Alternative lead-free method to the analysis of sucrose
Conventional polarization analysis uses lead acetate as clarifying agent for the sugar juice. An alternative method using near infrared polarimetry that does not need lead acetate was tested and provided good quality results.
Non-chemical alternative: near infrared polarimetry
Lead acetate basic (acetic acid, lead salt, basic) is suspected of causing cancer, damaging the unborn child and fertility and very toxic to aquatic organisms.
Diatomite, used as filtering material, may cause eye, skin and respiratory irritation, according to C&L Inventory.
Polarisation is determined for sugar juice in order to establish the content in sucrose.
Analysis methods using wavelength 598 nm necessitate lead acetate as clarifying agent. Instruments operating at longer wavelength, e.g. laser (830 nm) or near infra-red (840 – 889 nm) regions are less sensitive to sample colour and can be applied after a filtration phase that eliminates turbidity.
Parallel tests with the conventional lead acetate method and with an alternative method (abbreviated NORPOL) using a near infra-red polarimeter (wavelength 882.6 nm) were performed on 150 ml samples filtered on 3.5 g diatomite (celite).
Results showed an excellent agreement (correlation R2 = 0.998 out of 1) between the NIRPOL and the conventional method with lead acetate. Repeatabilities and reproducibilities of the two methods were also comparable.
The substitution is easy to implement but needs another type of equipment. The alternative eliminates the use of a substance that contains lead and is self classified by some sources as suspected carcinogen and reprotoxic. Costs with the management of chemical supply and chemical waste are reduced.
Type of information supplier
The presentation is based on: LF van Staden and E Mdlalose ’Lead-free pol analysis using near infrared polarimetry (NIRPOL)’,Proc S Afr Sug Technol Ass (2000) 74Type of publication and availability
Scientific article, freely available on internet
Original document: click here
Publication or last update: 27 November 2012