This article describes how to construct a simple, inexpensive, and flexible UV-photometer using one LED (355 nm) as the light source and another (355 nm) as the detector, one resistor, some wiring, a few Lego bricks, and a millivolt meter. The photometer is used to explore several aspects of molecular absorption spectrometry. As practical applications, the amounts of folic acid in folic acid tablets and cinnamaldehyde in cinnamon were found. The results were in accordance with those obtained using a commercial spectrophotometer.

This article describes a combined UV-photometer and fluorimeter constructed from 3 LEDs and a few wires, all held in place with Lego bricks. The instrument has a flexible design. In its simplest version, two UV-LEDs (355 nm) are used as light source and to detect absorption, and a third LED, in the visible spectrum (e.g., 525 nm), is used to detect fluorescence. Various experiments are described: fluorescence as a function of concentration and light source intensity; quantitative measurements of quinine in tonic water, using absorption and fluorescence measurements, with results in line with those obtained on scientific instruments; a demonstration of the inner filter effect reducing fluorescence at higher concentrations; investigation of the effect of drinking tonic water on the fluorescence of quinine in urine; temperature effects on fluorescence; chloride-ion quenching of fluorescence with result comparable to those previously reported; and, finally, a demonstration of phosphorescence.

Normal and reversed-phase chromatography can be easily illustrated using thin layer chromatography for the separation of green leaf extracts within a short time and at a low cost.

In organic chemistry textbooks (S)-(−)-limonene, (−)-limonene or Llimonene, is often given credit for the smell of lemons, while the R-analogue, (+)-limonene or D-limonene, is credited with that of oranges. Results from two odor tests revealed that few persons in the test associated (R)-(+)-limonene with oranges and (S)-(−)-limonene with lemons, when these compounds were of analytical grade. Quality and composition of standard compounds and mixtures used in these olfactory tests were corroborated by gas chromatographic analyses. The statement of (R)-(+)-limonene being responsible for orange odor and (S)-(−)-limonene for the lemon odor apparently stems from an often quoted article from 1971. This investigation was a lesson for both our students and us. Textbooks in organic chemistry that still promote (R)-(+)-and (S)-(−)-limonene as, respectively, the "orange" and "lemon" smell ingredient should be corrected.

An easily constructed and inexpensive polarimeter with an optical rotation angle resolution of about 0.5° is presented. It is made from small pieces of polarizing film, 2 LEDs, a protractor, and a few wires, all held in place with plastic interlocking toy bricks, such as Lego bricks. The instrument was used to demonstrate the optical rotation of plane polarized light as a function of concentration, path length, temperature, and wavelength, and to determine enantiomeric excess in solutions of arabinose, the amount of limonene in citrus ski wax remover, and optical rotations of various types of honeys and essential oils. Results were comparable to values obtained on a commercial scientific instrument, and with literature values.