Payment rates over time.

<p>Decay in payment rates after email sent for control and treatment groups.</p

Effect of intervention on payment of tuition fees.

<p>Model 1 shows logistic regression coefficients for treatment effect and Model 2 also includes covariates for gender, age, initial amount of debt, year (2013/2014 or 2014/2015), and round of reminders (November or February).</p

Gas Chromatography–Mass Spectrometry Method for the Determination of Free Amino Acids as Their Dimethyl-<i>tert</i>-butylsilyl (TBDMS) Derivatives in Animal Source Food

The suitability of a one-step derivatization procedure using <i>N</i>-methyl-<i>N</i>-(<i>tert</i>-butyldimethylsilyl)­trifluoroacetamide for the simultaneous assay of 22 free amino acids and its application for their analysis in six animal source foods (pork, dry cured ham, chicken stock, fresh cheese, ripened cheese, and dry salted sardine) by GC-MS were studied. All 22 free amino acid derivatives were correctly detected and resolved. Reproducibility (%RSD) of the method was in the range of 1.9–12.2%. Detection and quantitation limits of the analytical procedure ranged from 0.01 to 0.46 mg/100 g dry weight and from 0.02 to 1.55 mg/100 g dry weight, respectively. The calibration curves were linear within the range 0.1–15.0 mg/100 g with correlation coefficient values (<i>R</i>²) from 0.9891 to 0.9983. All analyzed food products showed free amino acid contents similar to those found in the scientific literature. The proposed GC-MS method for the determination of free amino acids in animal source food can be used in routine for both analytical and research purposes