**3. Conclusion**

*Pests, Weeds and Diseases in Agricultural Crop and Animal Husbandry Production*

enzyme-linked immunosorbent assay (ELISA) method.

Therefore, they fixed the LOQ at 1 ng mL<sup>−</sup><sup>1</sup>

by LC–MS/MS (whose LOD is 0.5 ng mL<sup>−</sup><sup>1</sup>

investigate concentration above 1 ng mL<sup>−</sup><sup>1</sup>

in breast human milk samples and 0.1 μg mL<sup>−</sup><sup>1</sup>

at low concentrations (<LOD and 1.93 μg mL<sup>−</sup><sup>1</sup>

reported a GLYP concentration below 15 μg kg<sup>−</sup><sup>1</sup>

0.023 and 0.033 μg mL<sup>−</sup><sup>1</sup>

milk containing 1 μg mL<sup>−</sup><sup>1</sup>

MS/MS method (*R*<sup>2</sup>

content of 150 μg kg<sup>−</sup><sup>1</sup>

0.5 μg kg<sup>−</sup><sup>1</sup>

0.5 ng mL<sup>−</sup><sup>1</sup>

authors (and these authors agree), this methodology could be competitive with the

Steinborn et al. reported of a survey on the GLYP content in 114 breast milk samples collected in Bavaria and Lower Saxony, Germany, by comparing the data obtained by LC-MS/MS and GC-MS/MS analyses [100]. The two analyses required (a) an ultrafiltration and chromatography on an anion exchange column for

LC–MS/MS and (b) a clean-up step on a cation exchange column and derivatization with trifluoroacetic acid anhydride (TFAA) and heptafluorobutanol (HFB) for the GC–MS/MS. The authors deeply investigated the difference between the chromatograms obtained with the two methods, especially for evaluating parameters such as precision, accuracy, LOD, and LOQ. Basically, GC–MS/MS allowed to reach instrumental detection limit (IDL) lower than that found in LC–MS/MS (0.02 vs.

not manage to identify (all reagents, ultrapure water, all components were tested).

128% with RSD < 17% for LC–MS/MS and between 71 and 102% with RSD < 13% for GC–MS/MS. Resuming, the GC–MS/MS is powerful at lower concentrations, but it simultaneously gives more bias than LC–MS/MS; both methods manage to

Two papers investigated the GLYP and AMPA content in human milk and urine samples. In the first, a high-throughput LC–MS/MS method using stable isotope labeled internal standard and clean-up with methylene chloride allowed to reach very low LODs (0.92 and 1.2 for GLYP and AMPA in human milk samples and

recoveries (GLYP ranging between 92 and 107% in both matrices, AMPA between 89 and 107%) with low RSDs (<7.4 and <11.6% in human milk and urine samples, respectively) [101]. The authors also studied the matrix stability over a storage in 5°C (refrigerator) and at –20°C (freezer): in the first case, the recoveries were acceptable also after 24 hours, whereas in the second case, they were good also after 3 months. On the other hand, the second paper investigated the presence of GLYP and AMPA in milk (41 samples) and urine (40 samples) from healthy lactating women from Russia and the United States [102]. The authors used the same analytical procedure as reported above (i.e., LC-MS/MS, the use of stable isotope labeled internal standard and two fragments, such as precursor and product ion transitions, for the quantification) for the analysis, that is, the same analytical parameters. The results showed GLYP and AMPA in milk samples at levels below the LODs, whereas

respectively, in urine samples). The authors extrapolated the maximum intake of

The presence of MRLs for GLYP in barley, wheat, rye, and hops is regulated by

; RSD < 4.1%) [103]. Among the numerous samples analyzed, 8 samples

. The authors pointed out the attention on beer brands of

the raw agricultural commodities for beer beverage. Jansons et al. (2018) analyzed 100 beer samples from 24 different producers and distributors in Latvia with LC–

showed levels below the LOD and 9 samples below the LOQ, whereas 80 samples

> 0.999 in the range of 0.2–25 μg kg<sup>−</sup><sup>1</sup>

"undisclosed" origin, that is, no country production reported on the labeling (it sounds strange to the authors of this review considering the restrictions on food

expected levels should be 12,000 times lower than the health concern.

EU Regulation (EC) No. 396/2005 (i.e., 20, 10, and 0.1 mg kg<sup>−</sup><sup>1</sup>

in human urine samples) and LOQs (10 μg mL<sup>−</sup><sup>1</sup>

), but they detected an interference on a GLYP peak, which they did

, the same concentration determined

with high precision and accuracy.

). The recoveries ranged between 83 and

in human urine samples), high

and <LOD and 1.33 μg mL<sup>−</sup><sup>1</sup>

of GLYP for a 5-kg infant: their conclusions were that the

for both

,

; LOQ

) [37, 38]. These are

; LOD 0.2 μg kg<sup>−</sup><sup>1</sup>

and 1 sample reached a GLYP

**110**

This long *excursus* wanted to cover the novel or advanced methodologies based on chromatographic analysis reported in the literature. The GLYP determination in foods is a really important issue, even if the different international agencies still do not totally agree on the human health concern. The importance of a continuous monitoring of such compound (and its main metabolite, AMPA), and GLUF as well, is well known by scientists and politics worldwide due to its large use in agriculture. The suggestion is to continuously develop new methods, more accurate and sensitive, based on GC-MS/MS or LC-MS/MS analysis but also routine method based on inexpensive or use-friendly detectors (FID, FPD, or NPD).

In any case, the fear for the future is that the refinement of analytical methods increasingly leads to alarmist attitudes based on the discovery of very low quantities of GLYP, which is possible for a very wide range of products, even extremely toxic, without forgetting that in nature the zero residue does not exist.
