The haemoglobin concentration in the OC-Sensor FIT is determined in nanograms of haemoglobin per millilitre of buffer in the sample tube (ng/ml).
The pre-analytics and sample extraction are standardised for all OC-Sensor sample tubes:
Each sample tube contains 2 ml of stabilising sample buffer in which, with the aid of the test-wand, 10 mg of stool sample is suspended.
The haemoglobin concentration, determined by the OC-Sensor analysis device in ng per ml of sample buffer, is specific to the OC-Sensor sample tubes. A straightforward conversion into μg Hb per gram of faeces enables non-system-dependent comparison.
μg Hb / g stool = ((ng Hb/ml) x (buffer volume in the system, in ml))/(mass of faeces in mg)
Conversion table for OC-Sensor concentrations:
ng Hb /mL Buffer (OC-Sensor) µg Hb/g Stool 10 2 50 10 100 20 250 50 1000 200
The OC sensor instruments utilize a unique squeeze function pass liquid though the integrated filter into the collection cup portion of the sample bottle. Once released, the sample aliquot is pulled back into the buffer chamber as the bottle regains its shape. This makes the sample bottles spill proof when removed from the machine (without having to recap) and placed into the refrigerator for storage and prevents the sample drying out or becoming concentrated.
In the event that repeat measuring of the sample is required, the analysis device includes a “re-test” function. In this mode the test can be repeated under the same conditions, without making a new hole in the aluminium foil.
Normally two barcode labels are given on the OC-Sensor sample tubes: the top one can be stuck onto the voucher, while the bottom barcode is left for the analysis and safe labelling of the sample on the sample tube.
If the laboratory should use its own internal barcoding for data administration, the laboratory's own barcode label can be stuck onto the sample tube. The OC-Sensor analysis devices can read all current barcode types. If necessary, please talk to us beforehand. It is also possible to order OC-Sensor sample tubes without pre-set barcodes.
Very specific polyclonal, anti-human HbA0 rabbit IgG antibodies are used, bonded to latex particles.
When the polyclonal antibodies detect the epitopes of antigens and bind to them, this causes an agglutination reaction.
FIT immunochemically detect the globin component in the haemoglobin protein. For this reason, they have a significantly better analytical specificity for human haemoglobin but are sensitive to proteolytic degradation of the haemoglobin protein by microbial proteases in the gut flora. This degradation starts in the gut and continues after the sample has been taken.
Haemoglobin in native faeces (with no stabilising buffer) is highly unstable. Haemoglobin concentrations that had been determined in native faeces by means of various different FIT tests were reduced within a few days to below the detection limit.
The degradation of haemoglobin can be slowed significantly through the use of optimised, stabilising buffer systems, into which the stool sample is transferred by the user as soon as it has been taken. In the case of OC-Sensor FIT, a stabilising sample buffer of this type is integrated into the sample-taking system (OC-Sensor sample tube).
The outstanding efficacy of the OC-Sensor sample buffer system has been confirmed in both internal and external trials.
Stool samples in OC-Sensor sample tubes may be stored, between being taken and their analysis in the laboratory, for one week at room temperature or 28 days under refrigeration.
The period of time in which the samples are exposed to varying temperatures should be kept to a minimum, including but not limited to, the transfer of samples between collection and analysis and the storage of samples at room temperature.
Manufacturer’s statement: For samples that were stored in OC-Sensor sample tubes for 28 days at 2-8o C, a haemoglobin detection rate of 95% ± 14.7 (2 SD) was calculated. After 7 days’ storage at 25oC a detection rate of 96% ± 20.4 (2 SD), while at 30oC 89% ± 20.5 (2S D), was calculated.