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Questions and Answers
Which boron isotope is more suitable for NMR applications due to its higher sensitivity?
Which boron isotope is more suitable for NMR applications due to its higher sensitivity?
What is the quantum number of isotope 10B?
What is the quantum number of isotope 10B?
What is the purity percentage of boric acid mentioned in the content?
What is the purity percentage of boric acid mentioned in the content?
From which supplier was sodium tetraborate sourced?
From which supplier was sodium tetraborate sourced?
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Which of the following was used to enhance the sensitivity of the NMR study?
Which of the following was used to enhance the sensitivity of the NMR study?
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What is the primary application of boron-11 NMR spectroscopy mentioned in the document?
What is the primary application of boron-11 NMR spectroscopy mentioned in the document?
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Who are among the authors of the paper discussing boron-11 NMR?
Who are among the authors of the paper discussing boron-11 NMR?
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When was the paper on quantitative boron-11 NMR published?
When was the paper on quantitative boron-11 NMR published?
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What type of spectroscopy is highlighted in the document for boron analysis?
What type of spectroscopy is highlighted in the document for boron analysis?
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What is the significance of using boron-11 NMR in the analysis of biocides?
What is the significance of using boron-11 NMR in the analysis of biocides?
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Which additional author is mentioned alongside the main contributors to the paper?
Which additional author is mentioned alongside the main contributors to the paper?
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What was the main focus of the research outlined in the document?
What was the main focus of the research outlined in the document?
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What is the chemical form of boron primarily analyzed in the research?
What is the chemical form of boron primarily analyzed in the research?
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What is the limit of detection for boric acid using the validated method?
What is the limit of detection for boric acid using the validated method?
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Which value represents the limit of quantification for boric acid?
Which value represents the limit of quantification for boric acid?
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What is the range of recovery reported for the method?
What is the range of recovery reported for the method?
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Which characteristic of the method has an R2 value greater than 0.99?
Which characteristic of the method has an R2 value greater than 0.99?
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What is the range of intra- and inter-day precision reported?
What is the range of intra- and inter-day precision reported?
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What is the reported uncertainty of the method?
What is the reported uncertainty of the method?
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How many different commercial biocides was the method successfully applied to?
How many different commercial biocides was the method successfully applied to?
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Which nucleus has been less frequently measured for quantification compared to dipolar nuclei?
Which nucleus has been less frequently measured for quantification compared to dipolar nuclei?
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What is the primary focus of the studies mentioned in the content?
What is the primary focus of the studies mentioned in the content?
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Which species of Al3+ ions is mentioned as being quantified in the studies?
Which species of Al3+ ions is mentioned as being quantified in the studies?
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What type of NMR is used for determining boric acid content according to the studies?
What type of NMR is used for determining boric acid content according to the studies?
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Which of the following substances is specifically mentioned in relation to agricultural applications?
Which of the following substances is specifically mentioned in relation to agricultural applications?
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The content provides an overview of a specific type of NMR. What distinguishes quadrupolar qNMR from other NMR types?
The content provides an overview of a specific type of NMR. What distinguishes quadrupolar qNMR from other NMR types?
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Which type of ion complex is mentioned as a subject of quantification in the studies?
Which type of ion complex is mentioned as a subject of quantification in the studies?
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What analytical method is primarily discussed for quantification purposes in the content?
What analytical method is primarily discussed for quantification purposes in the content?
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Which of the following is NOT addressed as part of the studies on qNMR?
Which of the following is NOT addressed as part of the studies on qNMR?
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What is the primary purpose of using 11B qNMR as mentioned?
What is the primary purpose of using 11B qNMR as mentioned?
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Which acquisition parameter indicates the time over which data is collected?
Which acquisition parameter indicates the time over which data is collected?
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What software is mentioned for processing the NMR spectra?
What software is mentioned for processing the NMR spectra?
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What is the relaxation delay value used in the NMR acquisition parameters?
What is the relaxation delay value used in the NMR acquisition parameters?
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What was applied to the total FID prior to Fourier transformation?
What was applied to the total FID prior to Fourier transformation?
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How many data points were used in the NMR acquisition?
How many data points were used in the NMR acquisition?
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Which ion is NOT mentioned as a soluble polyborate ion in the content?
Which ion is NOT mentioned as a soluble polyborate ion in the content?
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Which aspect is characterized by the term 'quadrupolar nature' in relation to boron-11?
Which aspect is characterized by the term 'quadrupolar nature' in relation to boron-11?
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Study Notes
Introduction to Quantitative Boron-11 NMR
- NMR (nuclear magnetic resonance) has historically had limitations in sensitivity compared to other analytical techniques.
- Recent advancements in NMR spectrometers have improved sensitivity.
- NMR is a valuable tool for analyzing structural and quantitative data from 1/2 spin isotopes.
- Quadrupolar nuclei (I > 1/2) have fewer research applications for quantitative analysis.
- Quantitative NMR (qNMR) is useful for determining the quantity of an unknown compound in a mixture using known standards or calibration curves.
- ¹H qNMR is widely used in organic molecules.
- qNMR uses direct proportionality between the integral of each signal and the number of protons.
- NMR is non-destructive and can simultaneously determine multiple analytes, even in complex mixtures.
- Boron-11 is a suitable element for this method.
Boron-11 NMR Method for Quantitative Analysis
- A new boron-11 NMR method (11B qNMR) was developed for determining boric acid in different commercial biocides.
- Limit of detection (LOD) 0.02% w/w
- Limit of quantification (LOQ) 0.04% w/w
- High linearity (R² > 0.99)
- High recovery (93.6%-106.2%)
- High precision (intra- and inter-day, 0.7 to 2.0%)
- Low uncertainty (3.7 to 4.4%)
- Minimal matrix effects
- Successful application using ICP-MS (inductively coupled plasma mass spectrometry) for comparison
Sample Preparation and Analysis
- Biocide pellets were ground, homogenized, and stored.
- Samples (150 mg) were extracted with D₂O.
- Vortex stirring, centrifugation, and supernatant transfer were used.
- Multiple extractions were necessary for higher concentrations.
- ICP-MS samples were prepared using 500 mg in 500 mL Milli-Q water with sonication for 30 min.
- NMR spectra were recorded on a Bruker Avance 300 spectrometer using a direct probe head.
- 11B chemical shifts are relative to BF₃·OEt₂ (0 ppm).
- Spectral parameters: TD, AQ, D1, FIDRES, NS, DE
- The impact of scans, acquisition time, and recycle delay on NMR signal was evaluated and optimized.
Method Validation
- Validation of the method was performed on a commercial biocide (0.01% boric acid).
- The linear range of the method was confirmed.
- The R² was 0.9996. Validation ensured reliability in routine analysis.
- Selectivity: No interfering signals were observed.
- Precision: Intra-day and inter-day precision were in line with guidelines.
- Trueness (recovery): Avg. recoveries at 0.5, 1.5 and 4.0% were 106, 94 and 101% respectively.
- LOD was 0.02% and LOQ was 0.04%, for a SNR of 3:1 and 10:1 respectively.
- Uncertainty was evaluated using a bottom-up approach with values of 4.4% (low conc.), 3.9% (1.5%), and 3.7% (4.0%).
- The matrix effect was validated.
- The method was validated using a calibration curve.
- Calibration curve for borax (sodium tetraborate) demonstrated successful application. (Linear)
Sample Analysis and Results
- 5 different commercial biocide samples were tested for boric acid content.
- Multiple extractions were required in certain samples.
- 11B qNMR spectra of the samples were analyzed.
- Quantitative results were compared with those by ICP-MS.
- Differences between methods were within acceptable limits (under 6%).
Conclusions
- A quantitative Boron-11 NMR method was developed for the determination of boric acid in commercial biocides.
- It is sensitive enough, fast, and reliable with minimal matrix effects.
- It can be applied to other complex matrices.
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Description
Test your knowledge on boron isotopes and their applications in NMR spectroscopy. This quiz covers sensitivity, quantum numbers, and the purity of boric acid, among other important details. Perfect for students or professionals in chemistry and materials science.
