The Analytical Column

Every peak is a subject, in the order of an analysis. Height = how many pieces. Width = how much they range. Tap a peak to see its pieces.

Read like a student: select any passage (or tap the ✎ pen) to put it in your own words, research it across the site, share it, or ask me about it.

Foundations

Foundations for the working analyst — each piece grounded in the literature and checked before it ran.

No. 1 · Density & viscosityReading concentration from a single numberA binary solution hides its composition in its density. Why that one number is enough — and where it stops working.
No. 2 · Density & viscosityThe power of the densitometerDensity is one number, measured in a minute. This is what it does on its own, and what it does when you give it a second measurement to work with.
No. 3 · Density & viscosityWhen one number isn't enoughDensity can name one unknown. Add refractive index and you can name two. Here is how the pair resolves a mixture neither could resolve alone.
No. 4 · Density & viscosityFingerprinting a fluidDensity says how heavy a fluid is. Viscosity says how it flows. Measure both and you stop weighing a fluid and start recognising it.
No. 5 · Density & viscosityThe oscillating U-tube, in depthA modern density meter turns a frequency into a density with one equation and two constants. Here is how a vibrating glass tube does it.
No. 6 · Density & viscosityThe second number your density meter already measuresMany density meters also clock how fast sound travels through the sample. That number is an independent handle on composition — most useful where density struggles.
No. 7 · Density & viscosityCalculated, not measuredSome of the numbers on a fuel report were never measured. They are computed from density and a distillation curve — and density is the load-bearing input.
No. 8 · Density & viscosityViscosity index, and what it really tells youEvery liquid thins as it warms. Viscosity index is a single number for how fast it thins — and for what that number leaves out.
No. 9 · Density & viscosityWhen one viscosity number isn’t enoughFor water, viscosity is one number. For paint, grease, and blood, it depends on how hard you push — and one number becomes a trap.
No. 10 · Density & viscosityReading wear from bulk propertiesYou do not have to name every molecule in a used oil to know it is in trouble. A drift in cheap bulk properties, from a known baseline, is the early warning.
No. 11 · Calibration & standardsThe number the instrument can't give youAn instrument reports a response — an area, an absorbance, a current. Never a concentration. Building the curve that maps one to the other is where you actually learn the analysis — if you read what it's telling you.
No. 12 · Calibration & standardsCalibrate inside the sampleWhen the sample itself bends the response and you cannot rebuild that matrix in a standard, you move the calibration to where the problem lives — and pay for it in a way worth respecting.
No. 13 · Calibration & standardsThe reference that rides alongYou rarely inject exactly the same volume twice, or lose exactly the same amount in prep. So you stop trusting the raw signal and trust a ratio — the analyte measured against a companion that suffers what it suffers.
No. 14 · Calibration & standardsWhere the signal loses to the noiseEvery method has a floor: a level below which you cannot say how much analyte is present, and a lower one below which you cannot even say it is present. Both are set by two things together — how much the blank wanders, and how steeply the method responds.
No. 15 · Calibration & standardsWhere the line stops being straightA calibration is only good where the response actually tracks concentration. Above that, the curve bends, the top standard falls off the line, and a straight fit forced through it distorts the whole calibration. So you prove where linearity ends — you do not assume it.

Analytically Speaking

Essays first published on LinkedIn, 2024–2025 — thirty years of lab life, in my own words.