Green Analytical Chemistry (GAC) metrics include a variety of criteria, such as the regent amounts and toxicity, energy consumption, generated waste, among others. The analytical greenness metric (AGREE) and its variant for sample preparation (AGREEprep) cover different aspects that contribute to the environmental sustainability of sample preparation. White Analytical Chemistry (WAC) considers not only environmental aspects but also analytical and practical aspects with a holistic vision based on a Red-Green-Blue color model.

A multicommutated flow system was designed and evaluated for the determination of selenium by hydride generation atomic absorption spectrometry (HG-AAS). It was applied to the determination of total selenium in samples of cow's milk (fluid and powder) and infant formulae. Linearity was satisfactory in the range up to 27.5 µg L⁻¹ (h = 0.082 C + 0.0033, h = peak-height, absorbance, C = concentration in µg L⁻¹, r² = 0.999). Detection (3s) and quantification (10s) limits in solution were LD = 0.08 µg L⁻¹ and LQ = 0.27 µg L⁻¹, corresponding to LD = 3.2 µg kg⁻¹ and LQ = 10.8 µg kg⁻¹ in solid samples, and to LD = 0.8 µg L⁻¹, LQ = 2.7 µg L⁻¹ in fluid milk samples. Trueness was verified by analysis (n = 5) of two reference materials (NIST 1549, Non-fat Milk Powder and NIST 1846 Infant Formula). At the 95% significance level, results were statistically equivalent to the certified values. Instrumental precision (s_r(%), n = 5) was in the range 1.4% to 11.7%, analytical precision (s_r(%), n = 5) being 4.2 and 9.3% respectively for the determination of the above mentioned reference materials. The sampling frequency of the system was 160 hour⁻¹.

A novel analytical method for zinc (Zn) determination in aqueous samples was developed and validated using magnetic solid-phase microextraction (MSPME) combined with element detection via energy-dispersive X-ray fluorescence (EDXRF).

An on-line preconcentration system for the simultaneous determination of Copper (Cu) and manganese (Mn) in water samples was developed and coupled to a microwave-induced plasma optical emission spectrometer (MIP OES). The flow injection system was designed with a minicolumn packed with sisal fiber (Agave sisalana). A multivariate experimental design was performed to evaluate the influence of pH, preconcentration time, and eluent concentration. Optimal conditions for sample preparation were pH 5.5, preconcentration time was 90 s, and HCl 0.5 mol L⁻¹ was the eluent. The main figures of merit were detection limits 3.7 and 9.0 µg L⁻¹ for Cu and Mn, respectively. Precision was expressed as a relative standard deviation better than 10%. Accuracy was evaluated via spiked recovery assays with recoveries between 75–125%. The enrichment factor was 30 for both analytes. These results were adequate for water samples analysis for monitoring purposes. The preconcentration system was coupled and synchronized with the MIP OES nebulizer to allow simultaneous determination of Cu and Mn as a novel sample introduction strategy. The sampling rate was 20 samples/h. Sisal fiber resulted an economical biosorbent for trace element preconcentration without extra derivatization steps and with an awfully time of use without replacement complying with the principles of green analytical methods.