InfraLUM_ID_Losartan

Utility description: InfraLUM ID Losartan

InfraLUM ID Losartan — Losartan Identification by IR Spectroscopy

ℹ️  Utility checks IR spectrum compliance with reference (Ph. Eur. / Russian Pharmacopoeia):
    • Correlation coefficient with reference spectrum: ≥0.995
    • Peak 3440 cm⁻¹ (N-H/O-H imidazole and alcohol stretching): ±20 cm⁻¹
    • Peak 1605 cm⁻¹ (biphenyl C=C): ±10 cm⁻¹ — CORE MARKER
    • Peak 1470 cm⁻¹ (imidazole C=N): ±10 cm⁻¹
    • Peak 1260 cm⁻¹ (C-O hydroxymethyl): ±10 cm⁻¹
    • Peak 1050 cm⁻¹ (tetrazole ring skeletal): ±10 cm⁻¹ — TETRAZOLE MARKER
    • Baseline noise: ≤0.005 Abs

⚠️  IMPORTANT: Losartan is the first representative of the sartan class (AT₁ receptor antagonists).
    Structure contains three key fragments:
    1. Biphenyl system — hydrophobic core providing receptor binding.
    2. Imidazole ring with hydroxymethyl substituent — receptor interaction point.
    3. Tetrazole ring — carboxylic acid bioisostere, critical for activity.
    Loss of any of the three fragments leads to loss of pharmacological activity.

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

Input format:
BatchNumber,CorrelationCoefficient,Peak3440_cm1,Peak1605_cm1,Peak1470_cm1,Peak1260_cm1,Peak1050_cm1,BaselineNoiseAbs,PreparationMethod

Example (PreparationMethod: KBr / ATR / Nujol):
  LOS-ID-2026-055,0.9992,3438.0,1607.0,1468.0,1262.0,1048.0,0.0016,KBr

— WHY IS THIS NEEDED?
Losartan potassium is an antihypertensive agent, angiotensin AT₁ receptor antagonist.
• Tetrazole ring is acidic (pKa ~5–6) and exists as anion at physiological pH.
• In potassium salt form, tetrazole gives characteristic peaks around 1050 cm⁻¹.
• Imidazole ring appears through C=N vibrations at ~1470 cm⁻¹.
• Reference spectrum established in Ph. Eur. Losartan potassium and Russian Pharmacopoeia FS.2.4.00214.18.
• InfraLUM FT-08/FT-10 instruments are widely used in Russian QC laboratories.

⚠️  CRITICAL:
• Correlation ≥0.995 — strict matching criterion with reference.
• Peak 1050 cm⁻¹ (tetrazole) — primary pharmacophore marker.
  Absence or significant shift indicates tetrazole ring loss
  or substitution with non-tetrazole sartan (e.g., telmisartan).
• Peak 1605 cm⁻¹ (biphenyl C=C) — central hydrophobic core marker.
  Distinguishes losartan from non-biphenyl sartans (azilsartan).
• Peak 1470 cm⁻¹ (imidazole C=N) — confirms imidazole ring presence.
  Distinguishes losartan from valsartan (no imidazole).
• Peak 1260 cm⁻¹ (C-O) — hydroxymethyl substituent marker.
• Peak 3440 cm⁻¹ (N-H/O-H) — broad band; sensitive to moisture.
• 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. Losartan potassium and Russian Pharmacopoeia FS.2.4.00214.18.
• Control of five characteristic peaks + correlation + spectrum quality.
• Differentiation from other sartans via tetrazole + imidazole + biphenyl combination.
• Full LabWare LIMS compatibility.

Critical parameters:
• Correlation Coefficient: ≥0.995
• Peak 3440 cm⁻¹ (N-H/O-H): 3440 ± 20 cm⁻¹
• Peak 1605 cm⁻¹ (biphenyl C=C): 1605 ± 10 cm⁻¹
• Peak 1470 cm⁻¹ (imidazole C=N): 1470 ± 10 cm⁻¹
• Peak 1260 cm⁻¹ (C-O hydroxymethyl): 1260 ± 10 cm⁻¹
• Peak 1050 cm⁻¹ (tetrazole skeletal): 1050 ± 10 cm⁻¹
• Baseline Noise: ≤0.005 Abs

💡 Usage tips:
1. KBr tablets must be dry — pre-dry at 120°C before use.
   Losartan potassium is hygroscopic! Moisture distorts the 3440 cm⁻¹ region.
2. Sample concentration in KBr: 0.5–1.0% (w/w).
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 crystal-sample contact.
6. Reference spectrum should be obtained on the same instrument under identical conditions.
7. Store substance in airtight container with desiccant.

⚠️ Note: Losartan potassium exists as a monohydrate. Loss of crystallisation water
    alters the 3440 cm⁻¹ region and may reduce correlation below 0.995.
    If only the 3440 cm⁻¹ peak fails, perform water content test (KF).
    Tetrazole ring in potassium salt form also gives a characteristic peak ~1380 cm⁻¹
    (N=N/N-C anionic vibrations), serving as additional confirmatory marker.
    Chloro-substituted phenyl (2-chlorophenyl) appears in the 750–800 cm⁻¹ region
    (C-H out-of-plane ortho-substitution) — distinguishes losartan from candesartan and irbesartan.
    Azide impurity (potential genotoxic synthesis contaminant) has an intense peak
    ~2100 cm⁻¹ (N₃ asymmetric stretch). Presence of a peak in this region requires
    immediate investigation even if the identity test passes!