InfraLUM_ID_Metformin

Utility description: InfraLUM ID Metformin

InfraLUM ID Metformin — Metformin Identification by IR Spectroscopy

ℹ️  Utility checks IR spectrum compliance with reference (Ph. Eur. / Russian Pharmacopoeia):
    • Correlation coefficient with reference spectrum: ≥0.995
    • Peak 3370 cm⁻¹ (N-H guanidine stretching): ±20 cm⁻¹
    • Peak 3170 cm⁻¹ (NH₂⁺/NH⁺ salt stretching): ±20 cm⁻¹ — HYDROCHLORIDE MARKER
    • Peak 1625 cm⁻¹ (C=N guanidine group): ±10 cm⁻¹ — CORE MARKER
    • Peak 1470 cm⁻¹ (CH₃ deformation + CN skeletal): ±10 cm⁻¹
    • Peak 1060 cm⁻¹ (C-N dimethylamino): ±10 cm⁻¹
    • Baseline noise: ≤0.005 Abs

⚠️  IMPORTANT: Metformin belongs to the biguanide class, not sulfonylureas.
    The molecule contains a guanidine group that is a strong base and exists
    in protonated form as hydrochloride salt.
    Protonation creates a hydrogen bonding network manifesting as a very broad
    and intense absorption band in the 3100–3400 cm⁻¹ region.
    This band is the most characteristic diagnostic feature of metformin and
    distinguishes it from most other oral antidiabetic agents.

Usage:
  InfraLUM_ID_Metformin.exe                            → demo mode (console output)
  InfraLUM_ID_Metformin.exe input.csv output.json      → evaluate your data

Input format:
BatchNumber,CorrelationCoefficient,Peak3370_cm1,Peak3170_cm1,Peak1625_cm1,Peak1470_cm1,Peak1060_cm1,BaselineNoiseAbs,PreparationMethod

Example (PreparationMethod: KBr / ATR / Nujol):
  MET-ID-2026-071,0.9995,3368.0,3172.0,1623.0,1468.0,1062.0,0.0013,KBr

— WHY IS THIS NEEDED?
Metformin hydrochloride is the first-line therapy for type 2 diabetes mellitus.
• Mechanism of action: AMPK activation, reduction of hepatic gluconeogenesis.
• Does not stimulate insulin secretion (not a hypoglycemic agent).
• IR spectroscopy is the primary identity confirmation method per Ph. Eur. and Russian Pharmacopoeia.
• Reference spectrum established in Ph. Eur. Metformin hydrochloride and Russian Pharmacopoeia FS.2.4.00225.18.
• InfraLUM FT-08/FT-10 instruments are widely used in Russian QC laboratories.

⚠️  CRITICAL:
• Correlation ≥0.995 — strict matching criterion with reference.
• Peak 1625 cm⁻¹ (C=N guanidine) — primary biguanide core marker.
  Absence indicates guanidine group destruction or substitution.
• Peak 3170 cm⁻¹ (NH₂⁺) — specific hydrochloride salt marker.
  For free base this peak is absent or significantly shifted.
  Distinguishes metformin HCl from other salt forms.
• Broad band 3100–3400 cm⁻¹ — result of strong hydrogen bonds
  in hydrochloride crystal lattice. Shape change may indicate
  polymorphic transition or HCl loss.
• Peak 1060 cm⁻¹ (C-N) — confirms dimethylamino group presence.
• Noise >0.005 Abs renders spectrum unsuitable for identification.

Key features:
• Uses NAMED TUPLE (record struct EvalResult) —
  eliminates positional field access errors.
• Specification based on Ph. Eur. Metformin hydrochloride and Russian Pharmacopoeia FS.2.4.00225.18.
• Control of five characteristic peaks + correlation + spectrum quality.
• Differentiation of salt and free base forms via NH₂⁺ peak at 3170 cm⁻¹.
• Full LabWare LIMS compatibility.

Critical parameters:
• Correlation Coefficient: ≥0.995
• Peak 3370 cm⁻¹ (N-H guanidine): 3370 ± 20 cm⁻¹
• Peak 3170 cm⁻¹ (NH₂⁺ salt): 3170 ± 20 cm⁻¹
• Peak 1625 cm⁻¹ (C=N guanidine): 1625 ± 10 cm⁻¹
• Peak 1470 cm⁻¹ (CH₃ deform + CN skeletal): 1470 ± 10 cm⁻¹
• Peak 1060 cm⁻¹ (C-N dimethylamino): 1060 ± 10 cm⁻¹
• Baseline Noise: ≤0.005 Abs

💡 Usage tips:
1. KBr tablets must be DRY — pre-dry at 120°C before use.
   Metformin HCl is VERY hygroscopic! Moisture radically distorts the 3100–3400 cm⁻¹ region.
2. Sample concentration in KBr: 0.3–0.7% (w/w). Metformin gives very intense
   absorption bands; exceeding concentration leads to detector saturation.
3. Record spectrum in 4000–400 cm⁻¹ range, 4 cm⁻¹ resolution, 32 scans.
4. Record background spectrum of pure KBr before each measurement.
5. For ATR method, ensure tight contact; metformin contacts crystal well.
6. Reference spectrum should be obtained on the same instrument under identical conditions.
7. Prepare sample QUICKLY under low humidity conditions (<40% RH).

⚠️ Note: Metformin HCl has a characteristic "fingerprint" in the 3100–3400 cm⁻¹ region —
    a very broad band with multiple maxima caused by complex NH₂⁺···Cl⁻ hydrogen bond network.
    Band shape is sensitive to polymorphic form and hydration state. Any significant shape
    change (narrowing, new maxima appearance) requires additional investigation by PXRD
    or DSC even if correlation test passes.
    Cyanoguanidine impurity (synthetic precursor) has a sharp peak ~2160 cm⁻¹
    (C≡N nitrile group). Presence of ANY peak in the 2100–2200 cm⁻¹ region
    is a CRITICAL DEVIATION requiring immediate investigation,
    as cyanoguanidine is toxic.