> ## Documentation Index
> Fetch the complete documentation index at: https://primerlab-genomic.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# SYBR Green Melt Curve Analysis

> Feature documentation: SYBR Green Melt Curve Analysis

Predict melt curve characteristics for SYBR Green qPCR amplicons.

## Overview

The melt curve module predicts:

* **Amplicon Tm** - Melting temperature of the PCR product
* **Melt Profile** - -dF/dT curve shape
* **Peak Detection** - Single vs multiple peaks
* **Quality Score** - Assessment of amplicon suitability

## Why Melt Curve Analysis?

SYBR Green binds to all double-stranded DNA. Melt curve analysis helps:

1. **Confirm Specificity** - Single peak = single product
2. **Detect Primer-Dimers** - Lower Tm peaks
3. **Identify Non-Specific** - Multiple peaks

## Python API

### predict\_melt\_curve

```python theme={null}
from primerlab.core.qpcr import predict_melt_curve

result = predict_melt_curve(
    amplicon_sequence="ATGC" * 25,  # 100bp
    na_concentration=50.0,
)

print(f"Predicted Tm: {result.predicted_tm}°C")
print(f"Single peak: {result.is_single_peak}")
print(f"Grade: {result.grade}")
```

### Report Generation

```python theme={null}
from primerlab.core.qpcr import (
    predict_melt_curve,
    generate_melt_markdown,
    generate_melt_csv,
)

result = predict_melt_curve("ATGC" * 25)

# Markdown report
md = generate_melt_markdown(result)

# CSV data for plotting
csv = generate_melt_csv(result)
```

## Optimal Amplicon Properties

| Property | Optimal   | Acceptable |
| -------- | --------- | ---------- |
| Length   | 80-120 bp | 70-200 bp  |
| GC%      | 40-60%    | 30-70%     |
| Tm       | 80-88°C   | 75-92°C    |

## Interpreting Results

### Single Peak (Grade A-B)

✅ Indicates specific amplification:

* One clean melt peak
* Sharp transition
* Consistent Tm between replicates

### Multiple Peaks (Review Required)

⚠️ May indicate:

* **Lower peak** - Primer-dimers
* **Higher peak** - Wrong target
* **Shoulder** - Non-specific products

## Output

### MeltCurveResult

```python theme={null}
@dataclass
class MeltCurveResult:
    amplicon_sequence: str
    predicted_tm: float
    tm_range: Tuple[float, float]
    peaks: List[MeltPeak]
    melt_curve: List[Dict]  # {temperature, derivative}
    is_single_peak: bool
    quality_score: float
    grade: str
    warnings: List[str]
```

### MeltPeak

```python theme={null}
@dataclass
class MeltPeak:
    temperature: float
    height: float      # Relative (0-1)
    width: float       # °C at half-max
    is_primary: bool
```

## Grading

| Grade | Score | Interpretation                        |
| ----- | ----- | ------------------------------------- |
| A     | ≥90   | Excellent - clean single peak         |
| B     | 80-89 | Good - single peak with minor issues  |
| C     | 70-79 | Acceptable - review recommended       |
| D     | 60-69 | Poor - may have non-specific products |
| F     | \<60  | Fail - redesign primers               |

## See Also

* [Probe Binding](probe-binding)
* [qPCR Amplicon QC](/docs/concepts/features/amplicon)