Can be frozen for extended life.
 

Notes:

i) Lactate methodology has excellent precision at all levels, stable calibration, and is remarkably free from interferences.
ii) Alternative standards at 1.8 and 2.7 g/L are available in addition to the kit calibrant of 8.0 mmol/L (0.72 g/L).
iii) The enzyme lactate oxidase is 100 % specific to L-Lactate. D-lactate is not measured.