Electricity: measuring and testing – Particle precession resonance – Spectrometer components
Reexamination Certificate
2001-10-18
2002-09-24
Lefkowitz, Edward (Department: 2862)
Electricity: measuring and testing
Particle precession resonance
Spectrometer components
C324S322000, C324S300000
Reexamination Certificate
active
06456078
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The invention relates to a nuclear magnetic resonance device (hereinafter referred to as “NMR device”) wherein a sample supply source and the NMR device are connected through a flow path, so that a sample supplied from the sample supply source can be analyzed on-line. For example, the present invention is applied to a case such that a liquid chromatograph (hereinafter referred to “LC”) device and the NMR device are connected through the flow path, and the sample taken out of the LC device is sequentially sent to the NMR device to carry out a measurement.
In the NMR measurement, there has been widely used an off-line measurement wherein the sample is collected to respective sampling tubes with bottoms by using a heavy water type (heavy alcohol-type) solvent necessary for the measurement, and the respective sampling tubes are separately attached to an NMR probe, i.e. measuring probe, positioned in a measuring space of the NMR device to carry out the NMR measurement. However, recently, in order to automate the measurement, there has been also used an NMR device of an on-line measurement to send the sample through a flow path directly from the sample supply source without using the sampling tubes with the bottoms.
FIG. 3
is a block diagram showing a conventional liquid chromatograph-nuclear magnetic resonance system (hereinafter referred to as “LC-NMR system”) wherein the LC device and NMR are connected on line. The system includes an LC portion and an NMR device.
In the LC portion, a mobile phase
1
is sent to a flow path by a liquid sending pump
2
, and a sample is introduced from a sample introducing portion
3
disposed on a middle way of the flow path. The introduced sample is subjected to component separation at a column
4
, and every component is sequentially sent through the column
4
. The movable phase
1
is prepared by controlling concentrations of a heavy water-type solvent which has a high ability for allowing the column to absorb the sample, and a heavy alcohol-type solvent which has a low ability for allowing the column to absorb the sample. Incidentally, the reason why a light water-type solvent and a light alcohol-type solvent are not used is that in case an NMR measurement, described later, is carried out, it is necessary to use the heavy water-type/heavy alcohol-type solvents instead of the light water-type/light alcohol-type solvents. Then, the sample components passing through the column
4
are detected by a detector
5
for carrying out the measurements by an electric conductivity and UV.
The NMR device is structured such that a measuring space is provided in a ferromagnetic field space formed of electromagnets, and an electromagnetic wave necessary for the NMR measurement is generated in the measuring space by a device control portion. Also, an NMR coil
20
for receiving and sending the measured electromagnetic wave signal is attached thereto.
A sample flow path
21
is connected to the latter step of the detector
5
of the LC portion so that the flow path
21
passes through the NMR coil
20
in the axial direction. Then, a capacity of the pipe from the detector
5
to the NMR coil
20
is measured in advance and a liquid transfer speed, i.e. liquid transfer quantity per unit hour, of the mobile phase can be obtained from the rotation number of the pump, so that a time from a moment when the sample to be measured is detected at the detector
5
to a moment when the sample to be measured arrives at the NMR coil position, can be calculated.
Therefore, when the detector
5
detects the sample to be measured, a time when the sample to be measured arrives at the NMR coil position is calculated based on a pipe capacity and a liquid transfer speed and the liquid transfer of the mobile phase is stopped immediately after the arriving time elapses, so that the sample can be retained in the NMR coil position. Thus, the NMR measurement of the substances present in the sample flow path area at the NMR coil position can be carried out. Or, even if the liquid transfer is not stopped, when the measurement is started corresponding to the time when the sample passes through the NMR coil position, the NMR measurement of the sample to be measured can be done.
Thus, since the NMR measurement can be carried out only at the portion passing through the NMR coil
20
out of the entire sample flow path
21
, an NMR probe
22
for the measurement is substantially formed by the NMR coil
20
and the part of the sample flow path
21
passing through the NMR coil
20
. Incidentally, the end portion of the sample flow path
21
is connected to a drain to thereby abandon the sample after measurement.
FIG. 4
is an enlarged drawing of the NMR probe portion in FIG.
3
. The NMR coil
20
is wound around a cylindrical tube
23
. The sample flow path
21
passes through the tube
23
.
As described above, in the conventional NMR probe
22
, the hollow sample flow path
21
passes through the NMR coil
20
as it is. In case the sample is measured in the device, there is employed either a method wherein when the sample is sent, the sample is measured within the time while the sample flows in the NMR probe
22
, i.e. on-flow measurement, or a method wherein when the sample is sent, the liquid transfer pump
9
is stopped to temporarily stop flow of the sample so that the sample is retained in the NMR probe
22
to extend an integrating time and measure, i.e. stopped-flow measurement.
However, in case the on-flow measurement is carried out, for example, there may be a case wherein when a flow speed of the sample is fast, a sufficient measuring time can not be taken and a proper integrating process can not be done, which results in a measurement with a lower S/N ratio. On the other hand, in case of the stopped-flow measurement, since the sample is inevitably dispersed in the back-and-forth direction in the flow path during the suspension, for example, there may be a case wherein only the sample in the order of 30% of the entire quantity remains in the vicinity of the NMR coil. Even if the integrating time is extended through the integrating process, the sufficient S/N ratio can not be obtained due to dilution of the sample dispersion as a whole. Also, due to the dispersion of the sample, a quantitative measurement may not be carried out.
Also, when the sample to be measured arrives at the position of the NMR coil
20
, the NMR measurement is carried out. However, it is very difficult to accurately determine the timing. For the sake of safety, the sample is normally sent in a slightly dispersed state so that a flow path length where the sample to be measured is present becomes longer when compared with the length of the sample flow path in the NMR coil. Thus, even if the timing is slightly shifted, it has to be practiced that the sample is present in the position of the NMR coil. Therefore, the quantity of the sample actually contributing to the measurement is only a part out of the whole measuring sample sent from the sample supply source, so that there has been a limit for raising the S/N ratio.
Further, the expensive heavy water/heavy alcohol-type solvents have to be used at the time of the NMR measurement. However, such an expensive solvent should be used as little as possible. In other words, if possible, light water/light alcohol-type solvents should be used as much as possible. Especially, since the heavy alcohol-type solvent is extremely expensive, it is desirable to reduce its using quantity. In a system wherein the LC portion is connected in the preceding step of the NMR device as described above, since the separation column is provided, it is necessary to use a mixture wherein the heavy alcohol type-solvent is mixed in the mobile phase (because it is difficult to allow the sample to pass through a long column by only the heavy water-type solvent), a large quantity of the expensive heavy alcohol is required.
Furthermore, while it is necessary to keep the sample at a high concentration as much as possible during the NMR measurem
Kanesaka & Takeuchi
Lefkowitz Edward
Shimadzu Corporation
Shrivastav Brij B.
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