Development of a fast isocratic LC-MS/MS method for the high-throughput analysis of pyrrolizidine alkaloids in Australian honey

Abstract

Honey samples originating from Australia were purchased and analysed for targeted pyrrolizidine alkaloids (PAs) using a new and rapid isocratic LC-MS/MS method. This isocratic method was developed from, and is comparable with, a gradient elution method and resulted in no loss of sensitivity or reduction in chromatographic peak shape. Isocratic elution allows for significantly shorter run times (6 min), eliminates the requirement for column equilibration periods and, thus, has the advantage of facilitating a high-throughput analysis which is particularly important for regulatory testing laboratories. In excess of two hundred injections are possible, with this new isocratic methodology, within a 24-h period which is more than 50% improvement on all previously published methodologies. Good linear calibrations were obtained for all 10 PAs and four PA N-oxides (PANOs) in spiked honey samples (3.57-357.14 µg l(-1); R(2) ≥ 0.9987). Acceptable inter-day repeatability was achieved for the target analytes in honey with % RSD values (n = 4) less than 7.4%. Limits of detection (LOD) and limits of quantitation (LOQ) were achieved with spiked PAs and PANOs samples; giving an average LOD of 1.6 µg kg(-1) and LOQ of 5.4 µg kg(-1). This method was successfully applied to Australian and New Zealand honey samples sourced from supermarkets in Australia. Analysis showed that 41 of the 59 honey samples were contaminated by PAs with the mean total sum of PAs being 153 µg kg(-1). Echimidine and lycopsamine were predominant and found in 76% and 88%, respectively, of the positive samples. The average daily exposure, based on the results presented in this study, were 0.051 µg kg(-1) bw day(-1) for adults and 0.204 µg kg(-1) bw day(-1) for children. These results are a cause for concern when compared with the proposed European Food Safety Authority (EFSA), Committee on Toxicity (COT) and Bundesinstitut für Risikobewertung (BfR - Federal Institute of Risk Assessment Germany) maximum daily PA intake limit of 0.007 µg kg(-1) bw day(-1).

Analysis of Pyrrolizidine Alkaloids in Queensland Honey: Using Low Temperature Chromatography to Resolve Stereoisomers and Identify Botanical Sources by UHPLC-MS/MS

“…Internationally it has been reported that such toxins can be found in honey due to transfer by bees of pollen/nectar from certain flowers, including Heliotropium, Crotolaria, Echium and Senecio species. Concern has been raised as to the extent of contamination in Australian honey [11,12] but their presence in Queensland honey has not previously been examined. Previously, investigations into the presence of PAs in Australian honey have concentrated on the introduced pest plant Echium plantagineum L. (Paterson's curse) as the major likely PA source [11][12][13].…”

“…Concern has been raised as to the extent of contamination in Australian honey [11,12] but their presence in Queensland honey has not previously been examined. Previously, investigations into the presence of PAs in Australian honey have concentrated on the introduced pest plant Echium plantagineum L. (Paterson's curse) as the major likely PA source [11][12][13]. However, rigorous eradication and biological control programs in recent decades have decreased the prevalence of this weed in Australia [14].…”

Determination of Pyrrolizidine Alkaloids in Honey with Sensitive Gas Chromatography-Mass Spectrometry Method

“…Around 40% of Europe's consumption needs are met through honey imports (CBI 2017). As it was revealed, the honey of Central and South America or Australia can contain high rates of PA positive samples with high individual PA levels (EFSA 2011;Dübecke et al 2011;Griffin et al 2015a;Valese et al 2016).…”

Spread of Jacobaea vulgaris and Occurrence of Pyrrolizidine Alkaloids in Regionally Produced Honeys from Northern Germany: Inter- and Intra-Site Variations and Risk Assessment for Special Consumer Groups

“…Senecio jacobaea , tansy ragwort) in the U.K. and from Echium plantagineum growing in Australia, respectively [ 16 , 17 ]. Since then, several studies worldwide (summarized in chronological order in Table S1 ) focused on developing methods and identifying PA/PANO in honey from known plant sources and geographical origins (examination of raw/bulk or regionally produced honey) [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ] and in honey from retail [ 19 , 20 , 21 , 24 , 28 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ]. Raw and regionally produced honeys showed higher PA/PANO levels than blended retail honeys, while the latter usually showed higher rates of contamination.…”