β-Glucuronidase (Escherichia coli)

When investigating endocrine disorders, it is essential to assess a comprehensive quantitative profile of sex (pro)hormones in plasma including conjugates. Thus, the present study aimed to develop and validate a comprehensive mass spectrometry-based multimethod combining the direct analysis of unconjugated sex (pro)hormones and oxidation products thereof (by GC), as well as their sulfates and glucuronides present in higher concentrations (by LC) with the indirect quantification of glucuronides present in lower concentrations after selective glucuronide hydrolysis (by GC) and its application to plasma derived from ten pre- and postmenopausal women and men each. Even guideline-compliant validation experiments cannot completely reflect overestimation of analyte concentrations due to effects depending on the individual ratio of analytes (i.e. chemical formation of analytes or incomplete removal of interfering analytes). Thus, the extent of processes not accounted for by the calibration strategy were investigated and maximum over- or underestimations of analyte concentrations were assessed for each plasma sample individually. 34 analytes were successfully calibrated, validated (median accuracy 101.1 %, median inter-day precision 8.1 %) and 31 were detected above the detection limit in plasma samples. The sporadic maximum individual over- or underestimation of analyte concentrations amounted to less than 20 %.

A simple and effective approach for HPLC-MS/MS based multi-mycotoxin analysis in human urine samples was developed by application of dried urine spots (DUS) as alternative on-site sampling strategy. The newly developed method enables the detection and quantitation of 14 relevant mycotoxins and mycotoxin metabolites, including citrinin (CIT), dihydrocitrinone (DH-CIT), deoxynivalenol (DON), fumonisin B₁ (FB₁), T-2 Toxin (T-2), HT-2 Toxin (HT-2), ochratoxin A (OTA), 2′R-ochratoxin A (2′R-OTA), ochratoxin α (OTα), tenuazonic acid and allo-tenuazonic acid (TeA + allo-TeA), zearalenone (ZEN), zearalanone (ZAN), α-zearalenol (α-ZEL), and β-zearalenol (β-ZEL). Besides the spotting procedure, sample preparation includes enzymatic cleavage of glucuronic acid conjugates and stable isotope dilution analysis. Method validation revealed low limits of detection in the range of pg/mL urine and excellent apparent recovery rates for most analytes. Stability investigation of DUS displayed no or only slight decrease of the analyte concentration over a period of 28 days at room temperature. The new method was applied to the analysis of a set of urine samples (n = 91) from a Swedish cohort. The four analytes, DH-CIT, DON, OTA, and TeA + allo-TeA, could be detected and quantified in amounts ranging from 0.06 to 0.97 ng/mL, 3.03 to 136 ng/mL, 0.013 to 0.434 ng/mL and from 0.36 to 47 ng/mL in 38.5%, 70.3%, 68.1%, and 94.5% of the samples, respectively. Additional analysis of these urine samples with an established dilute and shoot (DaS) approach displayed a high consistency of the results obtained with both methods. However, due to higher sensitivity, a larger number of positive samples were observed using the DUS method consequently providing a suitable approach for human biomonitoring of mycotoxin exposure.

Breadfruit starch was subjected to heat-moisture treatment (HMT) at different moisture content (MC). HMT did not apparently change the starch granule morphology but decreased the molecular weight and increased the amylose content. With increased MC, HMT transformed the crystalline structure (B → A + B → A) and decreased the relative crystallinity. With ≥25% MC, the scattering peak at ca. 0.6 nm⁻¹ disappeared, suggesting the lamellar structure was damaged. Compared with native starch, HMT-modified samples showed greater thermostability. Increased MC contributed to a higher pasting temperature, lower viscosity, and no breakdown. The pasting temperature of native and HMT samples ranged from 68.8 to 86.2&‌deg;C. HMT increased the slowly-digestible starch (SDS) and resistant starch (RS) contents. The SDS content was 13.24% with 35% MC, which was 10.25% higher than that of native starch. The increased enzyme resistance could be ascribed to the rearrangement of molecular chains and more compact granule structure.