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The paper reviews analytical methods of quality control and specifications for a new food A1-Free Category consisting of dairy products produced exclusively from milk that is naturally free from the a1 form of beta-casein. Evaluation of an A1-free milk Inter-Laboratory Round Robin trial revealed that positive samples had no statistically significant differences between participants, despite reporting varying concentrations ranging from 0.04-5.07%. Following consideration of various analytical methods reported in the literature, we recommend intact a1 beta-casein protein as the most suitable molecular species for quantification, and propose potential category definitions, specifications, and laboratory methods of quality control for retail, business-to-business and global trade practices.

Phosphatidylinositols (PIs) constitute a minor class of phospholipid with wide-spread influence throughout various cellular functions. Monitoring the distribution of these lipids can therefore provide insight as to the state of cellular processes or reveal the development of various pathologies. The speciation of these compounds is often performed either as part of a comprehensive characterisation of lipids, or specifically targeted using the same methods, however, such methods were intended to maximise coverage of lipid classes rather than provide an in-depth analysis of any single class. In the particular case of PIs, the majority of reported molecular diversity is limited to a small proportion of the already minor class, as such the cursory glance enabled by such methods is insufficient. Therefore, this work compared the suitability of both established and novel LC-MS buffers with the aim of maximising the ionisation efficiency of PIs, in an attempt to enhance coverage of the class. Through experimentation, it was determined that a 0.25 mM ammonium fluoride buffer provided up to a 6-fold increase in signal intensity, and on average a 38-fold increase in the signal-to-noise ratio. Using these new conditions, 14 PI species, and 12 PI candidates were identified within a dilute lipid extract sourced from canola seed, compared to 0 species identified using the generalised method. As a result, it is suggested that this procedure has yielded the highest number of PI species identifications for a sample of this concentration. Methods which therefore intend to characterise PI species in dilute quantities, such as those extracted from mammalian cells, are henceforth provided with the means to conduct more comprehensive characterisations.

Using LC-LTQ-Orbitrap MS we were able to identify 10 major phosphatidylinositol (PI) species present in 32 infant formulas (IF) collected from Australia, Europe and the USA. Based on the species fingerprint, the 32 formulas can be classified into several distinct groups by PCA analysis; this grouping pattern reflects origin and the label information of the formulas. The total content of all PI species was determined by LC-Triple Quadrupole MS in negative MRM mode using external standard calibration. The content of PI showed large variation between formulas and was very high in certain cases, which is believed to be related to the use of soybean lecithin in these products. Our study indicates that the content and speciation of PIs have significant contribution to the total amount of inositol in all 32 products surveyed; this contribution may be important for the fine nutritional profile and biological functions of IF products.

Low level exposure to organophosphate (OP) pesticides can be determined by the measurement of dialkylphosphate (DAP) metabolites in urine. An analytical method is presented here which can measure the metabolites dimethyl phosphate (DMP), diethyl phosphate (DEP), dimethyl thiophosphate (DMTP), dimethyl dithiophosphate (DMDTP), diethyl thiophosphate (DETP), and diethyl dithiophosphate (DEDTP) at low levels. This was achieved by lyophilization of the urine, derivatization with pentafluorobenzyl bromide (PFBBr) and quantification by negative ion chemical ionization GC/MS-MS. The detection limits for the metabolites were 0.5 microg L(-1) DMP, 0.1 microg L(-1) DEP, 0.1 microg L(-1) DMTP, 0.04 microg L(-1) DMDTP, 0.04 microg L(-1) DETP and 0.02 microg L(-1) DEDTP. The RSD for the analytical method was 4-14% for the six metabolites. The method was used to monitor a group of non-occupationally exposed individuals in Sydney, Australia. The metabolites DMP, DEP, DMTP, DMDTP, DETP and DEDTP occurred in 73, 77, 96, 48, 100 and 2% of the samples with median values of 13, 3, 12,1, 1 and 1 microg L(-1) respectively. The method is simple to use, sensitive and suitable for routine analysis of non-occupational exposure levels. These detection limits are between one and two orders of magnitude lower than those previously reported in the literature.

A routine gas chromatographic (GC) method is described for the analysis of dialkylphosphate metabolites in the urine of workers occupationally exposed to organophosphorus insecticides. The procedure involves derivatizing a freeze-dried urine sample with pentafluorobenzyl bromide and then determining the metabolites using dual capillary column GC with flame photometric detection.