Blog
qPCR analysis insights, method guides, and software updates from the AnnealIQ team.
SYBR Green vs TaqMan: Choosing qPCR Chemistry by Specificity, Cost, and Throughput
SYBR Green vs TaqMan probe chemistry compared on cost, specificity workflow, multiplex capability, and verdict by lab reader-type.
Biological vs Technical Replicates in qPCR: Why N Matters More Than You Think
Why qPCR statistics fail when wells are treated as biological N. Worked p-value comparison, MIQE replicate reporting, and aggregation rules.
Pfaffl vs Delta-Delta Ct: When Efficiency Correction Actually Matters
Decision rule for choosing Pfaffl over 2^-Delta-Delta Ct in qPCR: efficiency spread thresholds, worked-number bias, MIQE 2.0 reporting requirements.
Multiplex qPCR Probe Design: Fluorophore Pairing, Quenchers, and Spectral Separation
Multiplex qPCR probe design: fluorophore selection, BHQ quencher pairing, probe Tm, and primer concentration calibration for clean triplex assays.
Normalizing qPCR Without a Reference Gene: Spike-Ins, Total RNA, and When Each Works
Normalize qPCR without a reference gene using spike-ins, total RNA mass, or global mean. Decision tree by panel size and sample handling.
Digital PCR vs qPCR: When Sensitivity and Precision Justify the Cost
Pick qPCR or digital PCR by abundance, precision needs, and budget — not the absolute-vs-relative axis. Thresholds and costs for the switch.
qPCR Controls Demystified: NTC, gDNA Contamination Check, and Interplate Calibrators
Design NTC, NRT, and interplate calibrators for qPCR. Cq thresholds, gDNA contamination checks, melt-curve diagnosis when controls fail.
RNA Quality for RT-qPCR: RIN Scores, Degradation, and When to Proceed Anyway
No single RIN cutoff works for RT-qPCR. Decide by RIN range and amplicon length, with FFPE exceptions and MIQE reporting notes.
Absolute vs Relative Quantification in qPCR: Choosing the Right Approach for Your Experiment
Absolute vs relative quantification qPCR: when copy numbers vs fold change is right, standard curve requirements, and a decision tree by reader-type.
Analyzing qPCR Data in Excel: Formulas, Stats, and Common Calculation Errors
How to analyze qPCR data in Excel: formulas, statistical analysis, and the calculation errors that quietly invalidate fold-change figures.
MIQE Guidelines for qPCR: What Reviewers Expect in Your Methods Section
The MIQE checklist items reviewers flag most often in qPCR methods sections. What to report, common omissions, and what MIQE 2.0 changed.
Validating Reference Genes with geNorm and NormFinder: Step-by-Step Protocol
Step-by-step protocol for validating qPCR reference genes with geNorm and NormFinder. M-values, stability thresholds, and when they disagree.
Primer Efficiency Variation Across Samples: Why It Invalidates Delta-Delta Ct
When the same primer pair produces different efficiencies across samples, delta-delta Ct breaks. How to detect it and what to do instead.
Setting Threshold and Baseline in qPCR: How Misplacement Distorts Your Fold Changes
Step-by-step guide to setting qPCR threshold and baseline correctly. Includes a worked example showing how misplacement inflates fold-change calculations, plus an auto-vs-manual decision table.
Reading qPCR Melt Curves: What Multiple Peaks Actually Mean
Systematic decision tree for interpreting qPCR melt curves with multiple peaks. Covers primer-dimers, off-target amplification, AT-rich double peaks, and when to trust vs. discard your data.
7 qPCR Primer Design Mistakes That Wreck Your Efficiency Numbers
Avoid the 7 most common qPCR primer design mistakes for Tm, GC content, amplicon size, and self-complementarity. Includes specific thresholds, fixes, and a quick-reference checklist to hit 90-110% efficiency.
The Delta Delta Ct Method Explained: Assumptions, Calculation, and When It Fails
Step-by-step delta delta Ct calculation for qPCR gene expression with a worked example. Covers the two critical assumptions (equal efficiency, ~100% efficiency), when to use the Pfaffl method instead, statistical testing on delta Ct values, and MIQE reporting requirements.
Choosing Reference Genes for RT-qPCR: Stability Testing and Common Pitfalls
How to select and validate reference genes for qPCR normalization using GeNorm, NormFinder, and BestKeeper. Covers candidate gene panels, stability thresholds, geometric mean normalization, and MIQE reporting requirements.
Calculating qPCR Efficiency: Standard Curve Method and What Poor Efficiency Means
Learn how to calculate qPCR primer efficiency from a standard curve using the slope formula E = 10^(-1/slope) - 1, with a worked example, troubleshooting guide for results outside 90-110%, and MIQE reporting requirements.