Method and system for real-time, non-invasive monitoring of a biological material in a sealed container
A biological material such as platelets is sealed inside a container with a dead space to accommodate a metabolic gas. The concentration of the gas in the dead space is monitored while the container remains sealed. In some embodiments, the container is permeable to the gas. In other embodiments, the biological material is the only growth medium in the container. The disposal of the biological material is in accordance with the monitored gas concentration. Preferably, the gas concentration is measured spectroscopically. A container for a biological material includes a main body that retains the biological material but that is permeable to a gas and a reservoir in fluid communication with the main body that is transparent to an optical wavelength that is absorbed by the gas.
1. A method for in situ real-time non-invasive monitoring of contaminations in a sealed platelet bag, said method including the steps of:
(a) providing a sealed platelet bag comprising:
(i) a main body which comprises platelets and a dead space to accommodate a metabolic gas; and optionally
(ii) a reservoir in fluid communication with said dead space, said reservoir being transparent to an optical wavelength which is absorbed by carbon dioxide;
(b) providing a detection apparatus comprising:
(i) a tunable mid-infrared (mid-IR) light source, wherein said mid-IR light source is a quantum cascade laser (QCL);
(ii) an infrared detector; and
(iii) an electronic signal processor; and
(c) determining the concentration of carbon dioxide in the dead space of said sealed platelet bag or in said reservoir in fluid communication with said dead space by:
(i) positioning said sealed platelet bag or said reservoir between the tunable QCL and the infrared detector of said detection apparatus;
(ii) measuring the absorption coefficient of the laser at the IR detector for several wavelengths in the mid-IR spectral range; and
(iii) determining the concentration of carbon dioxide inside said platelet bag without using an etalon and without sampling and/or incubating a sample;
wherein an increase of the concentration of carbon dioxide in said dead space or in said reservoir in fluid communication with said dead space relative to a reference concentration is indicative of a contamination, and
wherein determining the concentration of carbon dioxide in step (c)(iii) is made via a nonlinear minimization model S(x, λi) as provided by function s(x) below:
s
(
x
)
=
∑
i
=
1
n
-
1
[
log
(
S
(
x
,
λ
i
)
+
ε
)
S
(
x
,
λ
n
)
)
-
log
(
S
i
+
ε
S
n
)
]
2
where ε is a noise level at the detector, and S(x, λi) is provided by the following equation:
S
(
x
,
λ
i
)
=
b
∫
λ
min
λ
max
f
(
λ
-
λ
i
)
ⅇ
-
α
λ
(
x
+
c
0
l
0
)
ⅆ
λ
where b is a constant, ƒ(λ−λi) is the laser spectral distribution function around the central wavelength λi, αλ, is the absorption coefficient, x=cl wherein c is the gas concentration inside the container, l is the path length inside the container, c 0 is the concentration of the probed gas outside the container and l 0 is the path length outside the container between the infrared source and the detector.
2. The method of claim 1 wherein the mid-IR spectral range used in step (c)(ii) is 2355 cm −1 to 2410 cm −1 .
3. The method of claim 1 wherein said contamination is a bacterial or a fungal contamination.