Mia Brkljača

Flow injection spectrophotometric determination of N-Acetyl-L-cysteine as a complex with palladium(II)

We describe a new method using flow-injection analysis with spectro-photometric detection, suitable for the determination of N-acetyl-l-cysteine (NAC). The proposed method is appropriate for the determination of NAC in reaction with Pd2+ ions in the concentration range from 1.0 × 10−5 mol L−1 to 6.0 × 10−5 mol L−1. The detection limit NAC was 5.84 × 10−6 mol L−1 and the recorded relative standard deviation of the method is in the range from 1.67 to 4.11%. NAC and Pd2+ form complexes of Pd2+:NAC molar ratios of 1:1 and 1:2, depending on the ratio of their analytical concentrations. The cumulative conditional stability constant for the Pd(NAC)22+ complex is β12’ = 2.69 × 109 L2 mol−2. The proposed method was compared with the classic spectrophotometric determination of NAC, using the same reagent, PdCl2, and had shown certain advantages: a) shorter analysis time; b) the use of smaller volumes of sample and reagents, which make the proposed method cheaper and faster for NAC determination in real samples without sample pretreatment.

Determination of Metals in Olive Oil by Electrothermal Atomic Absorption Spectrometry: Validation and Uncertainty Measurements

The determination of trace metals in organic matrices is still highly demanding despite improvements in analytical instrumentation. The present study was undertaken in order to evaluate electrothermal atomic absorption spectrometry for the determination of cadmium, copper, iron, lead, and nickel in olive oil. A variety of approaches were used. The most suitable digestion procedure was heating the samples at 300°C for 24 hours and ashing in a muffle furnace at 450°C for 16 hours. The validation data were detection limits of 0.2–153 ng g−1; mean trueness on certified reference materials of 81–94%; mean recovery on spikes of 90–120%; and repeatability of 12–53%. The combined relative uncertainty was 0.298–0.766. Oils processed by pressing had higher copper, iron, and lead concentrations than oils processed by centrifugation. The reported method provides an efficient way for monitoring trace metal content during olive oil production.

Determination of Cadmium, Chromium, Copper, Iron, Lead, Magnesium, Manganese, Potassium, and Zinc in Mint Tea Leaves by Electrothermal Atomizer Atomic Absorption Spectrometry in Samples Purchased at Local Supermarkets and Marketplaces

The concentrations of Cd, Cr, Cu, Fe, K, Mg, Mn, Pb, and Zn in 14 different samples of mint leaves (Mentha piperitae folium) and tea bags purchased in local supermarkets and marketplaces in Split, Croatia were determined. Electrothermal atomic absorption spectrometry (ETAAS) was applied in this work. Mint tea samples purchased at marketplaces contained: Cd (0.021–0.357 mg kg−1), Cr (<0.01–52.3 mg kg−1), Cu (3.23–5.56 mg kg−1), Fe (47.7–208 mg kg−1), K (7.47–21.7 g kg−1), Mg (2.16–15.9 g kg−1), Mn (24.2–667 mg kg−1), Pb (1.31–1.49 mg kg−1), and Zn (2.33–19.5 mg kg−1). Those ones purchased at supermarkets contained: Cd (0.19–0.34 mg kg−1), Cr (7.3–99 mg kg−1), Cu (1.70–5.21 mg kg−1), Fe (0.16–1.42 g kg−1), K (0.23–60.8 g kg−1), Mg (0.13–16.3 mg kg−1), Mn (0.30–0.93 mg kg−1), Pb (<0.01–1.73 mg kg−1), and Zn (<0.01–24.9 mg kg−1). In order to get a better insight into the elemental patterns in mint leaves, a One-Way ANOVA program R was used for statistical data analysis. The One-way ANOVA was performed with the amount of each metal as the dependent variable and market as the independent variable. The PCA (principal component analysis) was applied to analyze the grouping of mint leaves on supermarket and marketplace samples.

Monitoring content of cadmium, calcium, copper, iron, lead, magnesium and manganese in tea leaves by electrothermal and flame atomizer atomic absorption spectrometry

Abstract Due to the simplicity of tea preparation (pouring hot water onto different dried herbs) and its high popularity as a beverage, monitoring and developing a screening methodology for detecting the metal content is very important. The concentrations of Cd, Ca, Cu, Fe, Pb, Mg and Mn in 11 different samples of sage (Salvia officinalis L.), linden (Tilia L.) and chamomile (Matricaria chamomilla L.) purchased at local herbal pharmacy were determined using electrothermal atomizer atomic absorption spectrometry (ETAAS) and flame atomizer atomic absorption spectrometry (FAAS). The concentrations determined were: Cd (0.012 – 0.470 mg kg−1), Ca (5209 – 16340 mg kg−1), Cu (22.01 – 33.05 mg kg−1), Fe (114.2 – 440.3 mg kg−1), Pb (0.545 – 2.538 mg kg−1), Mg (2649 – 4325 mg kg−1) and Mn (34.00 – 189.6 mg kg−1). Principal Component Analysis (PCA) was applied to identify factors (soil and climate) influencing the content of the measured elements in herbal samples. The proposed methodology developed in this work was successfully applied to the detection of metals in herbal samples. The analysis showed that the content of toxic metals in herbal teas was below the maximum dose recommended by the World Health Organization (WHO).

Survey of content of cadmium, calcium, chromium, copper, iron, lead, magnesium, manganese, mercury, sodium and zinc in chamomile and green tea leaves by electrothermal or flame atomizer atomic absorption spectrometry

Abstract Due to the simplicity of tea preparation (pouring hot water onto different dried herbs) and its high popularity as a beverage, monitoring and developing a screening methodology for detecting the metal content is very important. The concentrations of Cd, Ca, Cr, Cu, Fe, Pb, Mg, Mn, Hg, Na and Zn in 8 samples of green tea (Camellia sinesis) and in 11 samples chamomile (Matricaria chamomilla L.) purchased both at local herbal pharmacies and supermarkets were determined using electrothermal atomizer atomic absorption spectrometry (ETAAS) and flame atomizer atomic absorption spectrometry (FAAS). The found concentrations in chamomile were: Cd (0.008 – 284 mg kg−1), Ca (2.42 – 6.29%), Cr (0.91 – 6.92 mg kg−1), Cu (6.27 – 11.39 mg kg−1), Fe (133.5 – 534 mg kg−1), Pb (0.561 – 1.277 mg kg−1), Mg (2.27 – 3.73%), Mn (62.2 – 165.6 mg kg−1), Hg (0.660 – 1.346 μg kg−1), Na (0.91 – 1.28%) and Zn (63.37 – 108.5 mg kg−1), in green tea Cd (36.29 – 202.1 mg kg−1), Ca (2.77 – 6.40%), Cr (1.520 – 5.278 mg kg−1), Cu (9.354 – 22.56 mg kg−1), Fe (162.6 – 513.3 mg kg−1), Pb (1.808 – 4.770 mg kg−1), Mg (1.41 – 2.62 %), Mn (1.147 – 1.729 g kg−1), Hg (1.045 – 2.802 μg kg−1), Na (0.44 – 0.98%) and Zn (30.65 – 115.6 mg kg−1), respectively. Principal Component Analysis (PCA) was applied to identify factors (soil, climate and country of origin) influencing the content of the measured elements in herbal samples. The proposed methodology developed in this work was successfully applied to the detection of metals in herbal samples. The analysis showed that the content of toxic metals in green tea samples was significantly higher and very close to the maximum dose recommended by the World Health Organization (WHO).