DEPTQ, DEPT & APT: Carbon Multiplicity Determination
DEPT is an essential companion to C-13 NMR, revealing whether each carbon is CH₃, CH₂, CH, or quaternary.
While standard C-13 NMR shows all carbons in your molecule, it doesn't distinguish between different carbon types. When you request DEPT analysis, we use DEPTQ (DEPT with retention of Quaternary carbons) as our default technique, which provides superior multiplicity information compared to traditional DEPT or APT experiments.
What are DEPTQ, DEPT, and APT?
⭐ DEPTQ is Our Default DEPT Technique
When you request DEPT analysis, we run DEPTQ by default because it provides superior information compared to traditional DEPT-135, DEPT-90, or APT:
- Shows ALL carbons - Including quaternary carbons (which are absent in standard DEPT)
- Identifies multiplicity - Still distinguishes CH₃, CH₂, CH, and quaternary C
- Single experiment - More efficient than running multiple DEPT angles
- Phase editing - CH₃/CH point up, CH₂ points down, quaternary carbons point down
Note: DEPTQ is a companion to C-13 NMR, not a replacement. If you request C-13 NMR, you'll receive a standard C-13 spectrum. If you also want multiplicity editing, request DEPT (we'll run DEPTQ).
For comparison, here are the traditional editing techniques:
DEPTQ (Our Standard)
DEPT with Quaternary retention :
- CH₃ - Positive (↑)
- CH₂ - Negative (↓)
- CH - Positive (↑)
- Quaternary C - Negative (↓) ✓
Advantage: Shows quaternary carbons!
DEPT
Traditional DEPT uses different pulse angles (45°, 90°, 135°):
- CH₃ - Positive (↑)
- CH₂ - Negative (↓)
- CH - Positive (↑)
- Quaternary C - Absent (no signal)
Requires comparison with C-13 to find quaternary carbons
APT
Simpler one-pulse experiment:
- CH₃ - Positive (↑)
- CH₂ - Negative (↓)
- CH - Positive (↑)
- Quaternary C - Negative(↓)
Less sensitive than DEPTQ
Why Carbon Multiplicity Matters for Structure Determination
Dramatically Speeds Up Structure Elucidation
Knowing whether a carbon at 30 ppm is CH₃, CH₂, or CH immediately narrows down the possibilities and guides your structural assignment.
Example: A signal at 25 ppm could be:
- CH₃ group on an aliphatic chain
- CH₂ group in a ring
- CH group at a branching point
DEPT/APT tells you instantly which one it is!
Key Benefits
1. Identify Quaternary Carbons
These carbons have no attached hydrogens and are invisible in DEPT/APT. This immediately flags branching points, aromatic substitution sites, and C=O carbons without H.
2. Distinguish CH₂ from Others
CH₂ signals point down (negative phase) while CH₃ and CH point up. Instantly identify methylenes vs methyls.
3. Simplify Complex Spectra
With carbon types identified, you can piece together the molecular structure much faster than C-13 alone.
How to Read DEPT and APT Spectra
| Carbon Type | Number of H's | DEPTQ (Our Standard) | DEPT 135° | APT |
|---|---|---|---|---|
| CH₃ (Methyl) | 3 | Positive ↑ | Positive ↑ | Positive ↑ |
| CH₂ (Methylene) | 2 | Negative ↓ | Negative ↓ | Negative ↓ |
| CH (Methine) | 1 | Positive ↑ | Positive ↑ | Positive ↑ |
| Quaternary C | 0 | Positive ↑ ✓ | Absent | Absent |
🌟 Key Advantage of DEPTQ
Notice the highlighted row: DEPTQ shows quaternary carbons (positive signal), while standard DEPT-135 and APT don't show them at all!
This means with DEPTQ, you get complete carbon information in a single experiment - no need to compare separate C-13 and DEPT spectra to identify quaternary carbons.
Typical Analysis Workflow
Most customers order both C-13 NMR and DEPT together for complete characterization:
- Request C-13 NMR + DEPT when submitting your sample
- Receive C-13 NMR spectrum - shows all carbons for an accurate carbon count
- Receive DEPTQ spectrum - Phase-edited, identifies carbon types:
- CH₃ and CH = positive peaks (pointing up)
- CH₂ = negative peaks (pointing down)
- Quaternary C = negative peaks (can be distinguished by cross-referencing with C-13 and H-1)
- Use both spectra together - C-13 for confirming carbon count, DEPTQ for multiplicity assignment
DEPTQ is typically run alongside C-13 NMR as a complementary experiment.
Why We Use DEPTQ Instead of Traditional DEPT or APT
| Feature | DEPTQ (Our Default) | DEPT-135 | APT |
|---|---|---|---|
| Shows quaternary carbons? | YES ✓ | No (absent) | No (absent) |
| Multiplicity editing? | YES (CH₃/CH up, CH₂ down, Quat up) | YES (CH₃/CH up, CH₂ down) | YES (CH₃/CH up, CH₂ down) |
| Need separate C-13 to see all carbons? | No ✓ | Yes (quaternary C are invisible) | Yes (quaternary C are invisible) |
| Number of experiments | 1 (single acquisition) | 1 (but need C-13 for quaternary) | 1 (but need C-13 for quaternary) |
| Quantitative? | No (edited) | No (edited) | No (edited) |
| Best for | Complete multiplicity info ✓ | Basic multiplicity (if quaternary C aren't important) | Quick multiplicity check |
Why DEPTQ is Our Default DEPT Technique
When you request DEPT analysis, we run DEPTQ because it's simply better:
- ✓ Shows quaternary carbons - Traditional DEPT/APT don't show them at all
- ✓ Complete information - See all carbon types in one spectrum
- ✓ Easier interpretation - No need to compare DEPT with C-13 to find quaternary carbons
- ✓ Same acquisition time - No penalty for better data
- ✓ Same pricing - Superior technique at no extra cost
For complete carbon characterization, request both:
- C-13 NMR - For characterization of carbons
- DEPT - DEPTQ for multiplicity editing (shows CH₃, CH₂, CH, quaternary)
Together, these two experiments give you everything you need for complete carbon analysis.
When DEPT/APT is Essential
- Complex organic synthesis - Verify structure of synthetic intermediates and products
- Natural product structure elucidation - Essential for assigning complex molecular frameworks
- Unknown identification - Narrow down structural possibilities quickly
- Pharmaceutical development - Confirm drug molecule structures
- Polymer analysis - Identify monomer units and chain structure
- Quality control - Verify product structure and purity
- Academic research - Structure proof for publications
Sample Requirements
DEPTQ uses the same sample requirements as standard C-13 NMR:
- Sample amount: 5-10 mg minimum (May require long run), 50-100 mg recommended
- Solvent: Deuterated solvents (CDCl₃, DMSO-d₆, D₂O, etc.)
- Concentration: 10-30 mM typical
- Purity: Higher purity gives cleaner results
DEPTQ acquisition time is comparable to standard C-13 NMR.
Turnaround Time & Pricing
When submitting your sample, specify which experiments you need:
- C-13 NMR only - You'll receive a standard C-13 spectrum
- DEPT only - You'll receive a DEPTQ spectrum (our default DEPT technique)
- C-13 + DEPT - You'll receive both (recommended for complete characterization)
Standard Service
Turnaround: 2-5 business days for both C-13 and DEPTQ
What you receive when you order DEPT: DEPTQ spectrum showing all carbons with multiplicity editing
Pricing: DEPT is typically offered at a reduced rate when ordered together with C-13 NMR
Alternative DEPT Techniques Available Upon Request
While DEPTQ is our default, we can run other DEPT experiments if specifically requested:
- Traditional DEPT-45, DEPT-90, DEPT-135
- APT (Attached Proton Test)
- Other specialized editing sequences
Just note your preference when submitting your sample.
For pricing information, please visit our Pricing page or contact us.
What You'll Receive
If You Order C-13 NMR
- Standard C-13 NMR spectrum
- Peak list with chemical shifts
- Accurate integrations
- Raw data files (Bruker format)
- PDF report
If You Order DEPT
- DEPTQ spectrum (phase-edited)
- Peak list with chemical shifts
- Raw data files (Bruker format)
- PDF report
Recommended: Order Both for Complete Analysis
When you order C-13 + DEPT together, you receive:
- C-13 NMR spectrum - for quantitation and accurate carbon count
- DEPTQ spectrum - for multiplicity identification (CH₃, CH₂, CH, quaternary)
- Both spectra can be overlaid for easy comparison
- Complete structural characterization in one submission
How DEPTQ Results are Presented
- Single spectrum showing all carbons with phase editing
- Positive peaks (↑) = CH₃, CH, and quaternary C
- Negative peaks (↓) = CH₂
- All carbon types clearly identifiable by phase
Distinguishing CH₃/CH from Quaternary Carbons
Since DEPTQ shows all three (CH₃, CH, and quaternary C) as positive peaks, use these methods to distinguish:
- Chemical shift range - Quaternary carbons appear in characteristic regions
- Cross-reference with H-1 NMR - Quaternary carbons have no protons
- Compare with C-13 spectrum - If ordered together, quaternary C will have different integration
- 2D HSQC - Quaternary carbons won't show C-H correlations
Ready for Complete Carbon Characterization?
Order C-13 NMR + DEPT for complete carbon analysis with multiplicity editing
When you request DEPT, we'll run DEPTQ (our superior default technique) at no extra charge
Submit a Sample Request a Quote
Phone: (858) 793-6057 | Email: NuMegaLab@NuMegaLabs.com
Related NMR Services
C-13 NMR
Carbon skeleton analysis
H-1 NMR
Proton NMR
2D NMR
HSQC, HMBC for complete assignment
Quantitative NMR
Purity analysis