Analytical methods have been developed for the determination of trace amounts of inorganic tin and methyltin compounds. Tin compounds in aqueous solution at pH 6.5 are converted to the corresponding volatile hydride, SnH4, CH3SnH3, (CH3)2SnH2, and (CH3)3SnH, by reaction with sodium borohydride. These are scrubbed from solution, cryogenically trapped on a U-tube, and separated upon warming. Detection limits are approximately 0.01 ng as Sn when using a hydrogen-rich, hydrogen-air flame emission type detector (SnH band). Parts-per-trillion concentrations of methyltin compounds were found in a variety of natural waters and in human urine.
The ability to enhance compliance with therapeutic tasks such as homework may be a crucial therapeutic skill that determines the success of psychotherapy in real-world clinical settings. This article presents guidelines for enhancing homework compliance through careful attention to: features of homework assignments, such as whether they are meaningful and doable and include a clear rationale and backup plan; and the therapist's manner when developing and reviewing homework assignments, such as whether that therapist is curious, collaborative, and reinforces all behavior that supports the homework's purposes. Clinical examples are used to illustrate the application of the guidelines.
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