Ph meter

Physiochemical parameters of yogurt samples during the cold storage were determined using standardized instrumental methods [25 ]. The pH was determined with a Metrohm pH meter (Metrohm AG, Herisau, Switzerland) at room temperature. Total solids, total fat, and titratable acidity of the samples at different storage times were determined as described [26 ]. Syneresis of the yogurt samples at different storage times was determined as described [27 ]. Briefly, yogurt samples (30 g) were centrifuged at 1677× g for 10 min, and then the supernatant was poured off, weighed, and recorded as a percentage syneresis.

Individual stock standard solutions of sodium benzoate and potassium sorbate were prepared in deionized water (1000 mg/kg) and natamycin stock standard was in methanol (1000 mg/kg). The mixed standard solutions were prepared by diluting the stock solutions appropriately with mobile phase to give a concentration between 5 mg/kg and 40 mg/kg.
The pH of samples was measured by 827 model of Metrohm pH meter according to Iranian national standard (ISIRI) [17 ]. A mass of 10 g sample was weighted in a beaker and diluted with 35 mL solution of acetic acid 1% and methanol (35 : 65 v/v) and then shaken for 15–30 min on stirrer. Then, all content of beaker was transferred to the 50 mL volumetric flask and diluted with extraction solution. Finally, the prepared solution was filtered with 0.45 μm PVDF syringe filter and was injected to HPLC.

Soils were sampled from two sites that are undisturbed and associated with dust emission in the field: Ze’elim sandy area (31.16° E/34.53° N) at the western Negev Desert [11 ], and the Yamin plateau (31.04° E/35.08° N) at the northeastern Negev Desert in Israel [12 ]. The soil samples were analyzed for elemental composition by X-ray fluorescence (XRF) using an Axios spectrometer (PANanalytical, Malvern, UK). Mineralogical phase identification was performed by X-ray powder diffraction (XRPD) using an Empyrean Philips 1050/70 diffractometer (PANanalytical, Malvern, UK). Particle size distribution (PSD) was performed by laser diffraction using Analysette 22 MicroTec Plus (Fritsch International, Idar-Oberstein, Germany). XRF, XRPD and PSD analyses were performed at the Ben-Gurion University of the Negev in Beer-Sheva. pH was measured using a Metrohm pH meter (Metrohm, Herisau, Switzerland). Water content in soils was measured gravimetrically. Total organic content (TOC) was determined by titration of the dissolved organics with ammonium iron sulfate using an 848 Titrino plus (Metrohm, Herisau, Switzerland) at the Geological Survey of Israel.