Every substance in this catalogue is offered on a single ladder of pack sizes, from one gram to ten tonnes. The ladder is not one product scaled up. It spans two different grades, and the change happens between the 25 kg and 1 t steps.
Laboratory grade — 1 g to 25 kg
Pack sizes up to 25 kg are supplied as laboratory grade, typically to a purity of at least 99 % and against a recognised pharmacopoeial or analytical specification such as p.a., ACS or Ph. Eur. Each lot carries a certificate of analysis with the measured values, not merely the limits.
At this end of the ladder the price has little to do with the cost of the material. It is dominated by the packaging, by the analytical work behind the certificate, by lot traceability and by the handling of small quantities. A gram of a common inorganic salt costs almost nothing as material; what is paid for is the assurance that it is what the label says it is.
Technical grade — 1 t and above
Tonnage quantities are supplied as technical grade and priced on a commodity basis, against a specification that states the guaranteed minimum assay and the limits on the impurities that matter for the intended use. The material is fit for industrial and agricultural purposes and is not intended for analytical or pharmaceutical work.
Why the price per kilogram falls sharply
Because the two ends of the ladder are different products, the price per kilogram drops steeply between the 25 kg and the 1 t step. This is expected and is not a pricing error. Comparing the per-kilogram figure of a 100 g laboratory pack with that of a tonne of technical material compares two things that are not alike.
What the CAS number does and does not tell you
A CAS registry number identifies a substance. It says nothing about purity, particle size, physical form or production route — that is what the grade specification is for. Two materials sharing a CAS number can be entirely appropriate and entirely inappropriate for the same task. Where a substance is not a discrete compound at all, as with polyaluminium chloride, the registry number is broader still and the specification carries the whole weight.
Commercial grades and physical forms of these substances are described in the fertilizer products and chemical products sections.
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