If theres any steps that needs to be skipped, its your vinegar step because its completely unnecessary. Unnecessary because pH is not tested to determine overdiluted urine samples. Only creatinine and specific gravity (S/G) are tested to determine overdilution. pH is checked to determine adulteration (use of bleach, additives, etc; to spike a dirty urine sample).

It must be understood that creatinine and S/G checks have become lab SOP in recent years, making sample "color" the least aspect in determining overdilution. Even samples with a nice yellow color to them can still register unsatisfactory S/G and creatinine levels. Therefore, when utilizing dilution techniques, it is now more important to make sure the creatinine and S/G are within satisfactory limits.