Continuous crystallisation PAT: measurement choices and endpoint definitions
What to measure inline when crystallisation runs continuously, which PAT tools fit which regime, and how endpoint stops being a moment and becomes a window.
Category
Explainers
Evergreen technical primers on the methods, instruments, and data analysis behind modern process analytics.
NIR vs process Raman for fertiliser and phosphoric acid streams: how to choose
Fertiliser and phosphoric acid streams stress process NIR and Raman in different ways. Here is how to choose between them, one analyte at a time, before writing the URS.
Inline Raman for polymer resin production: how the technique fits the process
Polymer resin plants live and die by endpoint, viscosity, and free-monomer numbers. Inline Raman puts those numbers on the reactor, but only where the chemistry, the optics, and the process geometry actually agree.
RMSEP, RMSEC, and RMSECV: what each chemometric error metric actually says
RMSEC, RMSECV, and RMSEP are all reported in units of the property being predicted. They mean three different things, and confusing them is how process labs quietly overpromise model accuracy.
Acid number in alkyd resin production: titration versus inline spectroscopy
Acid number is the operator's read on alkyd esterification progress. This piece sets ISO 2114 potentiometric titration against inline NIR and Raman for continuous endpoint control.
Total nitrogen in fertiliser granules: measurement approaches for continuous production
Kjeldahl and Dumas remain the reference methods behind the total-N figure printed on every bag, but the plant floor wants a faster loop. What NIR, Raman, and LIBS can and cannot deliver on coated granules.
Endpoint control of amino-resin polycondensation: measuring UF and MUF cure inline
Urea- and melamine-formaldehyde resin producers judge polycondensation endpoint by offline viscosity. Inline Raman moves the call to the reactor, and the chemistry beats a single number.
Process mass spectrometry: where MS fits in PAT today
Quadrupole and membrane-inlet mass spectrometers sit between gas chromatography and inline spectroscopy in the PAT toolkit. The placement and the limits of the technique are settled, even if vendor marketing is loose.
FBRM in process analytics: what the chord-length distribution actually measures
Focused beam reflectance probes return a chord-length distribution, not a particle-size distribution. The difference is what determines whether the signal is useful in crystallization and slurry monitoring.
Multivariate SPC for process spectroscopy: T-squared and Q-residual
Univariate SPC watches one number. A spectroscopic analyser produces a thousand. Multivariate SPC condenses them into two statistics that have been the standard since the early 1990s.
Inline, online, atline, offline: the working vocabulary for sample placement
ASTM E2363 fixes four terms that engineers and scientists frequently misuse. A short reference for getting placement vocabulary right when scoping a process analytics project.
Quality by Design (QbD): the PAT framework's parent
QbD is the broader regulatory philosophy that PAT serves. A primer on the ICH and FDA documents that built it, the vocabulary it introduced, and how process analytics fits inside it.
SERS in process analytics: when surface enhancement actually helps
SERS makes Raman a billion times stronger and a hundred times more fragile. For most inline measurements that is the wrong trade. The places where it pays off are narrow but real.
What is process analytical technology (PAT)?
A primer on PAT - the FDA-driven framework for measuring chemistry where it happens, why pharmaceutical and chemical manufacturers adopt it, and the tools that make it practical.
Raman vs NIR for inline chemistry: a decision framework
Both techniques measure chemical composition without sampling. The choice is rarely close once you map your process onto five questions: water, fluorescence, specificity, dynamic range, and probe access.
Chemometrics 101: the math that turns spectra into decisions
Spectra are not answers. The bridge between a 1,000-channel spectrum and a number you can act on is chemometrics - a small toolbox of multivariate methods, used the same way for forty years.
PCA vs PLS: when to use each in chemometric work
Both methods take a 1,000-channel spectrum and compress it into a handful of latent variables. They are not interchangeable. PCA describes; PLS predicts. The decision is older than most of the software.