Differentiation Between Humic and Non-Humic Substances Using Alkaline Extraction and Ultraviolet Spectroscopy.

BACKGROUND: Although humic substances are the principal ingredients in processed humic products, there has been no practical way to determine if a material is humified, allowing fake products to be used by farmers instead of genuine humic substances. OBJECTIVE: To develop a test method using conventional laboratory techniques to determine if a material is humified. METHOD: A neutralized extract is prepared using the standardized extraction protocols specified in ISO 19822:2018(E). A portion of the extract is used to determine the concentration of dissolved organic matter on an ash-free basis. A portion of the remaining neutralized extract is diluted to a concentration of 30 mg/kg of dissolved organic matter and transferred to a quartz UV cuvette for ultraviolet-visible (UV-Vis) spectroscopy. UV-Vis absorbance is recorded over a wavelength range of 220-500 nm at 5 nm intervals. The absorbance data are normalized by conversion to scaled absorbance, which is compared to a reference scaled absorbance spectral curve for humic substances to determine if the tested material is humic or non-humic. RESULTS: This method was able to differentiate legitimate humic substances from non-humic adulterants in a multiple-laboratory validation study (P ≤ 0.05). CONCLUSION: This method can differentiate humic from non-humic substances in materials intended to be used as ingredients in commercial humic products or for research. HIGHLIGHTS: This method uses common laboratory procedures and equipment.

Incidence of injury in adult elite women's football: a systematic review and meta-analysis.

AIM: To estimate the incidence of injury in adult elite women's football and to characterise the nature and anatomical location of injuries. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Combinations of the key terms were entered into the following electronic databases (PubMed, SPORTDiscus, Science Direct and Discover) from inception to May 2021. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: (1) Used a prospective cohort design; (2) captured data on elite adult women players; (3) reported injury incidence by anatomical site; (4) captured data of at least one season or national team tournament; (5) included a definition of injury; and (6) written in English. RESULTS: The search identified 1378 records. Twelve studies published between 1991 and 2018 were included in our review and sampled 129 teams. In domestic club football, injury incidence rate was estimated to be 5.7/1000 hours (total), 19.5/1000 hours (match) and 3.1/1000 hours (training). In tournament, football match incidence was estimated to be 55.7/1000 hours. The knee (22.8%; 368/1822) was the most common site of injury in domestic club football. The ankle (23.7%, 105/443) was the most common site of injury in tournament football. Ligament sprains were the most common type of injury (27.8%), followed by muscle strains (19.1%). Severn studies (58%) had a high risk of bias associated with exposure definition and measurement and considerable heterogeneity exists between the included studies (I2=49.7%-95%). SUMMARY/CONCLUSION: Ligament sprains occur more frequently in adult elite women football players. We advise caution in interpretating point estimates of the incidence of injury due to high statistical heterogeneity. Standardising injury reporting and the accurate recording of match and training exposure will overcome such limitations. PROSPERO REGISTRATION NUMBER: CRD42019130407.su.

A new standardized method for quantification of humic and fulvic acids in humic ores and commercial products.

Increased use of humic substances in agriculture has generated intense interest among producers, consumers, and regulators for an accurate and reliable method to quantify humic acid (HA) and fulvic acid (FA) in raw ores and products. Here we present a thoroughly validated method, the new standardized method for determination of HA and FA contents in raw humate ores and in solid and liquid products produced from them. The methods used for preparation of HA and FA were adapted according to the guidelines of the International Humic Substances Society involving alkaline extraction followed by acidification to separate HA from the fulvic fraction. This is followed by separation of FA from the fulvic fraction by adsorption on a nonionic macroporous acrylic ester resin at acid pH. It differs from previous methods in that it determines HA and FA concentrations gravimetrically on an ash-free basis. Critical steps in the method, e.g., initial test portion mass, test portion to extract volume ratio, extraction time, and acidification of alkaline extract, were optimized for maximum and consistent recovery of HA and FA. The method detection limits for HA and FA were 4.62 and 4.8 mg/L, respectively. The method quantitation limits for HA and FA were 14.7 and 15.3 mg/L, respectively.