Agent skill
bio-metabolomics-targeted-analysis
Targeted metabolomics analysis using MRM/SRM with standard curves. Covers absolute quantification, method validation, and quality assessment. Use when quantifying specific metabolites using calibration curves and internal standards.
Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/data/targeted-analysis
SKILL.md
Targeted Metabolomics Analysis
Skyline Data Export Processing
library(tidyverse)
# Load Skyline export
skyline_data <- read.csv('skyline_export.csv')
# Expected columns: Replicate, Peptide/Molecule, Area, Concentration (for standards)
colnames(skyline_data)
# Filter to quantifier transitions
quant_data <- skyline_data %>%
filter(Quantitative == TRUE | is.na(Quantitative))
# Pivot to matrix format
intensity_matrix <- quant_data %>%
select(Replicate, Molecule, Area) %>%
pivot_wider(names_from = Replicate, values_from = Area)
Standard Curve Fitting
# Standard curve data
standards <- data.frame(
concentration = c(0, 1, 5, 10, 50, 100, 500, 1000), # nM
area = c(100, 5000, 25000, 50000, 240000, 480000, 2300000, 4500000)
)
# Linear regression (log-log for wide range)
fit_linear <- lm(area ~ concentration, data = standards)
fit_loglog <- lm(log10(area) ~ log10(concentration + 1), data = standards)
# Weighted linear regression (1/x^2 weighting)
fit_weighted <- lm(area ~ concentration, data = standards,
weights = 1 / (standards$concentration + 1)^2)
# R-squared
summary(fit_linear)$r.squared
summary(fit_weighted)$r.squared
# Plot standard curve
ggplot(standards, aes(x = concentration, y = area)) +
geom_point(size = 3) +
geom_smooth(method = 'lm', se = TRUE) +
scale_x_log10() +
scale_y_log10() +
theme_bw() +
labs(title = 'Standard Curve', x = 'Concentration (nM)', y = 'Peak Area')
Calculate Concentrations
calculate_concentration <- function(area, fit, method = 'linear') {
if (method == 'linear') {
coef <- coef(fit)
conc <- (area - coef[1]) / coef[2]
} else if (method == 'loglog') {
coef <- coef(fit)
conc <- 10^((log10(area) - coef[1]) / coef[2]) - 1
}
return(pmax(conc, 0)) # No negative concentrations
}
# Apply to samples
samples <- data.frame(
sample = paste0('Sample', 1:10),
area = c(12000, 45000, 8000, 120000, 35000, 78000, 22000, 95000, 41000, 63000)
)
samples$concentration <- calculate_concentration(samples$area, fit_weighted)
# Account for dilution factor
dilution_factor <- 10
samples$concentration_original <- samples$concentration * dilution_factor
Internal Standard Normalization
# Data with internal standard
data_with_istd <- data.frame(
sample = paste0('Sample', 1:10),
analyte_area = c(12000, 45000, 8000, 120000, 35000, 78000, 22000, 95000, 41000, 63000),
istd_area = c(50000, 52000, 48000, 51000, 49000, 53000, 47000, 50000, 51000, 49000)
)
# Calculate response ratio
data_with_istd$response_ratio <- data_with_istd$analyte_area / data_with_istd$istd_area
# IS-normalized concentration (using IS-corrected standard curve)
istd_conc <- 100 # nM - known ISTD concentration
data_with_istd$concentration <- calculate_concentration(
data_with_istd$response_ratio * istd_conc,
fit_weighted
)
Method Validation Metrics
# Accuracy and precision from QC samples
qc_data <- data.frame(
level = rep(c('Low', 'Medium', 'High'), each = 6),
nominal = rep(c(10, 100, 500), each = 6),
measured = c(
c(9.5, 10.2, 11.1, 9.8, 10.5, 10.0),
c(98, 102, 95, 105, 99, 101),
c(485, 510, 495, 520, 490, 505)
)
)
# Calculate metrics
validation_metrics <- qc_data %>%
group_by(level, nominal) %>%
summarise(
mean = mean(measured),
sd = sd(measured),
cv_percent = sd(measured) / mean(measured) * 100,
accuracy_percent = mean(measured) / nominal * 100,
bias_percent = (mean(measured) - nominal) / nominal * 100,
.groups = 'drop'
)
print(validation_metrics)
# Acceptance criteria
# CV < 15% (< 20% at LLOQ)
# Accuracy 85-115% (80-120% at LLOQ)
Limit of Detection/Quantification
# LOD/LOQ from standard curve
# LOD = 3.3 * (SD of response / slope)
# LOQ = 10 * (SD of response / slope)
# Residual standard deviation
residuals_sd <- sd(residuals(fit_weighted))
slope <- coef(fit_weighted)[2]
LOD <- 3.3 * residuals_sd / slope
LOQ <- 10 * residuals_sd / slope
cat('LOD:', round(LOD, 2), 'nM\n')
cat('LOQ:', round(LOQ, 2), 'nM\n')
# Signal-to-noise based LOD (from blank samples)
blank_areas <- c(100, 120, 95, 110, 105)
LOD_SN <- mean(blank_areas) + 3 * sd(blank_areas)
Multi-Compound Analysis
# Multiple analytes with individual standard curves
analytes <- c('Glucose', 'Lactate', 'Pyruvate', 'Citrate', 'Succinate')
# Store calibration curves
calibrations <- list()
for (analyte in analytes) {
std_data <- standards_all[standards_all$analyte == analyte, ]
calibrations[[analyte]] <- lm(area ~ concentration, data = std_data,
weights = 1 / (std_data$concentration + 1)^2)
}
# Quantify all samples
quantify_sample <- function(sample_data, calibrations) {
results <- data.frame(analyte = names(calibrations))
results$concentration <- sapply(names(calibrations), function(a) {
area <- sample_data$area[sample_data$analyte == a]
calculate_concentration(area, calibrations[[a]])
})
return(results)
}
Python Workflow
import pandas as pd
import numpy as np
from scipy import stats
from sklearn.linear_model import LinearRegression
import matplotlib.pyplot as plt
# Load data
data = pd.read_csv('targeted_data.csv')
# Standard curve fitting
def fit_standard_curve(concentrations, areas, weighted=True):
X = np.array(concentrations).reshape(-1, 1)
y = np.array(areas)
if weighted:
weights = 1 / (np.array(concentrations) + 1)**2
model = LinearRegression()
model.fit(X, y, sample_weight=weights)
else:
model = LinearRegression()
model.fit(X, y)
r2 = model.score(X, y)
return model, r2
model, r2 = fit_standard_curve(standards['concentration'], standards['area'])
print(f'R² = {r2:.4f}')
# Calculate concentrations
def calculate_conc(areas, model):
return (np.array(areas) - model.intercept_) / model.coef_[0]
samples['concentration'] = calculate_conc(samples['area'], model)
# Validation metrics
def calc_cv(values):
return np.std(values) / np.mean(values) * 100
def calc_accuracy(measured, nominal):
return np.mean(measured) / nominal * 100
# Plot results
fig, axes = plt.subplots(1, 2, figsize=(12, 5))
# Standard curve
axes[0].scatter(standards['concentration'], standards['area'])
x_line = np.linspace(0, max(standards['concentration']), 100)
axes[0].plot(x_line, model.predict(x_line.reshape(-1, 1)), 'r-')
axes[0].set_xlabel('Concentration')
axes[0].set_ylabel('Area')
axes[0].set_title(f'Standard Curve (R² = {r2:.4f})')
# Sample concentrations
axes[1].bar(samples['sample'], samples['concentration'])
axes[1].set_xlabel('Sample')
axes[1].set_ylabel('Concentration')
axes[1].set_title('Sample Quantification')
plt.tight_layout()
plt.savefig('targeted_results.png', dpi=150)
Quality Control
# QC sample tracking
qc_chart <- function(qc_values, target, warning_sd = 2, action_sd = 3) {
mean_val <- mean(qc_values)
sd_val <- sd(qc_values)
ggplot(data.frame(run = 1:length(qc_values), value = qc_values)) +
geom_point(aes(x = run, y = value), size = 3) +
geom_line(aes(x = run, y = value)) +
geom_hline(yintercept = target, color = 'green', linetype = 'solid') +
geom_hline(yintercept = target + warning_sd * sd_val, color = 'orange', linetype = 'dashed') +
geom_hline(yintercept = target - warning_sd * sd_val, color = 'orange', linetype = 'dashed') +
geom_hline(yintercept = target + action_sd * sd_val, color = 'red', linetype = 'dashed') +
geom_hline(yintercept = target - action_sd * sd_val, color = 'red', linetype = 'dashed') +
theme_bw() +
labs(title = 'QC Levey-Jennings Chart', x = 'Run', y = 'Measured Concentration')
}
Export Results
# Final results table
results_final <- data.frame(
sample = samples$sample,
concentration_nM = round(samples$concentration, 2),
concentration_uM = round(samples$concentration / 1000, 4),
cv_percent = round(samples$cv, 1),
qc_flag = ifelse(samples$cv > 20, 'FAIL', 'PASS')
)
write.csv(results_final, 'targeted_results.csv', row.names = FALSE)
Related Skills
- xcms-preprocessing - Peak detection for targeted features
- normalization-qc - QC-based normalization
- statistical-analysis - Group comparisons
Recommended Agent Skills
Expand your agent's capabilities with these related and highly-rated skills.
agent-ops-spec
Manage specification documents in .agent/specs/. Use when user provides requirements, acceptance criteria, or feature descriptions that need to be tracked and validated against implementation.
agent-ops-state
Maintain .agent state files. Use at session start, after meaningful steps, and before concluding: read/update constitution/memory/focus/issues/baseline consistently.
agent-ops-spec
Manage specification documents in .agent/specs/. Use when user provides requirements, acceptance criteria, or feature descriptions that need to be tracked and validated against implementation.
agent-ops-testing
Test strategy, execution, and coverage analysis. Use when designing tests, running test suites, or analyzing test results beyond baseline checks.
agent-ops-testing
Test strategy, execution, and coverage analysis. Use when designing tests, running test suites, or analyzing test results beyond baseline checks.
agent-ops-state
Maintain .agent state files. Use at session start, after meaningful steps, and before concluding: read/update constitution/memory/focus/issues/baseline consistently.
Didn't find tool you were looking for?