Green leafy vegetables are good for you. They are an easy go to for a range of vitamins and minerals, including vitamin A, E and K, folate, calcium, magnesium, and potassium. While once a less desirable vegetable that needed cartoon sailors to promote it, spinach has gained popularity due to its versatility as an ingredient and nutrient density, even among other green leafy vegetables.
Something that must be considered when growing spinach is the possibility of high amounts of trace elements in the product, the regulations pertaining to the food and the elements and how to measure their levels. Heavy metals can accumulate in soil and be passed into the crops grown in that soil. When a person consumes the crop the trace elements are absorbed and can accumulate to toxic levels.
To ensure minimal consumer risk, it is possible to quantify the levels of trace elements such as heavy metals in food products. Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) it is possible to analyse food products such as spinach for trace metal levels. ICP-MS can quantify elements at extremely low concentrations, and so is an ideal method for trace metals. Samples are digested in concentrated acid (nitric or combination of nitric and hydrochloric) and then introduced to argon plasma and ionised. From there the mass spectrometer can measure concentrations of the metals.
Beyond heavy metal toxicity, another good reason to quantify heavy metals in spinach crops is to conform with government regulations. The European Food Safety Authority (EFSA), defining spinach as a ‘leaf vegetable’ in Regulation (EC) No 629/2008 3.2.13, has limits of 0.2mg/kg lead and 0.05mg/kg cadmium.
In Australia, Schedule 22 ‘Foods and classes of foods’ of the food standards code classifies spinach as a ‘leafy vegetable’. Leafy vegetables have a maximum permitted level of 0.1mg/kg of cadmium in Food Standards Code: Schedule 19 ‘Maximum levels of contaminants and natural toxicants’.
Chinese regulation also define spinach as a ‘leaf vegetable’. The Chinese regulation GB 2762-2012: National Food Safety Standard Maximum Levels of Contaminants in Food places maximum limits of has limits of 0.3mg/kg lead and 0.2mg/kg cadmium in leaf vegetables.
By using ICP-MS to analyse trace metal levels in spinach, product contaminants can be quantified and conformance to international regulations can be assured.
U.S. Food and Drug Administration (04/11/2018) Metals, Available at: https://www.fda.gov/Food/FoodborneIllnessContaminants/Metals/default.htm (Accessed: 20/08/2018).
European Commission (02/07/2008) Commission Regulation (EC) No 629/2008 of 2 July 2008 amending Regulation (EC) No 1881/2006 setting maximum levels for certain contaminants in foodstuffs, Available at: https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:32008R0629 (Accessed: 20/08/2018).
Australia New Zealand Food Standards (25/03/2015) Australia New Zealand Food Standards Code – Schedule 22 – Foods and classes of foods. Food Standards (Proposal P1025 – Code Revision) Variation, Available at: https://www.legislation.gov.au/Details/F2015L00433 (Accessed: 20/08/2018).
Australia New Zealand Food Standards (25/03/2015) Australia New Zealand Food Standards Code – Schedule 19 – Maximum levels of contaminants and natural toxicants, Available at: http://www.foodstandards.gov.au/code/Documents/Sched%2019%20Contaminant%20MLs%20v157.pdf (Accessed: 20/08/2018).
National Standard of the People’s Republic of China: GB 2762-2012 ( 01/06/2013) National Food Safety Standard Maximum Levels of Contaminants in Food, http://www.seafish.org/media/publications/china_max_levels_of_contaminants_in_food.pdf