What Is a CryoProbe?

Bruker's ultra-low temperature probes have been developed. In order to meet different application needs, various types of ultra-low temperature probes have come out one after another. For example, Q NP probes provide 31P, 13C and 15 N or 19F, 31 P and 13 C options in addition to 1 H ; Selective ultra-low temperature probe can observe 19 F, 2 H or 3H; 10 mm 13C / 1H dual-core ultra-low temperature probe variable temperature range can reach 135 , but whether it is a trans or formal ultra-low temperature probe, generally has a low-temperature cooling RF coil and front The power amplifier is also equipped with a deuterium lock channel, a Z gradient coil and a temperature change unit.

DCH Ultra-low temperature probe technology DCH ultra-low temperature probe

The inner coil of the dual-core probe is tuned to a specific X-core (such as ¹³ C), and the outer coil is decoupled and observed at 1H. Studies on structural confirmation, metabolomics, and high-throughput screening of natural products require high observation sensitivity of ¹³ C. Therefore, after the introduction of the TXI ultra-low temperature probe, a DUL dual-core ultra-low temperature probe suitable for ¹³ C observation was developed quickly. Because the measurement time is inversely proportional to the square of the probe sensitivity at a given signal-to-noise ratio, so when ¹³ C and ¹ H When the sensitivity increases by 3 to 4 times, the measurement time of the sample will be an order of magnitude faster. Similarly, when the measurement time is constant, the amount of sample required will also be greatly reduced. The leap in sensitivity essentially redefines the application limit of ¹³ C NMR .

Unlike the 10 mm DUL ultra-low temperature probe, which focuses on improving the sensitivity of ¹³ C, the new 5 mm DCH ultra-low temperature probe enhances the sensitivity of 13 C and also enhances the performance of the 1 H channel. The linear specifications of the ¹ H DCH ultra-low temperature probe and TXI It is the same as the TCI ultra-low temperature probe, and the better linear index means that for narrow proton nuclear magnetic resonance frequency range, better resolution can be obtained. Therefore, the quality of the reverse and heteronuclear chemical shift-related experimental spectrum is improved. Even the spectral quality of the water peak suppression experiment can be compared with that of TXI or TCI ultra-low temperature probes. In natural product chemistry or metabolomics research, small sample sizes are often encountered. For such problems, 400 to 700 MHz DCH ultra-low temperature probes Is the ideal solution. ^[2]

QNP Ultra-low temperature probe technology QNP ultra-low temperature probe

Dual-core and trans-ultra-low temperature probes can only be used for the detection and decoupling of one or two X-cores at most. When other cores need to be detected in the experiment, it takes a long time to change the probe. To solve this problem, in QNP ultra-low temperature probes are provided on 400, 500 and 600MHz spectrometers. In addition to QH P / C / N ultra-low temperature probes, the best X channel can be selected between ¹³ C, ¹⁵ N and ³¹ P. Compared with traditional Compared with QNP probes, the sensitivity of the four cores of the QNP ultra-low temperature probe has been increased by 4 times, and the selected four X cores can obtain the maximum sensitivity that can be achieved at present. For example, the ¹³ C sensitivity of the QNP ultra-low temperature probe can reach DCH probes have the same level. For 400 MHz spectrometers, we recently introduced QN PF / P / C ultra-low temperature probes, where the X channel can be selected from ¹⁹ F, ³¹ P and ¹³ C. Many studies on organic compounds or inorganic compounds I am interested in the detection of ¹⁵ N, but due to the low natural abundance, detection of ¹⁵ N is usually very difficult. Natural products or drugs often contain heterocycles. When there is no direct relationship between nitrogen and hydrogen in a heterocycle When the keys are connected, DEPT The HSQC experiment cannot be performed. Therefore, when using a TXI probe, it is often necessary to use a trans long-range displacement correlation experiment (such as HMBC) to determine the chemical shift of the nitrogen atom. However, long-range coupling is usually unknown or approaches 0, so HMBC does not Relevant signals can always be detected. Moreover, for many inorganic compounds, since there is no hydrogen atom at all, the reverse detection of ¹ H cannot be performed. At this time, direct detection of ¹⁵ N is the only reliable method to determine the chemical shift of nitrogen. For organic chemistry and natural product chemistry, it is generally believed that HMBC can obtain all possible relevant information of ¹ H and ¹⁵ N, so the direct detection of ¹⁵ N is not necessary. However, the chemical exchange process will cause relevant signals in HMBC or HSQC experiments Loss of signal, or signal loss in direct detection experiments, often leads to inaccurate and complete information not being obtained in experiments. This happens mainly because different chemical shifts and coupling constants can cause different exchange rates. In the chemical system, there may be a case where the nuclear exchange rate is fast and a nuclear exchange rate is slow, as shown in Figure 4. Shown, the signal 260 at the ¹⁵ N spectrum heterocyclic compound is lost, but the correlation peak appears in the HMBC ¹ H spectrum. On the other hand, the signal spectrum nitrogen at 385, but not produce detectable in the HMBC Therefore, in order to obtain all ¹⁵ N chemical shifts, both HMBC and nitrogen spectra must be done to complement each other. The 1H sensitivity of the QNP ultra-low temperature probe is lower than the TCI ultra-low temperature probe, but its 90 ° pulse of ¹⁵ N is relatively short. Therefore, if the ¹⁵ N chemical shift range of interest in the sample is relatively large, doing trans experiments (such as HMBC and HSQC experiment), the QN P ultra-low temperature probe has great advantages. In the larger ¹⁵ N bandwidth range, the more uniform the excitation, the better the coherent transition, correlation peak sensitivity and ¹⁵ N offset can be obtained. TCIP ultra-low temperature probe TCIP ultra-low temperature probe is developed based on TCI ultra-low temperature probe. ³¹ P replaces ¹⁵ N to become the third channel, which has the best sensitivity for ¹ H, and ¹³ C sensitivity is greatly enhanced. Therefore, TCIP ultra-low temperature probe is very suitable For the study of nucleic acids. For nucleotides with a standard helix, the sequence designation can generally be obtained by 1 H NO E of consecutive base pairs. But for non-standard structures, this method does not work. Therefore, a method using three-dimensional H, The C and P triple resonance experiments have been developed for the sequence authentication method. This method uses J coupling to separate the 3 end of H3 / C3 , H4 / C4 and 5 end of H4 / C4 and H5 from the phosphate bond. And H5 / C5 are connected. The enhanced ¹³ C sensitivity of the TCIP cryogenic probe makes it convenient to detect ¹³ C in nucleic acids labeled with ¹³ C. Because the resolution of the chemical shift of protons on ribose is usually very low, so the hydrogen spectrum The results given are often ambiguous, and the TCIP ultra-low temperature probe, which provides the highest possible ¹ H, ¹³ C, ³¹ P, and Y nuclear sensitivity, is a fairly effective tool for studying nucleic acids and organophosphorus compounds.

10 mm DUL 13C/1H Ultra-low temperature probe technology 10 mm DUL 13C / 1H ultra-low temperature probe

¹³ C NMR plays a very important role in polymer analysis, such as determining the proportion of each monomer in various copolymers and the average molecular weight. The new 10 mm DUL ¹³ C / ¹ H ultra-low temperature probe not only provides current The highest sensitivity of ¹³ C, the temperature range can reach 135 , which is usually required for polymer research. This low temperature probe is equipped with a Z gradient field coil to make conventional one-dimensional gradient shimming can be performed.