Determination of influential factors during sample preparation for staphylococcal enterotoxin detection in dairy products

The experimental design method was applied to the study of influential factors on sample preparation for staphylococcal enterotoxin detection in cheese products. Statistical evaluation has shown only one significant factor of food extract composition - concentration by dialysis -. The levels of other factors were chosen in order to have an easy-to-use and optimal preparation procedure before detection

Determination of ochratoxin A in red wine and vinegar by immunoaffinity high-pressure liquid chromatography

A method is described for the determination of ochratoxin A (OTA) in red wine and vinegar using an acidic chloroform extraction, an immmunoaffinity clean-up step, and a high-performance liquid chromatographic determination with fluorescence detection. The detection limit was estimated at 0.002 μg/liter. The mean recovery factors were found at 91.3 and 96.6% for wine and vinegar, respectively. Thirty-one samples of red wine originating from Mediterranean sea countries and 15 samples of vinegar were examined for the presence of OTA. All red wine samples contained OTA. Seventy-two percent of these samples were found to be contaminated over 0.1 μg/liter. Among them, nine samples contained ochratoxin A in the range of 0.5 to 3.4 μg/liter, 12 samples in the range of 0.10 to 0.50 μg/liter (median: 0.176 μg/liter), and 9 samples in the range of 0.010 to 0.100 μg/liter (median: 0.041 μg/liter). All 15 vinegar samples showed the presence of OTA. The most contaminated ones were three balsamic vinegar samples containing 0.156 μg/liter, 0.102 μg/liter, and 0.252 μg/liter of OTA. In the remaining 12 samples, ochratoxin A levels ranged from 0.008 μg/liter to 0.046 μg/liter (median: 0.012 μg/liter). These data are in good agreement with the hypothesis that wine originating from Southern countries might contain significant OTA concentration and showed the possible occurrence of traces of OTA in vinegar

Avidin-Biotin Enzyme Immunoassay of Osteocalcin in Serum or Plasma

Abstract We describe a competitive enzyme immunoassay, the ExtrAvidin-biotin system, for determining osteocalcin in human serum or plasma. Antibodies were raised against bovine osteocalcin. Binding of the antibodies to osteocalcin was calcium-dependent. Limit of detection is 0.07 nmol/L (0.4 microgram/L). The standard curve for method is linear between 0.3 and 17.6 nmol/L (1.9 and 100 micrograms/L). Interassay CV over the range 0.9 to 14.8 nmol/L (5.3 to 84 micrograms/L) is 7.5% to 11.7%. Analytical recovery is 105% +/- 5% (mean +/- SD). The measurement, which is adapted to microtiter plates, requires only 20 microL of serum and 5 h. The coefficient of correlation between the concentrations measured by this method and by a commercially available radioimmunoassay kit (CIS Biointernational) is 0.91. Osteocalcin can be measured in serum or heparinized plasma. Hemolysis (174 mumol/L hemoglobin) reduces osteocalcin concentration by 54%. High concentrations of triglycerides (7 mmol/L) give an overestimation of 63%. Serum concentrations of osteocalcin measured in 130 healthy subjects (ages 15-64 years) and 86 children (ages 4-14 years) were 1.4 +/- 0.8 and 4.0 +/- 1.5 nmol/L (8.1 +/- 4.6 and 22.5 +/- 8.6 micrograms/L), respectively (mean +/- SD).</jats:p