Ask an analytical chemist which instrument they reach for first when a new material arrives at the receiving dock, and the answer is very often the FTIR spectrometer. Fourier transform infrared spectroscopy occupies this position in pharmaceutical analysis because it answers, within seconds and usually without harming the sample, the two questions that drive most daily laboratory work: what is this material, and has it changed? A single mid-infrared spectrum can carry the chemical identity of an active ingredient, the fingerprint of an excipient, the folding pattern of a protein, or the polymer family of a packaging film. Very few techniques span such different sample types with one measurement principle, which is why FTIR remains a fixture of the modern spectroscopy testing laboratory even as newer and larger instruments come and go. This article walks through FTIR applications the way laboratories actually encounter them: organized by sample type, from active ingredients and formulations to biologics, packaging materials, and unknown contaminants, with practical guidance on matching sampling modes to each kind of sample.
Molecules are not rigid objects. Their bonds stretch, bend, twist, and rock, and each of these vibrations absorbs infrared light at a frequency set by the masses of the atoms involved and the stiffness of the bonds that connect them. An FTIR spectrometer sweeps the mid-infrared region, conventionally 4000 to 400 cm-1, and records which frequencies the sample absorbs and how strongly. The result is a spectrum of peaks and troughs that reads like a barcode of the molecule's functional groups: a carbonyl stretch appears near 1700 cm-1, N-H stretching around 3300 cm-1, and aromatic C-H vibrations just above 3000 cm-1. Because every molecule combines these group frequencies with its own unique coupled vibrations, no two compounds produce identical spectra.
The "Fourier transform" in the name describes how the data are collected. Rather than scanning wavelength by wavelength, the instrument directs infrared light through an interferometer, records the resulting interference pattern, and applies a mathematical Fourier transform to convert that pattern into the familiar spectrum. Since all wavelengths are measured simultaneously, a high-quality spectrum accumulates in seconds, and dozens of scans can be averaged to reveal bands far weaker than anything a monochromator-based instrument could detect. In practice this means a clean spectrum costs less than a minute of instrument time, and the same spectrometer adapts to powders, liquids, films, gels, and surfaces simply by changing the sampling accessory.
Two regions of the spectrum do different jobs, and experienced analysts read them in sequence. Above roughly 1500 cm-1, the group frequency region, bands are assigned to specific functional groups and answer the question "what kinds of chemistry are present?" Below 1500 cm-1 lies the fingerprint region, where skeletal and coupled vibrations produce intricate patterns so specific that closely related compounds, different salt forms, and even different polymorphs of the same molecule can be told apart at a glance. Identification work therefore proceeds from broad structural clues to a decisive fingerprint match against reference spectra.
Pharmaceutical development generates an unusually diverse stream of samples, and FTIR fits this stream better than most techniques for a combination of practical reasons:
These strengths make FTIR an ideal first-pass tool, with other techniques taking over where their information content is deeper. For a new chemical entity, NMR testing ultimately delivers the complete covalent structure that IR alone cannot, and orthogonal methods resolve questions FTIR raises but cannot close. The table below summarizes how the principal molecular spectroscopies divide this labor in a pharmaceutical characterization package.
Table.1 FTIR Compared with Complementary Spectroscopic Techniques.
| Technique | Core Information Delivered | Typical Pharmaceutical Role |
| FTIR | Functional groups, fingerprint identity, sensitivity to salts, hydrates, and hydrogen bonding. | First-line identification, compatibility screening, contaminant and packaging analysis. |
| NMR spectroscopy | Complete covalent structure, stereochemistry, connectivity. | Definitive structure confirmation of new molecules and degradation products. |
| Raman spectroscopy | Symmetric and nonpolar bonds; compatible with water and glass containers. | Complementary solid-state form analysis, chemical distribution mapping. |
| UV-Vis spectroscopy | Chromophore absorbance, straightforward quantification. | Assays, dissolution monitoring, solution stability studies. |
| Mass spectrometry | Molecular mass and fragmentation patterns. | Trace impurity identification, structural confirmation of unknowns. |
| X-ray diffraction | Crystal lattice dimensions and crystallinity. | Definitive polymorph assignment and crystallinity quantification. |
Active pharmaceutical ingredients and their synthetic intermediates are the most classical objects of FTIR analysis, and the technique serves them at every stage from route development to routine batch release. Three tasks dominate the workload: confirming that the intended molecule was made, distinguishing the solid form in which it exists, and watching for the spectral signatures of impurities or degradation. Each task exploits a different strength of the infrared spectrum, and together they explain why an FTIR spectrum appears in nearly every small-molecule characterization package.
In a full structure characterization package, the FTIR spectrum plays a clearly defined role: it confirms that all expected functional groups are present and that no unexpected ones appear. A molecule designed with an ester and an aromatic ring must show the carbonyl stretch, the ring C=C bands, and the aromatic C-H pattern at their characteristic positions; the spectrum is read against the proposed structure, and any missing or extra band triggers a closer look. This confirmation is complementary to NMR and mass spectrometry rather than redundant, because infrared detects features such as hydrogen bonding, hydrate water, and residual inorganic content that the other methods can miss or misassign.
Once a molecule is known, FTIR shifts into its highest-throughput role: routine identity verification. A batch of incoming material, an intermediate isolated overnight, or a freshly prepared reference standard is pressed against an ATR crystal, and the resulting fingerprint region is compared with a reference spectrum recorded earlier. The comparison is fast, consumes micrograms of material at most, and requires no solvents or consumables. For intermediates, the same measurement doubles as a reaction monitor: the disappearance of a nitro stretch or an acid chloride carbonyl, and the appearance of the product's amide bands, tells the chemist at a glance that the transformation proceeded. In this mode FTIR functions as a simple yes/no checkpoint that protects downstream instruments, and downstream decisions, from receiving the wrong material.
Two samples can be chemically identical yet critically different: the same molecule packed into two crystal lattices, or converted from its free acid or base into a salt. Because these changes alter hydrogen bonding patterns and intermolecular interactions without changing any atom, they are invisible to mass spectrometry and easy to miss chromatographically, yet they reshape the infrared fingerprint in ways FTIR detects readily. Polymorph pairs typically differ through shifted carbonyl positions, reshaped O-H stretching envelopes between 2500 and 3600 cm-1, and reordered fingerprint bands below 1000 cm-1. Salt formation produces its own unmistakable signature: when a carboxylic acid becomes a carboxylate, the sharp C=O stretch near 1700 cm-1 disappears and is replaced by the paired asymmetric and symmetric COO- bands near 1600 and 1400 cm-1; when a basic amine is protonated, its N-H stretching and bending regions shift characteristically.
FTIR rarely carries the solid-state question alone. X-ray diffraction (XRD) provides the definitive lattice assignment, differential scanning calorimetry contributes the thermal signature, and Raman spectroscopy adds a complementary vibration set that is especially useful for symmetrical bonds and aqueous systems. The practical value of FTIR in this panel is speed: during a polymorph screening or salt form screening campaign, dozens of crystallization outcomes must be triaged quickly, and a one-minute ATR measurement separates the intended forms from physical mixtures, solvates, and unconverted starting material before the slower definitive methods are engaged on the shortlisted candidates.
FTIR is not the primary tool for quantifying trace impurities; that role belongs to chromatography. Its contribution is faster and more diagnostic: it flags gross chemical change, and it helps identify what changed. A sample that suddenly shows a broad O-H envelope where none belongs, a new carbonyl band, or an amide pattern in a molecule with no nitrogen suggests hydrolysis, oxidation, or contamination in a single measurement. Analysts apply this in three common situations. First, as a rapid screen of stressed samples: material held under heat, humidity, or light is checked for new spectral features before expensive chromatographic work begins. Second, within a structured impurity profiling program, IR data help connect chromatographic peaks to structural families and narrow the search during investigations. Third, in dedicated degradation product analysis, the spectrum of an isolated degradant, or of the partially degraded bulk, supports the assignment of degradation chemistry, for example distinguishing hydrolysis of an ester from oxidation of a sulfur or aromatic system, each of which leaves a characteristic infrared trace.
Table.2 Characteristic IR Absorption Bands Frequently Used in Pharmaceutical Identity Work.
| Wavenumber (cm-1) | Vibration | What It Tells the Analyst |
| 3200–3600 | O-H and N-H stretching | Alcohols, phenols, amines, hydrate water; band shape and width flag hydrogen bonding and moisture. |
| 2850–3100 | C-H stretching (aliphatic below 3000, aromatic above) | Hydrocarbon framework and aromatic content of the molecule. |
| 2500–3300 (broad) | Carboxylic acid O-H | Free acid form; disappears upon salt formation. |
| 1660–1760 | C=O stretching | Ester, ketone, amide, or acid class; position narrows the functional group and shifts reveal interactions. |
| ~1600 and ~1400 (pair) | COO- asymmetric and symmetric stretching | Carboxylate salt confirmation; band separation carries structural information. |
| 1500–1600 | Aromatic C=C stretching | Ring presence; exact positions hint at substitution and conjugation. |
| 690–900 | Aromatic C-H out-of-plane bending | Ring substitution pattern; strongly fingerprint-like for isomer distinction. |
| 400–1500 | Coupled skeletal vibrations (fingerprint region) | Unique identity; the zone where polymorphs, salts, and solvates are most clearly separated. |
From identity confirmation to polymorph and salt form differentiation, our FTIR specialists deliver clear, decision-ready spectra for small-molecule samples with rapid turnaround.
Development does not stop at the pure active ingredient. The moment an API enters a formulation, the analytical questions multiply: which excipients are present, do they interact with the drug, and is the finished dosage form built the way it was designed? FTIR answers all three, and it does so in materials that are mixtures, which is precisely where many identification techniques begin to struggle. Because each component contributes its own spectral fingerprint, and because interactions between components rewrite parts of those fingerprints, the infrared spectrum of a formulation is a compact record of both its composition and its internal chemistry.
Common pharmaceutical excipients are spectroscopically distinctive. Lactose and other sugars show their O-H and C-O envelopes, microcrystalline cellulose presents its polysaccharide fingerprint, magnesium stearate displays its long-chain aliphatic and carboxylate pattern, and povidone contributes its lactam carbonyl. A reference library built from these spectra turns incoming material verification into a minutes-long task: an ATR measurement of the as-received powder, a library search, and a match assessment replace slower wet-chemical identification tests. The same comparison catches supplier variation and confirms that a substitution or lot change delivered the intended grade of material. In deformulation and reverse-engineering projects, excipient fingerprints are among the most reliable clues, since the major components of a blend survive manufacturing largely unchanged and remain identifiable even in finished tablets.
Before a formulation is engineered, its chemical feasibility must be established, and drug-excipient compatibility studies are where FTIR earns particular respect. The logic is direct: the spectrum of a physical blend of drug and excipient should be, to first approximation, the sum of the two individual spectra. Any departure from that sum, a new band, a shifted carbonyl, a disappeared acid O-H envelope, is chemical testimony that the components are interacting. Classic troublemakers are well documented spectrally: primary and secondary amines combined with reducing sugars can progress toward Maillard-type adducts, whose early C=N signature appears near 1650 cm-1; basic drugs mixed with acidic excipients such as stearic acid or citric acid convert the acid to its carboxylate salt in the spectrum; strong hydrogen bonders pull neighboring carbonyl and hydroxyl bands by tens of wavenumbers.
Compatibility assessment gains its full value when the blends are stored under stressed conditions and re-examined over time. A mixture whose spectrum is unchanged after elevated-temperature storage is behaving as a physical blend; a mixture whose carbonyl region drifts week by week is telling the formulator to walk away while the cost of doing so is still low. Interpreting these observations follows a consistent pattern:
Table.3 Interpreting FTIR Observations in Drug-Excipient Compatibility Studies.
| Spectral Observation | Most Likely Explanation | Suggested Follow-Up |
| New band absent from both components | Chemical reaction product between drug and excipient. | Isolate and identify the product; reformulate with an alternative excipient. |
| Carbonyl or O-H shifts of 10–30 cm-1 | Hydrogen bonding between components. | Usually acceptable; cross-check with DSC and stability observations. |
| Acid C=O replaced by COO- pair | Acid-base salt formation in the blend. | Assess consequences for dissolution and long-term stability. |
| Progressive broadening across storage points | Amorphization or moisture uptake. | Confirm with XRD crystallinity measurement. |
| Spectrum unchanged after stressed storage | Physically compatible pair. | Proceed to extended stability evaluation with confidence. |
In finished products, the questions become spatial: is the drug evenly distributed, and is the coating what and where it should be? FTIR, particularly in its imaging mode, addresses distribution directly by collecting a spectrum at each point across a sample surface or cross section and converting the result into a chemical map. A tablet cross section reveals whether the API-rich domains are dispersed uniformly or segregated; a blend uniformity study can compare the distribution of characteristic API bands against excipient bands across many sampled fields. Where near-infrared methods take the lead for very fast at-line blend monitoring, NIR analysis and mid-IR imaging frequently operate side by side, with the mid-IR providing the sharper spectral detail needed for method development and troubleshooting.
Coated products add a layer, literally, of questions that FTIR is well built to answer. An ATR measurement pressed against the tablet surface returns the spectrum of the coating itself, confirming the polymer family, whether a functional coating was applied, and whether the surface chemistry matches the coating formulation. A microtomed or fractured cross section examined under the FTIR microscope shows the coating as a chemically distinct band whose thickness and continuity are visible in the image, complementing the physical picture from microscopy with direct chemical evidence. For quality investigations, this combination answers questions that visual inspection cannot, such as whether a coating failure is a thickness problem or a composition problem, and whether a discoloration on the surface is drug migrating into the coating or an external contaminant settling onto it.
Biologics bring a different question to the spectroscopy laboratory. For a protein, peptide, antibody, or nucleic acid sample, the covalent structure is largely fixed by design; what developers need to follow instead is conformation, the higher-order structure that determines whether the molecule is folded, active, and stable. Infrared spectroscopy answers this question with a directness that few techniques match, because the peptide bond vibrations that report on secondary structure are strong, well characterized, and measurable in almost any physical state, from dilute aqueous solutions to frozen solids and lyophilized powders.
The amide linkage of the protein backbone produces a family of infrared bands, of which the Amide I band between 1600 and 1700 cm-1 is the workhorse. Arising chiefly from the C=O stretching of the peptide bond, the Amide I position depends on the hydrogen-bonding geometry of the backbone, and therefore on secondary structure: alpha-helical segments absorb near 1650 to 1658 cm-1, beta-sheet structures near 1620 to 1640 cm-1 with a companion band around 1680 to 1695 cm-1, and unordered segments in between. Because these components overlap in the measured band, analysis applies resolution enhancement, second derivatives, and band fitting, or full spectral deconvolution, to recover the fractional content of each structural class. The supporting bands extend the picture: Amide II near 1540 cm-1 from coupled C-N stretching and N-H bending, Amide III between 1220 and 1330 cm-1, and Amide A near 3300 cm-1 from N-H stretching.
Water is the historical obstacle in protein IR, since liquid water absorbs strongly across the Amide I region, and two practical solutions remove it. Short-pathlength ATR measurement reduces the water contribution to a manageable level that can be subtracted using a reference spectrum, and solvent exchange into D2O shifts the interfering water band away from the Amide I window. Once handled, aqueous measurement is routine, and ATR tolerates the high protein concentrations common in modern biologic formulations without dilution, allowing samples to be analyzed exactly as they are filled. For an independent view of secondary structure, particularly in dilute solution, CD spectroscopy testing provides a complementary measurement, and agreement between the two techniques considerably strengthens any structural conclusion.
Because Amide I analysis is rapid and non-destructive, it slots naturally into stability work. Samples pulled from thermal stress, freeze-thaw cycling, agitation, or extended storage are measured and compared, and the structural readout tracks the molecule through the stress in a way that assays of activity alone cannot: a protein that retains potency but shows a rising beta-sheet fraction is signaling an aggregation pathway, since intermolecular beta structure accompanies many aggregation processes. The same measurement supports comparability exercises, where batches produced by different processes, scales, or sites must be shown equivalent in their higher-order structure; overlaying the Amide I profiles of the batches, together with their fitted component bands, provides direct spectral evidence for the assessment. Lyophilized products extend the reach further, because solid-state FTIR measures the lyophile directly, with no reconstitution, revealing whether the drying cycle preserved the native fold, information that is essentially inaccessible to circular dichroism in the solid state.
Biologic formulations lean on excipients, sugars, surfactants, amino acids, buffers, to hold the protein in its native state, and FTIR observes these protective relationships spectrally. When trehalose or sucrose hydrogen-bonds to the protein backbone, as part of a water-replacement stabilization mechanism, the interactions register in the OH stretching region of the sugar and in subtle shifts of the protein amide bands; a formulation that preserves the Amide I profile through stress has, in that single observation, evidence that its stabilizer system is functioning. Screening proceeds the same way as in small molecules, but with structure as the endpoint: candidate formulations are stressed, measured, and ranked by how nearly their Amide I profile matches the unstressed reference. Surfactant interactions, buffer species effects, and even container-surface adsorption events have all been examined through this lens, making FTIR one of the most broadly useful instruments in the biologic formulation laboratory.
Table.4 Amide Bands Used in Protein FTIR Analysis.
| Band | Typical Position (cm-1) | Molecular Origin | Structural Insight |
| Amide A | ~3300 | N-H stretching of the peptide bond. | Hydrogen-bonding environment of the backbone. |
| Amide I | 1600–1700 | C=O stretching (~80% of the intensity). | Primary secondary-structure readout: alpha-helix ~1650–1658, beta-sheet ~1620–1640 and ~1680–1695, unordered ~1640–1648. |
| Amide II | 1510–1580 | C-N stretching coupled with N-H bending. | Supporting conformational band; shifts upon hydrogen-deuterium exchange. |
| Amide III | 1220–1330 | Coupled C-N and N-H motions. | Corroborates Amide I assignments, useful in aqueous measurement. |
| Side-chain bands | 1400–1600 | Asp/Glu carboxylates, Tyr ring modes. | Local environment and ionization state of specific residue classes. |
Every analytical laboratory eventually receives the samples no one planned for: a visible particle in a vial, a black speck on a tablet, an unknown film on a manufacturing surface, or a packaging material that must be identified and qualified. For this open-ended, detective-style work, FTIR is the default first instrument, because it asks no prior knowledge of the sample, works on virtually any physical form, and compares what it finds against reference libraries containing thousands of polymers, chemicals, and common contaminants. In this supporting role, the technique protects products, explains anomalies, and closes investigations that would otherwise stall.
Pharmaceutical packaging is dominated by a manageable set of polymer families, polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, cyclic olefin copolymers, ethylene-vinyl acetate, and elastomeric closures for injectable containers, and each carries a diagnostic infrared fingerprint. ATR measurement of a container surface or a excised fragment, followed by library comparison, identifies the material within minutes, supporting supplier qualification, material changeover, and failure analysis. Multilayer structures, laminated films, foil adhesives, and coated closures are examined in cross section under the FTIR microscope, where each layer yields its own spectrum and the architecture of the laminate is read layer by layer. Within an extractables and leachables testing program, FTIR contributes on several fronts: the identity of the contacting materials defines what might migrate, extracts are screened spectroscopically for polymer-derived species, and any deposit or discoloration on a product-contact surface can be compared directly against the packaging material library to confirm or exclude the container as its source.
When a particle appears where it should not, the investigation follows a workflow that FTIR microscopy was designed for. The particle is isolated, whether by filtration from solution, dissection from a tablet surface, or retrieval with a fine needle, and photographed to record its morphology and optical behavior. It is then brought under the microscope, where a measurement spot as small as roughly ten micrometers is selected, and a spectrum is collected in transmission, reflection, or micro-ATR mode depending on the particle's size, transparency, and shape. The resulting spectrum is searched against spectral libraries, and the identification is interpreted in context:
Because the measurement is non-destructive at the particle scale, the same specimen remains available for elemental or chromatographic confirmation when the infrared answer is ambiguous. In practice, a large share of particle investigations is resolved by the FTIR spectrum alone, which is why the technique anchors nearly every foreign-matter workflow in the industry.
After equipment cleaning, the question is whether product and cleaning-agent residues were actually removed, and FTIR addresses it both directly and through collected samples. ATR pressed against an accessible equipment surface returns the spectrum of whatever remains on that surface, identifying rather than merely detecting a residue; a swab wiped across a surface and analyzed, neat or after solvent extraction, extends the approach to complex geometries. The infrared answer is specific enough to distinguish residual active ingredient from cleaning detergent, from lubricant, from biofilm components, which matters because each implies a different corrective action. Spectral findings integrate naturally into a structured cleaning verification program, where they confirm removal of the previous product's chemical signature, support investigations of swab results that need identification beyond a total-carbon number, and validate that dedicated cleaning procedures leave nothing recognizable behind. The same surface-measurement logic applies to single-use components, tubing, filters, and containers, where extractable surface films and processing residues can be examined directly before the component enters service.
Our FTIR microscopy and surface analysis team identifies unknowns from the micrometer scale upward, delivering spectral evidence you can act on.
The versatility described throughout this article comes from a single design fact: the FTIR spectrometer is separated from the sample by an interchangeable accessory, and choosing the right accessory for the sample at hand is half of good infrared practice. Four sampling modes cover essentially the entire pharmaceutical sample stream, and knowing when to use each, and what each mode's spectra are worth, turns a routine instrument into a flexible problem-solving platform.
Attenuated total reflectance has become the default mode of modern pharmaceutical infrared work, and for good reason. The sample is pressed against a high-refractive-index crystal, commonly diamond or germanium; infrared light directed into the crystal at angles beyond total internal reflection generates an evanescent wave that penetrates a short distance, on the order of 0.5 to 2 micrometers, into the contacting sample, where it is absorbed before the reflected light returns to the detector. The practical consequences are transformative: solids need only be held firmly against the crystal, liquids and gels are simply dropped onto it, and tablets, packaging fragments, and equipment surfaces are measured as-is, with no dilution, grinding, or windows. Measurements take under a minute, and cleanup is a wipe. Two caveats keep results honest: ATR probes only the contacting surface layer, so heterogeneous solids deserve measurements at several spots, and the shallow, wavelength-dependent penetration distorts relative band intensities slightly, which matters when comparing ATR spectra against transmission reference libraries and can be corrected with standard ATR corrections.
Classical transmission remains the reference mode for quantitative work and library-consistent spectra. Solids are prepared as dilute potassium bromide pellets, in which the sample is ground to submicron particles and pressed with infrared-transparent KBr, or as mulls in mineral oil; liquids are held in cells with fixed pathlengths from tens of micrometers down to a fraction for strongly absorbing samples; and soluble materials can be cast as thin films. Because the pathlength is known and controlled, absorbance follows directly from concentration, transmission spectra match the historical libraries built over decades, and weak bands can be strengthened simply by increasing the amount in the beam. The costs are the preparation itself, the hygroscopic behavior of KBr, which demands dry handling and storage, and the requirement that the prepared specimen actually transmit infrared light. For quantitative methods, for archival-quality spectra, and for materials that dissolve cleanly, transmission is still the mode of record.
Diffuse reflectance, collected with a DRIFTS accessory, addresses samples that neither press cleanly against an ATR crystal nor transmit: coarse powders, rough or abrasive solids, catalyst residues, and materials whose surface chemistry, adsorbed species, surface treatments, is the analytical target. Infrared light floods the sample cup and the diffusely reflected component, which carries absorption information from the sample interior, is collected over a large solid angle and directed to the detector. Preparation is nearly nil, often just sieving or gentle grinding to a consistent particle size, which keeps results reproducible. Diffuse reflectance spectra are shaped by scattering and particle-size effects, so quantitative work applies the Kubelka-Munk transformation and relies on matrix-matched references, but as a fast, preparation-free survey mode for difficult solids it fills a niche the other modes do not.
FTIR microscopy couples the spectrometer to a microscope whose optics both image the sample and define the measurement region, bringing full infrared spectroscopy down to spots roughly ten micrometers across. Measurement options mirror the benchtop modes, transmission for thin or microtomed sections, reflection for polished or opaque surfaces, and micro-ATR for the highest spatial resolution on rough materials. The step from single-point measurement to imaging is where the technique becomes three-dimensional in value: a detector array collects spectra from thousands of points across a mapped area, and each chemical species is rendered as a false-color distribution image. Pharmaceutical applications concentrate exactly where heterogeneity matters, layered packaging laminates, tablet coatings and cores, phase-separated dispersions, contaminated surfaces, and particle fields in which many individual particles are measured and identified in one automated session. An imaging dataset answers not only what is present but where, and how much, which is often the difference between noticing a problem and understanding it.
Table.5 FTIR Sampling Modes Matched to Pharmaceutical Sample Types.
| Sampling Mode | Best-Fit Pharmaceutical Samples | Practical Strengths | Points to Watch |
| ATR | Powders, tablets, neat liquids, gels, polymer films, equipment and packaging surfaces. | No preparation; seconds per measurement; minimal sample consumption. | Probes only the top 0.5–2 μm; measure multiple spots on heterogeneous solids. |
| Transmission (KBr pellet, mull, film, liquid cell) | Compressible or soluble solids, low-water liquids, cast films. | Known pathlength supports quantification; spectra match classical reference libraries. | Hygroscopic KBr; preparation time; sample must transmit infrared light. |
| Diffuse reflectance (DRIFTS) | Coarse powders, rough or abrasive solids, adsorbed surface species. | Essentially no preparation; well suited to diffuse and irregular surfaces. | Scattering and particle-size effects; use Kubelka-Munk treatment and matched references. |
| FTIR microscopy and imaging | Single particles and fibers, cross sections, laminates, coatings, contaminated surfaces. | Micrometer-scale spatial resolution; chemical distribution images; automated particle fields. | Longer acquisition; flat or sectioned surfaces give the best data quality. |
BOC Sciences operates its FTIR capability as one node of an integrated analytical services platform, serving pharmaceutical, biotechnology, and fine-chemical clients from early research through commercial supply. Our infrared laboratory combines modern spectrometers with the full set of sampling modes described above, ATR, transmission, diffuse reflectance, and microscopy with imaging, so that the method follows the sample rather than the reverse. Projects range from single-sample identification to multi-year programs in which FTIR data sit alongside chromatographic, thermal, and diffraction results inside one coordinated package.
Our core FTIR analysis service accepts essentially the full pharmaceutical sample stream: APIs and synthetic intermediates, excipients and raw materials, finished dosage forms, protein solutions and lyophilized biologics, packaging components, surface and swab samples, and isolated particles or unknowns. Each submission is matched to an appropriate sampling mode, measured against curated reference libraries, and reviewed by scientists who read spectra in the context of the sample's history and the client's question. Standard deliverables include the processed spectrum, library search results with match assessment, band assignments for the diagnostic regions, and a plain-language interpretation that states what the data support and what they leave open. Where a question exceeds the reach of a single spectrum, the same team escalates naturally to complementary techniques without the sample leaving the platform.
Some questions require infrared detection to be coupled to a separation or a stress step, and our platform is equipped accordingly. TGA-FTIR testing couples the spectrometer to a thermogravimetric analyzer so that every weight-loss event is accompanied by the spectrum of the evolved gases, identifying residual solvents, hydrate water, and decomposition products directly and distinguishing overlapping mass losses that would otherwise be ambiguous. GC-FTIR testing places the infrared detector after a gas chromatograph, delivering full spectra for each resolved volatile component and resolving positional isomers and structurally similar species that mass spectra alone often cannot separate. Beyond the hyphenated configurations, FTIR data are routinely combined with Raman, XRD, DSC, and NMR results to close solid-state and structural questions, with our scientists assembling the multi-technique picture rather than leaving the client to reconcile disconnected reports.
When FTIR graduates from screening to a quantitative role, the method behind it must be built and demonstrated fit for purpose, and our laboratory provides that service end to end. Method development begins from the analytical question, which analyte, at what level, in which matrix, and proceeds through sampling-mode selection, spectral-region optimization, chemometric or univariate calibration modeling, and robustness tuning, with challenging matrices handled through dedicated sample-preparation strategies rather than forced onto a generic configuration. Method validation then documents specificity, linearity and range, accuracy, precision, detection and quantitation limits, and robustness against deliberate variations, so that results from the method carry documented weight. Validated methods are delivered with full documentation and support for transfer to client laboratories, where our team remains available through the transfer and its early operation.
Table.6 FTIR Related Services at BOC Sciences.
| Service Name | Description | Inquiry |
| Fourier Transform Infrared Spectroscopy Analysis | Full-sampling-mode FTIR analysis for APIs, excipients, formulations, biologics, packaging, surfaces, and unknown samples, with library searching and expert interpretation. | Inquiry |
| Hyphenated Spectroscopic Techniques | Coupled measurements, including TGA-FTIR and GC-FTIR, that pair separation or stress steps with infrared detection for evolved-gas and volatile-component identification. | Inquiry |
| UV-Vis Testing | Complementary absorbance spectroscopy for quantitative assays, dissolution monitoring, and solution-phase stability studies. | Inquiry |
| DSC Testing | Thermal analysis that pairs with FTIR for polymorph, hydrate, and compatibility investigations through melting, desolvation, and interaction events. | Inquiry |
| Impurity Isolation and Identification | Isolation of trace impurities and unknowns followed by multi-technique identification, with FTIR contributing structural and fingerprint evidence. | Inquiry |
| Method Development, Validation and Transfer | Fit-for-purpose FTIR method development with full validation documentation and supported transfer to client laboratories. | Inquiry |
Connect with our FTIR specialists to discuss your sample types, from APIs and formulations to biologics, packaging, and unknowns, and receive a tailored analytical plan.
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